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    Foundations of Amateur Radio

    Starting in the wonderful hobby of Amateur or HAM Radio can be daunting and challenging but can be very rewarding. Every week I look at a different aspect of the hobby, how you might fit in and get the very best from the 1000 hobbies that Amateur Radio represents. Note that this podcast started in 2011 as “What use is an F-call?“.

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    Copyright: ℗ & © 2015 - 2020 Onno Benschop

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    New arrangements for Australian Amateur Radio Jan 21, 2024
    Show notes

    Foundations of Amateur Radio

    From the 19th of February 2024, the ACMA, the Australian Communications and Media Authority, the regulator, is modifying the rules for amateur radio in Australia by moving to an amateur class license where all amateurs will operate under the same license instead of under an individual one.

    You must be qualified to operate under the new class license and all currently licensed radio amateurs should now have been issued with a recognition certificate for their current qualification level.

    Keep this certificate safe, it authorises you to operate as an amateur and shows which callsigns you currently hold. I've just received a revision that now correctly identifies my callsign VK6FLAB as a four-letter callsign, rather than three-letters which caused concern over the longevity of my call.

    There's no annual charge to operate as an amateur, no charge to keep a callsign, and no charge to do an exam, however, if you operate a repeater or beacon, you'll continue to require a transmitter license. There are once-off charges for applications to consider and issue recognition certificates and callsigns but those are not new.

    The document that legally defines amateur radio in Australia, colloquially the LCD, is replaced by the Radiocommunications (Amateur Stations) Class Licence 2023. The regulator carefully states that: "To operate an amateur station under the amateur class licence, you must comply with the conditions within it", but doesn't clarify if those conditions have changed or not. External commentary claims they haven't, but it was completely re-written and it's difficult to compare the precise actual wording side-by-side.

    This has happened before, for example, when the regulator introduced the Limited license in 1954, the Novice license in 1975, abolished Morse in 2004, and introduced the Foundation, Standard and Advanced licenses in 2005. It was replaced again in 2015 and has been revised since, most recently on the 17th of November 2021.

    I suspect lawyers will find potentially unintended but material differences between documents, but to my knowledge, that investigation has not yet occurred. I think this is a perfect example of where the peak bodies claiming to represent amateur radio in Australia have a responsibility.

    There are many rules around the who, how and where to conduct a qualification exam. For example, the regulator has decided that online or residential exams are not permitted, leaving venues, printed exams and postal delivery as an ongoing cost and concern.

    There are plenty of questions left.

    An amateur at Advanced level can hold a club station callsign but it appears that at a Foundation or Standard level you can no longer hold a club station license like VK6BSG and VK7HSD. You still need to log usage of a remote club station. Describing the requirements the regulator uses both "revise their arrangements" and "current arrangements will be retained" in the same paragraph, apparently contradicting itself.

    The regulator will ask you every five years if you want to keep your callsign. This infers a system to contact you. What does that look like, how will it be maintained, are there requirements for keeping it current, does it need to have the location of your station, an email address, or just any means of contacting you, and is it public? The official register of radio communication licenses will no longer hold amateur licenses so it's unclear how you'll be able to contact another amateur, or how we'll be able to know who holds which callsigns at what level in which location and when a reminder is due. The details around the new callsign register are incomplete to say the least.

    What does breaking the rules look like? With individual amateur licenses your ability to operate is directly linked to you and if found in breach, your license can be cancelled. Under a class license, your ability to operate hinges on knowledge that cannot be taken away.

    The regulator publishes the relationship between some international amateur licenses and qualification levels in Australia and as an international visitor you can apparently operate in Australia for 365 days if your current license is recognised. After that, unless you hold a Harmonised Amateur Radio Examination Certificate or HAREC, you need to apply for a recognition certificate after either paying for recognised prior learning or passing an exam, even though you were already automatically recognised as having the appropriate qualifications when you entered the country. Does the list of recognised licenses get longer as more international amateurs pay for prior learning and if you leave the country and return, will the clock reset?

    There's more. For example, the date that you got your US Technician license determines your recognition. Before 23 September 2016 you're recognised at an Australian Advanced level, after that at a Foundation level.

    And finally, if I were an accredited unpaid volunteer assessor, authorised to administer an amateur exam on behalf of the regulator, would I be permitted to comment like I am here, or would I be expected to speak directly with the regulator about my concerns? What happens if speaking directly to the regulator breaks down? What's the penalty for speaking out? Is the regulator going to stop you from being an unpaid volunteer?

    Before you ask why I didn't put these concerns to the regulator, I'll point out that it's not up to me to fix these issues, nor is it my place to make recommendations. I don't represent anyone and in my opinion this should be a community wide public conversation, not held in secret talks behind closed doors.

    As an amateur outside Australia I'd recommend that you pay attention, because I'm sure that bean counters will be taking notes to see if there's money to be saved at your regulator.

    I'm Onno VK6FLAB


    How to see 56 MHz of bandwidth... Jan 14, 2024
    Show notes

    Foundations of Amateur Radio

    The other day I stumbled on a project called Maia SDR by Daniel EA4GPZ. Maia, spelled Mike Alpha India Alpha, is a star in the Pleiades cluster. The Maia SDR project homepage proclaims that it is "An open-source FPGA-based SDR project focusing on the ADALM Pluto".

    Now, I can completely understand if that collection of words is gibberish to you, but take it from me, it's not, let me explain.

    PlutoSDR or Pluto is the common name of a piece of hardware which is officially called the ADALM-PLUTO Evaluation Board. It's a sophisticated device made by Analog Devices that provides a radio platform with some very interesting properties. Specifically it's both a radio transmitter and receiver with the ability to use frequencies between 70 MHz and 6 GHz. It runs embedded software you can tinker with because it's all Open Source and it's all very well documented.

    Many people have used the Pluto as a remote transceiver by controlling the on-board radio with a USB cable. While that's neat, it's not what I have been wanting to do for a number of reasons.

    The Pluto has the ability to sample data at a rate of 61.44 mega samples per second or MSPS. That translates to a bandwidth of 56 MHz. A typical amateur radio has a bandwidth of 2.5 kHz.

    This bandwidth comes at a price. For starters, USB on the Pluto isn't fast enough to handle 56 MHz of data, so if you're using it as a remote radio over USB, you need to lower your expectations.

    However, the hardware itself can process data at that rate, as long as it stays inside the radio. So, if you had a way to process data inside the radio and a way to show what you did with the data across USB, you could use all of the 56 MHz at once.

    The Maia SDR project does exactly that. It processes the data and presents it to the world as a waterfall image, like the one you might have seen in WSJT-X, fldigi or SDR++. If you've seen the voice version of my podcast on YouTube, you'll also have seen a waterfall. It's an image that scrolls vertically, showing frequencies left to right, and signal strength by colour, traditionally, a rainbow that uses blue for low power and red for high power. Every time period the image scrolls adding another row representing the radio spectrum at that time. It's a very useful way to show massive amounts of radio spectrum data in close to real-time.

    The waterfall that WSJT-X produces is about 2.5 kHz wide. The waterfall that Maia SDR produces is 56 MHz wide. To give you some context, the entire HF spectrum, between 2200m and 6m easily fits within 56 MHz.

    Now, there's a wrinkle. As I said, the Pluto frequency range starts at 70 MHz, so that means we can't use it to listen to HF. Well, not without the help of another gadget, called a transverter. Essentially it moves a set of frequencies from one range to another. The gadget I have, a SpyVerter 2 HF Upconverter, translates anything between 1 kHz and 60 MHz and moves it to between 120 MHz and 180 MHz.

    If you combine the Pluto with Maia SDR and a SpyVerter, you can plug your antenna into the SpyVerter, connect that to the Pluto, connect to the Maia SDR website that's running on your Pluto, tune it to 120 MHz, and see 56 MHz of HF bandwidth scrolling past as fast or slow as you want. You'll find the 10m band at 148 MHz, the 15m band at 141 MHz and the 20m band at 134 MHz.

    Now if that's not cool enough for you, Maia SDR is as I said Open Source. This means that the project publishes all of the code that makes this happen. The Pluto comes with a number of devices on-board that process information. At the antenna end is an AD9363, essentially a chip that converts RF into digital and back. The digital information is processed by a device called an FPGA, a Field Programmable Gate Array. Field Programmable means that mortals like you and I can change the software that it runs.

    Essentially an FPGA is a programmable circuit board used for information processing. To scratch the surface of what that means, you could for example program an FPGA to behave like a microprocessor, or you could use it to do accelerated matrix multiplications used for neural networks like you can with a graphics chip, or in this case, a device that does all of the digital signal processing. Finally the Pluto has a dual core ARM processor. You'll find those inside most Android phones and Raspberry Pi's to name a few. It's used to extract data from the FPGA and present it on a web page. Oh, and there's a progressive web app for your phone, so you can see this waterfall on your mobile phone if you want.

    So, thank you to Daniel EA4GPZ for sharing your project, it's very much appreciated!

    There are some caveats. The Pluto is easily overwhelmed by strong signals, so you probably need filters. I'm using a wide 2m band pass filter between the SpyVerter and the Pluto, just so that my local WiFi network doesn't overwhelm the whole thing. You're receiving between 0 and 56 MHz, so you'll need an appropriate antenna. The frequency response for the Pluto isn't linear, so the same colour on two bands might not be the same signal strength. You need to update the firmware of the Pluto, so make sure that you have a copy of the official firmware before you start because some of the FPGA functionality has been removed by Maia SDR to make this stuff work, most notably, the ability to use the Pluto across USB as a remote radio which is restored if you re-install the official firmware.

    It's all documented really well and I'd encourage you to have a go if you're so inclined. If you're a software developer, Maia SDR aims to encourage FPGA development in the radio sphere using Amaranth, the project About page has more details.

    As random Internet searches go, Maia SDR was a lovely surprise and I can't wait to dig deeper, but that will have to wait until my computer stops processing something like 6 billion WSPR records, which it's been doing for the past two weeks.

    What have you found worth sharing?

    I'm Onno VK6FLAB


    The Art of operating QRP Jan 07, 2024
    Show notes

    Foundations of Amateur Radio

    The attraction to amateur radio for me lies in the idea that it provides a framework for experimentation and learning. There's never an end to either. Each time you go on-air is an opportunity to do both and every chance I get, I cannot help being sucked into another adventure. My weekly scribbles are an attempt to both document what I've been up to and to encourage others to take a step on the path that I'm discovering, moment by moment, week by week.

    One of the more, lets call it, comment inducing, activities I like to explore is low power operation. This is not to the liking of many operators who are happy to run their shack at full legal power. For me, full legal power is 40 dBm, or 10 Watts. That's not to say that I've never experienced the thrill of running a pile-up on a contest station, I have. What's not to like? You speak with people from communities far-and-wide, they're clamouring to talk to you and making contact is pretty easy, almost effortless. The lure towards more power, bigger antennas, more bands and more radio is always there, but it's not all there is to this hobby.

    My year-long efforts of running a 10 dBm, or 10 mW, Weak Signal Propagation Reporter, or WSPR, beacon, is evidence that you can make it 13,945 km from me in VK6 to PA where it was heard by Jaap, PA0O in Zuidwolder, just outside Groningen in the North East of 't kikkerland. In fact, across 2023, my 10 dBm beacon was reported 4,849 times by 58 stations, many inside Australia, but there were reports from Indonesia, Japan, New Zealand, Taiwan, Antarctica, Sweden, and as I said, the Netherlands.

    One of my friends, Charles NK8O, is a mostly mobile operator who loves to set up for both Parks On The Air, also known as POTA, as well as World Wide Flora and Fauna, WWFF. His chosen mode is CW, but you'll find him using digital modes like FT8 and even as a rare DX event you might strike it lucky and hear his voice. Most of his activity uses batteries, so you'll rarely make contact with him when he's using more than 47 dBm or 50 Watts. A couple of weeks ago during the weekly F-troop net he announced that for the duration of 2024, Charles intends to operate using low power, or QRP.

    Operating QRP isn't for everyone, but I'd hazard a guess that if tried, there's plenty to learn and experience by dialling the power down to play in a low power environment. Think of it like this. If you're into cars, it's the thrill of driving fast. It's not the only way to drive and enjoy yourself. Driving sedately, touring the back roads, will get you to your destination just as well and along the way you'll have the opportunity to look out the window, to even have the window down and to enjoy the environment, rather than spending every second being on a hair trigger.

    If fishing is more your thing, high power radio is like dynamite fishing. You'll easily catch all the fish in the pond, but once you have, there's nothing left to do. Fly fishing on the other hand gets you a different but perhaps just as satisfying experience.

    So, if you've never done this QRP thing, what can you expect when you turn the power down? First of all, reception works just the same. So, everyone you heard before will continue to be heard. Transmission is going to be a little different. If you've ever changed over radios you might already have experienced the jolt between what you can hear and what you can work which can differ significantly between two radios. If you're used to high power operation, you'll essentially work most stations you can hear, but when you're using low power, there's going to be stations that you have little or no chance to work. Most of those are obvious so-called alligators, all mouth, no ears. That said, plenty of loud stations have years of honing their skill and station and your QRP call can just as easily be heard as the next station.

    You'll likely sharpen your calling skills. There's no point in calling when other stations are blotting out your call, so you become adept at dancing around other signals. You'll spend more time considering propagation and the best band to make your signal count.

    Another side effect you'll likely notice is less wear and tear on your gear. There's also little chance of having RF inside your shack upsetting your computer, or getting complaints from the neighbours who happen to have a crappy TV that stops working as soon as you key up. If you make mistakes, your station is more forgiving and less likely to be damaged when an unexpected fault occurs.

    Speaking of faults. The other day a coax switch in my shack caused my radio to stop transmitting. Luckily with the power setting at its lowest, there was no permanent damage. After testing with a multimeter I discovered that it shorted the centre pin to shield in one position. When I opened up the switch, I discovered that the blade that gets moved between ports had become slightly twisted, which in turn caused it to ground against the body. A slight turn with some needle-nose pliers fixed the problem, well, at least for now. I have begun searching for alternatives in earnest. I am quite taken by the notion of building my own switch from relays and controlling those via a network connection. More research and experimentation is needed because there's plenty I don't know about this subject.

    Between you and me, it's never too late for another experiment and I'd encourage you to spend some time testing the QRP experience and given the current state of the solar cycle, there's no better time than right now.

    I'm Onno VK6FLAB


    Finding the right frequency. Dec 31, 2023
    Show notes

    Foundations of Amateur Radio

    Today I'm going to spend a little longer with you than usual, but then, I think this is important and it's good to end the year on a bang.

    Have you ever attempted to make contact with a specific DXCC entity and spent some time exploring the band plan to discover what the best frequency might be to achieve that? If you got right into it, you might have gone so far as to attempt to locate the band plan that applies to your particular target. If you have, what I'm about to discuss will not come as a surprise. If not, strap yourself in.

    When you get your license you're hopefully presented with a current band plan that is relevant to your license conditions. It shows what frequencies are available to you, which modes you can use where, and what power levels and bandwidth are permitted. It should also show you if you're the primary user or not on a particular band. If you're not sure what that means, some frequency ranges are allocated to multiple users and amateur radio as one such user is expected to share. If you're a primary user you have priority, but if you're not, you need to give way to other traffic.

    It should come as no surprise that this is heavily regulated but as a surprise to some, it changes regularly.

    Across the world, frequency allocation is coordinated by the International Telecommunications Union, the ITU, and specifically for amateur radio, by the International Amateur Radio Union, the IARU. It coordinates frequencies with each peak amateur radio body. The ITU divides the world into three regions, Region 1, 2 and 3, each with its own band plan. Within each region, a country has the ability to allocate frequencies as it sees fit - presumably as long as it complies with the ITU requirements. As a result, there's not one single picture of how frequencies are allocated.

    And this is where the fun starts.

    In Australia there's an official legislated band plan, cunningly titled F2021L00617. It contains the frequencies for all the radio spectrum users as well as a column for each ITU region. The document is 200 pages long, and comes with an astounding array of footnotes and exclusions. It's dated 21 May 2021. There's a simplified version published by the Wireless Institute of Australia, which comes as a 32 page PDF. It was last updated in September 2020. When I say "simplified", I'm of course kidding. It doesn't include the 60m band which according to the regulator is actually an amateur band today. The 13cm band according to the WIA shows a gap between 2302 and 2400, where the regulator shows it as a continuous allocation between 2300 and 2450 MHz. The point being, who's right? What can you actually use?

    Oh, the WIA does have a different page that shows that 6m "has had some additions", but they haven't bothered to update their actual band plan.

    To make life easier, the regulator includes helpful footnotes like "AUS87". This is particularly useful if you want to search their PDF to determine what this actually says, since it only appears 156 times and it's not a link within the document. In case you're curious, it's related to three radio astronomy facilities operated by the Commonwealth Scientific and Industrial Research Organisation, better known as the CSIRO, two by the University of Tasmania and one by the Canberra Deep Space Network. Interestingly the Australian Square Kilometer Array and the Murchison Widefield Array don't feature in those particular exclusions, they're covered by footnote AUS103.

    If that wasn't enough. The regulator has no time for specific amateur use. You can find the word Amateur 204 times but there's no differentiation between the different classes of license which means that you need to go back to the WIA document to figure out which license class is allowed where, which of course means that you end up in no-mans land if you want to discover who is permitted to transmit on 2350 MHz.

    If we look further afield, in the USA the ARRL publishes half a dozen different versions, each with different colours, since black and white, grey scale, colour and web-colour are all important attributes to differentiate an official document. Of course, those versions are now all six years out of date, having been revised on the 22nd of September 2017. The most recent version, in a completely different format, only in one colour, has all the relevant information. It shows a revised date of 10 February 2023, that or, 2 October 2023 because of course nobody outside the US is ever going to want to refer to that document - seeing as there's only amateurs in the USA, well at least according to the ARRL.

    Interestingly the US Department of Commerce, the National Telecommunications and Information Administration, Office of Spectrum Management publishes a colourful chart showing the radio spectrum between 3 kHz and 300 GHz. You can't use it as a technical document, but it's pretty on a wall to amaze your non-amateur friends. The FCC has a band plan page, but I couldn't discover how to actually get amateur relevant information from it.

    If you think that's bad, you haven't seen anything yet.

    The British are special. The RSGB publishes a variety of versions, each worse than the next. It appears that their system creates a single HTML page for each band, their 32 page PDF is a print out of that and their interactive viewer wraps all that into some proprietary system that makes using it an abysmal experience. Fortunately, they also link to a band plan made by the regulator, presented as a five page PDF which is much more concise and has the helpful heading: "The following band plan is largely based on that agreed at IARU Region 1 General Conferences, with some local differences on frequencies above 430MHz."

    Unfortunately it doesn't specify which particular General Conferences apply, but it does helpfully tell us that it's effective from the first of January 2023, unless otherwise shown. That said, 2023 only appears in the headers and footers and 2024 doesn't appear, so who knows what date exceptions exist.

    One point of difference is that the RSGB also publishes their band plan as an Excel Workbook. This might start your heart beating a little faster with visions of data entry, sorting, filtering and other such goodies, like figuring out which frequency to use for a particular mode. Unfortunately the authors have used Excel as a tool for making tables like you'd see in a word processing document. Start and Stop frequencies in the same cell, random use of MHz, spacing between bandwidth and frequencies and descriptions intermingled. In other words, this is not an Excel Workbook and it does not contain information in any usable form, unless you want to do some free text searching across the 32 worksheets - what is it with 32 anyway? Perhaps this is their authoring tool and they save as HTML from within Excel or print to PDF. Who knows?

    One point that the British do get right is version control. You can see specifically what change was introduced when. For example, on the 6th of March 2009 the 17m QRP frequency was corrected to 18086 kHz. Mind you, there's several pages of updates, helpfully scattered across multiple worksheets. Yes, they're really using Excel as a word processor.

    Before I dig into any other countries, I should mention the United Nations Amateur Radio peak body, the IARU, presumably a model that countries should aspire to. The IARU has links to three different sets of band plans. Region 1 breaks the band plan into HF and higher frequencies and the higher frequencies are broken into notional bands, each with their own PDF. Regions 2 and 3 each provide a single PDF, but the Region 3 document is hosted on the Region 2 website. Region 1 documents contain a revision and an active date as well as an author. Region 2 and 3 documents contain a date and are formatted completely differently.

    In Germany the DARC attempts to link to the IARU-Region 1 band plan, but the link is pointing at a non-existent page.

    In the Netherlands, VERON points at a 2016 edition of the IARU-Region 1 HF band plan and the current Region 1 mixed band plan for higher frequencies.

    In Canada the RAC points at a HTML page for each band and presents all the HF frequencies as a single image, yes an image. All the other bands are essentially text describing how to use a particular band. The HF image states that it applies from the first of June 2023, the rest of the pages carry various dates that conflict with each other. For example, the 2m band states on the landing page that it was updated on the 23rd of September 1995, but the page itself refers to a new 2m band plan that was approved in October of 2020. The linked band plan contains all the credit, who is responsible for the plan, naming the entire committee, adding notes and requesting donations, straight from the RAC newsletter, page 36 and 37 of the November / December 2020 edition, rather than providing a stand-alone technical document.

    Let's hop back across the Atlantic and see what else we can learn.

    In Switzerland things are a little different. Its regulator publishes a frequency allocation plan that is a thing of beauty. It presents as a table on a web page, but it has a search box you can use to filter the frequencies that you're interested in. So if you use the word "amateur", you end up seeing the whole amateur radio spectrum as it exists within the borders of Switzerland. You can also set frequency ranges and as a bonus, if you type in 1 MHz and change the unit to kHz, it actually changes the number to 1000. As I said, a thing of beauty. Oh, and the footnotes? Yeah, they're links and they open a new window with the relevant information, and you can keep clicking deeper and deeper until you get to the actual legislation driving that particular entry. If that's not fancy enough for you, from within the search, you can download an offline HTML copy, you can pick services, rather than use search terms, and the PDF version, because of course there is one, actually has the same active links to footnotes.

    That said, it has some idiosyncrasies. It specifies when amateur radio is the primary or the secondary user of a band, except when it doesn't. I presume that this is a regulatory thing and that it's a shared resource, but as an outsider I'm not familiar with Swiss law, but if I was inclined, I could become familiar, since the documents are all written in multiple languages, including English. Another oddity is that some frequencies show no text at all, but I presume that's a bug, rather than by design.

    Speaking of bugs, or features, depending on your perspective. Consider the frequency 2300 MHz. Every single document I looked at mixes up how this is shown. Some have a space between the number and the unit, some don't. Some countries put a space between the 2 and the 3, some a dot, some a comma, the Swiss use an apostrophe. Just so we're clear, these are technical documents we're talking about. They're not literary works, there are standards for how to do this, but it seems that the people writing these documents are blissfully unaware of any such references. Even the IARU cannot agree on how to represent the same number, let alone use the same formatting for the same band plan in each of its three regions.

    At this point you might come to the conclusion that this is all an abhorrent mess and I'd agree with you. In my opinion, it goes directly to how important our hobby is in the scheme of things and just how little funding is allocated to our activities.

    It also shows that there are contradictory sources of truth and not a single unified view on how to present this information to the global amateur community. In case you're wondering why that matters, electromagnetism doesn't stop at the political boundaries of the location where we might find ourselves and if that doesn't matter to you, consider again how you'd best talk to an amateur of any given DXCC entity and on what particular frequency you might achieve that.

    So, aside from whinging about it, what can you do about this?

    I have started a project, of course I have, that attempts to document two things, well, three. First of all I use the WIA version of the DXCC list - since the ARRL doesn't actually publish that for free anywhere - and use that to track a list of hopefully official frequency allocation documents. I'm also in the process of capturing the content of each of those documents into a database, so we can all figure out what the best frequency is to talk to another country.

    I'm still in the design stages for the database, for example, do we want to store a frequency in Hertz, in kHz, or pick a magnitude and store a number? Each of these choices has long term implications for using the tool. Then there's things like discovering which band plan applies to Scarborough Reef, the San Felix Islands and Pratas Island to name a few, since I've really only scratched the surface with the plans I've explored.

    I had visions of putting this on GitHub, but perhaps this should be part of the Wikipedia collection and it should live there. I'm still considering the best plan of attack. In the meantime, you can help. Please send an email to cq@vk6flab.com with the official band plan link for your own DXCC entity, and if you have thoughts on how best to structure the database or where this project should live, let me know.

    For example, should the database include just band plans, or should we also include things like modes. For example, the official VK calling frequency for 40m is 7.093 MHz. Should that be in the database and should we include the preferred Olivia calling frequency? While looking at that, consider the band labels we use. Australia doesn't have a 75m band, but others do. Some countries refer to the 4mm band, others refer to it by frequency.

    So, over to you. Let me know what you think. I'll leave you with a quote by Daren 2E0LXY:

    "It is not the class of licence the Amateur holds but the class of the Amateur that holds the licence."

    I'm Onno VK6FLAB


    It's the little things ... Dec 24, 2023
    Show notes

    Foundations of Amateur Radio

    Walking into your shack is often a joyous experience. You take a moment to smile at your setup and, at least mentally, rub your hands in glee anticipating some fun. Well, that is how it is for me, but recently it's been less of that and more of an audible groan at the accumulated cruft that makes it nigh on impossible to sit down, let alone achieve anything fun.

    It's not as bad as it could be. I'm forced to keep my station at least operational to host my weekly net, but if that wasn't there, it would have been overtaken by anything and everything finding a flat surface to put stuff on. It got to the point where I had to move some radio equipment off my desk, just so I could pile more stuff onto it.

    So, on Tuesday I finally had enough. It was a pretty normal day, waiting for others to get stuff done, deadlines be damned, but I took one look at the shack and snapped. This has happened before and I suspect that it will continue to happen throughout my life, but that day I'd crossed the line.

    Before I share what I achieved, I should mention a couple of other things. If you've been here for a while you'll know that I am an unashamed computer geek. Software Defined Radio, or SDR, appears to have been invented just for me, embedded computers, digital modes, networking, data analytics, Linux, Docker, you name it, I'm there. Mind you, this isn't new. It's been true for nearly forty years now, ever since I set foot into my high-school computer lab where I found myself looking at a bank of Apple 2 computers. Then I bought the first computer in my class, a Commodore VIC 20. Life was never quite the same.

    This to tell you just how much computing features in my day-to-day.

    I have a long term plan to use embedded computers like for example a Raspberry Pi to essentially turn my analogue Yaesu FT-857d into a networked SDR. The idea being that I use my main computer to do the processing and the Pi to control the radio and feed the audio in and out across the network. I want to make it so that you can use any traditional SDR tool with such a radio, and if I get it right, any other radio.

    For more context, I'm getting more and more deaf. I swear my SO is speaking softer each day and hearing tests tell me that audio above 2 kHz is pretty much gone. I have been playing with audio signal processing with a view to tailoring the audio coming from my radio into something more audible to me.

    On Tuesday I had an ah-ha moment. I could keep waiting until I got all that done and then set-up my shack just so, or I could embrace the analogue nature of my gear and use the mixing desk I have to feed the audio through its on-board audio processing and at least improve my audio experience today, rather than some nebulous future time.

    Finally, I purchased a peg board some time ago for the specific purpose of strapping my coax switches to so I would not have to contend with coax all over my desk whilst trying to remember which switch did what when I finally had a moment to play.

    All this came together in a new version of my shack, albeit an alpha pre-release, to be treated with extreme caution, if you break it, you get to keep both parts and it will kill a kitten without notice.

    To get started, I removed all non-radio stuff from my desk. Including half a dozen computers, a dozen patch leads and adaptors left over from the harmonics testing project, there were monitor cables, USB cables, a variety of power supplies and a stray binder with empty pages.

    I found all the radio gear that I really wanted to have on my desk, placed it where I could actually use it and figured out how to connect the audio output from each radio to the mixing desk which also found a home.

    Then I jumped on the RF side of things. Getting started was the hardest part. I decided that it would make sense to split the peg board in two, one half for HF, the other for VHF and UHF. I have two coax switches that I use as the entry point onto the board. They're each fed with the antenna coax and each have one port connected to the other. The idea being that during a thunderstorm I can connect the two antennas to each other and isolate the rest of the shack. It won't protect against an actual direct hit, but all charge being built up should dissipate between the two antennas. Feel free to give me suggestions on how better to do this in a shack located on the second floor of a house in Australia. Note that the rules for grounding across the world are drastically different, so don't assume that your laws apply in Australia.

    The HF coax side has a strapped down Bias-T which powers the SG237 antenna coupler that's outside. Then there's a switch so I can connect HF to a radio or to a beacon, which I also strapped to the peg board. On the VHF side there's just a second coax switch to select between two radios, but only one is currently connected. I plan to strap my PlutoSDR to the other port.

    I powered everything up and couldn't trigger the local repeater. I got out my handheld and tried. That worked fine. I could even hear it on my main radio, but it wouldn't trigger. No SWR issues, I could hear local broadcast stations, but still couldn't trigger the repeater. It took an embarrassingly long time to discover that I had managed to feed the HF antenna into the VHF/UHF side. The SWR was fine because it was triggering the SG237, so, fun.

    On the audio side I can now change the compression of a signal, change the low, mid and high frequencies and if I feel inclined change the balance between my ears. Microphone is via the hand microphone, for now. There's no CAT control at the moment and I still need to plumb in the push to talk, or PTT, foot pedal. I also need to move the peg board so RF cables aren't dangling in the breeze, but overall, a massive improvement and best of all, I turned on my radio and it wasn't even Saturday morning.

    So, what's your excuse for procrastinating?

    I'm Onno VK6FLAB


    The visibility of our radio community. Dec 17, 2023
    Show notes

    Foundations of Amateur Radio

    Cars have been here for well over a century and so has radio. Cars pretty much start when Carl Benz first applied for a patent for his "vehicle powered by a gas engine" on the 29th of January 1886 which is regarded as the birth certificate for automobiles. Radio starts as a thing when Heinrich Hertz proves that radio waves exist in 1888.

    Since then things have changed, a lot.

    Today, both these technologies, cars and radio, are everywhere. It's estimated that there are 1.47 billion vehicles on the planet today, in contrast, there are only 44 thousand broadcasters across the globe, serving about 4 billion people, or half the population. So, cars win, right?

    Not so fast. The Wi-Fi Alliance estimates that there's 3.8 billion Wi-Fi devices being shipped this year alone and there's about 19.5 billion in use. Many of those are mobile phones, so they're not only using Wi-Fi, but GSM, CDMA, 3G, 4G or 5G radios. In many cases they'll have Bluetooth on board and will be receiving GPS information from the currently five constellations in orbit around Earth. Some will even have an FM receiver on board, just to cram another radio inside the same box.

    To give you a better sense of scale, 2022 saw 4.9 billion Bluetooth devices shipped. In 2010 it was estimated that there were a billion GPS users, today there are more than six billion users being served by GPS systems for positioning, navigation and precision timing.

    I haven't even talked about other uses of radio, like radar, astronomy, remote sensing, remote control, keyless entry and countless other related and interconnected technologies.

    So, while there's a car for every five or so people, there's at least two Wi-Fi radios per person and probably more like a dozen radios per person when you start counting those embedded in our daily lives.

    So, why is it that we have an estimated car enthusiast population of 10% and an estimated radio amateur population of 0.04%?

    It's not to do with the popularity of the topic. Google trends shows that both cars and radio are consistently trending downwards at about 2% each year since 2016. Radio is consistently twice as popular as cars. When you rank the global popularity of cars vs radio, out of 47 countries, 40 countries care more about radio than cars.

    South Africa and India care about cars 74% to 26% radio, even New Zealand, 56% vs 44%, cars to radio. At the other end of the scale, Peru, 2% cars, 98% radio. Germany, home for both Heinrich Hertz and Carl Benz, 92% radio, 8% cars.

    Popular search engines aside, there are other places to look for content. Take platforms like Prime Video, Netflix, Apple TV+ and YouTube.

    When you search for radio or cars on those platforms it's interesting to see what comes back and explore how relevant it is. I'll encourage you to do the experiment, but as a surprise to nobody, the results are universally woeful but illustrative. Searching for cars returns mostly relevant content, but a search for radio brings back results that have absolutely nothing to do with the topic. Seriously, on Netflix, two documentaries about Pele and Beckham, both famous footballers, neither known for their interaction with radio, rank higher than a documentary on Prime about radio astronomy, cunningly titled, wait for it: "Radio Astronomy".

    Even the initially promising Netflix result "Amateur" in response to the term "radio" is about a 14 year old basketball player navigating the dark side of sports. While we're at it, just for giggles, I checked the closed captioning for the movie and the word "radio" doesn't appear in the movie, at all. Speaking of representation, Netflix recently published their entire list of content for the first half of the year. The word radio appears exactly once, "John Mulaney: Kid Gorgeous at Radio City" and that doesn't even turn up as a search result when you go looking for "radio". The word "cars" appears 18 times in the Netflix library.

    So, why is it that topics like "radio", which is demonstrably twice as popular as "cars", and perhaps a dozen times more, let's call it, numerous, in society, has such a poor showing and what can we as connoisseurs on the topic of "radio" do about this?

    Cars are represented in a plethora of movies, series and shows featuring reviews, mods, restorations and entertainment. There's topic specific channels and social media. There's shops, events, races and so much car merchandise. Is that what's missing in radio, or more specifically, amateur radio, marketing, or is it something else? I'm keen to hear your thoughts. My email address is cq@vk6flab.com, get in touch.

    For my efforts, I'm publishing my podcast on YouTube and manually working my way through my back catalogue of over six hundred episodes, complete with a, YouTube imposed, limited five thousand character summary of the transcript, just to increase the chances of radio being a relevant search result when someone who's interested in our community comes looking.

    I'm Onno VK6FLAB


    Report on Radio Harmonic Power Dec 10, 2023
    Show notes

    Foundations of Amateur Radio

    There is a perception in the community that the hobby of amateur radio is an expensive way to have fun. While it's entirely possible to spend thousands of dollars on equipment, in much the same way that it's possible if your preferred hobby is golf, getting started does not have to require that you start planting money trees.

    Lots of fun can be had using cheap amateur radio transceivers that are used all around the world. If you do start with such a radio, the chances are good that you'll come across amateurs who make disparaging remarks about the lack of compliance of such radios.

    When I say compliance, I'm talking about specific measurements specified by the International Telecommunications Union, the ITU. When you transmit on a specific frequency, there are rules about how much that signal is allowed to be unintended, or to use the official term, spurious emissions.

    Specifically, the signal you transmit has to meet the requirements for the mode you're using and it must also stay within limits on other frequencies. For example, if you have a 2m handheld radio that uses FM, the transmitter must stay within the required width for FM and it's not allowed to transmit above a certain level on any of the harmonic frequencies.

    When someone claims that all cheap radios are non-compliant, they're saying that such radios are either not transmitting a valid FM signal, or that the levels of the signal exceed the limits specified by the ITU.

    Given that such radios are in wide use, Randall VK6WR, Glynn VK6PAW and I got together to see if we could come up with something a little more scientific in the way of comment about such radios. With access to Randall's HP 8920A RF Communications Test Set we came up with a repeatable way to test a radio and then went to the local HAMfest where we subjected a pile of radios to our tests. In total we did 75 tests. Overall we tested 39 distinct models across 12 brands.

    So, what did we learn?

    All so-called "name brand" radios were fully compliant.

    All radios that were sold in Australia by Australian distributors were compliant.

    Baofeng radios made up the largest sample of inexpensive radios. Seven out of the 26 tested were compliant, eight were non-compliant and the rest, 11 were borderline. More on that shortly.

    We also tested many radios that had been purchased online. We didn't test enough of each model to make specific comments, but it's worth pointing out that half of all the online radios were compliant.

    Now, I mentioned borderline compliance. What we learnt was that there were some radios that fell within 6 dB of being compliant. The HP test set hasn't been calibrated for a while and we felt that allowing for a 3 dB random measurement error and a 3 dB systematic error would prevent us from marking a radio non-compliant when in fact it was. We categorised 16 radios as borderline.

    Our report is of course public. You can find it on my GitHub page as both a PDF and a markdown document.

    Whilst we were writing our report, we discovered uncorroborated suggestions that some radios might fail an emissions test after suffering unspecified damage in the output filtering stages. We looked at the schematic of one radio that suggests that a simple capacitor failure might cause a filter to fail without preventing the transmitter from operating.

    This might mean that a non-compliant transmitter might be made compliant again by replacing the faulty capacitor. We haven't tried and we don't know if a failed capacitor actually makes a radio non-compliant or not, or even if such a failure could occur and if-so, how.

    In other words, this might be a red-herring, we just don't know.

    One other comment worth pointing out is that it was suggested that some radios might use a specifically designed antenna to suppress the second harmonic. Given that some radios failed only on the second harmonic spurious emission requirement, but not the third, this seems plausible. All radios we tested had removable antennas and were tested without an antenna, since compliance relates to the transmitter, not the antenna. It does raise a more interesting question. What happens if you fit a different antenna to the radio?

    One adage that stands is that "you get what you pay for", but given the amount of cheap testing equipment available, it's relatively easy to test every handset in your shack.

    I'm Onno VK6FLAB


    What about promoting the hobby? Dec 03, 2023
    Show notes

    Foundations of Amateur Radio

    Amateur radio is an activity enjoyed by many people around the world. How many exactly is cause for debate. The most recent official figure we have is from the IARU, the International Amateur Radio Union. In 2020 it counted over 3 million people, but an article written a year later puts that figure at 1.75 million.

    In Australia there's a common narrative that the total amateur population is in undeniable decline, some think that it's on a stark decline. Interested in hard data, for years I've been collecting information around the amateur population in Australia and I can report that across the nine years that I have data for the total variation is within two percent and it's not a straight line down either. There was a dip in 2020, potentially associated with training and callsign allocation being moved from the Wireless Institute of Australia to the Australian Maritime College, something which is going to change again shortly when amateur licensing in Australia will revert to the regulator, the Australian Communications and Media Authority. If you're familiar with amateur licensing in Australia, that's not the only change, but that's not what I'm looking at today, mainly because the available information associated with the upcoming changes are limited at best, seemingly buried in invective at worst.

    Back to the topic at hand. One of the often heard responses in relation to the decline of our hobby is recruitment of new amateurs. It's a topic that I've spent plenty of time over the past decade contemplating. How do you share the joy of amateur radio with a general public who is apathetic to the preconceived ideas associated with this hobby, you know, old white men sitting in the dark with Morse keys.

    For the record, I prefer a shack with light and I still don't know how to use a Morse key, other than to make my radio beep. The rest is genetic.

    In the quest for spreading the word there's a repeated emphasis on the young, often coalescing around the annual Jamboree on the Air, or JOTA, as organised between Scouting groups and radio amateurs. I have previously said that JOTA was how I first came across amateur radio, but at the time, aged 15 or so, I had no money for such endeavours and the experience didn't resonate with me until decades later. So, you could argue that this is what changed me into an amateur, but the reality is that I had to come across the hobby a few more times before I got interested enough to investigate, something which I have spoken about before, in short, Meg, then VK6LUX introduced me to the concept of controlling a 2.4 GHz drone using higher power than was permitted with standard Wi-Fi equipment. I was hooked and got my license less than a month later. I then discovered that I needed more permissions and set about studying, only to get distracted with everything I could already do. I'm still being distracted today.

    So, JOTA is a potential touch point, but I see little evidence that the initial spark goes anywhere in a hurry. I'm not dismissing it as a way to have amateur radio gain relevance outside our own community, but perhaps there are other ways to make this happen. In the early days of my journey I attended country fairs with my club and we'd set-up a radio or six to show and tell. There was talk of doing this in a shopping centre, at the local hardware store and even brief discussions about doing this at the local electronics store. As enjoyable as this was, none of it ever appeared to generate any permanent interest and I don't recall seeing new amateurs suddenly appear at the club after any outings.

    Last week Glynn VK6PAW and I, set-up at the local airport, YPPH, that's Perth International Airport if you're not familiar with the designation allocated by the United Nations arm, ICAO or the International Civil Aviation Organization. Perth has a public viewing area. It's situated at the south western end of runway 03/21. It's an elevated position with minimal shade, some seating and you're 320 m from the runway centreline. It's a place where plane spotters congregate and now a few radio amateurs.

    One thing we have in common is an interest in radio. We were told that the plane spotters often listen to one or two frequencies and if they're into video, they might record one radio channel to include on their YouTube videos. When Glynn and I visited we had a few radios with us. When I say few, in amateur terms we only had about five or so, but I suppose that comes with the territory. As it happens, admittedly not by accident, our radios could receive airband frequencies, so we could tune to Perth Tower, Perth Arrival, Perth Ground, Perth Departure and Melbourne Central, all at the same time. Next time we'll likely bring some HF gear so we can also listen to HF aviation frequencies as well.

    While I was hosting F-troop, the weekly net for new and returning amateurs, midnight UTC, every Saturday morning for an hour, Glynn was busy talking and sharing with the plane spotting community. There were conversations around what radios and antennas to use, how you could tune to more than one frequency at the same time, how you could use software defined radios, how to set-up radios so you could have different channels appear at the left or the right, in the middle, or somewhere in between, which will allow you to focus on a particular radio call as it happens. Also, I should mention a piece of software called rtl-airband which allows you to use an RTL-SDR dongle to do this at home, but I digress.

    There was a steady stream of people looking at planes and their age was surprising, aged 3 to 93 or so. Of course not all were into the radio, but plenty were.

    Afterwards it occurred to us that there might be other venues like this, attracting people who are interested in radio for their own purposes. I have no doubt that we'll be back to Perth Airport, but I suspect we'll also see if we can find some other spotters. Train, ship and other airports come to mind immediately. I can't wait to learn about other people's uses and interests in radio, even if radio isn't the main attraction in their hobby. Perhaps you can think of some that you'd like to share.

    Getting on air and making noise is one way to get outside, but publicly listening to frequencies that others are interested in is a perfect excuse to play with radios.

    I'm Onno VK6FLAB


    Spontaneously getting out and about ... Nov 26, 2023
    Show notes

    Foundations of Amateur Radio

    For years I've been hosting a weekly net called F-troop. It's a one hour opportunity for new and returning amateurs to get together and share their questions, and sometimes answers, about anything and everything amateur radio, with side trips into astronomy, electronics, circuit boards, testing gear and whatever else takes our fancy on the day. The net runs for an hour every Saturday morning starting at midnight UTC, which for some is a time when they're fast asleep, though truth be told, several of our regulars are night owls.

    In VK6 where I am, midnight UTC is a more reasonable 8am, unless we have another referendum when we can decide if we want daylight saving, or not. So far we've had four of those, yes, really, in 1975, 1984, 1992, and 2009, and each time daylight saving or summer time was rejected. All I'm saying is that the chances are good that midnight UTC is going to be 8am in VK6 for a while yet.

    Anyway, that time of the morning affords me the luxury of getting out of bed at a sensible hour, having a shower, making a cup of coffee with my Significant Other, or SO, and ambling into my shack to get ready. It's a comfortable process, something I've done for over 12 years with very little in the way of variation with the exception of the 500th and 600th episodes which I hosted outdoors at a local radio club, complete with BBQ and many visitors. That and the Friday Night Technical Net with Reg VK6BQQ, but that's a story for another day.

    Last week a good friend, Glynn VK6PAW, asked me if I wanted to go out and have some fun, and having been pretty much cooped up for several years now, of course I said "yes". We're going to the viewing platform at the Perth International Airport, that's airport code YPPH, where I'll host the net in whatever way we figure out at the time. It's not an event, we haven't told anyone about it, and telling you now won't ruin the surprise for anyone, since this weekly rambling hits the airwaves after F-troop concludes. I knew there was a reason.

    Anyway, at this point you have every right to ask me, "Onno, why should I care?"

    Indulge me and let me see if I can explain.

    Most, if not all, of my amateur radio activities are planned. From time-to-time I might get in my car and drive to a nearby park and get on HF, but truth be told, I haven't done that for several years. I have regularly told you about contests I've done, often whilst operating portable, often with friends, but sometimes alone. I have activated all manner of things, climbed summits, played in parks, gone to lighthouses and other such places. Every, single, time, those activities were planned, often to within an inch of their life. What should I bring? Where am I going to set-up? What gear do I need? What spares are required? What logging tool is needed? Will I need food and water? You know, a typical 7p activity, Proper Planning and Preparation Prevents Piss Poor Performance.

    This time the plan consists of: "Do you want to go to the airport?" and "Sure!"

    Mind you, that's in the context of Glynn normally having several radios in his car and me not having a clue what to expect. The other day I actually had my first ever look at the location in Google Street View, only to discover that there's a shelter there, so hopefully we won't fry in the forecast 38 degrees Celsius, that's 100 degrees in Ray Bradbury's temperature scale, if you're wondering.

    Now, on the whole, this is a pretty low risk activity. Nobody is going to die if I don't manage to get the net going, though I do have Echolink on my phone, which reminds me, I should probably check if that still works. I'll put a pencil and a notepad in my pocket for logging and I'll bring a bottle or six of water and probably some coffee. Sorry, I can't help myself.

    In other words, it's entirely possible to get on air and make noise without having to go to the Nth degree of planning and still have fun. As it happens, fun is something that's been in short supply of late, so, that's also a welcome change.

    As an aside, in a completely unrelated and random observation, I recently installed a new font on my computer, called Hack. It's mono-spaced, sans-serif, intended for source code, and licensed under the MIT License. I'm using it right now and I'm in love. So secretly, between you and me, that's what goes for fun around here. Oh, in case you're wondering, no, I did not get paid to say that, the authors have no idea I exist, unless they're unexpectedly radio amateurs, I'm just a happy user.

    Also, if you're wondering about Echolink, no need to fret. I just tested and it just works straight out of the box. Gotta love that.

    Now, here's a question for you. When was the last time you spontaneously got on air to make noise?

    I'm Onno VK6FLAB


    Failure to simulate ... Nov 19, 2023
    Show notes

    Foundations of Amateur Radio

    During the week I started a new project. If you know me at all, this is not unusual. Having worked in the IT industry for nearly 40 years it's also not unusual that projects have a way of surprising you and this project was no different.

    Recently I've been talking about antennas, a topic close to the heart of many amateurs and one that garners a lot of opinion and in my experience, much less in the way of facts, so being a firm believer of facts, I set out to add some of those to the discussion.

    After having described that the environment is not often discussed in the context of antenna behaviour, coupled with the personal experience that it has by far the biggest influence, I set out to discover if I could use my computing skills to simulate this problem to build a picture that would speak a thousand words. Prompted by a friend who shared with me a link to an opinion that stated that dipole antennas didn't have 2.15 dBi gain, but in fact, apparently, had 8.5 dBi gain, I was energised to find out where this number came from.

    I figured I'd spin up some antenna modelling software, use a standard model of a dipole, then simulate it at various heights above the ground and see what I could learn. Any good journey starts with a single step, so I started with looking for a generic model of a dipole antenna. I've played in this space before, so I was familiar with the fact that most, but not all, antenna modelling tools use a piece of software called NEC2 to do the actual calculations. Its models are described using text files ending in the .NEC extension. This software goes back to punch card days, so the format for the NEC2 files is essentially a stack of punch cards, so much so that every line in the text file is called a card and any software that uses the underlying NEC2 tool describes it in that way.

    I won't bore you with the syntax, it's, let's put it this way. If you've been around computers for as long as I have, you're familiar with a tool called "sendmail", which is known to be user-friendly, just very particular with whom it makes friends. The NEC2 card format is much the same. It's not that surprising, and for added nostalgia, NEC2 was written in FORTRAN, originally in 1981 at the Lawrence Livermore Labs by Jerry Burke and Andrew Poggio. It was later released to the public. There's translations to C and C++, but they use the same notion of cards, so no magic progress there.

    I started learning the syntax, and eventually came across a text-book with an example of cards that describe a dipole. Mind you, there were plenty of disclaimers around how poorly the ground was simulated and wouldn't you know it, the file format uses meters as the dimension, rather than wavelengths, so as far as I can tell, you can't simulate a quarter wave antenna, you have to simulate one of a specific length, so much for using a standard model of a dipole.

    I found a tool that uses Python to issue NEC2 commands and as a surprise to nobody, it too uses cards. I used it to discover that for a particular type of ground, at some unknown height, the optimum length for a 10m WSPR dipole antenna is 5,225.87 millimetres long, apparently. You know it's true, it says so right there on the screen. I'm skipping over having to compile the software that was supposed to be a ready made Python library, but I digress.

    There was a tool, written in TCL, that visualised NEC2 output, last updated 18 or so years ago and I unsuccessfully tried to make it work. Then there were those who suggested to fire up some random Windows tool on my Linux box, but as far as I can tell, I'd have to do the height adjustments manually, not ideal if you want to visualise from say, ground to geostationary orbit, one millimetre at a time and output an image at every step.

    I searched the net for others who would surely have trodden this path long before I came along, only to discover that my search-fu is clearly broken, or any website with promising information has long ago been booted off the Internet, leaving "For Sale" signs on the domain name.

    I came across one file which simulated a dipole in free space. It had, to use the NEC2 terms, 11 cards. When I run that through "nec2c", it generates a 12 megabyte file with over 104-thousand lines of output. Only takes 650 milliseconds to generate. If only I could visualise it.

    I also came across a whole range of physics programs, which is not that surprising, since essentially antenna design is physics, but those tools require that I start learning a whole new way of building antennas, apparently from electrons, preferably whilst getting a degree in physics with a specialisation in computational electromagnetics. Then there was the Wolfram Alpha notebook model for a simple dipole, only 3,200 lines of code, so, you know, trivial to use.

    So, here's the thing. Has nobody in living memory simulated a dipole at more than three heights and documented the process? Am I really the first human on the planet to think of this?

    Oh, yes, I did find a project that simulated different lengths of dipoles, but I'll leave those for another day. And finally, I also found "xnecview", which does generate images, but it too is very particular whom it makes friends with and I've yet to discover if it can generate what I'm looking for.

    As for the 8.5 dBi, I'm still looking. My current best guess is that at some specific height a dipole has an ugly spike that has 8.5 dBi gain and that someone used that number without looking at the detail, but, who knows, there's plenty of opinion to go around.

    I'm Onno VK6FLAB


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