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Foundations of Amateur Radio

Foundations of Amateur Radio

By: Onno (VK6FLAB)
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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?".℗ & © 2015 - 2025 Onno Benschop Physics Science
Episodes
  • A new year with new services to the public .. in 1905

    A new year with new services to the public .. in 1905
    Nov 15 2025
    Foundations of Amateur Radio Recently I spent some quality time digging into the origins of a word in common use. In doing so, I contacted the Postal Museum in the United Kingdom and received a lovely reply that included a photo of a document in their archive. The document, a Post Office Circular from Friday, December 30, 1904, number 1641, introduces a new service offered by the Post Office. Let me read to you what it says, and I quote: "Telegrams to and from Ships by Wireless Telegraphy. "(To be noted at Telegraph Offices only.) "With the present Circular is enclosed a list showing the wireless telegraph stations in the United Kingdom worked on the Marconi Company's system, and the hours up to which telegrams can be received at those stations for transmission by wireless telegraphy to certain ships fitted with Marconi apparatus. By another notice in this Circular, Postmasters and others concerned are requested to enter the names of the stations in the Code Book with the necessary particulars. Ships will be issued for insertion in the Post Office Guide. "On and from the 1st January, 1905, Telegrams may be accepted from the public on the following conditions:- "Subject to the Inland Regulations with regard to counting, the charge, which must be prepaid in the usual way by means of stamps, will be at the rate of 6 1/2d. [six-and-a-half pence] a word, with a minimum of 6s. 6d. [six-and-a-half shillings] per telegram. "The name of the wireless station will in each case pass as one word in the address. "The word 'Radio,' which is not charged for, should be telegraphed in the Service Instructions." When I read that, it made the hair stand up on the back of my neck. The introduction of a Wireless Telegram service, under the service heading of "Radio", with a photo of the actual document that introduced it into the world. I also learned that there's a dozen pennies in a shilling and over the years before decimalisation in 1971, the composition of coins changed, which made converting this into today's money interesting. As an aside, the Royal Society has a wonderful article: "The science of money: Isaac Newton's mastering of the Mint" Back to radio, this is 1904 bleeding edge technology and it's priced accordingly. The starting price for a radio telegram on new years day 1905: six bob and six; or three florin and sixpence; or a crown, a bob and a tanner; is worth just over 34 Great British Pounds today, that's just on 45 US Dollars, or nearly 69 Australian Dollars. That's the minimum price. The price per word, sixpence and halfpenny [sixpence hayp-ny] is just over 2 Great British Pounds today, nearly 4 US Dollars or almost 6 Australian Dollars. Compare that to the price of SMS, which started at about 21 cents here in Australia, today it's about 3 cents per message of 160 characters. This seems like a lucrative business to be in, but I digress, again. From my current, and ongoing research, it appears that until this point, the early 1900's, the word "radio" was always accompanied by another word, for example in this context, "radio telegraphy", another combination of the day is "radio active", as well as "radio tellurium", which today we know as polonium. Moving on, the response I received from the Postal Museum included other gems, including a reference to the "1904 Wireless Telegraphy Act", from the 15th of August, 1904, where I found something fascinating, from Section 2 paragraph 1: "Where the applicant for a licence proves to the satisfaction of the Postmaster-General that the sole object of obtaining the license is to enable him to conduct experiments in wireless telegraphy, a license for that purpose shall be granted, subject to such special terms, conditions and restrictions as the Postmaster-General may think proper, but shall not be subject to any rent or royalty." I think that's the birth of amateur radio licensing in the United Kingdom, right there. As an aside, because I cannot help myself, the definition for the expression "wireless telegraphy", is pretty interesting too, reminding me of a quote, variations going back to at least 1866, incorrectly attributed to Einstein that goes something like this: You see, wire telegraph is a kind of very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, and they receive them there. The only difference is that there is no cat. Seems that the drafters of the "1904 Wireless Telegraphy Act" had the same thing in mind when they wrote: "The expression 'wireless telegraphy' means any system of communication by telegraph as defined in the Telegraph Acts, 1863 to 1904, without the aid of any wire connecting the points from and at which the messages or other communications are sent and received" Now, as I said, I'm still working on this, because the word "radio" as a concept had to have been conceived before the Post Office...
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    7 mins
  • What do you call that .. radio?

    What do you call that .. radio?
    Nov 8 2025
    Foundations of Amateur Radio If you use a word often enough it starts to lose its meaning. The other day, during breakfast, well, coffee, whilst playing one of our start-the-day with a smile word games, the word "RADIO" turned up. I grinned and pointed out that this was my favourite word, to which my partner mentioned that in Italian, it's referred to as "La Radio", which made us both wonder where it actually came from, did the Italian language import the word, or export it, given that Guglielmo Marconi was Italian? A quick search advised us that it came from Latin, radius, meaning "spoke of a wheel", "beam of light" or "ray". Fully enlightened we finished our coffee and got on with our day .. except I couldn't stop thinking about this. Having recently spent some quality time looking into the history of the RF Circulator, I figured searching the patent records might be a solid way to get some handle on where this word "radio" came from. Initially Google Patent search unearths the oldest as being from 1996, not very helpful. Adding 1900 as the end date filter turns up a radio cabinet patent with a filing date of 1833, except that it was published and granted in 1931, which is confirmed by the patent itself. This level of corruption in the data affects at least a dozen patents, but I daresay that there's plenty more like that. 1857 turns up a patent with the word "broadcasting", in the context of "broadcasting guano", so, nothing much has changed in nearly 170 years, but I digress. Adding quotes to the search term unearths a patent from 1861, apparently iron roads, locomotives, large slopes and small radio curves relates to the other meaning of the word radius, in Spanish. 1863 gives us ruffle stitching, "made upon the radio", but the patent is so corrupt that it's pretty much unreadable. 1871 unearths an electromagnetic engine, but the text has so much gibberish that I suspect that the word "radio" is a happy accident. 1873 shows us a "Wireless signalling system", bingo, the patent shows us transmitter and receiver circuits, antennas, messages and frequencies and a whole bunch of relevant radio information, except that the date on the patent itself is 1919. And you wonder why people argue about who invented what when? I'll spare you the gas apparatus, petrol lamps with cigar cutter, running gear for vehicles and bounce to 1897, "Method of and apparatus for converting x-rays into light for photographic purposes", the first occurrence of "radio", in the form of "radiograph", complete with pictures of the bones of a hand drawn meticulously from presumably an x-ray. I confess I'm not convinced. Using the United States Patent and Trademark Office search for the word radio gives you 54,688 pages with 2.7 million records, ordered in reverse chronological order with no way to skip to the last page. The World Intellectual Property Organisation finds the same Spanish iron paths patents, but unearths "A Differential Arrangement for Radio Controlled Race Cars" from 1900, but inside we discover it's really from 1979. Seems this level of corruption is endemic in the patent field, wonder who's benefiting from this misinformation? Meanwhile, still looking, I discovered the Oxford English Dictionary, which claims that the earliest known use of the word "radio" is in the 1900's, but the earliest evidence is from 1907 in a writing by "L. De Forest", but you are granted the privilege of paying them to actually see that evidence .. really? On 18 July 1907, Lee de Forest, made the first ship-to-shore transmissions by radiotelephone, which adds some credence to the claim, but I have to tell you, I'm not particularly convinced. Taking a different approach, starting at Guglielmo Marconi, his first efforts in 1894 showed the wireless activation of a bell on the other side of the room. Six months later he managed to cross 3 kilometres realising that this could become capable of longer distances. The Italian Ministry of Post and Telegraphs didn't respond to his application for funding, so in 1896, at the age of 21, moving to Great Britain, he arrived in Dover where the customs officer opened his case to find various apparatus, which were destroyed because they could be a bomb. Lodging a patent "Improvements in Transmitting Electrical impulses and Signals, and in Apparatus therefor", was the first patent for a communication system on radio waves. It was granted a year later. One problem. It doesn't have the word "radio" in it, instead it talks about "a Hertz radiator", so close. So, we've narrowed it down to somewhere between 1896 and 1907, that's an 11 year window. Some observations. De Forest founded a company called "the Radio Telephone And Telegraph Company". It's unclear exactly when this happened, it collapsed in 1909 and was founded after disagreement with management of his previous company, apparently on 28 November 1906. A quick aside, apparently in 1881, Alexander Graham Bell used the word ...
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    8 mins
  • On the origins of the RF circulator

    On the origins of the RF circulator
    Nov 1 2025
    Foundations of Amateur Radio

    Recently I explored the use of a radio device aptly described by a fellow Aussie Electronics Engineer, "ozeng", as "Absolute witchcraft." .. I'm talking about an "RF circulator", one of which is sitting quietly on my desk, roughly 60 mm square, 30 mm thick, weighing in at just under half a kilogram, unexpectedly with a 200 year history.

    Let the spelunking commence ..

    The moment you start reading the "Circulator" Wikipedia page, you'll see this sentence: "Microwave circulators rely on the anisotropic and non-reciprocal properties of magnetised microwave ferrite material.", with a helpful reference to "Modern Ferrites, Volume 2: Emerging Technologies and Applications", a 416 page reference that promises to dig into the nitty-gritty, showing 55 hits for the word "circulator".

    Anisotropic you ask? It's the property that describes velvet, rub it one way, it's smooth, rub it the other way and the hair stands up on the back of your neck. Wood is another example, easier to split along the grain than across it.

    While we're at it, reciprocity in physics is the principle that you can swap the input and output of a linear system and get the same result.

    If you know me at all, it should come as no surprise that I went looking for an inventor. There's over twelve-thousand patents referring to a "circulator", including more than a handful relating to Nuclear reactors. In 1960, a prolific Jessie L Butler came up with patent US3255450A, "Multiple beam antenna system employing multiple directional couplers in the leadin", which states: "This circulator has the characteristic that energy into one port will leave another port to the exclusion of a third."

    If you recall, that's the exact phenomenon I used to describe the "RF circulator" on my desk.

    So, job done, we have our inventor. Not so fast. The patent goes on to say: "Circulators of this type are discussed in an article 'The Elements of Nonreciprocal Microwave Devices' by C.Lester Hogan in Volume 44, October 1956, issue of Proceedings of the IRE, pages 1345 to 1368." The IRE is the Institute of Radio Engineers.

    I found a copy of that tome, thank you worldradiohistory.com, which includes the following sentence: "Until a few years ago, all known linear passive electrical networks obeyed the theorem of reciprocity. Today several different types of passive nonreciprocal microwave networks are in practical use".

    A footnote refers to an article by Lord Rayleigh, "On the magnetic rotation of light and the second law of thermodynamics" and includes images of an optical one-way transmission system from 1901.

    In that 1901 article, Lord Rayleigh in turn refers to a paper published sixteen years earlier in which he observed that light polarisation can be made to violate the general optical law of reciprocity, using a system that consists of two so-called Nicol prisms, a crystal that can convert ordinary light into plane polarised light, invented by William Nicol in 1828. Using two prisms, arranged at a 45 degree angle, you can make light go through it in one way, but not the other.

    Lord Rayleigh, also known as John William Strutt, in a very sparse footnote, states: "That magnetic rotation may interfere with the law of reciprocity had already been suggested by Helmholtz."

    Further digging gets me to an 1856 publication of the "Handbuch der physiologischen Optik", or the handbook of the study of how the eye and brain work together, where Helmholtz says that, translated from German, "according to Faraday's discovery, magnetism affects the position of the plane of polarization."

    This gets us to 1845, where Michael Faraday experimentally discovered that light and electromagnetism are related. His notebook has the following sentence, paragraph 7718 written on the 30th of September 1845: "Still, I have at last succeeded in illuminating a magnetic curve or line of force and in magnetising a ray of light."

    Today we call that the "Faraday effect"

    The best part?

    You can read Michael Faraday's diary, right now, and see the whole thing.

    So, who then invented the RF circulator?

    From Mastodon to Circulators, to Modern Ferrites, to Nonreciprocal Microwave Devices, to Multiple beam antennas, to Magnetic Rotation, to Optical Reciprocity, to Nicol prisms, to the Faraday effect, this is the perfect example of standing on the shoulders of giants, and the result sits as a little box on my desk.

    Just so you don't feel left out, your mobile phone likely has one of these devices on board.

    I'm Onno VK6FLAB
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    6 mins
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