Tag Archives: Antennas

Giuseppe experiments with mediumwave loop induction

Many thanks to SWLing Post contributor, Giuseppe Morlè (IZ0GZW), who writes:

Dear Thomas and all friends of the SWLing Post,

I’m Giuseppe Morlè from Formia on the Tyrrhenian Sea…

I wanted to share this experiment of mine with all of you by tuning the medium waves with two separate loop cassettes and each for itself by exploiting the principle of induction between two conductors placed next to each other.

I superimposed one cassette on the other by matching the windings of the medium waves–each variable works only for its own box.

I’m tuning the Algerian JIL FM station on 531 kHz with the Tecsun H-501X connected to the box below…then, passing to the top box, the one without any physical contact with the receiver, I tuned this station again centering it perfectly thanks to the induction that creates between the two close windings.

My video will clarify any doubts and I would like to receive your comments about it.

My constructions are the result of continuous recycling and spending very little to get a good yield.

You can view this video below or on my Youtube channel:

[Note that you can translate this video into your language via YouTube’s automatic subtitles. Click here to learn how to do this.]

I’m available for any clarification…
Thanks to all of you and I wish you good listening.
73. Giuseppe Morlè iz0gzw.

Thanks so much for sharing your antenna experiments with us, Giuseppe! 

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Giuseppe upcycles and improves a homebrew MW antenna

Many thanks to SWLing Post contributor, Giuseppe Morlè (IZ0GZW), who shares the following:

Dear Thomas and Friends of SWLing Post …

This is Giuseppe Morlè. As always, I try recycling what I have and improving upon antennas I’ve built in the past. This is one way we radio lovers can experiment. Many years ago, I made an antenna only for medium waves; by adding a circuit, I can now listen to short waves.

I took advantage of a small frame that I recovered from an old commercial FM / AM stereo receiver by removing its coils for medium waves and I wound around it only two coils sufficient to have a frequency range from 3.5 to 18 MHz.

I remember that the antenna in question also receives medium waves as it was born.

I chose this small frame because I wanted everything to be small in order to carry this compact antenna everywhere.

Unlike my other projects for SW and MW, which have a cable that carries the SW signal to the receiver, this time I used the induction that is created around one end of the loop, which I spiraled to get inside the stylus of my Tecsun PL-660 and which then transfers the signal to the receiver.

I did some tests on my balcony the day after a strong storm and I noticed that the propagation was absent but I still wanted to make sure that everything was working.

[Note that you can translate this video into your language via YouTube’s automatic subtitles. Click here to learn how to do this.]

I will keep you updated on other tests on more favorable days of propagation … I still invite you to follow me on my Youtube channel.

I wish everyone a good listening …
73. Giuseppe Morlè iz0gzw.

Many thanks, Giuseppe. I, for one, love all of your homebrewed and recycled antennas. This one is no exception! What a fun project. I love how you use what you have and aren’t afraid to experiment! Thank you for sharing.

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Radio Waves: Antenna ID, DRM Receiver Requirements Revisited, BBC Broadcasting Technology, and Digital Sound Broadcasting Framework in Kenya

Radio Waves:  Stories Making Waves in the World of Radio

Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!


Identify that antenna by sight (Hackaday)

It’s a skill that radio amateurs pick up over years but which it sometimes comes as a surprise to find that is not shared by everyone, the ability to casually glance at an antenna on a mast or a rooftop and guess what it might be used for. By which of course I mean not some intuitive ability to mentally decode radio signals from thin air, but most of us can look at a given antenna and immediately glean a lot of information about its frequency and performance. Is this privileged knowledge handed down from the Elmers at the secret ceremony of conferring a radio amateur’s licence upon a baby ham? Not at all, in fact stick around, and I’ll share some of the tricks. [Continue reading…]

Minimum Receiver Requirement Document Revisited (DRM Consortium)

The latest version of the document (mrr.drm.org) describes the DRM (Digital Radio Mondiale) receiver characteristics for consumer equipment intended for terrestrial reception operating in the frequency bands below 30 MHz (i.e. DRM robustness modes A to D) and also those for the frequency bands above 30 MHz (i.e. DRM robustness mode E). The goals of the document are to: provide guidelines to receiver manufacturers for minimum receiver performance and technical features, to offer confidence to broadcasters that their DRM transmission can be received by all receivers in the market, to assist broadcasters to plan their network and to give full confidence to consumers that all important DRM features are supported by receivers and all DRM transmissions can be received when they acquire a digital DRM receiver.

Click here to download (PDF).

BBC broadcast tech: then and now (Engineering and Technology)

In its centenary year, we look at the BBC’s pivotal role in making the broadcast and radio technology field what it is today.

Daily London broadcasts by the newly formed British Broadcasting Company began from Marconi House on The Strand, on 14 November 1922, using the call sign 2LO, with transmissions from Birmingham and Manchester starting on the following day.

The first broadcast by the young company, which was heard as grainy, muffled speech, was read by Arthur Burrows, who joined the BBC as director of programmes. Notably, he was one of the first people to move from newspaper to broadcast reporting.

At the end of 1922, Scottish engineer John Reith, who was just 33 years old at the time, was appointed general manager of the BBC, which then had a staff of four. Reith is remembered for establishing the tradition of independent public service broadcasting in the United Kingdom.

Within months, the growing organisation moved into the same building as the Institution of Electrical Engineers at Savoy Hill (now the IET’s Savoy Place event venue), where it continued to expand. This was an obvious home for the young BBC, and for the next nine years this is where early innovations of broadcasting occurred.

The British Broadcasting Corporation, as it is known today, was established in January 1927 as a public corporation, and in 1934 it moved from Savoy Hill to the purpose-built Broadcasting House in Portland Place. [Continue reading…]

CA plans digital radio shift on shortage of frequencies (Business Daily Africa)

Kenyan broadcasters will be allowed to adopt a new digital radio standard, which will enable them to use their current spectrum to transmit their signals through a digital network, as the sector regulator moves to address the shortage of analogue frequencies.

The Communications Authority of Kenya (CA) has called for stakeholder and public views on a draft Digital Sound Broadcasting (DSB) framework it has formulated to ensure the efficient use of the available broadcasting spectrum and encourage investment in the sub-sector.

“The objective of this consultation is to develop a suitable framework for Digital Sound Broadcasting in Kenya to address the challenge of high demand and low availability for analogue FM broadcasting frequencies that is currently being experienced,” said the CA. [Continue reading…]


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Radio Waves: Cellular Scale Antennas, Space Comms, New Proposed Ham License in Australia, and Mid Century Television

Apollo 11 (Photo: NASA)

Radio Waves:  Stories Making Waves in the World of Radio

Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!


New miniature antenna can operate wirelessly inside of a living cell (Tech Explorist)

An intracellular antenna that’s compatible with 3D biological systems and can operate wirelessly inside a living cell.

A new study could allow scientists to create cyborgs at a cellular scale, thanks to MIT Media Lab for designing a miniature antenna that can operate wirelessly inside a living cell. This could have applications in medical diagnostics, treatment, and other scientific processes because of the antenna’s potential for real-time monitoring and directing cellular activity.

Scientists named this technology Cell Rover. It represents the first demonstration of an antenna that can operate inside a cell and is compatible with 3D biological systems.

Deblina Sarkar, assistant professor and AT&T Career Development Chair at the MIT Media Lab and head of the Nano-Cybernetic Biotrek Lab, said, “Typical bioelectronic interfaces are millimeters or even centimeters in size and are not only highly invasive but also fail to provide the resolution needed to interact with single cells wirelessly — especially considering that changes to even one cell can affect a whole organism.”

The size of the newly developed antenna is much smaller than a cell. The antenna represented less than .05 percent of the cell volume in research with oocyte cells. It converts electromagnetic waves into acoustic waves, whose wavelengths are five orders of magnitude smaller, representing the velocity of sound divided by the wave frequency — than those of the electromagnetic waves. [Continue reading…]

Space Audity (20,000 Hertz Podcast)

This episode was written and produced by Jack Higgins.

We’ve all heard the iconic recordings from the Apollo missions. But how exactly does NASA manage to run live audio between Earth and the moon? And how might we chat with astronauts on Mars and beyond? Featuring Astronaut Peggy Whitson, NASA Audio Engineer Alexandria Perryman, and Astrophysicist Paul Sutter.

Click here to listen on the 20,000 Hertz webite.

Australia: Proposed new ham radio licence (Southgate ARC)

Australia’s communications regulator ACMA has asked radio amateurs to comment on their proposed amateur class licence and considerations for higher power 1 kW operation

The ACMA say:

Following the extensive 2021 public consultation and associated response to submissions, we have released a consultation paper on the proposed amateur class licence and supporting operational arrangements, along with considerations for higher power operation. This is the next step in our review of regulatory arrangements for the operation of non-assigned amateur stations.

The draft class licence for amateur radio has been amended to incorporate changes suggested by representative bodies, amateur radio clubs and individual amateurs during the 2021 consultation.

The consultation paper, proposed class licence and details about how to make a submission are available on the ACMA website
https://www.acma.gov.au/consultations/2022-09/proposed-amateur-class-licensing-arrangements-and-higher-power-operation-consultation-312022

Submissions close COB, Tuesday 29 November 2022.

Questions about the consultation
If you have an important question about this consultation, please send it directly to [email protected]. Please note, we may use the Amateur radio update e-bulletin to answer frequently asked questions.

Subscribe to the ACMA Amateur Radio newsletter at
https://www.acma.gov.au/subscribe-our-newsletters

Mid Century Television – live, local and unpredictable late 1950s television (Southgate ARC)

In the late 1950s television networks ruled the airwaves from 7 to 11 PM, but outside of that timeslot television was live, local and unpredictable.

Jim Hanlon, W8KGI,  worked as a summer relief engineer at Cincinnati’s WCPO-TV from 1956 to 1958. At that time WCPO-TV did not have any video recording technology, so all local TV was live TV and provided a refreshing dose of live programming, equipment failures and production creativity that been lost in today’s pasteurized, homogenized TV ecosystem.

Join Jim as he recalls what it like producing live TV programming in the early days of television broadcasting.

Click here to view on YouTube.

Help keep communications history alive by becoming a member of the Antique Wireless Association at: https://www.antiquewireless.org/homepage/


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IARPA challenged to give small antennas higher gain

(Source: IEEE Spectrum via Dennis Dura)

A Four-Year Program to Tackle a Fundamental Antenna Challenge — IARPA hopes to break past an 80-year-old limit on making small radio antennas more effective

For 80 years, a class of antenna called electrically small antennas has been stymied by a seemingly insurmountable barrier. These antennas, which can receive signals with wavelengths that are much longer than the antennas themselves, are seemingly stuck with designs in which there is a trade-off between high bandwidth and efficiency.

Now, a new program by the U.S. Intelligence Advanced Research Projects Activity (IARPA) agency seeks ways to finally circumvent or overcome these historical limitations for electrically small antennas. Over the next four years, the research teams participating in the Effective Quantitative Antenna Limits for Performance (EQuAL-P) program will work through three phases of progressively more ambitious benchmarks in order to prove their ideas can work.

The simplest form of antenna is a dipole antenna, which is essentially just two pieces of wire placed end to end with a feed point in the middle. The length of this antenna is typically half the wavelength of the signal that is being received or transmitted, so a shortwave radio dipole working in the 20-meter band would be 10 meters long. An “electrically small” antenna is one that is significantly shorter than the wavelength of the signals it is designed for. These antennas typically take the form of small loops or patches.

The benefit of electrically small antennas is clear—as the name implies, they confer an advantage when space is at a premium. Satellites, for example, can use them to reduce mass and free up more space for other components.

But the trade-off with electrically small antennas is that as they get shorter, their bandwidth and radiation efficiency also shrink, eventually hitting something named the Chu-Harrington limit. This has meant that although such antennas have been in use for decades, they remain difficult to design and limited in their applicability. Historically, any attempts to widen the usable bandwidth have decreased these antennas’ radiation efficiency even more, and vice versa. This is the problem the EQuAL-P program is aimed at.

“Because it’s an 80-year problem, we want to give them a little more time to come up with solutions,” says Paul Kolb, the program manager for EQuAL-P. The eight teams participating will work through three increasingly ambitious phases during the next four years to prove their ideas can pass muster.

At the end of 18 months, Kolb says, he hopes to see that the teams have made meaningful progress toward the ultimate goal of a 10-decibel gain in antenna performance in the HF and ultrahigh frequency (UHF) bands. But because of the difficulty of the challenge, teams won’t be required to produce a working demonstration of their technology at that point. [Continue reading full article at the IEEE spectrum…]

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Small Unidirectional Loop Antenna (SULA) Part 3: Questions & Answers

Many thanks to SWLing Post contributor extraordinaire, 13dka, who brings us Part Two of a three part series about the new SULA homebrew antenna project. This first article describes this affordable antenna and demonstrates its unique reception properties. The second article focuses on construction notes. This third and final article will essentially be a Q&A about the SULA antenna. 

This wideband unidirectional antenna is an outstanding and innovative development for the portable DXer. I love the fact that it came to fruition via a collaboration between Grayhat and 13dka: two amazing gents and radio ambassadors on our SWLing.net discussion board and here on the SWLing Post. So many thanks to both of them!

Please enjoy and share Part 3:


Part 3: SULA Q&A

by 13dka

Q: Where can I ask questions, discuss all aspects of the the SULA or collaborate in its further development?

A: There is a thread dedicated to the SULA in the new SWLing.com message board: https://swling.net/viewtopic.php?t=55

Q: Since the antenna is “lossy”, what’s the point of having a “beam”?

A: The answer is once again “SNR”: First off, remember that the LNA is there to make up for most of the losses. Secondly, this is all about the noise pickup, 20dB less gain/more losses outside the main lobe means also a reduction of atmospheric/cosmic/whatnot QRN and of course everything manmade from all these sides. The wide horizontal lobe is more or less one hemisphere horizontally, but the flat-ish vertical pattern makes that only a slice of it. In other words, there will be less QRN and QRM pickup from the back and the top. The idea is that the SNR will ideally increase more than the preamp’s noise figure will cost and it often sounds like this is what actually happens. Of course it’s also nice that you can turn an unwanted signal down using the more or less pronounced notch in the backside pattern up to 21 MHz – also very helpful for direction finding.

Q: Do I need a rotor?

A: It depends. If you are one of the lucky few still having a low-QRM-environment at home and you want to put it in the backyard, you really may want to be able to turn it remotely. If you’re using it portable you can simply rotate the mast manually. If you have local QRM or can’t mount it very far away from your or other houses, you may want to rotate the back of the antenna towards that source, leave it at that position forever and enjoy what’s coming in on the pretty wide main lobe of the antenna. The horizontal lobe covers more or less half of the horizon, depending on your stations of interest and location you could get away with never turning the antenna at all.

Q: Is it better than the XYZ loop?

A: Hey, that’s exactly what I wanted to ask you! 🙂 Even though the SULA is very similar in appearance and performance to a good SML working in ideal (ground conductivity) conditions, the SULA is a pretty different animal with a different behavior: Regular small loops, besides being bidirectional, can lose quite a bit of their low angle sensitivity over “poor” ground while the SULA is supposed to be retaining its properties better over any type of ground. Also, while many SMLs are tuned for VLF through the lower portion of the shortwave, the SULA complements those with quite uniform (good) properties up to 30 MHz and beyond.

Q: I have an end-fed random wire or dipole strung up from the house to a tree etc. – can the SULA beat that?

A: That’s quite possible. To get low takeoff angles from horizontal wire antennas you need to string them up at least 1/2 wavelength high, that’s 20m/66ft on 40/41m, 10m/33ft on 20m and so on. If you can’t do that, the SULA may be your ticket to listen farther beyond the horizon. Also, wire antennas are often strung up to match space restrictions or avoid QRM vectors and that way you may end up with some directionality in directions you don’t want, or no directionality at all when the wire is too low. Another noteworthy point is the ground: For most horizontal antennas, better ground means a considerable higher takeoff angle so the dipole needs even more height for low angles. The SULA’s takeoff angle benefits a little from the better ground and only gets a little worse over poor ground.

Q: Do I really need an LNA?

A: I hope so? Of course it depends… if you are going to try this antenna in a very noisy environment, the LNA may have little to no benefit. The noise is limiting your “radio horizon” to very loud signals anyway and for those you may not need an LNA, ever. On the other hand, the antenna is very lossy and in a quiet environment where noise is not an issue at all, weak signals may drop below the sensitivity threshold of your receiver without the LNA. The less noise you have, the more you’ll be able to benefit from an LNA. You will also need one when your radio isn’t all that sensitive, similar to the requirements to run a YouLoop. Andrew kept the loop impedance as constant as possible in order to allow any low impedance coax preamp to work behind the Balun. Any LNA with 20dB of gain should do, as per usual, better stuff may bring better results.

Among the sparse offers for decent shortwave LNAs, the NooElec LANA HF seems to be the only decent LNA sold via Amazon. It’s comparatively low-cost and unlike the other offers on Amazon, ready to be powered via Bias-T or even via Micro-USB and therefore happy with 5V. Since I also had the balun from the same company I could simply connect that all with a couple of these cute little SMA plumbing bits and it worked. The downside is its unknown but perceivably low resilience against intermodulation (low 3rd-order intercept point), this is usually not a problem with such a small loop but it can be in the presence of nearby transmitters.

If you do have nearby transmitters and don’t mind sourcing an LNA from Europe, Andrew recently pointed me to preamps from here. They offer a moderately priced preamp with a 2N5109 transistor (based on the W7IUV design) for a high IP3 value and low noise, which is also available in PCB-only and fully assembled versions including a compartment. They also offer Bias-T boxes.

Q: What is special/different about this antenna? There are already very similar designs!

A: It’s supposed to be simpler and more compact/portable, and it seems to deliver more consistent results over the entire coverage range in different usage environments than similar designs. The SULA was designed to be made with things that are particularly easy to obtain, or which were already obtained — many of us SWLs have some of that Nooelec stuff in our drawer anyway, even when (or because) we’re not habitual antenna builders and balun winders. Now making a better balun and buying a better preamp is not hard and could even bring better results but the point is that you don’t have to. In summary, this is not meant to be a miracle antenna, just number of compromises re-arranged to create a particularly uncomplicated, small, unidirectional loop antenna that aims for DX, for apartment dwellers and DX nomads like me.

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Small Unidirectional Loop Antenna (SULA) Part 2: Construction Notes

Many thanks to SWLing Post contributor extraordinaire, 13dka, who brings us Part Two of a three part series about the new SULA homebrew antenna project. This first article describes this affordable antenna and demonstrates its unique reception properties. This second article focuses on construction notes. The third and final article will essentially be a Q&A about the SULA antenna. All articles will eventually link to each other once published.

This wideband unidirectional antenna is an outstanding and innovative development for the portable DXer. I love the fact that it came to fruition via a collaboration between Grayhat and 13dka: two amazing gents and radio ambassadors on our SWLing.net discussion board and here on the SWLing Post. So many thanks to both of them!

Please enjoy and share Part 2:


Part 2: SULA Construction notes

by 13dka

The drawing [above] has all you need to know. You basically need to put up a symmetrical wire diamond starting with a balun at the one end and terminating in a resistor at the other end of the horizontal boom, the sides are supposed to be 76cm/29.92″ long so you need to make yourself some…

Support structure:

I used 0.63″/1.6cm square plastic square tubing/cable duct profiles from the home improvement market to make the support structure. You can use anything non-conductive for that of course, broom sticks, lathes… The plastic profiles I used had the advantage of being in the house and easy to work on with a Dremel-style tool and everything can be assembled using the same self-tapping screws without even drilling. The profiles are held together with 2 screws, for transport I unscrew one of them and put that into an extra “parking” screw hole on the side, then I can collapse the cross for easy fit into the trunk, a rucksack etc.

These profiles are available in different diameters that fit into each other like a telescoping whip. This is useful to make the support structure variable for experiments and to control the loop shape and tension on the wire. The booms end up at 1.075m each, the profiles come in 1m length, so that’s 4 short pieces of the smaller size tube to extend the main booms by 37mm on each side

On the resistor end of the loop that smaller tube isn’t mounted in the “boom” tube but to the side of it in order to keep the wire running straight from the balun box on the other side.

Mast/mounting:

You can use anything non-conductive to bring it up to height. On second thought that is indeed bad news if you were planning on putting that up on your metal mast…and we have no data on what happens when you do it anyway. I don’t know if the smallest (4m) telescoping fiberglass poles would suffice for portable operation, but I’m a fan of just using the big lower segments of my 10m “HD” mast for the stiffness they give me (3 segments for the height, the 4th collapsed into in the base segment for easy rotation). Telescoping masts also give you easy control over…

Height:

The published patterns are for 3m/10′ feedpoint height over “average” ground. Increasing height further has no expectable advantage, instead it will deteriorate the favorable directional pattern of the loop. Flying it lower, or even a lot lower in windy weather on the other hand is causing a surprisingly moderate hit on performance.

Continue reading

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