Category Archives: Antennas

Sometimes the right tools lead to agreeable results

By Jock Elliott, KB2GOM

Listening to the HF ham bands can be a lot of fun. All you need is a shortwave receiver capable of receiving single sideband (SSB) transmissions and a chart of the amateur bands. You can find downloadable PDF charts of the United States Amateur Radio Band Plan here or a detailed explanation of the band plan here.

Tuning around to hear what people are talking about can be enlightening. You might hear hams chatting about ham radio equipment, house repair projects, religious discussions, news and views or the state of the country, disaster response communications, or almost anything.

Recently I was tuning through the 80 meter ham band when, at 3605 LSB, I encountered a group having a conversation. I couldn’t tell if this group had a formal “Net” name, but I did get the impression that they met regularly in the early morning on that frequency, so I made a note to revisit the frequency.

Yesterday, I did so. With the horizontal room loop hooked to my Grundig Satellit 800, all I could hear was noise. The same with the whip antenna on the Satellit 800.

But when I engaged the MFJ 1886 loop antenna I could clearly hear the group talking above the noise . . . but the noise was still pretty bad. So I tried bringing the MFJ 1045C active preselector online, to no avail. The 1045C did not make the conversation easier to hear.

The noise was like a hum, not a nice gentle hum like a bumble bee flying by; no this was a nasty, raspy hum, like a circular saw trying to get purchase on a particularly tough piece of wood. Listening to the chat group on 80 meters with that noise under it would be tiring on the ears.

Soooo, what to do? Then I plugged in the BHI Compact In-line Noise Eliminating Module into the headphone socket of the Satellit 800 and then plug headphones into the BHI device.

Turning on the BHI module, I adjusted the level of noise reduction, and – tah dah! – the noise just melted away. I could hear the conversation clearly, and all that was left of the noise was the trickling water sound that is an artifact of the noise reduction algorithm.

Sometimes, the right gear just works.

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Testing the MFJ-1886 Receive Loop Antenna

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By Jock Elliott, KB2GOM

Hang out any place online where shortwave listeners gather, and you won’t have to wait long before you hear something like this: “I recently moved to a condo, apartment, or house where there is a home-owners association. Listening conditions are pretty rotten, and I cannot string up outdoor antennas because of physical constraints or HOA rules . . . help!”

Ever since I got back into SWLing nearly two years ago, I have faced similar issues, as I explained here. During that time, I have frequently read that amplified small loop antennas work pretty darn well, and that has piqued my curiosity.

A couple of days ago, the good folks at MFJ (an SWLing.com sponsor) sent me their MFJ-1886 receiving loop antenna. Weighing just 2.5 pounds, the 1886 is a 36-inch-diameter loop of aircraft-grade with an amplifier attached in a weatherproof enclosure. Designed for receiving only, it covers .5 to 30 MHz.

The fit and finish of the 1886 is, in my opinion, great. Looking at the seamless loop and the molded enclosure for the amplifier, I have no reason to doubt what MFJ has to say about it: the MFJ-1886 is weather-sealed, very ruggedly constructed, and mechanically stable under all weather conditions. In fact, you can mount it permanently on any inexpensive TV rotor and direct it from the comfort of your shack . . . it also installs easily on a tripod or handheld mast for portable use.

From MFJ’s manual for the 1886 loop.

Important: the 1886 loop is a directional antenna. If you are looking through the open area in the middle of the loop (the flat side, if you will), you are looking in the direction in which the antenna tends to null out signals . . . in both directions. If you are sighting along the edge of the loop (at right angles to the flat side), that is the direction in which the antenna produces the most gain. As a result, you will get the most utility out of the 1886 if you can mount it in such a way that you can rotate it to maximize gain and/or null out noise or interfering signals as needed.

Since my mission was to test the 1886 indoors, I wrapped some parachute cord around the loop and hung it from a screw attached to the top of a window frame. Obviously, I am not getting the most from the 1886 by keeping it in a fixed position (in fact, I was getting maximum gain to the northeast and the southwest), but I did experiment with the antenna hanging from the ceiling so that it could rotate, and I did, indeed, find that signal strength rose and fell as the antenna changed position.

To see how the 1886 performed, I used my Grundig Satellit 800 as a test bed. The Satellit 800 has three different antenna inputs: a wire input, to which I attached the 50-foot horizontal room loop (an indoor antenna which runs around the perimeter of my radio room at about seven feet in the air); a coax input, to which I attached the MFJ 1886 loop, and the four-foot whip antenna that is built into the Satellit 800. By reaching around the back of the radio and sliding the antenna selection switch, I could easily change from one antenna to another and compare the 1886 loop with the whip and the horizontal room loop at various frequencies and settings.

Setting up the 1886 loop is super easy. First, attach a length of coax to bottom of the amplifier box. (The 1886 uses SO-239 connectors.) Attach that coax to the top of the Bias Tee. The Bias Tee supplies power to the amplifier mounted on the loop using the coax and without introducing noise. Run another piece of coax from the bottom of the Bias Tee to the receiver, and, finally, plug the power supply into the Bias Tee and the house power where you are using the antenna.

Operating the 1886 is even easier. To hear the signal from the loop without amplification, leave the Bias Tee switch in the OFF position. To hear the signal with amplification, just slide the switch to the ON position. That’s all there is to it. There are no fussy adjustments to make.

So how did the 1886 loop perform? Very well, thank you. In all cases, it clearly outperformed the Satellit 800’s whip antenna, providing more signal with less noise. When pitted against the 50-foot horizontal room loop wire antenna, the 1886 typically delivered more signal and less noise. In a few instances, the horizontal room loop was equal to the 1886 loop in terms of signal strength and low noise. In no cases, did the horizontal room loop outperform the 1886 loop.

Tuning around a bit, I found myself listening to a ham from Spain working DX on the 15 meter band. A little further up the band, a ham from central Bulgaria was dealing with a pile-up of U.S. hams trying to reach him. Of the three antennas options I had on the Satellit 800, the 1886 loop offered the most pleasant listening with more signal, less noise.

Then I tried the 1886 with a couple of my portable shortwave receivers. The Bulgarian ham was still on the air and was marginal on one portable and not hearable at all on the other on their native whip antennas. With the 1886 loop connected, however, the Bulgarian was clear and easy to hear. And – thanks to a ham friend who whipped up an additional coax “jumper” with amazing speed – I tried the 1886 loop with the MFJ 1045C active preselector and found the two made a very potent combo for pulling signals out of the mud.

So, would I recommend the MFJ 1886 Receiving Loop for a would-be HF listener who lives in a condo, apartment, or house with antenna woes? Absolutely . . . even if you have to hang it flat in front of a window. And if you can find a way to mount it so that it can be rotated, even better. (Someday, I hope to try the 1886 outside mounted on an inexpensive TV rotator. For now, there simply isn’t room in my cramped radio space.)

Of course, the performance at your location will depend on the conditions where you live. Nevertheless, I found the MFJ 1886 Receiving Loop to be easy to set up, easy to use, and effective.

Click here to check out the MFJ-1886 Receiving Magnet Loop Antenna at MFJ.

Suggestions for MFJ: offer a kit or accessory that would be make it easy to set the 1886 on a desk or table. Likewise a kit or accessory that would facilitate using the 1886 on a camera tripod seems like a good idea.

Additional note: The SWLing forum is a great place for discussing all things related to shortwave listening.

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

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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Chameleon RXL-Pro code for the SWLing Post

IARPA challenged to give small antennas higher gain

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(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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Giuseppe Demonstrates his homemade “Minimal Long-Distance Dipole”

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

Dear Thomas and Friends of the SWLing Post,

I’m Giuseppe Morlè from Formia, central Italy on the Tyrrhenian Sea.

This time I want to show you 2 QRP connections made with minimal antenna over long distance and very few watts of power…

The antenna is a simple dipole, 5 meters per arm, 1/4 wave for 20 meters, on a bnc / banana socket directly on the Icom 705. You’ll see that the ROS is really optimal.

I wanted to experience this very simple antenna, easy to prepare in this location surrounded by greenery, Monte Orlando Park in Gaeta on my favorite DX bench;
this location is at 120 meters above sea level and facing south / west following the long path. A suitable place for the extreme right made especially for a receiver like the Icom 705– fantastic modulation and without any kind of noise.

In the first video the contact with VK2GJC, Greg from Australia who struggles a little to listen to me but immediately understands my name. As you can hear Greg’s voice is without any imperfection even if his signal is not that high:

In the second video, another link with Australia, VK5AVB, Tony from Kangaroo Island.
Tony had a hard time understanding my name but with the help of Nicola, IU5EYV from Tuscany, in pure Ham Spirit, he finally managed to log me:

As you can see, even with very minimal antennas hoisted on nearby trees, not even high from the ground, you can listen and contact over long distances … that’s why I love this place so much!

Thanks to you all, a cordial greeting from Italy.

Many thanks, once again, Giuseppe for showing us just how much fun we can have by building our own antennas and hopping on the air with very little power. I must say: you certainly play radio in a beautiful part of the world! Thank you!

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