Category Archives: Antennas

Radio Waves: DRM Part of BBC Story, Antennas and Smith Charts, Shortwave “Hot Debate,” Carrington Event, and “Deep Freeze”

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!

DRM Is Part of the BBC World Service Story (Radio World)

The iconic broadcaster has been supportive of the standard for over 20 years

The author is chairman of the DRM Consortium. Her commentaries appear regularly at radioworld.com.

Our old friend James Careless studiously ignores DRM once more in his well-researched, but to our minds incomplete article “BBC World Service Turns 90” in the March 30 issue.

As an ex-BBC senior manager, I would like to complete the story now that the hectic NAB Show is over.

Having lived through and experienced at close quarters the decision to reduce the BBC shortwave about 20 years ago, I can confirm that the BBC World Service decision to cut back on its shortwave footprint — especially in North America, where reliable, easy-to-receive daily broadcasts ceased — has generated much listener unhappiness over the years.

In hindsight, the decision was probably right, especially in view of the many rebroadcasting deals with public FM and medium-wave stations in the U.S. (and later other parts of the world like Africa and Europe) that would carry news and programs of interest to the wide public.

But BBC World Service in its long history never underestimated the great advantages of shortwave: wide coverage, excellent audio in some important and populous key BBC markets (like Nigeria) and the anonymity of shortwave, an essential attribute in countries with undemocratic regimes.

BBC World Service still enjoys today about 40 million listeners worldwide nowadays. [Continue reading…]

The Magic of Antennas (Nuts & Volts)

If you really want to know what makes any wireless application work, it is the antenna. Most people working with wireless — radio to those of you who prefer that term — tend to take antennas for granted. It is just something you have to add on to a wireless application at the last minute. Well, boy, do I have news for you. Without a good antenna, radio just doesn’t work too well. In this age of store/online-bought shortwave receivers, scanners, and amateur radio transceivers, your main job in getting your money’s worth out of these high-ticket purchases is to invest a little bit more and put up a really good antenna. In this article, I want to summarize some of the most common types and make you aware of what an antenna really is and how it works.

TRANSDUCER TO THE ETHER
In every wireless application, there is a transmitter and a receiver. They communicate via free space or what is often called the ether. At the transmitter, a radio signal is developed and then amplified to a specific power level. Then it is connected to an antenna. The antenna is the physical “thing” that converts the voltage from the transmitter into a radio signal. The radio signal is launched from the antenna toward the receiver.

A radio signal is the combination of a magnetic field and an electric field. Recall that a magnetic field is generated any time a current flows in a conductor. It is that invisible force field that can attract metal objects and cause compass needles to move. An electric field is another type of invisible force field that appears between conductors across which a voltage is applied. You have experienced an electric field if you have ever built up a charge by shuffling your feet across a carpet then touching something metal … zaaapp. A charged capacitor encloses an electric field between its plates.

Anyway, a radio wave is just a combination of the electric and magnetic fields at a right angle to one another. We call this an electromagnetic wave. This is what the antenna produces. It translates the voltage of the signal to be transmitted into these fields. The pair of fields are launched into space by the antenna, at which time they propagate at the speed of light through space (300,000,000 meters per second or about 186,000 miles per second). The two fields hang together and in effect, support and regenerate one another along the way. [Continue reading…]

Smith Chart Fundamentals (Nuts & Volts)

The Smith Chart is one of the most useful tools in radio communications, but it is often misunderstood. The purpose of this article is to introduce you to the basics of the Smith Chart. After reading this, you will have a better understanding of impedance matching and VSWR — common parameters in a radio station.

THE INVENTOR
The Smith Chart was invented by Phillip Smith, who was born in Lexington, MA on April 29, 1905. Smith attended Tufts College and was an active amateur radio operator with the callsign 1ANB. In 1928, he joined Bell Labs, where he became involved in the design of antennas for commercial AM broadcasting. Although Smith did a great deal of work with antennas, his expertise and passion focused on transmission lines. He relished the problem of matching the transmission line to the antenna; a component he considered matched the line to space. Continue reading →

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The Satellit 800, the Tecsun PL-880, and two indoor antennas – an afternoon of experimentation

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Many thanks to SWLing Post contributor, Jock Elliott, who shares the following guest post:

The Satellit 800, the Tecsun PL-880, and two indoor antennas – an afternoon of experimentation

By Jock Elliott, KB2GOM

A search for “shortwave listening antennas” on the internet landed me on the page for the Par EndFedz® EF-SWL receive antenna, which is a 45-foot end-fed wire antenna connected to a wideband 9:1 transformer wound on a “binocular core” inside a UV-resistant box. A link on the page invited me to check out the eHam reviews of this antenna, which are here. What struck me is that there are just page after page of 5 star reviews of this antenna. Hams and SWLs apparently just love it. (If you want to buy of these antennas, they are now sold by Vibroplex and can be found here.)

As I reached for my credit card, I remember that I had an LDG 9:1 unun transformer lying around and some wire left over from the Horizontal Room Loop project. Maybe I could create my own end-fed SWL antenna by wrapping the wire around the perimeter of the room, attaching it to the 9:1 unun and then by coax to the back of my Grundig Satellit 800.

So I did exactly that. The wire for new end-fed antenna travels the same route around the perimeter of the room as the horizontal room loop. The main differences between the two antennas are that the end-fed is not a loop, and it terminates in the 9:1 transformer, which, in turn, feeds the Satellit though a coax cable. But in essence, we’re talking about two indoor wire antennas that are the same length and laid out along the same path about 7 feet in the air around the interior of the 8-foot by 12-foot room that serves as a library and radio shack: the horizontal room loop and the indoor end-fed.

The Satellit 800 has three possible antenna inputs: the very tall built-in whip antenna, two clips on the back of the 800 where the horizontal room loop attaches, and a pl-239 coax connector where the new end-fed antenna attaches. In addition, there is a three-position switch that allows me to quickly switch from one antenna to another.

Tuning up on the WWV time stations on 5, 10, 15, and 20 MHz and sliding the switch on the back of the Satellit 800 among the three different positions, I quickly found that the whip antenna was the noisiest of the three choices and offered the poorest signal-to-noise ratio. The comparison between the horizontal room loop and the indoor end-fed antenna was very, very close. While the horizontal room loop was quieter, it seemed to me that the signal offered by the indoor end-fed antenna was the tiniest bit easier to hear, so I decided to leave the Satellit 800 hooked up to the indoor end-fed antenna.

The 100-foot indoor end-fed antenna

Then I did something I had wanted to do for quite a while: I disconnected the horizontal room loop from the back of the Satellit 800 and attached one end of the wire to the indoor end-fed. So now, I had a roughly 100-foot end-fed antenna wrapped twice around the room.

Before we proceed any further, you need to understand this: my comprehension of antenna theory is essentially nil. As the old-timers would have it: you could take the entirety of what I understand about antenna theory, put it in a thimble, and it would rattle like a BB in a boxcar.

Ever since the successful creation of the horizontal room loop, I had wondered: if 50 feet of wire wrapped around a room improves the signal, would 100-feet of wire improve the signal even more? Inquiries to several knowledgeable people produced the same result: they didn’t think so.

Guess what? They were right . . . entirely and completely right. Tuning to the time stations and attaching and detaching the extra 50 feet of wire from the indoor end-fed, I saw (on the signal strength meter) and heard no difference in signal strength or signal-to-noise ratio.

The PL-880 and Satellit 800 comparison

So now, the Satellit 800 is attached to the indoor end-fed antenna, and there is an extra 50 feet wire wrapped around the room on the same path as the end-fed. Wouldn’t it be nice if I could find a way to hook that extra wire up to my Tecsun PL-880?

An old auxiliary wind-up wire antenna from a FreePlay radio came to the rescue. It was an annoying piece of gear; the wire was difficult to deploy and even more difficult to wind up again, and it had languished in a drawer for more than a decade. But it had a really nifty clip on the end that was designed to easily snap on and off a whip antenna.

Pulling an arm-spread of wire out of the reel, I cut it off, stripped the wire, attached it to the end of what had been the horizontal room loop, and clipped it to the whip on the PL-880. Tah-dah . . . instant improvement to the signal coming into the PL-880.

Some time ago, a reader had asked whether I found the Satellit 800 a little deaf in comparison to the Tecsun PL-880. Now, with two indoor antennas of approximately the same length and routed along the same path, I could do the comparison on shortwave frequencies. Starting with the time stations and later with hams in single-sideband on the 20-meter band, I alternated between the two radios. Although the PL-880 has more bandwidth choices, and the two radios have a slightly different sound to them (probably, I’m guessing, due to differences in their circuitry), the bottom line is this: anything I could hear with the Satellit 800 I could also hear with the PL-800 . . . and vice versa. (Note: I did not do any comparison between the two on medium wave or FM.)

In my not-so-humble opinion, both offer worthy performance that is improved with the addition of a 50-foot wire antenna, even if it is indoors.

And that brings us to the final point.

A word of caution

If you decide to add a bit of wire to improve the signal coming into your shortwave portable or desktop receiver, do NOT, under any circumstances, EVER deploy the wire where it could come into contact with a powerline or fall onto a power line or where a power line could fall on it.

As Frank P. Hughes, VE3DQB, neatly put it in his wonderful little book Limited Space Shortwave Antenna Solutions: “Make sure no part of any antenna, its support or guy wires can touch a power line before, after, or during construction. This is a matter of life and death!”

And when thunder and lightning threaten, make sure your outdoor antenna is disconnected and grounded.

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Video: Frans compares the GRAHN GS5 SE – VLF2 with a large loop antenna

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Many thanks to SWLing Post contributor, Frans Goddijn, who shares the following note and video originally posted on his blog:

Mr Grahn of https://www.grahn-spezialantennen.de/ had to stop working for a couple of months (medical reasons) but now he is back and I was able to get one of his highly sensitive Very Low Frequency modules to fit on my Grahn GS5-SE antenna tuner.

As before, the delicate device (“treat like glassware, do not throw”) was extremely well packed for its safe and intact arrival.

Click here to view on YouTube.

Click here to view Frans’ post which includes additional photos.

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Frans experiments with the MFJ-1026 Noise Canceling Signal Enhancer

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Many thanks to SWLing Post contributor, Frans Goddijn, who writes:

“Last week I purchased the MFJ-1026 ‘noise canceling signal enhancer’ and I posted two blogs with video about it. Initially the device seemed as useless as it is good looking but then I found a configuration where the device is not only pleasant to have but also useful for radio listening.”

Here are Frans’ reports which he kindly shares from these two posts originally published on his blog, Kostverlorenvaart:

Part 1: MFJ-1026 deluxe noise canceling signal enhancer

Using a GRAHN antenna, (a VENHORST wire antenna for noise reference), the iCOM R8600 radio and optional bhi DSP audio noise canceling, trying to see what’s the best way to cancel noise — on the antenna entry point of the radio or at the speaker output end.

In this case the MFJ-1026 seems ineffective. The DSP at the audio output end works well and easy.

I have also tried two GRAHN antennas on the MFJ-1026, one for MAIN and one for AUX but that was also not noticeably effective yet.

I will also try the little whip antenna that MFJ supplied with the box. Further tweaking may turn out to be helpful on some other frequencies / signals.

Before installing the MFJ i used the little TECSUN H-501x to scan the room for any devices producing radio noise. It turned out that the two Apple Homepods sit in a dense cloud of radio noise, the Macbook Pro also radiates noise, EVE smart plugs controlling lights also produce radio noise, two little label printers s well and the HP printer/scanner too. So I moved those to the other end of the toom or to another room. Continue reading →

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Frank finds a Sony ICF-SW7600G/GR replacement antenna

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Many thanks to SWLing Post contributor, Frank, who writes:

Thomas,

I have asked for and received help from your members a couple of times during the last year. I am sending this to you in an effort to “give something back” to your members.

I managed to stupidly break the built-in whip antenna on my Sony 7600GR and looked for a replacement. Several are on eBay for 5- 60 dollars which is a bit steep.

I eventually tried one (for $20) in the link below from eBay:

https://ebay.us/OpHEeP

It arrived very quickly (under 2 weeks from China) and it simply went into the radio with no problems and it works very well.

I am not a radio HAM or electronics expert so it may not be perfect but to me the reception is at least as good as the original.

If anyone needs one, it would be well worth trying.

Regards,

Frank from England

Thanks so much for sharing this useful tip, Frank!

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Joshuah says: “The Cross Country Wireless LAA++ amplifier rocks!”

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Image Source: Cross Country Wireless

Many thanks to SWLing Post contributor, Joshuah, who writes:

Dear Thomas,

I recently dedicated some funding to rebuilding my shortwave listening station.

I had paid attention to new amplifiers and became aware of some review data by an engineer at SDRPlay comparing amplifier performance that suggests the Cross Country Wireless amplifier, at a cost of only 80 dollars, had become a competitive design offering performance comparable to amplifiers costing 10 times that much.

I was hooked by the specific demonstrations showing that the LAA++ offered IMD characteristics more similar to a Wellbrook, with gain more similar to other high amplification designs. I had to have one.

I set up my station with the following components:

- A used Icron Ranger 2304 USB over ethernet extender off eBay
- A used Airspy Discovery off eBay
- A Cross Country Wireless receiver protector(or similar ferrite + gas discharge diode isolator)
- A custom ordered LAA++ amplifier from Cross Country Wireless built for 75 ohm with F connectors and a low pass filter at 14MHz
- A power inserter from an W6LVP that wasn’t cutting the mustard
- A pair of classic, solid transforming power adapter bricks
- An unshielded ethernet cable
- Some Fair-Rite ferrite snap ons with multiple turns

I obtained a weatherproof enclosure and some pex tubing and specialty cable glands and built an antenna housing. Inside the enclosure I mounted the amplifier, adding a large gauge copper wire for the antenna element, and used an affordable tri-shield RG11 with specialty connectors as the feedline for the antenna.

The antenna measures approximately a 2 meter diameter, and is mounted about 5 feet off the ground at the base of the antenna. It is located outside of a remote shed at the edge of my property, and the ethernet (alternatively, wireless repeating parabolic dish with router) mirrors the USB data back to the PC in my basement which serves as the shortwave receiving server host.

I have been overwhelmed both with the amount of new noise and new signal that this antenna picks up.

In shortwave, the other night, I was picking up stations around the world.

Tonight, I was able to very clearly make out CHLO. I am located in EM38, over 700 miles from the transmitter, which only operates at 250 watts during the night time.
I was also able to pick up some international NOAA NAVTEX alerts on 518kHz about a right whale slow zone in the Atlantic off the shore of New Jersey.

I would highly recommend this antenna amplifier.

Yours sincerely,

Joshuah

Thank you so much, Joshuah, for allowing me to post your note here in the SWLing Post. I’m so glad you found such an affordable way to cobble together an effective antenna system to not only mitigate interference, but also afford you DX-worthy reception.

I’ve only heard good comments about Cross Country Wireless as well.

Again, thank you for sharing your impressions and details about your setup!

Click here to check out the Cross Country Wireless amplifier.

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International Radio Club’s Reprints collection of 900+ articles

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Many thanks to SWLing Post contributor, Nick Hall-Patch, who shares the following announcement:

The International Radio Club’s Reprints collection of 900+ articles about antennas, radio propagation, receivers, accessories, plus items of general interest to MW DXers, continues to grow. We’ve published an update to the index, at https://www.ircaonline.org/editor_upload/File/reprints/irca-reprint-index.pdf , so that everyone can get access to these latest additions.

We’re also pleased to start offering reprints that did not initially appear in IRCA’s DX Monitor, but are not easily found elsewhere. For example, we’ve obtained permission from the family of the late prolific author, Dallas Lankford, to organize and republish his out of print articles.

(if you’ve used the index before, you may need to refresh the browser page to see the latest update, dated December 2021)

Click here to check out the IRCA Index (PDF).

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