Tag Archives: Antennas

Video: Giuseppe explains wiring/construction of DICA Homebrew Antenna

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

Dear Thomas and SWLingPost Friends,

I’m Giuseppe Morlè iz0gzw,

Many friends have asked for the DICA wiring diagram after my recent post and demonstration.

I’m not a technician but a simple passionate listener and qrp’er… I made this video with a drawing that I hope will be useful to understand the details and how it works…

[Please note that this video is in Italian, but you can use YouTube Closed Captioning; it can even translate the subtitles into English or any other language.]

Thank you all.
Giuseppe iz0gzw.

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D.I.C.A.: Giuseppe’s latest homebrew portable antenna

Many thanks to SWLing Post contributor, Giuseppe Morlè, who shares the following antenna project:

Dear Thomas and SWLing Post Friends ,

I’m Giuseppe Morlè, iz0gzw, from Central Italy, Formia on the Tyrrhenian Sea…
Some time ago I had drawn this minimal HF antenna on paper…

I took advantage of the New Year’s Eve rain to be able to build it with the usual leftover scraps…

The system consists of a 35 cm tube with two separate windings of telephone cable on it, 2.5 m on each side, green and white…in the center I connected the 4 ends to X…

The green lead with the white and the white with the green to the variable capacitor and the other two leads to the RG58 cable that goes to the receiver.

I started the test and noticed that the agreement was possible from 7 to 21 MHz…

I then placed a long ferrite inside the tube…

I noticed a strengthening of the signal and consequently of the noise picked up and the chord dropped to 3.2 MHz.

Tests inside my shack showed decent reception on all ranges…in the evening on the balcony on 80 m. I could perfectly listen to a QSO between Italian stations.

Everything is still in the experimental phase and I think I will try this minimal system also in QRP transmission.

In this first video I explain how this minimal antenna is made:

The second video concerns a 20 meter test by car. The antenna is placed on the dashboard of the car inside:

In the third video, I explain how it works without the ferrite and with the ferrite inside the tube:

In this video you can see the test on 40 m. outdoors on the roof of the house:

The tests are carried out at home in order to understand what can be achieved in an environment that is difficult to receive.

I will do more outdoor tests and I think this small minimal antenna will receive better. I will keep you informed.

Thank you all for your attention and I wish you all a new year full of satisfaction.

’73 de Giuseppe iz0gzw.

Fascinating, Giuseppe! I love all of these brilliant little antennas you design out of your “junk” drawer! We look forward to hearing more about this antenna and any modifications you make to it!

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Jack recommends antennas from Lowbander’s Antenna Mart on eBay

Many thanks to SWLing Post contributor, Jack Dully, who writes:

Happy Holidays to Y’all!!! Thomas, I have bought about 5 antennas from the eBay seller”Lowbander” over the last few years. […]They are well constructed, strong and really bring in signals on the fringe. He has a small operation, I believe, but dedicated to making the best antennas he can. His antennas will last through storms and such but grab signals like a fly on honey, no kidding. Perhps other SWLing Post members don’t know of these excellent antennas at what I think is a good deal and worth the cost for years in the air. Thanks.

Clic here to check out Lowbander’s antenna offerings on eBay.

Note: this is an eBay partnership link–purchases support the SWLing Post at no cost to you.

Thank you for the tip, Jack!

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Martin builds a simple ferrite rod to inductively couple radios to his external mediumwave antenna

Many thanks to SWLing Post contributor, Martin Tobisch, who shares the following guest post and videos from his home in Malta:


New AM Signal Coupler

Many AM medium wave listeners are looking for solutions to improve the reception performance of their radios.

After many attempts, which I don’t want to entertain anyone with, a coupler was created that feeds the external antenna directly into the ferrite antenna. I use my 66 foot long wire antenna on 50 ohm RG-58 cable, but other antennas will have similar success.

The clips available on YouTube speak for themselves:

 

Experiments with smaller ferrites and antenna rods met with no success. It is important that the coupler still works even at a distance from the ferrite antenna and without precise alignment.

With tube radios it easily bridges the distance from the housing to the ferrite rod Antenna
The finished coupler consists of 6 NiZn ferrite cores, which are connected with glue to form a rod. 8 turns of wire are wound over this and soldered to an RG-58 cable. Some electrical isolation tape and ready. So far I’ve just put it in a box. Of course there are finer solutions and it should be protected against shock. Ferrite cores are notoriously brittle.

Here is a link to the ferrites used (purchased at AliExpress).

Advantages: Advantages to what? Nothing comparable exists.

So there are advantages to feeding via an antenna socket. The signal coupler is also good for radios without an antenna socket. But in case of using an antenna socket, common mode wave interference picked up in the house goes unlimited into the radio. Due to the magnetic coupling to the ferrite antenna, common mode waves are completely suppressed. They do not create a magnetic field in the coupler.

No changes are necessary in the radio

The biggest advantage is, that you can listen to distant stations loud and clear, which previously only produced a quiet scratching noise.

I very much welcome reports of experiences.

[email protected]

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Guest Post: Switching a Remote Antenna, Low Noise Amplifier, and an Antenna and Audio Between Two Radios

Many thanks to SWLing Post contributor, Bill Hemphill, who shares the following guest post:


Remote Antenna Switching Remote Low Noise Amplifier Switching and Switching an Antenna and Audio Between Two Radios

by Bill Hemphill, WD9EQD

Remote Antenna Switching

I have two YouLoop Antennas.  I had been placing them at right angles to each other.  I would then put one of them on the AirSpy software defined radio.  But manually switching from one antenna to the other was a real pain.  If only there were a way to electrically switch between the two antennas.

It would be nice to place the antennas remotely from the radio (and computers) and then have some sort of remote switch that would select an antenna and then a single feed line to the radio.  It was research time.

The YouLoop and the Airspy both use SMA connectors.  An SMA switch would be required.  A little research and I came across the following small board that can switch between two SMA antennas:

From Amazon Description:  50 Ohms RF Switch Module, 3-5V Remote Wireless RF Switch Single Pole Double Throw Board Input Output Impedance for DIY Electric Doors (HMC349)

This board is perfect for RECEIVE only projects.  Apply 5V to the board and then 5V to the VCC (control pin) to switch from RF1 to RF2.

Now that I had the SMA switch module, a way to actually do the switch remotely was required.  Maybe WI-Fi or Bluetooth module would do the trick.  I found a nice Wi-Fi module on Amazon that looked like it would do the trick:

Amazon Description:  DIYmalls SV Safe Low Voltage WiFi Wireless Switch Module DC 5V-24V Phone APP Remote Control Smart Home for Amazon Alexa Google Assistant

But do I really want to use a phone app to switch antennas.  Further investigation discovered a really neat module that uses a Car Fob type control:

Amazon Description:  RODOT Mini Relay Wireless Switch, 433Mhz Remote Control Relay Switch, DC 6V 12V 24V 1CH Channel Relay Wireless Secure RF Transmitter and Receiver kit, Momentary Toggle Latched Mode

BIngo!!  I could just press a button and switch antennas.  But a problem quickly arose.  I hadn’t fully read the description of the RODOT switch:

The blue output wire is ALWAYS Vcc (input voltage)! The device only switches the ground.

So the RODOT switches the ground but the HMC349 uses positive voltage to switch.  OOPS.  Next step was to place a latching relay to take the on/off ground and convert it to on/off positive.  Again, another nice board was found:

Amazon Description:  HiLetgo 2pcs 5V One Channel Relay Module Relay Switch with OPTO Isolation High Low Level Trigger

The nice thing about the Relay Module is that it can be latched either High or Low, so the RODOT switching ground can be used to latch the relay and then provide a positive voltage to the HMC349 antenna switch.

All modules are powered by 5V.  There are other modules available that use higher voltages.  But I wanted to be able to use a 5V power source for everything.

I learned a quick lesson on the first layout I did. I had directly connected the antenna cables to the HMC349 module.  A quick accidental side yank on one of the antenna cables and the SMA connector tore off the board.  A replacement board and some quick wiring and I had a workable antenna switch that with the press of the car fob button, either antenna could be selected.

I found a nice small plastic box that allowed for the HMC349 module to be suspended between SMA bulkhead connectors.  By using bulkhead connectors, there is no strain placed on the HMC349 connectors. The relay module was attached to the box lid.  The modules are mounted using brass standoffs.  The finished box is about 3”x4”x 2” high.  Either battery or a 5V wall module can be used to power it.

Overall, I’m quite pleased with the results.  I find that sometimes switching antennas (and their orientation) can make a big improvement in the signals.  Other times, there’s very little difference.

Remote Low Noise Amplifier along with Antenna Switching

Now that the antennas can be switched, it would be nice if a Low Noise Amplifier could be switched in and out of the circuit.  Something like the Lana HF Barebones LNA made by NooElec:

For testing purposes, I first did a quick layout of just using one antenna with the ability to switch the LNA in and out.  Note:  I took a gamble on hooking the antenna cables directly to the HMC349 modules.  Luckily, the SMA connects didn’t tear off the boards.

Two HMC349 modules are used.  The first module selects the bypass or the LNA.  Likewise, the second module also selects either the bypass or LNA.  Note that the second module is turned upside down so that the switches match up when activated.  Two modules were used so that the LNA is totally switched out of the circuit. Continue reading

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Radio Waves: DW Launches “Sudan Now” on Shortwave, Mayor Saves AM Station, Tape Measure Turnstile Antenna, and Where Does AM Go From Here?

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!

Many thanks to SWLing Post contributors Dennis Dura and David Iurescia for the following tips:


“Sudan Now” – DW Arabic launches new radio program for Sudan (DW)

DW is now broadcasting a 30-minute daily Arabic-language radio program entitled “Sudan Now” on shortwave, Hotbird and SES-5 satellites and via the DW Arabic website.

As an unbiased radio program, “Sudan Now” will provide listeners in the target region with unbiased coverage of current issues in the region and will promote political, social and cultural dialogue through interviews, talk shows and reports.

Given the lack of independent information sources in Sudan and the limited ability of established media to broadcast due to internet outages and ongoing fighting, “Sudan Now” was specifically designed to be broadcast on shortwave and via the Hotbird- and SES-5 satellites. The satellite broadcast enables listeners in the target region to receive the program via their TV sets.

DW Managing Director Programming Dr. Nadja Scholz: “The conflict in Sudan is ongoing and has far-reaching effects on the entire region. It is absolutely necessary to provide the people there with a dedicated program that enables them to access independent, current and in-depth information. With shortwave radio, we further increase our ability to reach as many people as possible.”

Manuela Kasper-Claridge, DW editor-in-chief, said: “The humanitarian situation in Sudan remains catastrophic. There is a lack of everything – including free, independent information. This Arabic-language radio program is therefore urgently needed.”

The program broadcast will begin on Monday, June 26, 2023. It will air daily from Monday to Friday at 2:30 pm (local time, GMT+2) for a duration of thirty minutes. A repeat of the radio program will air daily at 8:30 pm.

“Sudan Now” can be heard in the afternoon on shortwave 15275 kHz/17800 kHz and in the evening on shortwave 15275 kHz/17840 kHz.

In addition, all broadcasts will be available on the DW Arabic website.

AM Matters: This CO Mayor Saved His Town’s Station (Radio Ink)

[…]Radio Ink: When Justin Sasso briefly mentioned KLMR’s story at Hispanic Radio Conference, it piqued the room’s interest. That’s a powerful AM story. How did this come to pass with you both?

Dan: So about a year ago in late July, KLMR was blown off the air from a micro-downburst. The previous owners couldn’t fix it and they were in danger of losing the license. When I saw the building, half the roof was gone and the antenna was dangling in the wind.

I’ve been in the radio business in Colorado for 40 years, with the last 20 in Colorado Springs, but I’ve never owned a radio station. And so when this opportunity came about, I reached out to Kirk. We had talked about possibly buying a company in Lamar previously. He’s not just the mayor, he’s my brother-in-law, but it was great that the mayor wanted to get involved in it too. So we’re off and running.

Radio Ink: For a mayor to step up and say, “This AM station is so important to my community that if nobody else will save it, I will,” is a huge testament to AM radio’s power and value.

Kirk: It’s vital. That’s what I had mentioned to Justin in that meeting about AM. When we look at rural Colorado and the ag market there, there’s a necessity for that. [Continue reading…]

A Quick And Easy Tape Measure Turnstile Antenna For Milsat Snooping (Hackaday)

The number of satellites whizzing by over our heads at any moment is staggering, and growing at a rapid rate as new constellations are launched. But sometimes it’s the old birds that are the most interesting, as is the case with some obsolete but still functional military communications satellites, which thanks to a lack of forethought are largely unsecured and easily exploitable. And all that’s needed to snoop in on them is a cheap ham radio and something like this simple and portable satcom antenna.

As proof of the global nature of the radio hobby, the design in the video below by Brit [Tech Minds] borrows heavily from previous work by Italian ham [Ivo Brugnera (I6IBE)], which itself was adapted to use 3D-printed parts in a German blog post a few years ago. [Continue reading…]

Not just cars: Where does AM radio go from here? (YouTube)

Joe and Jeff Geerling discuss AM radio station ownership, emergency use, rural listeners, and more.


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Frans checks out the MRA-QRP 20W QRP Passive Loop Antenna

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

Dear Thomas,

In the following video, I show a little loop antenna that I bought online from AliExpress:

On arrival one of the parts, the semi-transparant box with variable capacitor for antenna tuning turned out to be broken due to the bigger box having been thrown around in transit.

The seller promptly provided me with the necessary part (plus extra) for repairs.

Yesterday I repaired it and today I assembled the antenna and tested it a bit in the afternoon and early evening as soon as reception started to get well enough.

It’s a fun antenna, affordable too.

The video shows how effective the variable capacitor is.

Best regards,

Frans

Thank you, Frans. That is certainly a very affordable passive loop option. If you’re an urban QRPer, all the better. I should also mention, you have one of the nicest radio operating positions out there!

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