Category Archives: Antennas

A review of the outdoor Planespotter antenna prototype

Many thanks to SWLing Post contributor, Zach R., who shares the following guest post:


A review of the outdoor Planespotter antenna prototype

When it comes to airband monitoring, the stock whip antennas that ship with desktop and portable scanners are not the greatest. They’re fine if you’re at an airport and only interested in communications specific to your immediate area, but if you are someone like me who lives well out from any major airport, quality listening in can be impossible without some help in the antenna department.

Ideally, you want something like a discone or similar for omnidirectional listening, mounted as high as possible. This is not always possible or practical, however. SWLing Post contributor Ron recently reviewed the indoor Planespotter antenna, and I have one as well that works better than any rubber ducky, and can be easily hidden away when company comes.

Recently, the creator has come out with a prototype outdoor model. It’s the same design as the indoor unit, but with a longer run (25 feet) of coax, terminating in a BNC connector.

Besides the longer cable, the only other obvious change is the antenna is house in a skinnier PVC tube from the indoor model. It’s also sealed at the bottom so moisture won’t get in.

It has the same small metal hook on top, suitable from hanging from various mounts. I’d like more mounting options, but the hook does make for quick installation and removal. The half-wave length isn’t ungainly to handle and if painted it could easily be mounted on the side of a home without many people noticing.

The indoor version definitely works best on the VHF air band and seems to roll off aggressively above and below that band. The outdoor version, in side-by-side tests, seemed to perform the same on the air band but notably better on the VHF public safety band. It also pulled in more UHF air band traffic than the indoor model, despite being basically the same design.

The new outdoor version is a good choice for someone looking for a simple, already assembled antenna that’s suitable for temporary use or stealth mounting.

Disclosure: The outdoor prototype was supplied to me for free in exchange for a review. While taking more photos of the antenna I noticed the weatherproofing had come undone from the bottom. Hopefully this issue can be addressed before the antenna goes into production.

[Zach R. is the owner and editor of the Alabama Broadcast Media Page.]

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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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Ron recommends the Planespotter Indoor VHF Airband Antenna

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


If you like monitoring the VHF airband then this antenna might interest you.It is a half-wave dipole cut for the middle of the band. (Recall that half wave vertical dipoles do not need ground radials.)

It is very well built and pretty rugged but is not meant for outdoor use.

How well does it perform? That depends on several things…how far you are from your airport? What is the “lay of the land” where you live? Etc.

Does it work better than the supplied telescoping antenna that came with your scanner?
Yes indeed.

And you will also notice an improvement in comms from aircraft in flight, too.
I had hoped to hear the ATIS and VOR from my local airport but they are too far away (20 miles).

In addition, the eBay seller (and builder) is also very pleasant to deal with.

https://ebay.us/qV5Hsg

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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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Ham & HiFi offers readers a discount on the original CHA-RXL mag loop antenna

I received the following message/announcement below from Ethan at Ham & HiFi regarding some inventory they have of the original Chameleon CHA RXL loop antenna. This antenna is the one Dan Robinson originally reviewed and Josh at Ham Radio Crash Course demonstrated in a video.

Note that they’re offering this deal as an exclusive to SWLing Post readers and also volunteered to give back a modest percentage of the sales to the SWLing Post coffee fund. They would obviously like to move this inventory, hence the discounts, etc.

This antenna would benefit from a BCI filter especially if you live near a broadcast station; something like this one (you would need adapters for SMAs). As Ethan notes this loop has been replaced by the CHA RXL-Pro at Chameleon (click here to read Dan’s review of the new loop).

Many thanks to Ethan for sharing the following announcement/promotion:

Here’s a great chance to pick up a Chameleon RXL LOOP antenna at an unbeatable price! This broad-banded receiving antenna is perfect for shortwave listening and other applications as it covers 137.5KHz through 30.0MHz. The only difference between this antenna and Chameleon’s new RXL PRO is the preamp design, otherwise its construction is identical.

Ham & HiFi is making these RXL LOOP antennas available to SWLing.com subscribers for $300 + shipping ($20 less than the last time we had a sale). The new RXL PRO retails for $525, so this is a great chance to save some money! Again, this price is only available to SWLing Post subscribers, so please be sure to reference this promotion.

Place your order by contacting Ethan at 866-988-0073 or email at [email protected].

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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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High Noon: Belka MW shootout part 2, with a review of the AFA200C active MW ferrite antenna

High Noon: Belka MW shootout part 2, with a review of the AFA200C active MW ferrite antenna

by 13dka

When I reviewed the updated Belka (gen3, 2022) for its MW/LW performance in October last year, I just wanted to know if it’s any good with just the whip antenna and used the XHDATA D-808 as a reference radio because it’s a Jay Allen 2.5-star average performer on MW and my expectations were not high for MW reception on a short whip.  To my surprise that average bar turned out way too low for the Belka!

That was sure asking for a comparison with the most sensitive MW radio I have and gave me hope to use the Belka for ultra-portable MW DXing on the move.  The omnidirectional whip doesn’t allow me to null out unwanted co-channel interference though, therefore I wanted to find a reasonably sized loopstick antenna to pair with the Belka.  Continue reading

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