Category Archives: Longwave

How to Build a Simple Linear-Loaded Dipole for Low-Noise Shortwave Radio Listening

Many thanks to SWLing Post contributor and RX antenna guru, Grayhat, for another excellent guest post focusing on compact, low-profile urban antennas:


A linear loaded dipole for the SWL

by Grayhat

What follows is the description of an antenna which may allow to obtain good performances even in limited space, the antenna which I’m about to describe is a “linearl loaded dipole”(LLD) which some call the “cobra” antenna due to the “snaking” of its wires
The arms of the antenna are built using 3-conductors wire (which may be flat or round) and the 3 conductors are connected this way:

That is, connected “in series”, this means that, the electrical length of the antenna will be three times its physical one; this does NOT mean that the antenna will perform like a single wire of the same (total) length, yet it allows to “virtually” make it longer, which in turn gives it good performance even with relatively short sizes. Plus, the distributed inductance/capacitance between the wires not only gives it a number of “sub” resonance points, but also helps keeping the noise down (in my experience below the noise you’d expect from a regular dipole).  At the same time it offers better performances than what one may expect from a “coil loaded” dipole. Plus, building it is easy and cheap and the antenna will fit into even (relatively) limited spaces (a balcony, a small yard and so on…).

Interested–? If so, read on and let me start by showing my (short – 9mt total) LLD installed on a balcony:

Here it is in all its “glory”–well, not exactly–I fiddled with it lately since I’m considering some mods so the tape isn’t correctly stuck and it has been raised and lowered quite some times, but in any case that’s it.

Bill of Materials

Here’s what you’ll need to build it (the links are just indicative, you may pick different stuff or buy it locally or elsewhere).

  • Some length of 3-conductors electrical wire which will fit your available space (pick it a bit longer to stay on the safe side), it may be flat or round, in my case I used the round type since it was easily available and cheap: https://amzn.to/3g2eZX3
  • A NooElec V2 9:1 BalUn–or, if you prefer you may try winding your own and trying other ratios. I tested some homebuilt 1:1, 1:4 and 1:6 and found that the tiny and cheap NooElec was the best fitting one): https://amzn.to/3fNnvce
  • A small weatherproof box to host the BalUn: https://amzn.to/33vjZy3
  • A center support which may be bought or built. In the latter case, a piece of PCV pipe with some holes to hold the wires should suffice. In my case I picked this one (can’t find it on amazon.com outside of Italy): https://www.amazon.it/gp/product/B07NKCYT5Z
  • A pair of SMA to BNC adapters: https://amzn.to/37krHwj
  • A run of RG-58 coax with BNC connectors: https://amzn.to/2JckHcR

Plus some additional bits and pieces like some rope to hang the antenna, some nylon cable ties, a bit of insulated wire, duct tape and some tools. Notice that the above list can be shortened if you already have some of the needed stuff and this, in turn will lower (the already low) cost of the antenna.

Putting the pieces together

Ok, let’s move on to the build phase. The first thing to do will be measuring your available space to find out how much wire we’ll be able to put on the air; in doing so, consider that (as in my case), the antenna could be mounted in “inverted Vee” configuration which will allow to fit the antenna even in limited space.

In any case, after measuring the available space, let’s subtract at least 1m (50cm at each end) to avoid placing the antenna ends too near to the supports. Also, if in “inverted Vee” config, we’ll need to subtract another 50cm to keep the feedpoint (center/box) away from the central support.

Once we’ve measured, we may start by cutting two equal lengths of 3-conductor wire. Next, we’ll remove a bit of the external sleeve to expose the three conductors and then we’ll remove the insulator from the ends of the three exposed wire (and repeat this at the other end of the cable and for both arms).

The resulting ends of each arm should look somewhat like in the example image below

Now we’ll need to connect the wires in series. We’ll pick one of the cables which will be the two arms of our antenna and, assuming we have the same colors as in the above image, we’ll connect the green and white together at one end and the black and green together at the other end. Repeat the same operation for the second arm and the cables will be ready.

Now, to have a reference, let’s assume that the ends of each arm with the black “free” (not connected) wire will go to the center of our dipole.

Leave the two arms alone for a moment, and let’s install the balun inside the waterproof box. To do so, we’ll start by cutting a (small) hole through the single rubber cap found at one side of the box, then insert the cap reversed, so that it will protrude to the inside of the box and not to the outside. Slide the balun SMA connector through the hole so that it will protrude outside the box.

Now use a marker to mark the balun position and remove the balun from the box. Pick a piece of wood/plastic or other insulating material, cut it to size (refer to marking and to balun size) and drill four holes matching the one found on the balun board. Slide four screws through the holes and lock them with nuts, the screws should be long enough to extrude for some mm. Now insert the balun in the screws using the holes present on the balun board and lock it with nuts (be gentle to avoid damaging the balun). At this point, add some “superglue” to the bottom of the support we just built, slide the balun SMA connector through the rubber cap hole we already practiced, and glue the support to the bottom of the waterproof box.  Wait for the glue to dry.

Just to give you a better idea, see the photo above. That’s a photo of the early assembly of my balun. Later on, I rebuilt it as described above (but took no pics!), the image should help you understanding how it’s seated inside the box–by the way in our case it will be locked by the screws to the plastic support we glued to the box.

While waiting for the glue to dry, we may work on the dipole centerpiece.

If you bought one like I did, connecting the arm “black” (see above) wires should be pretty straightforward. If instead you choose to use a PVC pipe you’ll have to drill some holes to pass and lock the wire so that the strain will be supported by the pipe and not by the wire going to the balun box. In either case, connect a pair of short runs of insulated wire to the end (black) wire coming from each end. Those wires should be long enough to reach the balun wire terminal block inside the box.

Assuming the glue dried, it’s time to complete the feedpoint connection.

Bring the two wires coming from the centerpoint inside the waterproof box. Pick one of the wire terminal blocks which came with the balun (the “L” shaped one should be a good choice) and connect the wires to it. Then, slide the block in place until it locks firmly. After doing so, close the box and screw the SMA-BNC adapter onto the SMA connector coming from the balun. Our centerpiece and arms will now be ready, and will be time to put our antenna up!

I’ll skip the instructions about holding the arm ends and the centerpiece up, since I believe it should be pretty straightforward. Just ensure to put the antenna as high as possible and, if you have room make the arms as long as possible. In my case, due to my (self-imposed) limitations, the antenna was installed on a balcony. The arms have a length of about 3.5m each and the feedpoint (in the image above) sits at about 9m off the ground.

The more acute readers probably noticed those “blobs” on the coax, they are snap-on ferrite chokes I added to the coax (there are more of them at the rx end) to help tame common mode noise. I omitted them from the “BoM” since they may be added later on.

Anyhow, now that you have your LLD up it will be time to give it a test! In my case, I decided to start by running an FT8 session to see what the antenna could pick up during 8 hours, and the result, on the 20 meters band, is shown on the following map (click to enlarge):

Later, that same antenna allowed me to pick up signals from the Neumayer station in Antarctica–not bad, I think!

Some final notes

While running my “balcony experiment”, I built and tested several antennas, including a vanilla “randomwire”, a dipole, and a T2FD.

Compared to those, the LLD offers much less noise and better reception on a wide frequency range. By the way, it won’t perform miracles, but it’s serving me well on the LW band, on most ham bands, and even up to the Aircraft bands–indeed, was able to pick up several conversations between aircraft and ground air traffic control.

All I can suggest is that given a linear-loaded dipole is so simple, quite cheap, and may fit many locations, why don’t you give it a spin–?  🙂

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David shares a recording of the RTE longwave interval signal

Many thanks to SWLing Post contributor, David Shannon, who writes:

Hi Thomas

A little treat for my fellow readers of your blog (is that the right word?). The RTE interval signal, a rendition of O’Donnell Abú (“O’Donnell Forever”), that is played at 0529 daily, apart from the weekend when it’s played at 0629 (even interval signals need a lie in) and received on longwave here in Scotland.

I know that longwave broadcasting is a very European thing with the exception of the likes of Mongolia (holy grail stuff for me) but it’s where my fascination for the bands started way back in 1978/9.

Sláinte mhaith gach duine
(Irish Gaelic for good health everyone)

That’s a beautiful interval signal, David. Thank you so much for sharing it with your fellow Post readers! There are few things in this world that make me feel more nostalgic than an off-air recording of an interval signal. Go Raibh Maith Agat!

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Photo emerges of Droitwich mast and LF antenna

Many thanks to SWLing Post contributor, Dave Porter, who writes:

This picture [above] has just emerged, photographer unknown but most likely a rigger from the top of one of the 700′ masts there!

This was taken at Droitwich sometime after colour photography came in (late 1960’s) and before 1986 when the four wire Tee was replaced by a new design developed by BBC Antenna Engineer Tony Preedy, G3LNP that improved upon the 11-j85 Ohms driving point impedance giving a few more ohms and less capacitive reactance for the 2 x 250kW B6042 transmitters and a greater radiation efficiency.

Tony’s present LF array does not look so symmetrical as it comprises four separate Tee wires with the drops as a square box rather than the centre-joined drops of this one.

Tony also developed a low profile Tee antenna over 3 x 17m wooden telegraph poles for MF at up to 1 kW that was used when planning restrictions were enforced. Efficiencies were up to 40% at the 1500 kHz end of the band. However, if used by birds as an overnight roost it could provoke VSWR trips on solid state transmitters, the fix was to use a sliding reduced power detector that wound down the power to a level that did not trip the VSWR monitoring. Old tube transmitters were not affected!

The operating frequency for this LF Tee was 200 kHz at that time, now the antenna is on 198 kHz

Wow–thank you, Dave, for sharing this photo. We truly appreciate your impressive knowledge of UK broadcasting and history! And, wow! The views those riggers took in!

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Guest Post: Why does radio reception improve on saltwater coasts?

Many thanks to SWLing Post contributor, 13dka, who shares the following guest post:


Gone fishing…for DX: Reception enhancement at the seaside

by 13dka

In each of my few reviews I referred to “the dike” or “my happy place”, which is a tiny stretch of the 380 miles of dike protecting Germany’s North Sea coast. This is the place where I like to go for maximum listening pleasure and of course for testing radios. Everyone knows that close proximity to an ocean is good for radio reception…but why is that? Is there a way to quantify “good”?

Of course there is, this has been documented before, there is probably lots of literature about it and old papers like this one (click here to download PDF). A complete answer to the question has at least two parts:

1. Less QRM

It may be obvious, but civilization and therefore QRM sources at such a place extend to one hemisphere only, because the other one is covered with ocean for 100s, if not 1000s of miles. There are few places on the planet that offer such a lack of civilization in such a big area, while still being accessible, habitable and in range for pizza delivery. Unless you’re in the midst of a noisy tourist trap town, QRM will be low. Still, you may have to find a good spot away from all tourist attractions and industry for absolutely minimal QRM.

My dike listening post is far enough from the next small tourist trap town (in which I live) and also sufficiently far away from the few houses of the next tiny village and it’s located in an area that doesn’t have HV power lines (important for MW and LW reception!) or industrial areas, other small villages are miles away and miles apart, the next town is 20 km/12 miles away from there. In other words, man-made noise is just not an issue there.

That alone would be making shortwave reception as good as it gets and it gives me an opportunity to check out radios on my own terms: The only way to assess a radio’s properties and qualities without or beyond test equipment is under ideal conditions, particularly for everything that has to do with sensitivity. It’s already difficult without QRM (because natural noise (QRN) can easily be higher than the receiver’s sensitivity threshold too, depending on a number of factors), and even small amounts of QRM on top make that assessment increasingly impossible. This is particularly true for portables, which often can’t be fully isolated from local noise sources for a couple of reasons.

Yes, most modern radios are all very sensitive and equal to the degree that it doesn’t make a difference in 98% of all regular reception scenarios but my experience at the dike is that there are still differences, and the difference between my least sensitive and my most sensitive portable is not at all negligible, even more because they are not only receivers but the entire receiving system including the antenna. You won’t notice that difference in the middle of a city, but you may notice it in the woods.

When the radio gets boring, I can still have fun with the swing and the slide!

2. More signal

I always had a feeling that signals actually increase at the dike and that made me curious enough to actually test this by having a receiver tuned to some station in the car, then driving away from the dike and back. Until recently it didn’t come to me to document or even quantify this difference though. When I was once again googling for simple answers to the question what the reason might be, I stumbled upon this video: Callum (M0MCX) demonstrating the true reason for this in MMANA (an antenna modeling software) on his “DX Commander” channel:

To summarize this, Callum explains how a pretty dramatic difference in ground conductivity near the sea (click here to download PDF) leads to an increase in antenna gain, or more precisely a decrease in ground return losses equaling more antenna gain. Of course I assumed that the salt water has something to do with but I had no idea how much: For example, average ground has a conductivity of 0.005 Siemens per meter, salt water is averaging at 5.0 S/m, that’s a factor of 1,000 (!) and that leads to roughly 10dB of gain. That’s right, whatever antenna you use at home in the backcountry would get a free 10dB gain increase by the sea, antennas with actual dBd or dBi gain have even more gain there.

That this has a nice impact on your transmitting signal should be obvious if you’re a ham, if not just imagine that you’d need a 10x more powerful amplifier or an array of wires or verticals or a full-size Yagi to get that kind of gain by directionality. But this is also great for reception: You may argue that 10dB is “only” little more than 1.5 S-units but 1.5 S-units at the bottom of the meter scale spans the entire range between “can’t hear a thing” and “fully copy”!

A practical test

It’s not that I don’t believe DX Commander’s assessment there but I just had to see it myself and find a way to share that with you. A difficulty was finding a station that has A) a stable signal but is B) not really local, C) on shortwave, D) always on air and E) propagation must be across water or at least along the shoreline.

The army (or navy) to the rescue! After several days of observing STANAG stations for their variation in signal on different times of the day, I picked one on 4083 kHz (thanks to whoever pays taxes to keep that thing blasting the band day and night!). I don’t know where exactly (my KiwiSDR-assisted guess is the English channel region) that station is, but it’s always in the same narrow range of levels around S9 here at home, there’s usually the same little QSB on the signal, and the signals are the same day or night.

On top of that, I had a look at geological maps of my part of the country to find out how far I should drive into the backcountry to find conditions that are really different from the coast. Where I live, former sea ground and marsh land is forming a pretty wide strip of moist, fertile soil with above average conductivity, but approximately 20km/12mi to the east the ground changes to a composition typical for the terminal moraine inland formed in the ice age. So I picked a quiet place 25km east of my QTH to measure the level of that STANAG station and also to record the BBC on 198 kHz. Some source stated that the coastal enhancement effect can be observed within 10 lambda distance to the shoreline, that would be 730m for the 4 MHz STANAG station and 15km for the BBC, so 25km should suffice to rule out any residue enhancement from the seaside.

My car stereo has no S-meter (or a proper antenna, so reception is needlessly bad but this is good in this case) so all you get is the difference in audio. The car had the same orientation (nose pointing to the east) at both places. For the 4 MHz signal though (coincidence or not), the meter shows ~10dBm (or dBµV/EMF) more signal at the dike.

3. Effect on SNR

Remember, more signal alone does not equal better reception, what we’re looking for is a better signal-to-noise ratio (SNR). Now that we’ve established that the man-made noise should be as low as possible at “my” dike, the remaining question is: Does this signal enhancement have an effect on SNR as well? Even if there is virtually no local QRM at my “happy place” – there is still natural noise (QRN) and that wouldn’t that likely gain 10dB too?

Here are some hypotheses that may be subject of debate and some calculations way over my head (physics/math fans, please comment and help someone out who always got an F in math!). Sorry for all the gross oversimplifications:

Extremely lossy antennas

We know that pure reception antennas are often a bit different in that the general reciprocity rule has comparatively little meaning, many antennas designed for optimizing reception in specific situations would be terrible transmitting antennas. One quite extreme example, not meant to optimize anything but portability is the telescopic whip on shortwaves >10m. At the dike, those gain more signal too. When the QRN drops after sunset on higher frequencies, the extremely lossy whip might be an exception because the signal coming out of it is so small that it’s much closer to the receiver noise, so this friendly signal boost could lift very faint signals above the receiver noise more than the QRN, which in turn could mean a little increase in SNR, and as we know even a little increase in SNR can go a long way.

The BBC Radio 4 longwave recording is likely another example for this – the unusually weak signal is coming from a small and badly matched rubber antenna with abysmal performance on all frequency ranges including LW. The SNR is obviously increasing at the dike because the signal gets lifted more above the base noise of the receiving system, while the atmospheric noise component is likely still far below that threshold. Many deliberately lossy antenna design, such as flag/tennant, passive small aperture loops (like e.g. the YouLoop) or loop-on-ground antennas may benefit most from losses decreasing by 10dB.

Not so lossy antennas, polarization and elevation patterns

However, there is still more than a signal strength difference between “big” antennas and the whips at the dike: Not only at the sea, directionality will have an impact on QRN levels, a bidirectional antenna may already decrease QRN and hence increase SNR further, an unidirectional antenna even more, that’s one reason why proper Beverage antennas for example work wonders particularly on noisy low frequencies at night (but this is actually a bad example because Beverage antennas are said to work best on lossy ground).

Also, directional or not, the “ideal” ground will likely change the radiation pattern, namely the elevation angles, putting the “focus” of the antenna from near to far – or vice versa: As far as my research went, antennas with horizontal polarization are not ideal in this regard as they benefit much less from the “mirror effect” and a relatively low antenna height may be more disadvantageous for DX (but maybe good for NVIS/local ragchewing) than usual. Well, that explains why I never got particularly good results with horizontal dipoles at the dike!

Using a loop-on-ground antenna at a place without QRM may sound ridiculously out of place at first, but they are bidirectional and vertically polarized antennas, so the high ground conductivity theoretically flattens the take-off angle of the lobes, on top of that they are ~10dB less lossy at the dike, making even a LoG act more like something you’d string up as high as possible elsewhere. They are incredibly convenient, particularly on beaches where natural antenna supports may be non-existent and I found them working extremely well at the dike, now I think I know why. In particular the preamplified version I tried proved to be good enough to receive 4 continents on 20m and a 5th one on 40m – over the course of 4 hours on an evening when conditions were at best slightly above average. Though the really important point is that it increased the SNR further, despite the QRN still showing up on the little Belka’s meter when I connected the whip for comparison (alas not shown in the video).

The 5th continent is missing in this video because the signals from South Africa were not great anymore that late in the evening, but a recording exists.

Here’s a video I shot last year, comparing the same LoG with the whip on my Tecsun S-8800 on 25m (Radio Marti 11930 kHz):

At the same time, I recorded the station with the next decent KiwiSDR in my area:

Of course, these directionality vs noise mechanisms are basically the same on any soil. But compensating ground losses and getting flat elevation patterns may require great efforts, like extensive radial systems, buried meshes etc. and it’s pretty hard to cover enough area around the antenna (minimum 1/2 wavelength, ideally more!) to get optimum results on disadvantaged soils, while still never reaching the beach conditions. You may have to invest a lot of labor and/or money to overcome such geological hardships, while the beach gives you all that for free.

But there may be yet another contributing factor: The gain pattern is likely not symmetrical – signals (and QRN) coming from the land side will likely not benefit the same way from the enhancement, which tapers off quickly (10 wavelengths) on the land side of the dike and regular “cross-country” conditions take place in that direction, while salt water stretching far beyond the horizon is enhancing reception to the other side.

So my preliminary answer to that question would be: “Yes, under circumstances the shoreline signal increase and ground properties can improve SNR further, that improvement can be harvested easily with vertically polarized antennas”.

Would it be worthwhile driving 1000 miles to the next ocean beach… for SWLing?

Maybe not every week–? Seriously, it depends.

Sure, an ocean shoreline will generally help turning up the very best your radios and antennas can deliver, I think the only way to top this would be adding a sensible amount of elevation, a.k.a. cliff coasts.

If you’re interested in extreme DX or just in the technical performance aspect, if you want to experience what your stuff is capable of or if you don’t want to put a lot of effort into setting up antennas, you should definitely find a quiet place at the ocean, particularly if your options to get maximum performance are rather limited (space constraints, QRM, HOA restrictions, you name it) at home.

If you’re a BCL/program listener and more interested in the “content” than the way it came to you, if you’re generally happy with reception of your favorite programs or if you simply have some very well working setup at home, there’s likely not much the beach could offer you in terms of radio. But the seaside has much more to offer than fatter shortwaves of course.

From left to right: Starry sky capture with cellphone cam, nocticlucent clouds behind the dike, car with hot coffee inside and a shortwave portable suction-cupped to the side window – nights at the dike are usually cold but sometimes just beautiful. (Click to enlarge.)

However, getting away from the QRM means everything for a better SNR and best reception. In other words, if the next ocean is really a hassle to reach, it may be a better idea to just find a very quiet place nearby and maybe putting up some more substantial antenna than driving 1000 miles. But if you happen to plan on some seaside vacation, make absolutely sure you bring two radios (because it may break your heart if your only radio fails)!

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Tecsun PL-990 Hidden Feature: Toggling ferrite bar and telescopic whip antenna on MW & LW bands

Many thanks to Anna at Anon-Co who recently shared an interesting “hidden feature” of the Tecsun PL-990 which allows the user to toggle between the internal ferrite antenna and telescoping whip antenna while on either the mediumwave or logwave bands.

Procedure:

1) Turn on the radio and then select either the MW or LW frequency band.

2) Press and hold the [ 3 ] key for about 2 seconds.

When the display shows “CH-5” (actually an “S” which stands for shortwave telescopic antenna) the radio is now set to MW/LW reception using the telescopic whip antenna.

The display will show MW (or LW) and SW on the left side of the screen.

3) Press and hold the [ 3 ] key for about 2 seconds.

When the display shows “CH-A” (“A” stands for “AM”) the radio is now set to MW/LW reception using the internal ferrite antenna once again.

The display will also show only MW (or LW) on the left side of the screen.

Pressing and holding the [ 3] key essentially toggles between these two antenna settings.

I’ve actually found that, indoors, using the whip antenna on mediumwave has been more effective at mitigating RFI with strong local stations. The ferrite bar antenna has more gain, of course, but for locals it’s not necessarily needed.

Many thanks, Anna, for sharing this tip!

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Radio Waves: BBC radio reporters axed, Ham Radio on BBC Surrey, K6UDA on IC-705 features, and VLF balloon launched with request for detailed reception report

Radio Waves:  Stories Making Waves in the World of Radio

Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers.  To that end: 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 Mark Hist, Kris Partridge, John Palmer, and the Southgate ARC for the following tips:


Radio reporters to be axed by BBC and told to reapply for new roles (The Guardian)

Radio reporters to be axed by BBC and told to reapply for new roles
Critics fear end of an era because of plans to make audio journalists work across media platforms

BBC radio voices have described and defined modern British history. Live reports from inside a British bomber over Germany during the second world war, or with the British troops invading Iraq in 2003, or more recently from the frontline of the parent boycott of a Birmingham school over LGBT lessons have also shaped the news agenda.

But now the BBC plans to axe all its national radio reporters and ask them to reapply for a smaller number of jobs as television, radio and digital reporters, rather than as dedicated audio journalists. Many fear it is not just the end of their careers but the premature end of an era for the BBC.

“Radio reporting is a different job. Of course, you can do both, but a report designed for television starts from a completely different place. Radio is also more agile and also a lot less expensive,” said one experienced broadcast journalist. “I am pretty sure most of us will not be given new TV roles. It seems sad to lose all that specific radio expertise.”

Among the well-known voices likely to be affected are Hugh Sykes, Andrew Bomford – who has just completed a long feature on the child protection process for Radio 4’s PM show – and the award-winning and idiosyncratic Becky Milligan, as well as a wider team of expert correspondents.[]

Amateur radio on BBC Radio Surrey (Southgate ARC)

RSGB report Board Director Stewart Bryant G3YSX and SOTA organiser Tim Price G4YBU were interviewed on BBC Radio Surrey on Friday, September 11

The interview starts just before 1:43:00 into the recording at
https://www.bbc.co.uk/sounds/play/p08pkykw

RSGB https://twitter.com/theRSGB

What is Amateur Radio?
http://www.essexham.co.uk/what-is-amateur-radio

Free UK amateur radio Online Training course
https://essexham.co.uk/train/foundation-online/

10 Things That Make The Icom IC 705 A Revolution in Ham Radio (K6UDA YouTube)

 

VLF Balloon with 210m long antenna launches Sept 12 (Southgate ARC)

A high-altitude balloon experiment, launched by Warsaw University of Technology, is planned to lift off September 12, carrying a VLF 210-m-long fully-airborne antenna system, transmitting on 14.2 kHz

14.2 kHz is the former frequency of the Babice Radio Station in Poland.

The project is delivering very important data for a doctoral dissertation – any and all feedback on the reception of the signal (reception location, SNR, bandwidth etc.) is extremely important; your help with the listening to the transmission would be invaluable!

The balloon will also be transmitting APRS on 144.800 MHz FM, callsign SP5AXL.

Full details at
https://alexander.n.se/grimetons-sister-station-shall-reappear-in-the-stratosphere/?lang=en


Kris also points out this article which provides more detail about the station and request for reception reports:

Invented for the first time in 2014, in 2020 it will finally be implemented – the idea of „restoring” the TRCN, but in the stratosphere, where there are no mechanical limitations at the height of the antennas, and the achieved range can be gigantic.

The launch of a stratospheric balloon from the Przasnysz-Sierakowo airport of the Warsaw University of Technology is planned for September 12, 2020, in order to perform atmospheric tests – measuring UV radiation, recording the cloudy surroundings with a high-speed camera and conducting an inductive experiment at 14.2 kHz using a special antenna system.

The inductive system uses a modified long-wave transmitter (A1 emission, unkeyed) from the GLACiER project of the Warsaw University of Technology, implemented as part of the IGLUNA – a Habitat in Ice programme (ESA_Lab / Swiss Space Center). The power of the transmitter, due to the emission limits for this type of inductive devices, shall not exceed a few watts. The antenna system is a centrally fed (35: 1) dipole with capacitive (Hertzian) elements and a vertical axial coil. The electrical length is between 400 and 500 m, with a total system length of 210 m. The antenna is equipped with metalized radar reflectors.

The entire balloon mission will use 144.8 MHz (as SP5AXL) and 868 MHz (as part of the LoVo system) for navigation. Flight information will be available in advance in NOTAM (EPWW).
Planned balloon launch (even if the sky is full of ‘lead’ clouds) at 12.00 UTC (14.00 CEST, local time). The 14.2kHz experiment will be switched on on the ground, with the antenna initially folded in harmony. The predicted total flight time is 3 hours – around 13.30-14.00 UTC / 15.30-16.00 CEST it is planned to reach the maximum altitude of 30 km above sea level.

Source: https://trcn.pl/do-stratosfery-to-the-stratosphere/

How can you help with the experiment? By recording as much as possible! Every parameter is valuable – from the spectrum / screenshot with the spectrum, to the EM field strengths, SNR and bandwidth, to the change of the EM field strength over time. The collected data can be sent to our e-mail address: stowarzyszenie@radiostacjababice.org. On the day of launch, we plan to post updates on the launch, flight and the experiment itself via our Facebook page: facebook.com/radiostacjababice.
Stay tuned!


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Grimeton Radio / SAQ Transmission on Sunday, July 5, 2020

(Source: SAQ via Mike Terry)

The annual transmission on Alexanderson Day with the Alexanderson Alternator on VLF 17.2 kHz with the call sign SAQ will take place Sunday, July 5th, 2020.

Two transmissions are scheduled as follows:

Startup and tuning at 10:30 (08:30 UTC) with a transmission of a message at 11:00 (09:00 UTC).

Startup and tuning at 13:30 (11:30 UTC) with a transmission of a message at 14:00 (12:00 UTC)

Watch both transmission events live on our YouTube Channel.

QSL-reports to SAQ (please no E-mails) are kindly received via:

  • Reception report form
  • or via: SM bureau
  • or direct by postal mail to:

Alexander Association
Radiostationen
Grimeton 72
SE-432 98 GRIMETON
S W E D E N

The Amateur Radio Station with the call “SK6SAQ” will be QRV on the following frequencies:

  • 7.035 kHz CW or
  • 14.035 kHz CW or
  • 3.755 kHz SSB

QSL-reports to SK6SAQ are kindly received via:

  • Email to info@alexander.n.se
  • or via: SM bureau
  • or direct by postal mail (see address above)

Two stations will be on the air most of the time.

Due to the Corona pandemic, there will be no visitors to the radio station and there will be no visitor activities. Instead you can watch both transmission events live on our YouTube Channel. The association will try to carry out the two broadcasts to the world from the old Alexanderson alternator SAQ with minimal staffing in place.

World Heritage Grimeton Radio station and The Alexander Association

For further details, se grimeton.org or alexander.n.se

Alexanderson Day 2020

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