Category Archives: Antennas

Valentino experiments with a ferrite sheet loop antenna

Valentino’s homebrew ferrite sheet antenna.

Many thanks to SWLing Post conttributor, Valentino Barbi (I4BBO) who writes detailing a novel approach to FSL antenna design.

Please note that I translated Valentino’s message from Italian to English via Google translate so please forgive any errors. Valentino writes:

FSL antenna radio enthusiasts typically use numerous ferrite bars with high cost, weight and scarcity,

Ukrainian ferrite bar producers have now finished stocks and have raised their prices.

Normally you use this site to build FSL antennas:
http://www.am-dx.com/antennas/FSL%20Antenna%20Design%20Optimization.htm.

I’ve been experimenting with a new antenna design for about 10 days comparing it with a classic FSL with 20 ferrite bars.

Listening to the audio signals are the same, only instrumentally the antenna FSL in ferrite film
Loses -2dB.

The construction is very simple in that the two ends overlap 5 mm.

I did this:

  • I took a sheet of A4 paper, I cut 5mm paper at one end.
  • I laid this sheet on a 10 cm (10 cm) diameter PVC tube.
  • The uncovered part of the tube is cut, now we will have exactly the exact diameter to fix the A4 sheet of ferrite with the overlap of 5 mm.

As for where to source a ferrite sheet, after much research I discovered this supplier almost by accident:

Click here to view the product page and ordering information.

In summary, the main advantages of this antenna design is weight, cost and availability of A4 sheet of ferrite.

Click here to follow Valentino’s antenna project on his website.

Fascinating, Valentino! Please feel free to share any further information about this FSL antenna as you experiment. It’s true that ferrite bars are becoming difficult to source. Sounds like this is an affordable alternative antenna design for ultralight DXing.

eBay find: 2:1 Remote/Local Antenna Switch $26.99 shipped

Many thanks to Kenneth Crips who recently shared an eBay link to this antenna switch on the Gary J. Cohen’s Shortwave Listeners Global Facebook page.

The switch is not a kit–it is pre-built and appears to contain quality parts. The manufacturer, Electro Resales, makes a number of other products for the radio, astronomy, RC and model railroad markets. They have 99.9% positive feedback and a deep history of sales via eBay.

I’ve pasted the product description from eBay below:

Coaxial Electronic Switching unit for Antenna – 2:1 unit – Ready Built Unit

Switch 2 antenna to one radio or 2 radio to one antenna.

Using high quality Schrack Brand relays this antenna switcher works up to 200 MHz with SWR below 1:1 and minimal insertion loss.

Features include:
1. SO-239 input/output connectors
2. 8 Amp switching relay (Operation to 1 KW)
3. LED mimics indicate which port is active
4. Built in push switch for ease of operation – Selects relay coil to energize,
5. Remote installation operation possible
6. 1 KV Suppression capacitors and back EMF diodes on each relay coil
7. Relay coil : Capacitor tank frequency = 93 KHz – Minimizes RF interference on activation.
8. PCB Isolation Slots to minimize cross talk
9. 12 volt operation
10. Via stitching in critical signal paths and connector ground plane
11. Complete, self contained unit, ready to use. Not a Kit.

PCB dimensions are 4″ x 3.25″ (100 mm x 80 mm). Ready to mount in your installation

Pictures illustrate actual item that you will receive.

Questions – Please ask – Free Shipping as always

Sale includes:
1. Finished PCB with all components
2. Link to our on-line user guides

No other items such as power supplies, RF equipment or cables are included in the sale

I might purchase one of these as I have a remote antenna box with a solar-powered LDG ATU. This switch would allow me to change antennas without manually changing feed lines outside. I had planned to build a switch like this with my buddy, Vlado (N3CZ), but the price is awfully enticing! Have any SWLing Post readers purchased from this store before? If so, please comment.

Click here to view on eBay. 

Portable Powerhouses: Comparing the Bonito Boni Whip and Wellbrook ALA1530LNP Antennas

One fits in a car (well, most vehicles anyway) and another easily slides into a small daypack; which antenna is best for DXing on-the-go? The ALA1530LNP and Boni Whip are at opposite ends of the portability scale (as well as the price scale).

I’ve written about the ALA1530LNP in the pages of the SWLing Post before, where I compared it against another Wellbrook loop antenna on extremely weak medium wave signals. The ALA1530LNP currently costs $413 USD including shipping to the Seattle USA area where I live.

More recently I’ve been intrigued by UK Oxford Shortwave Log’s (YouTube) excellent videos demonstrating the DXing prowess of the very compact, highly portable Bonito Boni Whip antenna. Through a Bonito USA dealer I was able to purchase the Boni Whip at an attractive $99 USD price (plus $11 shipping).

So, is it fair to compare “apples and oranges”? Maybe not, but it was fun and interesting nonetheless to take both antennas to the countryside to find out how they perform head-to-head in a portable situation. My destination was a small forested campground, in a valley east of this beautiful Mount Rainier, Washington scene:

In mid-July, Tipsoo Lake near Mt. Rainier is still surrounded by snow.

Over the course of three days I compared the two antennas with these receivers:

  • Eton E1XM
  • Sangean ATS-909X
  • Elad FDM-S2

I set up the E1XM and ATS-909X receivers on a portable tote box with the antennas powered by SLA gel cell batteries and using a two-way antenna switch for instant comparisons.

Each antenna was mounted on its own “pro” speaker stand and separated 60 feet from each other. The antennas were connected to receivers by equal 100 foot lengths of RG-58 coax cable, and were over 80 feet away from my laptop computer (the only noise source in the area).

In keeping with the uber-portable theme of the Bonito antenna, I used a very compact 1.2Ah SLA gel cell battery for its power injector (junction box). Since the antenna consumes a mere 45 ma. of current, this small rechargeable battery will power the Boni Whip for many, many hours.

The Wellbrook ALA1530LNP requires a still reasonable 200 ma., and I brought along a much larger battery to power it.

Below are a selection of 30-second medium wave and shortwave recordings, each one of them beginning with the Boni Whip and switching to the ALA1530LNP midway through the recording.

Boni Whip vs ALA1530LNP – E1XM Receiver

660 kHz

870 kHz

1660 kHz

3330 kHz, CHU Canada

4960 kHz, VOA Sao Tome

9535 kHz, R. Algerienne

11600 kHz, Denge Kurdistan

11760 kHz, R. Havana Cuba

EDIT 7/14/2017: 11905 kHz, Reach Beyond Radio, Kununurra WA Australia (tentative; listen for the Aussie-accented weather forecast at the end of the Wellbrook loop portion. This catch was at 03:48 UTC, which matches up with the brief English language broadcast in Reach Beyond’s schedule for 11905 kHz. This catch does not appear to be China National Radio as  I first thought.)

Boni Whip vs ALA1530LNP – Elad FDM-S2

These 30-second videos are from the Elad SDR’s FDM-SW2 software. As above, the first half of each recording is the Bonito antenna followed by the Wellbrook loop. If you maximize the playback of a video to full screen you can read the signal-to-noise ratio (SNR) change (“Delta”) as the antenna is switched to the ALA1530LNP.

The compact Boni Whip is a unique commercial design of “mini whip” antenna, pioneered by Roelof Bakker, PA0RDT some years ago. As with all these compact e-field antennas they can be a significant “noise sponge”, collecting any RFI or interference in the area. This is especially true if the coax shield is not grounded. Despite using two Bryant/Bowers design of RF chokes in series, the Boni Whip’s reception was degraded by RFI emitted from my laptop over 80 feet from the antennas. The RFI was quite a bit worse without any RF chokes in-line. You’ll note though that even the Wellbrook loop received some interference from the laptop on the higher shortwave frequencies.

4840 kHz, WWCR, Nashville TN USA

5985 kHz, R. Taiwan Intl. via WYFR, FL USA

6090 kHz, The Caribbean Beacon, Anguilla (distorted, with transmitter problems)

6100 kHz, R. Havana Cuba

9600 kHz, unidentified station

11725 kHz, R. New Zealand Intl.

11790 kHz, R. France Intl., Issoudun

11840 kHz, R. Havana Cuba (target: Chile)

Observations. On medium wave (E1XM examples) the directionality of the Wellbrook loop could be noted on one, maybe two of the three recordings. This can be a benefit–or not–depending on your goal. (I did not rotate the Wellbrook loop to null or peak any specific MW signals.) The omni-directional Boni Whip would not be the antenna of choice for a hard-core medium wave DXer; however, it is extremely compact and lightweight for camping and travel if you will be DXing or SWLing on shortwave also. The Wellbrook though is highly regarded as a medium wave DX antenna, especially when used with a rotor to take advantage of its sharp broadside nulls.

I didn’t test the Boni Whip on long wave, but Oxford Shortwave Log and others report it does very well on LF. I tried the antenna on FM frequencies against the Eton and Sangean’s telescopic whip antennas but in every case the reception was worse on the Boni Whip.

As I expected on shortwave, the ALA1530LNP greatly outperformed the Boni Whip on some signals. On others, reception was extremely comparable! The 3330 kHz CHU recording surprised me with the neck-and-neck reception. At this tropical band frequency there may have been some directionality to the signal, and the loop may not have been oriented optimally. The 4960 VOA reception was also very close.

I was disappointed, but not surprised at the RFI pickup of the Boni Whip when using my laptop and the Elad SDR receiver. The two RF chokes tamed the spikes and hash a bit, but removal was far from complete. The Wellbrook wasn’t always “clean” in this regard though.

Final notes. I think the Boni Whip is an extremely high value in a “jack of all trades” very portable antenna. Like Oxford Shortwave Log and others, I find this active antenna’s noise level to be extremely low, helping its sensitivity reveal weak DX signals in a surprising fashion. I would not hesitate to use this antenna away from noise sources when traveling with a non-computerized receiver. Well done, Bonito!

Is the Wellbrook ALA1530LNP worth four times the Boni Whip’s USA price? To the serious DXer who has no room for large passive antennas (Beverages, phased delta loops, DKAZ, etc.), the 1-meter diameter Wellbrook is clearly in a class of its own. By the way, the US Dollar to UK Pound ratio has improved in recent months, so the Wellbrook is an improved value for USA radio hobbyists now.

Truly this was an “apples to oranges” comparison, but I thoroughly enjoyed using both models. I welcome your comments, particularly if you also own both of these fine antennas.


Guy Atkins is a Sr. Graphic Designer for T-Mobile and lives near Seattle, Washington.  He’s a regular contributor to the SWLing Post.

Brilliant hard-core DX with the USB-powered Bonito MegActive MA305 antenna

 

Hi there, you might remember my post from last month focussing on the Bonito MegActive MA305 E-field antenna, kindly supplied to me for testing, by Bonito themselves. That post was essentially a report on my experiences travelling to Crete with the MA305, navigating through security at London Gatwick and Heraklion airports (mostly with relative ease), but more importantly, how well it worked with the equally excellent Eton Satellit portable receiver. Whilst in Crete I managed to copy a number of personal firsts, including CRI on 7295 kHz, via their relay in Bamako, Mali, The Voice of Beibu Radio on 5050 kHz, Nanning, XSL ‘Slot Machine’ on 6251 kHz USB, Ichihara, Japan, S32 ‘The Squeaky Wheel’ on 3828 kHz and NHK World Radio Japan, 11910 kHz. I also copied RTM Wai/Limbang FM on 11665 kHz from Kajang, Myanmar Radio on 5985 kHz and AIR Bhopal on 4810 kHz, amongst others – all of which I would certainly consider to be difficult catches in Europe.

 The USB-powered MegActive MA305 is perfect for DXing on the move…

Despite excellent all-round results from the ultra-portable USB powered MA305, there was one signal I copied, which more than any other, demonstrated the DXing credentials of this antenna; Radio Tarma from Peru on 4775 kHz. With a TX power of 1 kW, this is a very difficult station to hear in Western Europe, even with a longwire. To catch this station in Crete, with a 22 cm antenna was incredible and it was at that point during my trip that I realised E-field antennas really can work superbly well for hard-core DXers on the move.

Upon my return to Oxford, I immediately started thinking about a DXpedition to the local woods I use for what I consider serious DXing. For obvious reasons, E-field antennas require an electrically quiet environment to ensure maximum SNR performance. In noisy environments, these types of antennas amplify the signal of interest and the background ‘electro-smog’, thus increasing signal levels but critically, not signal-to-noise. Fortunately, the Oxfordshire wood I have been using for a couple of years is only a 10 minute drive from my QTH as I sort of live in the countryside anyway and the QRM levels there are just about zero. Now, given that this was essentially an experiment to determine the best possible performance from the MA305, I decided to use my best portable radio. It was quite tempting to pack up the Elad FDM DUO which running on a home-brew battery pack has proven itself to be my best (pseudo) portable radio. However, this is supposed to be a real-world test and in this type of scenario, DXpeditions with the Bonito antenna are much more likely to be undertaken with a portable radio. For these reasons I decided to conduct the test with the venerable Sony ICF-2001D. Having proven to be a superb receiver over many, many dxpeditions (check out the evidence on my YouTube Channel Oxford Shortwave Log) and still regarded by DXers as one of the best ever portable radios – possibly the best – it was the obvious choice.

 My portable DXing kit comprising the Bonito MegActive MA305 antenna and the Sony ICF-2001D…a bit of a legend in DXing circles…

I ventured out in early June around 23:00 hrs BST (22:00 hrs UTC), parked the car on the edge of the wood and proceeded to set up my cheap camera tripod, slightly modified to accept a 2 metre-long stainless steel tube, into which a slightly thinner 1 metre tube was mounted, topped off with my partially disassembled ‘Selfie Stick’ – which made it back from Crete lol. The antenna was set up in less than 5 minutes and approximately 4 metres above the ground – much quicker and easier than de-spooling 100 metres of wire! With fresh batteries in the Sony and the MA305 powered up using the USB power brick supplied by Bonito, I was ready to start listening. Almost immediately I heard and recorded a personal first; Lao National Radio, Laos, signing on 6130 kHz, with an excellent signal. Hearing them in the UK was only made possible by the annual two week shut down of the PBS Xizang transmitter in Lhasa, Tibet, but hey, I’ll take it. A brilliant start to my listening session.

Over the next two hours I was amazed at what could be heard using this 22 cm amplified antenna. Bearing in mind I have spent many hours at the woods previously, listening via various 100 metre longwires and a 200 metre Beverage, my expectations were, I thought, realistic in that the MA305 coupled to the Sony would catch some very good DX. However, I did believe there might be an absence of at least some of the more exotic low power stations on the Tropical Band – afterall the MA305 is a very short antenna. Clearly I was wrong, because what transpired during the session surpassed anything I thought possible with this set-up. A list of reception videos follows below and further below, a selection of embedded videos. Some of the entries on this list simply stunned me at the time. Rádio Educação Rural for starters is such an incredibly difficult signal to hear in Europe, even with a very large antenna. Thus, to hear them on an ultra-compact set-up felt very special. Radio Mali is another station that is very difficult to catch with any modulation, except on a large antenna and yet there they were – at the first time of trying. Similarly, Rádio Nacional de Angola and Alcaravan Radio are exotics that at best deliver very weak audio – and most of the time no audio. Furthermore, the signals from Emisoras Pio XIIMyanmar Radio and Rádio Clube do Pará were verging on what I would call superb…I’d never heard anything like it previously except via 100 (or more) metres of wire.

 The ICF-2001D and MegActive MA305              Rádio Educação Rural transmitter site in Tefé, Brazil

So what’s next? Well it would certainly be an interesting experiment to compare the performance of the MegActive antenna with the Wellbrook ALA1530 active loop in a similar environment. I have used the Wellbrook on DXpeditions several times, with often excellent results, however, it’s not designed to be portable and if SNR performance could be demonstrated as similar between these two products, given a very favourable price delta, the Bonito antenna would add up to be a very compelling purchase decision. More on that to come. In the meantime, thank you very much for reading/watching/listening and I wish you all excellent DX.

Please click on the links below for the reception videos on the Oxford Shortwave Log YouTube channel.


Selected embedded reception videos from the list above:

Clint Gouveia is the author of this post and a regular contributor to the SWLing Post. Clint actively publishes videos of his shortwave radio excursions on his YouTube channel: Oxford Shortwave Log. Clint is based in Oxfordshire, England.

RadioWorld free eBook: Propagation Analysis for Profit

(Source: RadioWorld via Sheldon Harvey at the International Radio Report)

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