Category Archives: Antennas

Larry’s variation of the W6LVP amplified magnetic loop antenna

Many thanks to SWLing Post contributor, Larry Thompson (WPE8EKM), who writes:

I’ve just finished building a variation of the W6LVP amplified magnetic loop antenna. I was able to purchase the preamplifier, power inserter, and the power supply separately. I then created my own loop antenna using LMR400Max coax and designed my own knock-down PVC support. I wanted something extremely compact and portable to take on sae-kayaking expeditions and to DXpeditions to Africa.

I spent many years teaching in the DRC Congo and hope to return.

I’ve used a 6’ loop, a 9’ loop, a 12’ loop, and an 18’ loop. All do very well, but the 6’ and the 9’ seem to do the best. I’ve been using the 9’ length of coax doubled into two loops and that seems be be doing extremely well.

The signal strength from the W6LVP variation is equal to my Parr EF-SWL End-Fedz 45’ dipole, but the reduced noise level on the bands is amazing. I live in a central city high-rise with no possibility of an exterior antenna. The EF-SWL is strung out a 5th floor window down the side of the building. It performs well, but with a high degree of noise. My QTH is rampant with QRM and RFI noise. The W6LVP amplified magnetic loop has really resolved that in a big way.

The bands are horrible at the moment, so evaluating the loop antenna is difficult. But the cleaner, stronger signals of CHU Canada on 3339 kHz and 7850 kHz, as well as WWV on 10,000 kHz is impressive.

I’m impressed with the reduced noise level on the bands tuning across them, as well as the noise-free signal once you lock into a station. I’ve heard hams on the 17 mb for the very first time.

So far, I’m very impressed with the performance of this amplified magnetic loop.

Very cool Larry! You’ve build a compact loop that can bring the RFI down to a tolerable level–I’d say that’s a complete success. Thanks for sharing!

Click here to read our previous article about the W6LVP loop.

A review of the W4OP portable magnetic loop antenna

The following review first appeared in the August 2017 issue of The Spectrum Monitor magazine.


The W4OP Magnetic Loop Antenna (Photo Credit: LnR Precision)

What can one say about portable antennas? They’re up, they’re down, they’re basic in design:  they either work for an intended purpose or they don’t.  But, I wondered, could they provide their service easily and conveniently, even in the field?

Last year, I decided to purchase a portable field antenna, and at the Dayton Hamvention I became the owner of the three-band (40/20/10) EFT Trail-Friendly antenna from LnR Precision.

Then, I caught a bug: the National Parks on the Air (NPOTA) bug. And, wow, I caught it in a bad way…! Having activated seven sites during the 2016 Dayton Hamvention with my buddy Eric McFadden (WD8RIF), I found NPOTA the perfect excuse to play radio outdoors. Last year, from August to December, I activated all but that initial seven of my ninety-one NPOTA park activations. All of these activations were QRP and all of them were “field” activations; meaning, I set up my field antenna each time; no activations were made with a mobile (vehicle) HF installation.  And I made 85% of all of my activations using LNR’s EFT Trail-Friendly antenna.

The EFT Trail-Friendly antenna is incredibly compact and quite easy to deploy.

The EFT Trail-Friendly antenna is end-fed and requires some sort of support system to raise the end of the 33’ radiator. Most of the time, I simply hung the lightweight EFT from a sturdy tree branch. On a few occasions, I hung the end on a 31’ or 22’ fiberglass telescoping pole. I was altogether pleased with its performance; indeed, I can’t recommend it enough for someone who wishes to have a simple, roll-up, resonant antenna for QRP field work. But it does have one limitation: it requires that source of external support, which I worried could undermine some NPOTA activations.

In December 2016, my buddy Eric (WD8RIF) and I organized a mini NPOTA DXpedition in Ohio.  I decided that en route to Ohio, I’d make a run through West Virginia and activate some relatively rare parks along West Virginia’s mighty river gorges.

Eric had made the same activation run earlier that year, and had advised me that when I seek permission to activate these parks, I would be asked to apply for and pay at least one, sometimes more, “special use permit” fees merely to drape the lightweight EFT antenna over a tree branch or to stake a fiberglass support pole in the ground. Even if my equipment is less invasive in the great outdoors than the poles and stakes of a basic pup tent, I understood US park trees and shrubs can be delicate, rare, or endangered, and even park soil can be, for example, geologically or archaeologically sensitive, so of course I didn’t want a mere antenna to bring about any harm––however minor––to the parks I was enjoying.

Eric had simplified this step by strapping a fiberglass pole antenna to his vehicle, thus avoiding either penetrating the ground or using park vegetation as a support.  So as not to potentially harm sensitive park environs, nor be obliged to hop through time-consuming (and expensive) administrative hoops, I decided I would adopt an option similar to Eric: I would use a portable antenna that could stand on its own, thus not requiring external support from park property.

Enter the W4OP magnetic loop antenna

LnR precision had only a few weeks before announced their new portable, self-supporting, magnetic loop antenna: the W4OP loop ($329.99 US).

I contacted LnR in November to tell them about my upcoming December NPOTA DXpedition, and inquired whether they thought the W4OP loop would be a good fit? They responded by sending me a loaner unit to both use and review. After all, what better way to evaluate an antenna than by using it in the field?  I said I’d be happy to give it a test drive.

The W4OP loop arrived in early December, about one week before my trip.

Contents of the loop package are straightforward:

  • The main loop assembly and support
  • The coupling loop assembly and clamp
  • The tuning box
  • The support feet assembly
  • An owner’s manual

The main radiator is a sturdy, flexible-yet-rigid shielded cable. The tuning box is a heavy PVC box, and the tuning knob has an appropriate amount of brake and drives a 6:1 reduction drive on the tuning capacitor.  

The overall package feels well-built and of very decent quality. The only piece of the equipment package I didn’t like are the four support feet: these feet attach to the bottom of the tuning box with red thumb screws, a very basic way of supporting the unit, since the red screws are challenging to tighten and almost any movement from the feet loosens the screws.  Since my review, however, LnR has designed a tripod mount for the W4OP loop which promises to make it much, much easier to deploy this antenna in the field. With the tripod mount, one would only need to pack a sturdy (camera) tripod, and then toss out the included stabilizing feet.

The manual is fairly simple and concise, but certainly provides enough information to get you on the air in short order.

On the air with NPOTA

I’m a bit embarrassed to admit that I was something of a newbie when it comes to passive mag loop antennas. I’ve used a number of wideband mag loops over the years––receive-only versions, to be precise––but had never used one specifically designed for amateur radio transmitting.

My first proper NPOTA activation using the loop was on the Blue Ridge Parkway at the Folk Art Center in the mountains of western North Carolina. The loop operates best when raised off the ground and sitting on a dielectric base.

Having no tripod mount at that point, I simply sat the antenna on a plastic storage bin which sat on top of a picnic table where I operated. It’s not ideal to be so close to the antenna, of course, but I thought I’d give it a go.

And go I did.  What truly surprised me was how many contacts I racked up in relatively short order on the twenty and forty meter bands using SSB at QRP levels. I’ve always been a wire antenna guy in the field who believed in getting antennas up as high as possible; it still blows my mind that an antenna so compact, in such a compromised position, could rack up the contacts thousands of miles away.

This first activation was the only chance I had to properly learn the dos and don’ts of this antenna before I had to deploy it in the field on my river run through West Virginia. There, I simply didn’t have the time to worry about the process. I did take a few notes, however:

  • The W4OP loop is high gain and very narrow band; if you move off frequency even a few kHz, you’ll certainly need to re-tune;
  • The bandwidth is so narrow that, if you’re turning the capacitor too quickly in the field–especially in windy conditions– you’ll miss hearing the audio level increase when you make the loop resonant;
  • Sometimes being near the loop while tuning the capacitor can affect the results;
  • Loop antennas are not terribly practical for hunting and scanning for DX across the bands due to frequent re-tuning;
  • For NPOTA or SOTA type activations where you operate on one frequency, the loop performance is downright amazing!

Mini DXpedition

My excursion into the three river gorges of West Virginia––the Bluestone, New River and Gauley––took an amazing amount of planning for such a short trip. Firstly, I only had a limited amount of time to activate each site, yet these were rare sites and I wanted to log as many stations as possible at each site. Secondly, I had to announce my activation times and frequencies well in advance so chasers could find and spot me. Also, I knew a number of west coast chasers who really needed one or more of these sites, so had to plot on-air times to maximize 20 meter propagation. Finally, an actual valid activation site has a lot of requirements and is not easy to find on a map!

Surprise snow started falling well before I even entered West Virginia that morning.

And––oh, yes––the weather was really dodgy.

As soon as I hit the West Virginia state line on I-77, the snow started in earnest. Despite being from the southeast, I’ve no fear of driving in snow, but this was a bit unexpected and no roads had been prepared in advance. Also, I was driving into some pretty remote areas with my least snow-capable vehicle: a minivan. The snow was bad enough that I knew I would not attempt to activate the New River Gorge at the site I originally planned, which required negotiating a very long, steep, and winding road deep into the gorge. Instead, Eric advised me of another New River site option that was more easily accessed. I readily took him up on his suggestion.

And it was at the alternate New River site where the loop antenna truly saved the activation.

The activation site was essentially a one-car off-pavement parking spot next to a river access for small boats. Space was tight, but plenty big for the loop antenna.

It was about 20F with sharp wind, and spitting snow; wind gusts were high. I set up two plastic storage bins with the W4OP antenna on top, only about four feet off the ground; fortunately it did not blow over. I tuned the loop quickly to my pre-announced frequency of 14.312 MHz. I made a couple of calls, was answered by a chaser who spotted me…and whoosh! In less than an hour, as I sat there in the freezing wind, I worked 70+ chasers with 15 watts SSB with my Elecraft KX3. It was exhilarating.

As I packed up my station to move to the next site, I quickly scanned over my log sheet: I found I had worked much of the east coast of North America, almost all of the west coast states, several Canadian provinces, Italy, Slovakia and Croatia.  All with this incredibly modest antenna.

Weather was much better in the New River gorge.

Signal reports were averaging about S7.

Of course, I was a DX target, which, as any ham will tell you, gives you an automatic 30 dB of gain! Still, people could hear me clearly even though I was at a fairly low elevation in a gorge.

Impressive.  I was really beginning to appreciate this antenna.

Problems at Gauley River

My next destination, the Gauley River, was about a seventy-minute drive from the New River and at a much higher altitude. The light rain turned into snow again accompanied by more very strong winds. I was really feeling chuffed about the easy loop setup ahead of me at the site.

 

After arriving on site, I set up the loop quickly, my Elecraft KX3 quickly followed, and started the tuning process. Unfortunately, I could not get the antenna to find a match on the 20 meter band. No doubt, the cold, the wind, my frozen hands, and a desire to stay on the tight schedule all influenced my ability to tune the antenna.

After ten minutes of trying to tune the loop, I initiated Plan B, pulling out the trusty EFT Trail-Friendly antenna and launching it into a nearby tree. The EFT didn’t fail me: once I was on the air, I worked almost 100 stations in a little over one hour.

I felt a little badly about hanging an antenna in a tree limb since I did not seek permission from the NPS in advance. Still, I was the only person at the park that day. No one in their right mind would have been hanging out by the roadside, save your author. I took comfort in the fact that the mature tree that aided me was entirely unharmed, and by the fact that not only do I strictly adhere to the Leave No Trace philosophy, I also clean up other visitors’  trash in the vicinity of all of my activation areas, as a means of honoring the park. I don’t think even the CSI would be able to find evidence of my activation.

Back to the loop.  When I finally arrived at the QTH of my buddy, Eric, we took the loop out and he hooked his antenna analyser up to it. Again, we were not able to get the excellent match I had on 20 meters earlier that day at the New River. Eric and I both assumed (incorrectly, it turns out) that something had happened to the capacitor inside the tuning box.

Once I returned home, I called Larry with LnR and described what was happening. He quickly identified the problem: the coupling loop wasn’t positioned and clamped correctly. Whoops…I should have considered that.  Once I adjusted the coupling loop an inch or so, it worked fine again.

Summary

Every radio, accessory, and antenna has its pros and cons. When I begin a review of a product, I take notes from the very beginning so that I don’t forget some of my initial impressions. Here is the list I formed over the time I’ve spent evaluating the W4OP.

Note that, since this was my first proper experience with a loop antenna for QRP operations, many of these items are indicative of loops in general, not just the W4OP.

Pros:

  • Excellent build quality and overall value
  • Excellent gain when tuned to a frequency (see bandwidth con)
  • Overall impressive performance in the field and super fast and simple setup
  • Excellent choice for those living in high-density neighborhoods with antenna restrictions
  • LnR telephone customer support is excellent

Cons:

  • Bandwidth is very narrow and the loop requires re-tuning on frequency changes (see gain pro)
  • Supplied support feet are very basic; splurge for the new tripod mount
  • Not always convenient and accessible to tune the antenna on the antenna base (though LnR will soon produce a remote tuning W4OP loop)

LnR Precision has recently released a remote tuning W4OP loop ($354.99) and a 6m kit for the current loop.

The W4OP Remote Loop Antenna (Photo: LnR Precision)

I think a remotely-tuned W4OP loop would make this an excellent antenna for amateur operators who wish to set up the antenna as a semi-permanent home installation; certainly a bonus for those living in restricted neighborhoods. Without a remote tuner, you would need to go to the antenna to make frequency adjustments. Note that LnR even has an upgrade program if you wish to turn your W4OP loop into a remote loop.

Of course, this first version of the W4OP loop isn’t designed as a permanent home antenna; it’s designed for field use.

And am I impressed with the W4OP loop? Absolutely.

Like me, if you’ve never used a mag loop antenna for field operations, spend a little time at home learning how to deploy it and tune it in advance.

Most of the criticisms of the W4OP loop I mention in this review are simply indicative of passive mag loops in general: narrow bandwidth, sensitivity to nearby metal objects, and the need for frequent re-tuning.

I understand that the W4OP may have even narrower bandwidth than other similar field-portable antennas. While some may consider this a disadvantage, I think I prefer it; in fact, I would rather be inconvenienced by re-tuning in exchange for higher overall gain.  After all, even broader bandwidth loops require re-tuning if you move frequency more than a few kHz.

The W4OP antenna meant that my mini NPOTA DXpedition was a success, especially at the super-restrictive New River access point. Though I’ve used it in the field on a number of occasions now, I’m still in awe when such a compact antenna performs so well on such little power.  I unhesitatingly recommend it.  Great job, LnR Precision!

The W4OP is made in the USA by North Carolina manufacturer LnR Precision. The loop, and its accessories, can be ordered directly from LnR:

http://www.lnrprecision.com/loop-antennas/

Preparing for Your Next DXpedition – New Videos

Regular readers of the SWLing.com blog will be aware that I am passionate about going portable/mobile with my radio listening hobby. There’s just nothing like communing with both nature and a bunch of electrons whizzing along the wire!

As a follow-up to an article I wrote several years ago, I have now prepared two new YouTube videos entitled Preparing for Your Next DXpedition – Parts 1 and 2.  

Part 1 covers:

– why we should even think about bothering to go portable with the radio

– the goals to consider when undertaking a DXpedition

– planning your listening depending on the time of day and time of year

– the all important decisions regarding location


Part 2 discusses:

– choosing the right radio for portable operations

– your options for powering the radio

– the antennas you could consider including on the trip

– handy auxiliary equipment

– references and notes to take along with you

– the importance of operator comforts while away

– developing a checklist…..so that you don’t forget to take something important!

These videos will be of interest to shortwave radio listeners and new amateur radio operators. Hopefully, they may be able to assist you in further enjoying our great hobby. They are embedded in this blog post below. You can also view these and other videos on my YouTube channel at Rob Wagner’s YouTube Channel

 

As always, thanks for watching and your comments are always welcome. 73 and good DX to you all,

Rob VK3BVW

Rob Wagner, VK3BVW, is the author of this post and a regular contributor to the SWLing Post. He also blogs at the Mount Evelyn DX Report.

DXing in a large suburban garden with the Eton Satellit & Bonito MegActive MA305 antenna

Hi there, the garden at my house is pretty small and as a consequence, I am very limited in terms of what antennas I can usefully employ. You can’t position anything further than about 10 metres from the brickwork and to compound this, we are surrounded on all sides by neighbours in close proximity. All very nice people, but all very noisy – electrically speaking lol. I simply can’t get far enough away from these sources of electrical noise to achieve excellent SNR.

The solution to my problem was ultimately a Wellbrook ALA1530 magnetic loop, but prior to that I used an end-fed random wire, the performance of which deteriorated as the months went by as the ubiquitous blanked of local QRM continued to increase. Eventually, I was forced outdoors, well away from my town – effectively catalysing my forays into the Oxfordshire countryside on DXpeditions. That first experience of listening to the radio on shortwave, in the absence of any QRM was enlightening to say the least and of course, subsequently, DXpeditions have become a mainstay of my listening activities. However, despite enjoying some great DX successes out in the woods, one has to be realistic about how often it’s possible to leave the house just to listen to the radio. This led me to the purchase of the Wellbrook ALA1530 magnetic loop. It proved to be a triumph of electrical noise mitigation and an absolute necessity in copying transatlantic medium wave signals in such a noisy and compact space. A total game-changer. The brilliant performance of the Wellbrook eventually led to me purchase a second, cheaper active antenna; the E-field Bonito Boni Whip and in turn, that purchase led me to the MegActive MA305, kindly supplied by Bonito themselves for objective testing.

Have DXing kit, will travel…everything you need in a small flight case…

You might remember my initial tests at home confirmed, as expected, that E-field antennas don’t work well in electrically noisy environments (except at LW frequencies in my experience) but outdoors, away from noise, they are superb. I have a number of reception videos on my YouTube channel – Oxford Shortwave Log which clearly demonstrate identical performance of the Bonito MegActive MA305 antenna and Wellbrook ALA1530 magnetic loop out in the woods. So, what if you’ve got a large garden in a suburban area that allows you to be just far enough from sources of electrical noise…how much of a difference does it make to the noise floor of your receiving equipment? Can E-field antennas such at the Bonito MegActive MA305 do the job? Furthermore, how well does a random wire work in a larger garden?

 My MegActive MA305 antenna system for mobile DXing…and another use for a washing line…

I was fortunate enough to know someone who owns a house with a large garden, quite close to my QTH (a 10 minute walk) and who was more than willing to let me set up my DXing equipment and sit around until the early hours of the morning, listening to and recording various signals on my Eton Satellit. In preparation, I set up the Bonito MegActive MA305 antenna and hung the radiating element on the washing line – sounds ridiculous but actually worked very well, placing it about 2.5 metres above the ground. I also set up a 40 metre longwire, which at its closest point, was still approximately 25 metres from the house, and 30 metres from the neighbours. This post will focus on the performance of the MA305; a subsequent post will detail the performance of the longwire.

The large garden I ‘borrowed’ for my DXing session with the Bonito MegActive MA305 antenna

Suffice to say, the MegActive MA305 performed admirably during my first listening session. In the middle of the afternoon I copied a very strong signal from The Voice of Korea around 15:44 hrs UTC on the 25 metre broadcast band, followed at 17:10 hrs UTC with a superb signal from The Voice of the Broad Masses 2, Eritrea, on the 40 metre ham band. Later on in the evening I copied Radio Mail with excellent modulation, CHU Canada with voice announcements (almost impossible at home), Myanmar Radio with an untypically strong signal and XEPPM Radio Educación from Mexico City with a signal I would normally expect on a DXpedition-proper with a large antenna.

My conclusions to this experiment are simply that E-field antennas can work in a suburban environment, if you are able to site them far enough away from adjacent sources of electrical noise. I don’t have empirical data on this, however, I can confirm that 10 metres proximity is too close at my QTH and 30 metres is sufficiently far away at this test location. One has to assume the houses nearby are similarly equipped to mine with electrical appliances that generate electrical noise. Thus, if you’re interested in a very well-priced, compact antenna and you live in an urban or suburban environment with access to a large garden/ outdoor space, an E-field Boni Whip or MegActive MA305 might well be suitable – and you’ll have a superb portable antenna for those listening sessions away from home!

Finally, I should mention the Eton Satellit. Much-maligned in certain quarters when it was first introduced into the market, it continues to demonstrate superb DXing credentials. I won’t forget some words of wisdom from a friend of mine and fellow DXer, with more than 3 decades of experience in listening to the bands on HF. He told me that Judging from his own experience with some of the original Grundig Satellit models of the 1980s and early 90s (namely the 400, 500 and 700) he was quite sure that the Eton Satellit is a considerably better DX performer than those vintage sets, that offered great sound for casual listening to international broadcasters, but didn’t perform too convincingly on weak DX signals. The Eton Satellit has been a revelation and I’m pleased to have played a small part in turning around the rather widely held view that it was less than worthy of the Satellit branding.

Fresh out of the box, the Eton Satellit has surpassed all my expectations…

Please find embedded reception videos below and text links to the Oxford Shortwave Log YouTube channel. My next post on this subject will cover the performance of a 40 metre longwire in this large garden environment. Thank you for reading/watching/listening and I wish you all great DX!


Click here for video on Oxford Shortwave Log

 

Click here for video on Oxford Shortwave Log

 

Click here for video on Oxford Shortwave Log

 

Click here for video on Oxford Shortwave Log

 

Click here for video on Oxford Shortwave Log

 

Click here for video on Oxford Shortwave Log

 

Click here for video on Oxford Shortwave Log


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.

Antenna installation: John would like to use home satellite TV/RG6 port

Many thanks to SWLing Post contributor, John Minor, who writes:

I am going to set up a rig to start DXing, and getting my technical license. My plan is to buy a Kenwood TS-590 SG transceiver and a discone antenna.

My home’s previous owner had satellite TV, and my question to you is, can I use the existing cabling for my antenna?

There is a connector in my living room, and the cable runs to the connector/splitter box for the dish. Could I run a cable from the end of the existing cable at the splitter box, to the antenna?

I’ve attached some pictures to show you what the existing cables look like.
Picture 6 has a circle drawn on it to show where I’d like to mount the antenna.

I remember back when I was 9 or 10, laying under the covers at night slowing turning my AM transistor radio dial and seeing what I could pick up. It was a thrill to hear stations from Chicago, Cincinnati or Little Rock. I look forward to the same thrill listening to voices from across the country and around the world……

Thank you for your time, and for the wonderful website.

Thank you, John, for your question and for the kind compliment!

I’m publishing this question here, though, in hopes the SWLing Post community can help you.  I have very little experience matching antenna impedance this way especially when transmitting will be involved–there will be a mis-match, I’m pretty sure. With that said, I know many mag loop receive-only antennas actually use RG6. It would certainly be great to use an existing penetration for this application.

Post readers: If you can help John, please do comment. Quite frankly, this isn’t the first time I’ve been asked this question, so I’ll follow comments as well.

John, I’m sure you’ll soon have your radio on the air receiving the world just like when you were nine–or even better!  Great choice in that Kenny TS-590SG–it has a brilliant general coverage receiver for broadcast listening!