Tag Archives: Loop Antennas

Video: Homebrew AM Loop Antenna Project by Thomas Cholakov (N1SPY)

Many thanks to SWLing Post contributor, Thomas Cholakov (N1SPY), who shares his latest video explaining the operation of a simple homebrew AM loop antenna:

Click here to view on YouTube.

Brilliant video, Thomas! I love the fact you included a demonstration with your SDRplay RSP1A as well. Via the spectrum display, it’s easy to see the the loop’s bandwidth and also the gain it provides when tuned to a station.

I love your AM loop antenna as well–such a simple design and ideal for demonstrating the mechanics of a passive loop antenna since all of the components are visible. I’m willing to bet you built this antenna for less than $10. Smart design as it’s both portable and effective! Keep up the excellent work, Thomas! We look forward to all of your future videos.

Spread the radio love

Kenneth is impressed with the W6LVP Magnetic Loop Antenna

3 Replies

Many thanks to SWLing Post contributor, Kenneth Wigger, who writes:

One Friday evening I contacted Larry W6LVP and asked a question about the kind of coax that he would recommend for his Magnetic Loop antenna. I was surprised to get a response with technical information within an hour or so. With this kind of customer service I decided to go ahead and order one of his antennas later that evening. I actually received the antenna on Monday afternoon within a couple days.

I have extreme electrical noise that was S-8 most of the time on my Carolina Windom and made my radio almost unusable. I temporarily installed the Magnetic Loop antenna on a short 5 FT pole in the backyard. With the XYL as the null monitor at the radio I called her on my cell phone and rotated the antenna by hand and was able to get a sharp noise null of about S-1. Very tight null when rotating just a few degrees one way or the other. Went in the house and couldn’t believe the clear signals that were hidden by the previous high noise level. It reminded me of SWLing 50 years ago as a kid back in the good old days before the electrical noise environment turned so bad!

As I mentioned, the antenna arrived within a couple days and was of high quality construction and packed extremely well for shipment. I had read the previous reviews about Larry’s product quality and customer service and my experience was also very good!!

I am planning to mount the antenna on a Channel Master rotator one of these days to get the full effect of the excellent directionally of this Magnetic Loop antenna. I even read where Broadcast Band Listeners use this antenna to pick up and select between multiple stations on the exact same AM frequencies.

I highly recommend Larry W6LVP and his Magnetic Loop antenna to other Hams and SWL listeners. He responds personally to emails within a business day usually just an hour or two. What more could a customer ask for?

Thank you, Kenneth, for sharing your review! It’s nice to have an alternative to the pricier Wellbrook and Pixel Loop antennas. Someday, I’ll get around to reviewing the W6LPV loop antenna as well.

Click here to view W6LVP antennas on eBay.

Click here to view the W6LVP website.

Spread the radio love

Horizontal Loop Antenna Experiments

6 Replies

Man-made RF noise levels have increased dramatically at my place in the past six months. It has become much harder to hear weaker shortwave signals. Even the stronger stations are getting covered in all types of hash from all manner of electrical appliances.

So, I have been looking at ways to reduce the noise problem. I’m currently researching a few possible solutions, including trying a different antenna.

The HF horizontal loop has been around for many years now, but it’s a new antenna for me. I’ve never had a need to try one…..until now! There is some documentation out there praising this antenna’s low noise capabilities. So, it was time to find out for myself and start building an experimental version. So far, the results have been really quite pleasing!

I have prepared a YouTube video (below) in which I discuss the reasons for looking at this antenna, its design, and its installation. I also do some on-air comparisons of my experimental rectangular (!) version of the horizontal loop against my three regular double bazooka (coax) dipoles and the Par SWL End-Fed antenna.

Have you tried this antenna before? Your thoughts and feedback would be most appreciated.

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.

Spread the radio love

Video: Paul’s large aperture “Volleyball Net” loop antenna

9 Replies

Many thanks to SWLing Post contributor, Paul Walker, who shares the following video and notes:

Here is a 10 minute narrated, detailed video on my 25 foot long by 10 foot tall “Volleyball Net” Loop antenna using a Wellbrook ALA100LN amp control head and antenna interface.

Click here to view on YouTube.

Great job, Paul!

I like how Paul is using the antenna space he has so effectively. Though he has no antenna restrictions, his mag loop can be deployed and taken down quite easily; it’s obviously serving him well on both the HF and mediumwave bands. As he mentions, it’ s also manually steerable.

Those of you with the Wellbrook ALA100LN amplifier might try building this loop as well.

I also like how Paul is using the Tecsun ICR-100 recorder. Not only does it provide an easy way to record line-in audio from his radio, but the built-in speaker serves as an excellent monitor. It’s pretty affordable, too.

I agree with Paul about the Emtech ZM-2 ATU: it’s an exceptional little tuner that can be used for both QRP and SWL applications. I recently purchased the ZM-2 after having borrowed one from my buddy Eric (WD8RIF). Great value, in my opinion.

Thanks again, Paul!

Post readers: If you have an antenna design you’d like to share, please comment or contact me.

Spread the radio love

How to build a Milk Crate AM Broadcast Loop Antenna

17 Replies

Many thanks to SWLing Post contributor, James Townley, who shares the following guest post originally posted on his Shortwave/Medium Wave blog:

540 kHz to 1700 kHz Loop Antenna (Click to enlarge)

AM Broadcast Loop Antenna

by James Townley

Several years ago, I became interested in medium wave DXing. One of my limitations was the size of my yard, so I developed an interest in tuned loop antennas to compensate, because setting up a beverage antenna was out of the question. I experimented with different sizes of loops, and found that the bigger the aperture, the more gain the loop would have. The tuned loop antenna is also very directional, which allows you to reject, or null out interference from either noise or other stations. Loops are considered bi-directional in that they receive to the front and back, but not to the sides. The tuned loop antenna quickly became my weapon of choice for medium wave DXing.

Recently when the weather began allowing me to enjoy the outdoors, I decided to make another smaller loop antenna from a plastic milk crate I had lying around. I saw the idea on the internet when I observed that someone had used a milk crate for their loop. Click here to see a variety of tuned loop antennas that others have made. Whichever material you decide to make your loop antenna from, just make sure that it is not a conductive material. Wood, plastic, and cardboard seem to be popular materials for loop making. In the photo above, I am using my Sony ICF-2010 to listen to WCCO on 830 kHz. This station is nearly 200 miles south of me, but I am able to receive it with 9 LEDs lit on my signal strength meter while using the loop. There is no direct connection of the loop to the radio, it is inductively coupling with the radio’s own ferrite rod antenna.

If you are interested in making a loop antenna like mine, here are the materials you will need:
120 ft of 18ga insulated wire (I bought a 100 ft spool of cheap speaker wire and pulled the 2 conductors apart):

1 – Plastic milk crate
1 – 15 to 365 pF air variable capacitor (found in many old radios, or a google search to buy one from an internet store)
1 – Tuning knob. Any knob will do as long as it fits the shaft on the variable capacitor.
1 – Tape or wire ties. I used tape to secure the wire while winding, then hot glue when finished.

When you begin to wind your coil, use tape or a wire tie to secure the wire, and leave about a foot of wire. This extra foot of wire will later be soldered to the frame on the capacitor. As you wind your coil, pull the wire snugly and with each turn leave about a quarter inch spacing between each turn. The spacing isn’t critical as long as the spacing is consistent. I wound 21 turns on my crate. This may differ for you, depending on the size of your crate, or the value of you capacitor. If you find that the bottom frequency isn’t low enough, you can add more wire to make a few more turns. This will lower the bottom frequency for you.

After winding the coil, you can solder each end of the coil to your capacitor. The beginning of the loop gets soldered to the frame of the capacitor, and the other end of the coil to the rotor solder lug on the side of the capacitor. If you do not have a soldering iron, you can use alligator clips to connect your loop coil to the capacitor as well. I secured my capacitor to the inside corner of the crate with hot glue. I put a generous amount of the hot glue onto the bottom of the capacitor frame, and held it to the crate until the glue cooled enough for the capacitor to stay on it’s own. I used enough to get the job done, but not so much that it interfered with the plates in my capacitor. The hot glue seemed to adhere very well. I then checked the spacing of my coil turns, and secured them with the hot glue as well.

I was very impressed with the results after spending some time with the loop. It’s small enough to maneuver around easily, but big enough to give it some gain, so I can listen to daytime DX. I may make another tuned loop using two crates to see how much more gain I get with the larger aperture.

Happy DXing,
James Townley

Many thanks, James, for sharing your project with us! This loop appears to be relatively simple and accessible even to those with little knowledge of soldering or homebrewing. I’m now wondering how a loop made of four milk crates might perform!

Click here to view James’ Shortwave/Medium Wave blog.

Spread the radio love

A New Approach to FSL Antenna Construction

16 Replies

Introduction

I’m very fortunate to live across town from my good radio hobby pal Gary DeBock. He has been responsible for the rapid growth in Ultralight radio DXing and the construction of Ferrite Sleeve Loop (FSL) antennas. Living near each other as we do, I’ve benefited a lot from his expertise and creativity in the hobby. We’ve enjoyed visiting about Ultralight radios and antennas many times over a leisurely lunch. If you’re unfamiliar with Gary’s efforts, just do a YouTube search on his name and see just a few of the many FSL antenna variations he’s built!

Gary uses PVC tubing, “Fun Noodle” foam cylinders, sections of curved foam, and rubber plumbing adapters almost exclusively as the core supporting structures for his FSLs, from small 3-inch models to 17-inch monsters. Gary certainly has perfected his own techniques with these raw materials; he’s an expert in combining them. He even makes PVC table structures to support his FSLs during Oregon coastal DXpeditions, as seen in some of his YouTube videos.

These materials work well, but over time even FSLs as small as 7 to 8 inches in diameter begin to sag and lose their perfectly circular shape. This seems to be caused by the shifting of individual segments of foam which are wrapped around a “Fun Noodle” core and center PVC tubing.

What possibilities are there for other materials in FSL antenna construction? It would be a fun challenge to build a small to medium sized FSL antenna that would have these qualities:

Maintain a circular cross-section without sagging
An appearance less like a threatening explosive and more like a commercial product
Use alternate construction methods for those not skilled with cutting & gluing PVC tubing

I began to keep my eyes open for likely candidates as I visited hardware stores, department stores, and office supply outlets. Eventually some ideas began to gel.

Raw Materials

Here is a visual and descriptive list of what I used in this alternate design of Ferrite Sleeve Loop antenna. I won’t go into great detail about dimensions, quantities, and measurements, as other DIYers should be able to easily follow the general idea presented here. This article is mainly to get you thinking about other ways to construct a ferrite sleeve loop antenna.

The Core of the Matter

This 18-inch long, semi-rigid foam roller is six inches in diameter. It’s a workout and exercise aid which I found in the sports department of my local Walmart store. The cost was approximately $13. This one-piece foam is a perfect foundation for holding and protecting the fragile ferrite rods and keeping them in a circular arrangement; since the roller is in one piece there is nothing to shift around, or sag. When placed on this core, the final diameter of the FSL antenna is approximately seven inches.

So, what to put the antenna in? Something needs to suspend and protect the antenna as a substitute for the PVC frame previously used. This Sterilite tote box is the perfect size to hold the antenna. As shown in the photo, the dimensions are approximately 14-1/4″ X 9-5/8″ X 12-1/4″; the model number is 1896.

Early on, I decided that the flimsy “locking tabs” on the cover would not suffice for holding the relatively heavy antenna when carrying the tote by the handle. I drilled holes and attached a dozen small Nylon nuts and bolts to secure the cover. (Nylon avoids distorting the medium wave reception pattern of signals, as metal hardware could.)

An ample quantity of 200mm ferrite rods are needed, plus a air variable capacitor (preferably with a 8:1 reduction drive shaft), and Litz wire. 1162 strands/46 ga. Litz provides the most sensitivity but the coil will cover a greater width on the rods.

Gary likes to use waterproof medical tape, sticky side out, to hold the rods in place, but I like to use Gorilla brand tape, as it is extremely sticky and holds the rods better. My choice for the rod-to-coil spacing material is two turns of 1/8″ thick bubble wrap.

This is the foam core, ferrite rods, bubble spacer, and coil assembly prior to fitting in the Sterilite tote container. Before assembly to this point you’ll need to cut the foam roller to length using a serrated knife or electric carving knife. Two sturdy cable ties help hold all of the rods in place. A better alternative might be strips of 1/2″ wide Velcro straps purchased from a fabric shop or home improvement store.

Another key item to this construction method is the use of plastic drywall anchor screws. These are meant to be pushed and screwed into gypsum wallboard for sturdy attachment of bolts or picture hangers on walls. When screwed through drilled holes in the side of the Sterilite tote, they secure and suspend the foam roller/ferrite sleeve loop assembly. The density of the foam roller is sufficient to give a good grip to the drywall anchors. Eight to ten anchors per side are enough to hold the assembly in place. See the photo at the beginning of this article for a good view of this mounting method.

Every good FSL antenna design needs an official sounding manufacturer! With tongue firmly in cheek I’ve appropriated the name shown on this self-produced label. Clearly, a Ferrite Sleeve Loop antenna from Naughtabaum Ferrite Specialties Ltd. stands a better chance than most of passing through TSA checkpoints, right?

I hope this article has given you some new ideas for FSL antenna designs. There’s certainly room for improvement, including making the antenna’s ferrite rods look less intimidating…less like a bundle of dynamite! Perhaps the entire assembly can be wrapped with something that shields the rods from view, or you could use an opaque tote container rather than a clear model.

Be on the lookout for useful materials to repurpose. Trips to your local home improvement stores, office supply, and other outlets will give you further ideas on how to design your own Ferrite Sleeve Loop antenna.

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

Spread the radio love

Guest Post: Jerry’s Mediumwave DXing Powerhouse Mini FSL Antenna

2 Replies

Many thanks to SWLing Post contributor, Jerry Popiel, for the following guest post:

A MW DXing Powerhouse Mini FSL Antenna

by Jerry Popiel

In late February 2016 I completed construction of a modified version of Gary DeBock’s excellent 3 inch Mini FSL design (click here to view).

This new antenna is nothing short of a AM DXing powerhouse with unbelievable sensitivity for receiving stations across the entire AM Bandwidth both day and night. The tuning of stations is razor sharp and it has stunning nulling qualities. Consultation assistance was provided from DXing experts Steve Ratzlaff and Gary DeBock on the project.

Construction Details:

The Antenna was constructed using 9 – 100 mm Ferrite Bars wound on a 2.75 inch diameter x 4 inch styrofoam cake dummy form custom made by in Vancouver, B.C. Canada – ([email protected]) for $3.50 plus shipping.

The Coil wire consisted of 38 turns of high gain 660/46 Litz Wire. (Note: As can be seen 38 turns of the thicker Litz Wire left only 5/8” of room on each side of the Styrofoam Form to wire wrap the coil to the ruler frame. A longer Form ie 5” long would work much better for this build).

The insulation spacer used was 2 layers of 1/8 inch Aerotape self adhesive tape which also helped hold the 100 mm Ferrite Bars onto the Styrofoam Coil Form. Inductance measured 356 uH using a DM 4070 Meter which is well within the requirement of over 300 uH for AM Band Reception.

Side View Of 9-Bar FSL Antenna with 2.75” Diameter Styrofoam Cake Dummy.

Because of the extra thickness of high gain 660/46 Litz Wire which is a bit too big to solder to the inside terminals of the Tecsun PL-380 Radio, a 2 Position Terminal Block was superglued to the outside of the Ruler Frame to act as an interface connection point.

2 Position Terminal Block Superglued To Back Of Antenna Frame

Testing Results:

Both daytime and evening AM station captures have been spectacular. Stations as far away as KKOB / 770 kHz Alberquerque, New Mexico 1130 Miles from here in Winnipeg, Manitoba, Canada have been received. Country music station WSM / 650 kHz in Nashville, Tennessee 1082 miles distant is a daily evening pickup.

Station KKOB / 770 kHz Alberquerque, New Mexico 1130 Miles distance.

Station WSM / 650 kHz in Nashville, Tennessee 1082 miles distance.

Two Stations Received At 600 kHz 90 Degrees apart at the same time:

The amazing Nulling and Razor Sharp Tuning quality of this FSL was demonstrated when 2 stations at 600 kHz were received at the same time by rotating the Radio with attached FSL 90 degrees. In the North / South direction Station KSJB / Jamestown, North Dakota (219 miles distant) was received with a strong signal strength of 50 / 23. Then by rotating the Radio 90 degrees to the East / West direction Saskatoon, Saskatchewan station CJWW (442 miles distance) was captured with a similar strong signal strength of 44 / 24.

600 kHz Station KSJB / Jamestown, North Dakota.

600 kHz Station CJWW / Saskatoon, Saskatchewan.

Daytime Reception of 600 Watt Station 137 Miles Distant:

A major daily AM reception capture during the afternoon illustrating the amazing sensitivity of this antenna is 600 Watt station KKXL Sports Radio 1440 kHz (137 miles).

All Indoor Reception – For Now!

Due to winter conditions here in Winnipeg, all of the amazing station reception captures in this report were done inside the House facing towards the South window. Fortunately the red ruler platform sides can he used as handles when pointing the radio in the direction of best reception. Exciting times are ahead to see how well this mini 3” FSL will perform outdoors for likely even better AM DXing.

Summarizing:

The design of this new FSL Antenna attached to the Tecsun PL-380 Ultralite radio by Gary DeBock is a major breakthrough in AM DXing since the Radio is attached to the FSL. This new FSL Antenna needs to be constructed to be really appreciated. The application described here requires a bit more skill to construct and is also heavier than the original construction – but at least it is portable. For beginners Gary’s original 3” FSL Heathkit Design is highly recommended and can be reviewed in his You Tube Video posted at: https://www.youtube.com/watch?v=VY9u8MReGjk

Thanks,
Jerry Popiel
Winnipeg, Manitoba, Canada

Thank you, Jerry! It’s amazing what performance you and Gary DeBock have gotten out of these homebrew FSL antennas! Thank you so much for taking the time to share your construction details and performance notes!

Spread the radio love