Loop Antennas

Loop Antennas

Just as the name implies the “loop antenna” is an antenna made in some configuration of a loop. That’s a rather simplistic description of an effective antenna. These configurations aren’t necessarily round in shape, many people use lengths of copper tubing/pipe combined with 45 degree elbows to create the loop. There are some loop antennas which are actually round but they were built by someone with access to a tubing bender capable of bending copper.

Why are loop antennas mentioned on this web site? They would be difficult to use for in the field applications such as survivalists would encounter. But those that are staying put during SHTF, or those with nosy neighbors (or nazi HOAs) may want to look at the loop antenna. It isn’t an inexpensive antenna considering the cost of copper these days but still worth a look. To keep from blathering on about loop antennas a list of external web sites is posted below:

Some of these links may be dead, please contact us if you find a dead link so we can remove it from the site.

loop antenna


Icom IC-703

The Icom IC-703 is a great choice for radio communications out in the wild such as when the SHTF. Not only is the size of the IC-703 attractive to preppers and survivalists alike it has a great many features that could be a great assets in survivalist and/or prepper situation. Some people will comment that the IC-703 radio is “just a QRP rig” and they might be right in a way. But a radio’s performance is based more on the antenna than on its power output. A good QRP rig such as the IC-703 works very well in mobile radio situations as well as with base station use. Running an IC-703 portable, such as a prepper or survivalist would do, is a very good application for this versatile little ham radio. Here are some of the features of the IC-703 radio by Icom:
  • Comes with a general coverage receiver
  • Many memories
  • RIT (receiver incremental tuning)
  • Preamp as well as an attenuator (although preamps are generally though to be worthless on the HF bands)
  • Dual VFO’s
  • 1 Hz display for tuning into odd frequencies
  • DSP, auto-notch, and noise reduction
  • SWR meter
There are TWO IC-703 models out there so be sure you look at a prospective purchase closely before you buy it. The last IC-703 was designated as an Icom IC-703 Plus designating it as the IC-703 with 6 meters in it. The original radios sold by Icom stated “HF/50MHz” on the front panel but that was a printing error. The early IC-703 radios did not have six meters in them so beware when buying an IC-703! As any honest amateur radio operator will tell you, a good antenna is the main part of a communications system. It doesn’t matter what band you’re operating on, what mode you are using, or even what radio you’re running. Preppers and survivalists alike need to learn to employ the best antenna they can come up with while still maintaining some sense of portability. Wire antennas, vertical antennas, and dipole antennas are good performers in the field or other portable operations. As has been mentioned elsewhere in this web site: “A dollar spent on an antenna is worth ten dollars spent on the radio.” For some reviews of the IC-703: ICOM IC-703 REVIEWS. IC-703 radio

Indoor Antenna Projects 4

Indoor Antenna Projects 4

Indoor Antenna Projects 4: Tape Antennas

Tape antennas on sun-film windows:

Using the tape loop, discussed earlier, I tested the antenna on two types of sun-film windows. The first was a plastic film, often used in states such as Florida. There was no significant pattern or gain change for the antenna. The second type of film is the metal film sun screen.

Results here were dramatic. The pattern was severely disrupted. Be sure that your window films are not the metallic type if you plan to use indoor VHF/UHF antennas pointed out the window. The metallic film acts like a reflector to the signal. Attenuation is a strong factor concerning propagation. Some plastic films appear metallic, but may not be.

Tape antennas on screened windows:

There are three types of screen used as screening for windows. Plastic, fibre, and metal. The first two show some attenuation of the gain and pattern shape is similarly effected. Basically, the addition of the screen frame effects the VHF spectrum greater than the UHF spectrum. The screen frame size is near the size of VHF loops at frequency.

These texts were postings that have been collected from Ham_Tech by Wayne M. Sarosi, KB4YLY. Hermod Pedersen has edited them for online publication.

So you can see that antennas can be hidden in plain site when you have a need to do so.

These articles on stealth antennas are only meant as a guide for those using radio communications for survivalist needs such as hiking, camping, hunting, mountain climbing, or any other extreme or rugged outdoor activity.

Parts for stealth antennas can be readily available at your local hardware or home improvement stores. And be sure to also look in your local phone directory for shops who cater to the military surplus equipment crowd. You can find excellent deals on wire, ropes, poles, masts and a variety of other items needed to make your own stealth antenna.

When dealing with homeowners associations you need to make sure that your CC&R regulations don’t prohibit radio emissions or radio transmissions from your location. There are some HOA that have found out about clandestine antennas and have simply bypassed antenna regulations and went right to the prohibition of the emissions themselves. Think before moving into these particular areas because that would also mean that you could not use a radio mounted in your vehicle if you were parked on YOUR property!



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Indoor Antenna Projects 3

Indoor Antenna Projects 3

Indoor Antenna Projects 3: Attic VHF/UHF Rotables

In many instances, a listener can mount a VHF or UHF beam in the attic, on a rotor. They can achieve good results depending on their location and height off the ground. Antenna size limitations are solely dependent on the available room in the attic that allows rotation of the beam without hindering its rotation.

To check the attic for the maximum size antenna, the hobbyist must first enter the attic and measure the distances in the area planned for the set-up. Trusses, electrical wiring, air conditioning / heating ducts, and the items that are stored up there, can all play a factor in the actual antenna size.

Finding your antenna with a pair of long johns dragging off the front end is not a pretty sight.

After measuring the area in the attic, the antenna size and height off the attic cross members can be accomplished. Remember to allow for a base to accommodate the rotor. This too must be calculated into the system.

Building a sleek system, to rotate two or three small beams, can be dashed, when the system will not turn because of an oversight in the measured values of the attic area in question.

Turning radius is the important factor. Each antenna forms a rectangle ABCD where the maximum distance is AD or BC.

A————————————B | | | | —-|———————————-|—- BOOM | | | | C————————————D

For horizontal antennas, the turning radius is from the mounting point to the tip (either side) of the longest element. Multiple this figure by two for the turning diameter of the antenna.

For vertical antennas, the truss angle places the biggest problem as the height from the boom to the tip of the reflector (B or A). In essence, this will shorten your boom length or require a lower rotor mounting.

Indoor telescoping beams

One problem I have encountered from listeners living in apartments is the space to place a VHF/UHF antenna. This concerns operation of the beam from a bedroom or porch. In these cases, the listener can not keep the antenna up and must remove the antenna after he or she finishes.

Using telescoping elements can solve the problem. Adding a two or more section boom can further the portability for the antenna making it idea for field day, camping, or travel also.

Dimensions for beams have been discussed earlier, so I won’t rehash them here. The best portable and quickest for set-up is the four-element VHF antenna. A two-section quick clamp boom with mounting flange for a camera tripod provides the base. Each element contains two telescoping units and a snap on fitting for attachment to the boom.

The antenna described here can be stored in a briefcase save the camera tripod. A VHF four-element antenna can provide 9dBi of gain for the apartment dweller.



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Indoor Antenna Projects 2

Indoor Antenna Projects 2

Indoor Antenna Projects 2: VHF/UHF Discones

The discone antenna is a rather unique antenna for VHF and UHF. The discone has no gain to speak of, yet can provide the user with a range of ten times the design frequency for reception and transmissions. This means that a discone designed at 140 MHz will work fine up to 1.4 Ghz.

Hiding the discone outside may prove to be quite a feat. Unlike most antennas, the discone has a large skirt and is tall to boot. Its shape can draw attention. If you can place the antenna outside, it will give you excellent coverage over its range. Inside, the discone works well minus the attenuation caused by the building it’s in.

There are many Discones available on the market if you choose not to build one. Building one can be fun if you take the time and lay everything out ahead of time. There are a couple items I would like to point out about discones.

1) The gap between the top-hat and the skirt is critical.

2) The area under the skirt is a null to the antenna.

Design parameters are easy.

** The top-hat diameter is:

(0.1778 * (984/f MHz))*12

Example: at 140 MHz –> (0.1778 * (984/140))*12) = 15-in

** The diameter of the skirt, at the base, equals the length of the skirt elements. This gives the user the closest impedance 50-ohms. Thus a skirt element length is:

(0.2675 * (984/f MHz))*12)

Example: at 140 MHz –> (0.2675 * (984/140))*12) = 22.56-in

** The gap is:

(0.007114 * (984/f MHz))*12)

Example: at 140 MHz –> (0.007114 * (984/140))*12) = 0.6-in

A tin funnel works well as a starting base, to which you can solder brass skirt elements. A SO-239 chassis connector can be fit into the cut-off funnel end and the top-hat soldered to the center pin of the SO-239. Insulating spacers can be used to strengthen the gap. I’ve used a brass screw that was soldered between the center pin and the top-hat, but you can use anything that you can solder.

Wire beams indoor

For many of us, the antenna is the biggest problem. Radio fans have to contend with neighbors and the XYL in order to pursue their hobby. An interesting HF and VHF idea I’ve seen used is the wire beam.

The wire beam is unrolled and suspended in the direction required for operation. After the operation is complete, the wire beam is rolled up and stored for the next time. This type of beam is excellent for 10m and up to 1.25 m. You may be able to set up a wire beam for frequencies below 10m if you have the space to do so. This antenna is also excellent for suspension in an attic.

A simple model is shown below:

R DE D ———–||–|————-|———-|–||———– || | | | || || | | | || || | | | || ———–||–|————-|———-|–||———– || | | | || || | | | || || | | | || ———–||–|————-|———-|–||———–

Aside from the elements, the rest of the configuration is non-conductive. Wooden dowel supports are outside the ends of the antenna and string/rope can be used to support the elements. The wooden dowels are not required if suspension is taught.

You can see that variations of this set-up can be incorporated to accommodate most any frequency from 10 to 1.25 meters.



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Indoor Antenna Projects 1

Indoor Antenna Projects 1

Indoor Antenna Projects 1: Practical indoor antennas for everybody

HF Indoor Antennas:

Some practical indoor antennas that can be built by anyone:

** HF foil antennas

** VHF/UHF discones

** Wire beams

** Attic VHF/UHF rotables

** Tape antennas

** Telescoping VHF/UHF indoor beams.

HF Foil Antennas

HF foil antennas are too weak in their physical construction for outside use. Foil antennas are just what the title implies, foil. They are made from ordinary aluminum foil, the kind used for heavy duty cooking, such as roasting a turkey.

This antenna goes in the attic of your home or condo. Apartment dwellers may have a time with this antenna depending on their location within their complex. Materials needed are two to three rolls of aluminum foil, copper tape with electrically conductive glue, a staple gun and staples, and coax with connector. By stapling the foil in a loop or dipole configuration on the attic rafters, a simple antenna can be formed.

===================== ======================= || balun if desired | | | coax to shack

========================================== | | | | | | | | | | | | ==================== ===================== || Balun if desired | | coax to shack

These two configurations are excellent when used with a tuner for the various bands on amateur radio and SWL listening. They are cheap to install and can be made into other configurations, by the amateur, if desired. A relay can be installed to provide dual antenna configurations if needed. With this device you can switch between a dipole and the loop for different propagation conditions. Size and shape is dependent on the attic structure.

Connections from the foil to the coax or BALUN are via the copper tape. There are copper tapes available on the market that are used for EMI applications. These tapes are expensive so if you can get a piece of some of that tape from a buddy, it will work wonders for you.

Otherwise, there is a trick with regular copper tape and the aluminum foil that you can do. It’s a simple folding technique that insures a good connection and yet requires no soldering except for the coax/BALUN connection.

Practical indoor antennas for everybody

  ====================================== Aluminum |——————————|| foil | =============================== |————————————– Copper tape

This folding method insures good contact on more than one surface. One warning, do not leave air gaps, as it will have a capacitive effect. Solder doesn’t stick to Aluminum foil very well. With enough heat, you can solder anything. Too bad the aluminum foil won’t hold up at that temperature and neither will the solder.

You now can solder leads to the BALUN or solder the coax direct to the copper tape.

For an indoor antenna, the foil antenna works rather well. It can out perform a vertical and pull in the weak ones with ease. I think you’ll find it one of the most inexpensive antennas you can build yourself.



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Fence Antenna Ideas

Fence Antenna Ideas

antennas@qth.net list, Jan. 1999

John Matz: This reminds me of my yard about ten years ago. You have a wooden fence. Good.

One suggestion:

Get a good antenna tuner (if you don’t have one) and learn how to use it.

2. Get some insulated wire (house wire will work) and an eight-foot ground rod.

3. Put the ground rod in near the fence. That’s your coax ground.

4. Put a number of 1/4 wave radiators (234/f in feet), separated, up on the fence … like 8′ for 10m, 16′ for 20m, etc., all in parallel to the coax center conductor. They don’t have to be straight … just 6 feet up, and then over horizontally … or slanted at a 45 or so, and then bent over. Keep as much of the wire as high as possible.

If they can be placed far from the house, then you can put up at least three radiators for three bands easily.

Use the tuner inside the shack.

I’ve used this method on 75m too. It’s not as efficient as some antenna systems, but it is cheap.

You can use wire sizes such as 14 gauge wire for your fence antenna and no one will be the wiser when it comes to detecting your antenna.

These types of stealth antennas are great for the survivalist needs in radio communications because they are small, lightweight and portable. Multiple bands of these stealth antennas can be wound up on a spool and thrown into your bugout bag or your go box.

A survivalist new to radio communications may come into contact with certain radio and antenna “experts” who will say these fence antennas (or any stealth antenna) are “marginal”. The design of stealth antennas is that they are difficult, or even impossible, to detect. Its a given that they may not perform as well as a commercial antenna mounted high up on a tower or pole. But try to imagine dragging these aluminum antennas around with you as you try to set up a survivalist camp. You’d likely abandon the thing after you put it up the first time.

But stealth antennas such as this fence antenna can be placed against a fence or any other small structure in the yard of your home.

fence antenna

Carpet Loop Antenna part 4

Carpet Loop Antenna part 4

Carpet Loop Antenna part 4: Antenna Construction Choosing cable The kind of cable you use depends on where you’re putting it and how much you want to pay for the cable. If you plan on running it under carpet, then use the 5-conductor rotator cable mentioned in the parts list. This cable can easily withstand being stepped on; more importantly, there are no exposed wires to trip over. It’s also easier to wire than phone cable. If you’re not running it underfoot, or if you’re cheap, you can use 4-conductor flat phone cable, available just about everywhere. It’s a good choice for running around baseboards, around windows or in attics. When running the cable around, start at your receiver and go around the room–or the house–and back to the radio. If you’re using the rotator cable, you can make corners by folding the cable at a 45 degree angle, like folding paper. Wiring the cable to the tuner You should have two ends of the cable next to the tuner. Strip the ends and put spade lugs on all the wires. With the rotator cable, mark the *silver* conductor. Next, connect the wire to the tuner using the following diagrams: FOR 5-CONDUCTOR ROTATOR CABLE FOR 4-CONDUCTOR PHONE CABLE J1 J2 J1 J2 1 1 1 2 3 4 5 6 7 8 9 0 1 2 3 4_5 6 7 8 9_0 ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ Wire S C C C C S C C C C B Y R G B Y R G colors (4&5 jumpered) (9&10 jumpered)   ((S)ilver, (C)opper, (B)lack, (Y)ellow, (R)ed, (G)reen) Grounding Run a wire–preferably a large one–from the ground terminal on the tuner (or a mounting screw on the SO239 connector if you’re using one) to a suitable ground such as a cold water pipe; I grounded my tuner with a short length of RG58 coax connected to a baseboard heater via an alligator clip. Connect the tuner to your receiver; you’re now ready to use it. Using The Carpet Loop It’s easier to use than to talk about: Tune your receiver to the desired frequency. Adjust S1 and C1 (or the antenna trimmer on the radio) for strongest signal. For most situations, S2 (Loop/Longwire) can be left closed in the Loop position; you may find that setting S2 to Longwire may work better for mediumwave listening. Conclusion The Carpet Loop II is an inexpensive, easily built, high performance antenna that can work in almost all apartments. Contacting the Author I can be reached at the following addresses: Mail: David Moisan 86 Essex St. Apt. #204 Salem, MA 01970-5225 Email:dmoisan@shore.net WWW: http://www.shore.net/~dmoisan Let me know how the Carpet Loop works for you! –Dave Copyright © 1996, David Moisan Last Updated on April 20th, 1996  


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carpet loop antenna

Carpet Loop Antenna part 3

Carpet Loop Antenna part 3

  Carpet Loop Antenna part 3:  Tuner Construction Parts Availability With the exception of C1, all parts for the tuner are readily available from Radio Shack. C1, the 365 pf variable capacitor, can be gotten out of an old radio. Substitutions There are no critical parts in the tuner; as long as S1 has at least six positions, it will do. D1 and D2 can be any silicon diode. Use any enclosure that’s big enough to comfortably install components in. The choice for J3, the jack to the receiver, depends on what connector your radio uses for an external antenna. I used an SO-239 (RS #278-201); you could also use a TV antenna terminal strip (RS#274-663). Step-by-step Instructions Mount the components on the enclosure you’ll be using–all wiring is point to point. I suggest mounting J1 and J2 on opposite sides, S1 and C1 on top, and J3 on the other end of the enclosure. Wire S1 to J1 and J2. If you use the Radio Shack DP6T rotary switch, you’ll be using just one of the poles. The diagram of the switch is below: D C S1 DP6T rotary E o o B switch G o o A | o o | Viewing from P |o o| bottom of switch | o o | o o o o Wire as follows: (Note: If you’re using the Radio Shack terminal strip, you will need to drill a hole in the cabinet to pass the wires through from inside. Use a rubber grommet to keep the wires from chafing and fraying) S1 Term. –to–> J1 term. J1 term. –to–> J2 term. A #1 #2 #6 B #2 #3 #7 C #3 #4 #8 D #4 #5 #9 E #5 Connect a wire from J2 terminal #10 to the G terminal on S1, and this step is done.   Install and wire C1. Connect one terminal of C1 to the P terminal on S1. Connect the other end to J3. If using the SO239 or phono jack, connect to the center conductor. If using screw terminals, connect to terminal #1 on J3. Skip ahead to step 5. Connect the P terminal of S1 to J3. If you’re using the SO239 or phono jack, connect to the center conductor. If you’re using screw terminals, connect to terminal #1 on J3. Connect the G terminal on S1 to J3. Connect it to the ground shield if it’s an SO239 or phono jack, or to terminal #2 if it’s screw terminals. Connect D1 and D2 across J3’s terminals; remember that D2 is connected opposite of D1.   That completes construction of the tuner.  


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carpet loop antenna

Carpet Loop Antenna part 2

Carpet Loop Antenna part 2

Carpet Loop Schematics and Parts List Carpet Loop Antenna part 2: From Radio Gnd. Ant. S1 1 pole 6 position ! ! rotary switch ! D1 ! (RS# 275-1386) !—->I—-! +———-*—-I<—-! C1 365 pf variable ! ! D2 ! capacitor (see ! ! ! text) ! o o ! S2 SPST switch ! \ ! (RS#275-406) — S2 \ — C1 D1, D2 1N914 silicon ||| o — switching diodes (Earth ! ! (RS# 276-1122) Gnd.) ! ! ! ! J1, J2 6-position terminal ! ! strip (RS#274-659 or +G-o<—-o—-+ #274-653) ! Antenna cable: ! o S1 o ! !E !A 5-conductor rotator J1 ! ! o o ! J2 cable (RS#15-1201) ! ! !D o !B ! (see text) 1 |o|—-* ! ! !C ! ! 2 |o|——-*–!–!–!–!—–|o| 6 Miscellaneous: 3 |o|———-*–!–!–!—–|o| 7 4 |o|————-*–!–!—–|o| 8 Aluminum enclosure, 5 |o|—————-*–!—–|o| 9 spade lugs, connector |o| (not used) *—–|o| 10 and cable to radio (not used)|o| (see text), knobs [To Antenna] Note on Schematic symbols: ! -*- means: Intersecting wires are connected !   ! -!- means: Intersecting wires NOT connected ! How the Carpet Loop Works S1, C1, and the antenna cable connected to J1 and J2 form an L-network; when S1 is switched between positions A through F, and C1’s capacitance is varied, the impedance of the antenna system changes. When S1 and C1 are adjusted for best signal, the impedance between antenna and receiver is matched. D1 and D2 provide protection against static discharges. The G position of S1 grounds the antenna when not in use. S2 disconnects the ground from the antenna, making the antenna into a random wire.  


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carpet loop antenna