Build the Pennyloop UHF Antenna
Build the Pennyloop UHF Antenna

The Pennyloop UHF antenna offers high performance in a very simple and cost effective design. It is also a very compact design lending itself well to a variety of mounting options and locations inside and outside. Outside will give the best performance. The antenna is about 18" tall and 9" wide. The Pennyloop antenna started out as a single loop antenna and could be used with a reflector. It was found through extensive testing, at least in my area, that the UHF signal strength is very "layered". A single loop antenna, or even a simple thick element dipole for that matter, would pick up all of my distant stations - Just not at the same height! A new design emerged from this common issue with UHF signals. The antenna did not need to be excessively tall, but needed some additional height to cover each of the signal layers at the same time. This design goal was achieved in the Pennyloop by having a second loop installed on the original feed point. It served several purposes. It increased the gain substantially, focused more on the horizon where the signals were coming from, and gave the additional height needed to be in each of the signal layers simultaneously.

As with all antenna designs, there are compromises. Some antennas are omni-directional with little gain, and some are very directional with high gain. My antenna design, the Pennyloop, offers fairly high gain and is bi-directional without a reflector. It will work equally well, in both directions, which is great if you have antennas on each side of your location.The Pennyloop antenna was designed to be very easy to construct with basic tools and skill levels and the design is for coax feed - through an appropriate ground block - to the television set. This makes for a very easy and straightforward connection.

A few building and performance notes: Do not use any more coax than necessary to connect your antenna to the TV. Roughly speaking, you can expect about a .05dB loss per foot of cable [RG-6] at UHF frequencies. In a 50 ft. run of coax this equates to a loss of signal of about 2.5dB. A loss of 3dB is half of your signal! The prototype of the Pennyloop, pictured, has 51' of RG-6 that runs through a 3 Ghz ground block to the TV and it is mounted at a height of 18' on my mast - easily receiving all of the stations that are located 55 miles away! I do not use an amplifier. Also, all connections, especially those going through splitters, will reduce your signal to the TV. If you have to feed a couple of TV's or have a very long run of coax, it may be necessary to have an amplifier/booster near the antenna. If a connection is necessary between lengths of coax, be sure to use a low loss splice barrel connector. These are available, like the ground block, for 3 Ghz.

A search on www.tvfool.com can be nice to find information on station locations, power levels, etc. It will be necessary for you to aim the antenna towards the best, or desired, signals you wish to receive. The broadside or flat side should be pointing to the transmitting antenna and you should be able to look through the hole in the loop(s) towards the transmitting antenna direction. If you have multiple transmitters in one direction, or transmitters on both sides of your location, you can average it or you can point more in the direction of the lower powered stations. The antenna has a null off each edge, much like other loops, dipoles and yagi designs, but has a wide beamwidth (front and back - without a reflector installed) that makes it very nice for most installations.

Be aware that OTA (Over-the-air) television signals can be influenced by a number of things to include obstacles, terrain, weather, time of day and year, antenna height and aim, quality of build, etc. and you will have to figure out the best setup for your antenna system.

The #6 gauge bare copper wire is really great to work with. It is large enough to make an efficient element while still being easy to bend into shape by hand and with common pliers. #4 gauge copper wire could also be used, but will require more effort to attain the proper loop shape. Bending the ends of the wires, for attachment to the feed points, is where it gets tough if you choose the heavier wire. Many different materials and possibilities are available for this build and what I have presented here is what has worked best in the interest of simplicity and ease of construction. Be creative and experiment if you choose to do so. It is great fun to play around with element thickness and lengths, connections, etc. in the pursuit of better signal strength and quality.

*Many other websites have detailed information about mounting, aiming, grounding requirements, NEC requirements, etc.

The Pennyloop antenna requires very little hardware and offers great performance. Here is a list of what is needed for the build. (The list includes everything to build the Pennyloop as shown in the photos. You may choose to mount it in different ways and all the listed items might not be necessary. It is mounted about 3/4 of a wavelength from the mast. This distance is not critical and I have mounted horizontally polarized loops very close to my metal mast. Test the antenna in a few temporary setups to see what works best for you.)

1. Coax - RG6

2. Two feet of 3/4" PVC Schedule 40 (Either the white plumbing type or grey conduit type) along with 2 slip caps and a 90 degree elbow [ Some big box stores sell a short 2' length of PVC if you don't want to handle the 10' length]

3. #6 gauge bare copper wire (2 lengths of 28"-28 1/2")

4. #6 x 32 x 1" stainless screws and nuts (2 screws and 4
nuts)

5. #8 stainless flat washers (2 required) and 2 lock washers, if desired

6. 3 Ghz ground block ( RG-6 and a 3 Ghz ground block will ensure very low feedline losses)

7. Hose clamps (2) 2 3/4" will work for most mast installations

8. 300 to 75 Ohm matching transformer to connect to your coax.

9. 8" Black - UV resistant Zip-ties

10. Drill with a 1/8" drill bit

The Pennyloop antenna is a very simple loop antenna to build and offers very high performance. Only simple hand tools are used for construction and NO SOLDERING is necessary to build the antenna. A hacksaw or wood saw can be used to cut the PVC, a metal file to clean up the ends of the wires, a drill, a knife, regular and/or needle nose pliers.

Construction of the Pennyloop Antenna:

Please be safe! Use safety glasses and gloves to cut and shape the wire.

1. First step is to measure and cut 2 pieces of #6 gauge bare copper wire to a length of 28". If you are using something other than a hacksaw to cut the wire, leave the wire just a little longer than necessary (like an 1/8" or so). After the pieces of wire are cut, use a file to "clean up" the ends of the wire. Cutting with pliers will leave some very sharp edges so be careful with the ends until they are smoothed out.

2. Once the wires are at the correct length, use a pair of pliers to bend the small loops at each end of the element for attachment to the feed point. It is best to grip the wire with about 3/8" of wire going into the pliers from the side. You will end up with too large a loop to attach to the feed point, and the overall length of the element will be reduced, if you grab too much wire to start the bend. A close look at the photo will reveal what you are looking for: Make as small a loop as you can, on the end of the element, for it to fit around the #6 feed point stud. With one of the small end loops completed, bend the other side in the same direction and in the same "plane". It will make it easier in the next steps. You won't have to twist the wire into shape.

3. Now the big element loops can be bent into shape. They can be formed easily by hand. Just take your time as you go around keeping the smaller attach loops in the same plane as the large loop. (You should be able to lay the completed element flat on a table top) NOTE: Once the loops are bent to shape, It will be necessary to use pliers, or a vice, to make bends to allow the loops to be vertical and flat - yet have the attach points at a slight angle. A close look at the photos will reveal this. This is simply because the 2 stainless screws that are protruding from the 3/4" PVC cap will be angled outward. (More on that in a moment) Take your time making small adjustments until each loop is in the proper plane and the attach points are sitting flush at the feed point. They need not be perfect before they are installed. Once they are secured to the feed point screws, you can bend and tweak them into the proper place.

4. The PVC cap, that the feed point screws mount into, will most likely have a rounded end. To mark the cap for drilling, with an 1/8" drill bit, is very easy. Just measure across the cap to find the center and mark a location 1/4"-3/8" from the middle on each side. The two holes drilled for the screws should be 1/2" to 3/4" apart. Use a small nail and a hammer to mark exactly where you want to drill. It also serves as a tiny starter hole for your drill bit. If you want to be very precise, drill the hole with a smaller bit first, followed by the 1/8" bit. One good tap with a hammer should give you a good mark. This will be where the two #6 x 32 x 1" stainless screws mount. The main concern here would be to make sure that the elements from each side are not touching in the middle. Once you mark the locations to drill, hold the loop ends in place to see if there will be adequate separation there before drilling the holes. Also, you don't want to drill too wide. The screw heads on the inside of the cap have to fit close, but not into, the side wall of the cap. Install the screws from the inside of the cap. The head of the screw will be close to the edge of the cap preventing the use of an unmodified washer. The prototype used no washers on the inside of the cap. They are not necessary.

5. Once the screws are installed, fit the loops ends (of BOTH big loops) over each of the feed point screws followed by a #8 stainless washer, a stainless lock washer, if desired, and a stainless 6-32 nut. The top loop is placed onto the screws first followed by the lower loop on the prototype. There is no washer between the large loop elements.The washers are placed onto the studs after both loops are in place. Holding each of the loops in the proper orientation, tighten down progressively on each of the nuts. It is easy just to "eyeball it" or assembly could be done over a yard stick or ruler to verify they are up and down and centered. NOTE: A little bit of rough sanding or scuffing on the small loop ends adds a little friction to keep the loops in place. Not too much. Just take the shine off. I tightened this whole assembly quite a bit. Not enough to break something - but enough that I could tighten and loosen the balun (matching transformer) attach nuts onto the same stud and be able to remove them without the whole thing coming loose. Mashing the lock washers tight and a little extra from there should do it. Just snug it up very good.

* At this point, the antenna itself is actually done. Following will be a description of my mast mount. It is simple, easy, and cost effective. Any number of mounting options could work. PVC is low cost and a good insulator. The grey conduit is UV resistant to some degree, and would work just as well for the small mast and very low weight and wind load of the antenna.

6. To make the mount, simply cut two pieces of PVC. One of the pieces to 12" and the other to 6". The lengths are not critical and could be changed to fit your location. Clean up and bevel the ends of the PVC tubes with a sanding block and sand paper. Slip the pieces into a 90 degree elbow fitting. Doing them one at a time, use a mallet and tap them into place for a tight fit. No need for PVC cement. Set one end down on concrete and tap the other end with a rubber mallet (Or piece of wood). It can be noted in the photos that the 6" piece that attaches with hose clamps (2 3/4" size) to the mast goes up and not down. I chose to do this because the PVC elbow has a slight inward angle to it. Not sure if they all come this way. It allows the plane of the antenna to be angled slightly upwards instead of downwards. A PVC cap is also used at the end of the shorter mast mount tube. This is used to keep the entire assembly "flush" with the mast. Otherwise, the elbow alone will not allow a flush mount without some sort of spacer, etc.

After the mast mount is completed, simply slide the antenna onto the end of the PVC pipe. Again, no cement is used. This connection is only hand tight to allow removal, if necessary, to access the heads of the feed point screws for re-tightening or removal if necessary and it allows you to rotate the antenna, by hand, to align it vertically. (You may want to remove it later to experiment with different loop sizes and element diameters, etc.)

7. Install a 300 to 75 Ohm matching transformer and connect to your coax. Zip-tie your coax so that it has a drip loop, as seen in the photos, before making the coax to balun and balun to feed point connections.

I hope you enjoy the building and the performance of the Pennyloop antenna.

Step 1: Construction Photos

Build the Pennyloop UHF Antenna
Build the Pennyloop UHF Antenna
Build the Pennyloop UHF Antenna

Step 2: Optional Reflector

Build the Pennyloop UHF Antenna
Build the Pennyloop UHF Antenna

An Optional Reflector can be added to the Pennyloop antenna to increase the gain for very distant stations.

Two reflector rods, that are 26 1/4" inches long, are mounted horizontally, at a distance of 3.5"-4.0" inches behind the center of each loop. The temporary reflector in the photos was made using a 5/8" square wood dowel, #6 gauge wire reflectors, and a 3/4" conduit clamp. This is only an example of what could be constructed to hold the reflector rods in place. PVC or aluminum would be a good choice of material for an outside antenna and it could be incorporated into the mast mount. For testing of the reflector system, I wanted to be able to easily change out different length reflector rods and I wanted to be able to change the element to reflector spacing for optimum performance. Be creative. Rods from 24" to 26 1/4" were tested. Even the 24" rods were very good. The rods at the center of the loops showed the most increase in gain, but a higher number of rods could be added if you like. Perhaps on 3" or 4 1/2" centers. Two rods gave the most gain for the least amount of material and work.

Reflector rods are typically 1.05% of the lowest frequency wavelength. The 26 1/4" length is for 470 Mhz.

 
 

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