Introduction: 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 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 coax [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. The mast mount described in this Instructable makes it very easy to mount and aim your Pennyloop Antenna.
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 in the plans 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), #10 stainless flat washers (2 required)
6. 3 GHz grounding block ( RG-6 and a 3 GHz grounding 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 very careful with the ends until they are smoothed out.
2. Once the wires are at the correct length, use a pair of needle nose 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: As small a loop as possible [on the end of the element] to secure it to the 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.
From that point you should be able to lay the wire elements on a table with all of the wire touching the table. Not one end loop laying flat and the other loop standing up.
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 #10 stainless washer, a #8 stainless washer, 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 washer is placed onto the stud 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. Just snug it up very good.
Once your Pennyloop Antenna is completed from the plans, a number of mounting options are available. You may choose to mount the antenna inside, or in an attic, or mount the antenna on an outside mast. Below you will find a how-to description to build the prototype Pennyloop mast mount. It is quite simple and an effective solution to mount your Pennyloop antenna.
PVC works best for the construction of the mast mount because it is low cost, a good insulator, and is readily available. 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. The Pennyloop itself weighs 5 oz!
PENNYLOOP ANTENNA MAST MOUNT INSTRUCTIONS:
1. To make the mount, simply cut two pieces of 3/4" PVC tube. Cut 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. 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.)
2. Install a good quality 300 to 75 Ohm outdoor 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. If not, damage to the lead ends of the matching transformer could result. Most matching transformers come with some type of weatherproofing boot to protect from the environment. It is not shown in the above photos for clarity. The builder should make every effort to keep all connections out of the weather if possible.
Indoor or attic mounting opens up the possibility for many more mounting options. For instance, wood has been used successfully as the center insulator when the antenna has been mounted in a dry location. Others have mounted their antennas with lexan and thin plywood insulators to make a 'flush mount' to hide the antenna indoors on a book shelf or to simply hang the antenna on the wall behind the TV. This works really well with the optional direct coax feed described in the plans. It allows for a short length of coax and no worries to figure out how to mount a matching transformer. The lead ends of some matching transformers are not really designed to have the weight of the coax pulling on them without some type of support.
What makes the Pennyloop an Outstanding Antenna?
The Pennyloop antenna was designed to be a high performance, low cost antenna for indoor and outdoor use. The twin loop design is sized to be optimum for the new UHF Digital TV Spectrum. It uses solid copper elements and stainless hardware for superior all weather performance. The design also offers a very wide beam width on each side (broadside) making it very easy to aim. This wide beam width is very nice for locations that have multiple transmitting antennas. The Pennyloop loop elements are attached to a center PVC insulator that will slip onto a 3/4" PVC tube making it very easy to mount almost anywhere.
Step 1: Construction Photos
Here are a few photos during the building process. A round object that has a 7-8" diameter can be used as a form to shape very nice and smooth loops. Make sure that the small attachment loops are kept in the same plane while the larger element loops are being formed/shaped.
It can also be noted in the above photos that when the PVC cap is used it results in the feed point screws being angled outward. I use a pair of lineman's pliers to bend the loop ends to the proper angle for attachment. It is easy to just approximate the angles needed and finish up the final bending and shaping once both big loops are attached to the center insulator. One may choose to mount the twin loops to something other than a PVC cap and it would eliminate this step.
Once both loops are fitted over the feed point screws install a #10 stainless flat washer, a #8 stainless flat washer and the nut. The second nut seen in the photos is for the installation of the matching transformer.
Dimensions and photos of the Optional Aluminum Reflector can be found on the following page in Step 2.
Step 2: Optional Aluminum Reflector / Direct Coax Feed
Optional Aluminum Reflector
The Optional reflector is built using a single piece of stock aluminum measuring 1/2” x 1/20” x 96”, that is cut to size and (6) #6 x 32 x 3/4” screws, (6) #6 x 32 nuts, (2) #10 and #8 washers, and a 3/4” PVC conduit strap. (The #10 and #8 washers are used with the conduit strap. The #10 followed by the #8 washer and then the nuts.)
The two longer horizontal reflectors are 26” long and mounted 4 1/2” up and 4 1/2” down from the center of the 18” tall upright. The two shorter reflectors on the top and bottom are 13” in length. With a tape measure, mark out the lengths for the two longer 26” rods and the two 13” rods. Cut the pieces out on the lines that are marked. The remainder of the 96” piece that is used for the upright should be very close to 18”. All holes are drilled, in the center of the appropriate flat side, 1/4” of an inch from edge of the angle aluminum piece.[ For 1/2” angle aluminum ] The conduit clamp is centered on the vertical upright. Note: The conduit clamp screws are 90-degrees to the reflector screws. In the above photo –only one of the two screws were installed into the conduit clamp. The reflector is mounted at a distance of 3.5-4” aft of the loop elements. The long 26” reflector elements should be centered behind each loop and run horizontally. A reflector could consist of only two 26” reflector rods.Two half-wavelength rods behind the top and bottom ends of the loops give some additional gain. Many materials and options are available for the reflector, such as copper wire, copper tubing, square or round aluminum tubes, etc. The above reflector design uses a single piece of stock angle aluminum keeping cost to a minimum. Also the 1/2” flat sides make very efficient reflectors and the square sides allow for easily keeping everything square. It is not so simple or easy for round tubes unless perhaps using a drill press with a centering jig, etc.
Direct Coax Feed
As the Pennyloop is gaining in popularity, especially where signal strength is good enough for an effective indoor or attic antenna, more builders are choosing to connect directly with coax, no matching transformer, when mounting indoors. It eliminates the need to purchase a matching transformer along with finding a way to mount it securely indoors so as not to pull on the fragile twin lead connectors that are usually present on the typical transformer. (The Channel Master matching transformer has heavy leads and strong ring terminals that will work great indoors and outdoors). To make the connection with coax, the antenna end of the coax is carefully stripped of the outer jacket about an inch and a half from the end without cutting into the braid. Next, the braid is slowly loosened up and gathered to one side where it is twisted together and an appropriate ring terminal is crimped on. Most likely, a blue or red ring terminal for a #6 stud will be needed depending on the amount of braid. Next, an appropriate amount of the inner insulation is removed to expose the center conductor. Do not score the center conductor when removing the insulator. Enough insulation will have to be removed to be able to make a 'j-hook' on the end of the center conductor. Care needs to be taken to ensure that neither the foil nor the braid touch the same side of the antenna that the center conductor is attached to. If this happens, the antenna will not work until it is corrected. The Pennyloop pictured here has a 1 1/2"x 4" lexan piece that was used as the center insulator. Holes are drilled 3/4" apart to attach the loop elements and a hole is drilled farther down to zip tie the coax so that it doesn't pull on the connections. The builder must ensure that, if mounting this way, the coax crosses the bottom of the loop at a 90-degree angle ,as shown, if hanging on a wall, etc. and excess coax is not coiled up.
A matching transformer can always be used to make the connection. It is at the builder’s discretion to give the direct coax feed a try.
Step 3: OPTIONAL DIRECT COAX FEED FOR OUTSIDE USE
I have included a few more photos that detail the use of the Direct Coax Feed for outdoor use. Performance of the Direct Coax Feed has been equal to or slightly better than several matching transformers that were tested. I would like to give a brief description of how to accomplish this setup for anyone who may be interested in giving it a try. Many Pennyloop Antennas are currently using the Direct Coax Feed with exceptional results!
When making the open end of coax for outside use, whether it will be completely exposed to the elements or contained in a weatherproof box, the center conductor and the braid will need to have some additional protection. After opening the end of the coax the aluminum braid is gathered on one side of the coax and a liberal amount of dielectric grease is used to thoroughly coat the braid strands before they are twisted together and the crimp terminal connection installed. Once the j-hook on the center conductor is made for the feed point it also gets a coating of dielectric grease. Don't worry about using too much grease – the excess will squeeze out when the nuts are tightened slightly with a wrench and there will be metal to metal contact. Pay special attention to make sure that the very end of the center conductor wire gets grease. Once the connections are made at the antenna, additional grease can be smeared or brushed on for a little more protection. With the most common RG-6/U coax having a copper clad steel wire for the center conductor, it will be realized that without a good coating of dielectric grease (or some other protection), rust can begin to form at the very end of the wire where it was cut and work its way back over time if the connection is exposed to the elements. Also, care needs to be taken to route the coax in an upward direction initially to keep water from getting into the coax. Make sure to use several zip-ties to keep the coax steady in the wind. [The above photo of the open connection was only a test piece and the final assembly used electrical tape to help seal the end of the coax.]
A weatherproof box like the 1” conduit box shown in the pictures can be used to mount the Pennyloop with the feed points located inside instead of outside the box. On this particular setup the feed point holes are located 1” down from the top of the box and the feed points are separated by 3/4” horizontally. A PVC plug was used to fill the open hole in the box and a wood clamp was installed to keep the coax from being pulled on and twisted. The two pieces of wood were clamped together first, then a 1/4” drill bit was used to drill a hole between the two halves for the coax (See photo). Another single screw comes into the box to mount the wood clamp. Do not crush the coax in the clamp - only tighten as necessary. The photos above depict the Direct Coax Feed but the box will easily accommodate the use of a matching transformer also keeping everything out of the weather. The coax could be run in various ways from that point depending on your mounting requirements.
If you decide to mount the reflector while using the conduit box two (6x32x2”) screws can be mounted from the inside of the cover plate extending out behind the antenna. 1 1/2” spacers are used on the screws to keep the proper reflector and element spacing. To locate the holes on the cover plate I draw a line between the two existing holes and then measure 1/2” in from each existing hole edge and drill with an 1/8” bit. Also, when locating the holes in the reflector vertical support make sure that the reflector is centered behind the loops (vertically) and not centered on the cover plate.
As previously mentioned, a matching transformer can always be used to connect your Pennyloop to coax. If you have purchased or installed coax with the connectors already in place, I would not recommend using the Direct Coax Feed. The matching transformer will be just fine. Also, I would use a quality matching transformer with a good weather boot or the Direct Coax Feed in a weatherproof box if the antenna will be in a hard to reach location.
A few more notes on the Direct Coax Feed: The original intent of the Pennyloop Antenna was to provide a very simple and straightforward high performance design that was easy to build with locally purchased materials, including not having to purchase a matching transformer. If the builder uses a high quality coax with good shielding the performance can meet or exceed that of a Pennyloop Antenna with a matching transformer. That being said, the matching transformer is a very convenient method of attaching your coax to the antenna and there is nothing wrong with it's use. I am very confident in the outside Direct Coax Feed presented here. It has been in place for quite a while now in all types of weather and is performing exceptionally well. I included an early photo of a direct coax feed test on the Pennyloop Antenna. It can be noted that the crimp connection on the braid made that side a little long resulting in the braid leaving the coax at a fairly sharp angle before heading down to the feed point. I did go back at a later time and tested this connection to see if it had any noticeable effect on the signal strength. It was tested as seen in the photo and then a longer and more symmetrical connection (like the one shown in the box) was tested. There was no noticeable change in the signal strength, but I would recommend that if you are going to use the Direct Coax Feed make sure that the coax ends are symmetrical and that they taper smoothly back to the coax.
-The coax that I am currently using is locally available RG-6/U Dual-Shield with 60% braid and rated for Outdoor Use. I am also using Noalox dielectric grease with very good results. I would highly recommend that you wear gloves to smear it into the braid.
Many thanks for your interest in the Pennyloop Antenna!