Silverace The Smart Pig

Smart Information Column
Issue 7, January 2010
Under $10, 9 ounce, High-Performance, 10x15" HDTV antenna on Foam Board for UHF channels

The move to HDTV broadcasts in the USA has brought consumers a new world of picture clarity and resolution. However, the move of most major channels from VHF frequency broadcasts to UHF has brought reception problems to some viewers. The key to successfully receiving HDTV broadcasts is to know which channels you want to watch and whether they are broadcast on VHF or UHF frequencies. Once you know this, you can use the appropriate antenna(s) for your area.

1) Determime which channels can be received in your area, their signal strengths, and what frequencies are used by each TV station.
    Goto and enter your address or zip code.

    TV Fool is one of many websites which allow you to see which TV channels are broadcasting in your area that you can reasonably receive with a proper antenna. The key here is to go down the list of channels listed in order of relative dB signal strength until you see 0dB (or a negative number, eg. -6dB). With a good antenna, you should be able to receive all of the channels at 0dB or higher; you'll need a great antenna, typically a large rooftop antenna, in order to receive any TV channel with a negative relative signal strength - these are simply too far from you, or broadcasting with too little power for you to receive.

    In the Los Angeles/Orange County area, for example, most TV stations are on UHF - the major exceptions are channels 9, 11, and 13, which are still broadcasting on VHF frequencies. Thus, you will need a separate VHF antenna for these three stations unless you are close to these broadcast towers.

    Some UHF channels are so far, you will not be able to receive them unless you have a good antenna. For example, in Zip Code 92683, TV Fool shows channel 31 (which includes all subchannels, such as channel 31.1, 31.2, 31.3, etc) at around -6dB relative signal strength. Thus, a crafty UHF antenna is needed to pickup this low-power, distant channel.

2) Here is an antenna design that works well (out to Orange County in 92683) for all UHF channels broadcasting in Los Angeles all the way down TV Fool's list to channel 31 at -6dB.

    You will easily pickup 72+ digital HDTV channels with this antenna if placed in a north-facing window indoors, however, channels 9, 11, 13 will require a separate VHF antenna. The cheap fix for these VHF channels in Los Angeles? Simply buy a pair of rabbit ear VHF antennas and connect to the transformer for this project and/or directly to your TV. Typically $1-2 for a pair of rabbit ear antennas.

    If you have anything blocking your north-facing view, live in a heavily shielded structure, or have other sources of interference, you may need a better antenna or one placed on the rooftop. A more powerful VHF antenna may be necessary to pickup any VHF channels in your area.
The ANTENNA mounted on the roof is usually the only way you can receive all channels in very distant/troublesome locations.

    In any case, this coat-hanger antenna works significantly better than the Radio Shack single bow-tie UHF antenna they have for sale. Although the Radio Shack single-bow tie does pickup most UHF channels just fine, it does not pickup the 31.x channel in Los Angeles and requires some adjustment of location to pickup all channels well. The coat-hanger antenna pickups all UHF channels (72+ channels) well once placed in a north-facing window, including the -6dB 31.x channels; our large roof-top antenna naturally picks up all channels, UHF and VHF, without any trouble.

    Due to it's low cost, I would suggest that you try this coat hanger antenna first rather than buying the single bow-tie antenna. If it doesn't work well for you, you'll likely need to investigate even better performing indoor and outdoor antennas. It's small 10x15" size also allows for great portability, and you can attach a nice picture to the outside of the foam board so it blends better with the surroundings.

3) What you'll need

    a) $2-5.
        Foam board (2 pieces, 10x15x1/4")
        You can find this at Michael's craft store, Target, and office supply stores. Typically, you'll need two pieces that are 10x15" width x height, 1/4" thick. You can buy one large foam board and cut it to size if it's cheaper. You can substitute any stiff board (cardboard, plastic board, wood, etc) for this; however, do not use anything made of metal.
        If you don't care about appearance, the exposed sharp ends of the antenna, or having the internals visible for all to see, you can use just (1) one board instead and save money.

    b) Free to <$1 each from any dry cleaner shop.
         Wire coat hanger (2 hangers, metal, bare)
        You usually get these for free when you dry clean clothes. If you don't have any in your home, beg them from friends. Otherwise, most dry cleaners will sell them to you for <$1 each. You want the bare metal ones since they are easier to strip to make a good electrical contact; if you have coated ones, it'll take slightly more work to strip the plastic/paint coating off the corners.

    c) Free to <$1 each.
        Metal wire (1 foot length at most, any type)
        You'll need some metal wire to connect everything together, and you can use anything you have handy. Old cords you can cut apart, plant wire, speaker wire, Ethernet cable, etc. You'll need them only to connect the coat hangers together, and some extra to connect to the transformer (only if you don't want to attach the transformer directly to the coat hangers - either way is fine if you want to save money, but connecting the transformer to a pair of wires attached to a pair of coat hangers is more convenient when making adjustments).

    d) Free to <$1.
        Tape. (1 foot length at most, any type)
        You will need tape to hold down everything. Clear tape, packing tape, etc. will do.

    e) Free to <$5.
        300 Ohm to 75 Ohm TV transformer (1)       
        These used to come with VCRs, TVs, etc. when you bought them. Nowadays, you may need to visit your local $0.99 store, Radio Shack or other parts store to buy these. They are super-cheap and unless you're in a hurry, you should be able to buy one for $1-$2 at most. You will see one pair of leads for connecting the UHF antenna, one pair of leads for the VHF. On the other end, you will see a standard 75 Ohm, round, antenna plug that will go into your TV's round antenna jack.
        You should buy one with a cable long enough to reach your TV.

        Free to <$1.
        Two Binder Clips (2x, small)
        To clip the two pieces of foam board together. You can skip this if you use tape, staples, etc, and don't care about easily taking the antenna apart later on.

4) Antenna Assembly
    This is easy and will take about 15-60 minutes depending on your skill level and speed. Very easy and shouldn't be hard at all.

Figure 1: Transformer taped to outside of foam board. UHF leads attached to UHF antenna wires, taped together.

Figure 2: Inside face of foam board. Two wire hangers cut in half, attached to wires which lead in parallel to the other side.

    a) Cut the wire hangers in half, discard the top part that hangs on knobs. You don't need to be exact with this, simply cut away! You can make a slight half-cut in the hanger, then bend it back and forth (either with pliers - safer - or your hands) until it breaks if you don't have the arm strength to cut the hangers all the way through. The hanger halves should retain their original shape.

    b) At each corner of the hanger halves where the wires will connect, use a file, the concrete sidewalk, or brick surface to file away the coating until you can see the shiny, silver-colored metal. You need to do this so that the electrical current can flow from hanger to wire to hanger to transformer.

    c) Place the hanger halves on the 10x15" board as shown - trim ends as necessary to fit within the board space.

        The only major point? Two corners of the hangers pairs are approximately 6" from the next pair below them (See figure 2) and about 1 1/2-2" from each other. You can simply place the pieces on the 10x15" board as shown in Figure 2.

    d) Strip each wire end of it's plastic coating. Wrap them around each corner of the wire hanger several times to get a good connection (if you have a soldiering iron, you can solider everything together) as shown in figure 2 (the vertical, black wires connect the two lower hanger halves to the upper hanger halves). You will either connect the transformer's UHF leads directly to one pair of hanger halves, or as shown, to a pair of wires that are connected to one pair of hanger halves. The latter is more convenient if you want to mount the transformer on the outside of the foam board, and for adjusting the antenna later on.

    e) Use tape to securely fasten the wires to the hangers, then tape the hangers down on the foam board.

    f) If you are using two pieces of foam board, place the second board on top of the first one, and secure using the two binder clips (Figure 1). The antenna is now safely secured between two foam boards. (Otherwise, if you're only using one foam board, it will look like Figure 2.) You can tape the transformer UHF leads to the antenna wires, then tape the transformer itself to the board.

    g) You can mount the board anywhere, and tape a nice photograph, painting, etc. to the front facing foam board to hide it. It's only ~9oz, so it's lightweight and portable.