The creation of a high-range HDTV antenna is really nothing more than making the antenna more capable of receiving the signals that are coming over the air. This is done by constructing a bigger target. A backing reflector, the highest possible outside placement, more precise pointing at the transmitter and a preamp that boosts the strength of the signal to the television are all steps that will make a homemade HDTV antenna more high range.
Everyday Parts Make a High Tech Whole
Everything you need to make a great high-power HDTV antenna is right at hand. Start with a 41-inch length of 2-by-4. Add a total of 10 wire coat hangers, eight for "V"s that together make the bow ties, and the two others to interconnect them. Get wood screws and washers to secure each hanger segment, and a VHF/UHF antenna from a dollar store. That's the antenna proper.
Old metal shelving or oven grates make an excellent backing element, because they most closely approximate the backing of manufactured DB4 antennas (see Resources). However, a 30-inch by 16-inch piece of plywood or heavy cardboard covered with aluminium foil is an excellent DIY backing reflector, although it is better for the attic than outside because of its greater wind resistance.
Put It All Together
Affix the backing to one narrow side of the 2-by-4 with nails or screws. Then, attach each V section hanger to the opposite side of the 2-by-4, four to a side, 5 inches from the top, and 7 inches between each hanger. Repeat the sequence on the other side at exactly the same measurements, being sure the washers don't touch one another.
Two additional longer hanger lengths connect all the "V"s. Connect one from the top left "V" position, cross it over to right number 2, continue down through right number 3, and end at left number 4. Repeat the sequence, starting at top right, with the second hanger length. Once they're both secured beneath the washers, and both of the two crossing points are insulated to prevent shorting, screw down the two antenna leads halfway between bow ties numbers 2 and 3 to those two interconnecting hanger lengths.
Channel cut the bottom of the 2-by-4 to put it into a motorised base if remote-control positioning of the antenna is desired. Otherwise, mount the antenna in an attic or outside, position it for maximum signal strength, and free HDTV over-the-air channels are yours.
In remote areas far from transmitters, a preamp to boost the signal from the antenna to the television can provide a further signal boost.