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The gain of this antenna and its variants with or without reflectors and NARODs is shown below ( 4nec2 simulation). Some people even built bending jigs, but depending on your skills it may not be necessary. It should be noted that the NAROD elements and their reflectors are needed only if you want to receive VHF band. The antenna can be built with aluminum or copper wire or pipe of 4 to 8 mm diameter. There is an exception to this: the two reflectors for NARODs sit behind them at 29.2 cm. Reflector elements are located 10 cm behind the active elements. Of course, you may test reception without reflectors and if you're fine with that, you may keep the antenna without them. The overall gain improvement when using reflectors is significant and, although the build gets a little more complex, I recommend you add them. The top and bottom elements are called NARODs ( not a reflector or director) and have been added to allow reception of VHF channels. The above is a 4nec2 3D render of the antenna including reflector elements. The original design has been republished and distributed according to the GNU GPL version 3 license. The overall gain is not too much but, since it is easy to build and wideband it's worth a try. With some additional elements, this antenna can also receive the upper part of VHF from 170 to 230 MHz, with an average gain of 8.1 dBi with reflector and 6 dBi without it. The average gain in this frequency range is 13 dBi with reflector and 9.2 dBi without it.
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If that could have been a problem, it's not anymore. It only covered the lower part of UHF, from 470 to 720 MHz (21 - 52 channels). Hoverman and it was patented in the sixties. The Gray-Hoverman antenna has been designed by Doyt R. Frequencies starting from 600 MHz are being repacked for mobile networks. But, nowadays the UHF band for TV broadcasts is getting smaller. This is a large interval, covering two bands and it is difficult to receive with a single antenna. The VHF-Hi band covers 175 to 230 MHz, while UHF covers 470 to 860 MHz. In the past, air TV channels were broadcast on frequencies ranging from 170 MHz to 860 MHz. The antenna offers sufficient gain for DVB-T, DVB-T2, ISDB-T and ATSC reception. By adding some additional elements called NARODs you can also receive VHF band. Gray-Hoverman is an easy to build wideband UHF antenna.