Deconstructing reos Patent

PHILADELPHIA To receive TV broadcasts, you need some sort of antenna. And that antenna can't just be a paper clip or coat hanger, although both can work sometimes. The antenna must have some physical relationship to the wavelength of the signal being received. If it does, it approaches resonance and transfers the maximum level of signal to a receiver. We know the relationship between wavelength and frequency. They're inversely proportional to each other, and a quick way to determine the wavelength is to divide the frequency into 300. Example: The wavelength of a TV broadcast signal on Ch. 2, broadcasting at about 55 MHz, is about 5.45 meters. If you could actually see the radio wave, one complete cycle of the signal would measure 5.45 meters, or almost 18 feet.

In order for our antenna to resonate i.e., have gain at the desired frequency it needs to have some fractional relationship to the wavelength. So, a full-wave loop for Ch. 2 would measure 18 feet. A -wave dipole would then measure 9 feet, while a -wave whip antenna would measure about 4.5 about 54 inches.

That's not to say that our Ch. 2 antenna wouldn't work at other frequencies. It could also pull in signals at Ch. 3, or 4, or even 5 and 6. But it wouldn't be as efficient at those frequencies as it would on Ch. 2.

The same principle holds true for high-band VHF Ch. (7-13). To pull in Ch. 7, broadcasting at about 176 MHz, we'd like to have an antenna with a full wavelength of 5.6 feet. A - wave antenna would then measure about 2.8 feet, and a -wave whip antenna would measure about 1.4 feet, or 17 inches.

For UHF TV channels, let's pick 600 MHz (TV Ch. 36) for our example. A full wavelength here is 1/2 meter, or about 19 inches. A -wave antenna would then be 9.5 inches and a -wave whip antenna, such as you'd find on wireless microphone systems, would measure slightly less than 5 inches.

Again, that's not to say the -wave or -wave antennas mentioned wouldn't work on higher or lower UHF TV channels. It's just that they're most efficient at 600 MHz. All of this is just basic physics and innate knowledge to anyone who has worked with RF antenna and transmission systems, amateur or professional.

Each individual antenna in the Aereo system is about the size of a dime.

LINK:	http://www.tvtechnology.com/news/0110/deconstructing-aereos-patent/270...
	See more stories from tvtechnology

Most recent headlines