UHF log-periodic antenna. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Television antennas
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Here is a description of a log-periodic antenna for the UHF band (channels 21-60 470-790 MHz). KND is approximately 8,5.
The design of the antenna is shown in the figure. It contains a two-wire symmetrical distribution line made of two identical pipes arranged in parallel. Seven semi-vibrators are fixed on each of them in one plane, and each subsequent semi-vibrator is directed in the opposite direction relative to the previous one. In addition, the planes in which the semi-vibrators are located on each pipe of the line are parallel, and the semi-vibrators of the same length on different pipes are directed in opposite directions.
A coaxial cable with a wave impedance of 75 ohms passes inside one of the pipes of the line, moreover, the ends of the pipes at the feeder inlet are short-circuited with a metal plate. A dielectric bar is installed at the cable exit point to stiffen the structure. The shielding braid of the cable is soldered directly at the exit of the cable from the tube, and the central conductor is soldered to a lug attached to the plugged end of the other tube. The antenna does not need to be tuned.
Based on materials from Radio No. 8, 1990. Nanupanov G. Outdoor antennas for receiving UHF; Publication: cxem.net
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Comments on the article:
bassilla
I did it earlier, in the 80s, I used it for quite a long time, compared to other broadbands it is much more sensitive. After launching a close translator, the need disappeared. Now digital TV is being introduced, and there are already 20 channels on the long-distance transmitter, but we only have plans. I will make the antenna again, of the same design, because it proved to be good during long-term operation.
Nicholas
Please show how to connect the cable. Not strong in this matter. Where is the central, where is the screen. Thanks for explaining!
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