| 摘要 |
A high power TV antenna for operation at the ultra high frequency (UHF) frequency F includes a radiating antenna located at the top of a tower structure (often hundreds of feet high), a transmitter at the bottom of the tower and a main circular waveguide transmission line of diameter D1 between the transmitter and the antenna carried by the tower; the feed to and/or from the transmission line including transition sections such that wave propagation in the transition sections is below cutoff for the TM01 mode while it is above cutoff for the dominant TE11 mode while wave propagation in the main circular waveguide transmission line of diameter D1 is substantially totally in the dominent TE11 mode even while it is above cutoff for the TM01 mode, whereby the transition sections tend to inhibit wave propagation in the system in the undesired TM01 mode.
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