![]() ![]() This makes it difficult to drive as a transmit antenna but still usable as a receive antenna. ![]() If you shortened the antenna to 0.05 wavelengths, the radiation resistance is maybe an ohm or two in series with a capacitive reactance of 1000 ohms. So, at a quarter wavelength the reactive impedance (magenta colour) is zero and the radiation resistance (blue) is about 37 ohms. Simple reason 2: reflection of power back to the transmitting power amp that might cause the transistors to fail.Ī quarter wave monopole can be made "short" and its impedance will look both capacitive and resistive:. Simple reason 1: avoidance of power turned directly to heat due to a mismatch. Maintaining the correct impedance for a transmitting antenna is much more important than for a receiving antenna.
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