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Why can a lossy feeder make an antenna appear better matched than it is?

  • A.Loss reduces the power delivered so reflection is smaller
  • B.The measurement instrument compensates for cable loss
  • C.The reflected wave is attenuated twice on its way back
  • D.The feeder transforms the impedance to fifty ohms

Answer: C

A reflected wave travels the length of the cable a second time, so it is attenuated twice over and the standing wave ratio measured at the transmitter is closer to unity than the one at the antenna. A very lossy cable can make a completely faulty antenna look acceptable. The cure is to measure at the antenna end or to correct for the known cable loss. Impedance transformation depends on length rather than loss, and instruments do not correct unless told the cable characteristics.

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