E9D01

How does the gain of a parabolic dish antenna change when the operating frequency is doubled?

  1. Gain increases 6 dB

E9D02

What is one way to produce circular polarization when using linearly polarized antennas?

  1. Arrange two Yagis perpendicular to each other with the driven elements at the same point on the boom and fed 90 degrees out of phase

E9D03

How does the beamwidth of an antenna vary as the gain is increased?

  1. It decreases

E9D04

Why is it desirable for a ground-mounted satellite communications antenna system to be able to move in both azimuth and elevation?

  1. In order to track the satellite as it orbits the earth

E9D05

For a shortened vertical antenna, where should a loading coil be placed to minimize losses and produce the most effective performance?

  1. Near the center of the vertical radiator

E9D06

Why should an HF mobile antenna loading coil have a high ratio of reactance to resistance?

  1. To minimize losses

E9D07

What is a disadvantage of using a multiband trapped antenna?

  1. It might radiate harmonics

E9D08

What happens to the bandwidth of an antenna as it is shortened through the use of loading coils?

  1. It is decreased

E9D09

What is an advantage of using top loading in a shortened HF vertical antenna?

  1. Improved radiation efficiency

E9D10

What is the approximate feed-point impedance at the center of a folded dipole antenna?

  1. 300 ohms

E9D11

Why is a loading coil often used with an HF mobile antenna?

  1. To cancel capacitive reactance

E9D12

What is an advantage of using a trapped antenna?

  1. It may be used for multi-band operation

E9D13

What happens at the base feed-point of a fixed-length HF mobile antenna as the frequency of operation is lowered?

  1. The resistance decreases and the capacitive reactance increases

E9D14

Which of the following types of conductor would be best for minimizing losses in a station's RF ground system?

  1. A thin, flat copper strap several inches wide

E9D15

Which of these choices would provide the best RF ground for your station?

  1. A connection to 3 or 4 interconnected ground rods driven into the Earth

 

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