Frequently Asked Questions On Antenna Theory With Answers -18.


This page contains basic questions and short notes on some of the keywords on antenna theory:


86) What are the factors that affect the propagation of radio waves?
  • Curvature of earth.
  • Earth’ s magnetic field.
  • Frequency of the signal.
  • Plane earth reflection.


87) Define gyro frequency?

Frequency whose period is equal to the period of an electron in its orbit under the influence of the earths magnetic flux density B.


88) Define critical frequency?

For any layer, the highest frequency that will be reflected back for vertical incidence is
fcr = 9 √Nmax


89) Define Magneto-Ions Splitting?

The phenomenon of splitting the wave into two different components (ordinary and extra-ordinary) by the earths magnetic field is called Magneto-Ions Splitting.


90) Define LUHF?

The lowest useful HF for a given distance and transmitter power is defined as the lowest frequency that will give satisfactory reception for that distance and power.

It depends on:
  • The effective radiated power
  • Absorption character of ionosphere for the paths between transmitter and receiver.
  • The required field strength which in turn depends upon the radio noise at the receiving location and type of service involved.


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