RF4 A1

Define in words what is meant by the term “gain” in the context of an antenna.

Define in words what is meant by the term “directivity” in the context of an antenna.

Make a sketch showing the radiation pattern of a half-wave dipole. Indicate the directions of maximum and minimum radiation and state its maximum gain value.

Sketch a graph showing how the resistive and reactive parts of the impedance of a dipole vary as its length varies from zero to one wavelength.

What does the term “polarisation” describe in a radio or microwave radiation field?

What are the three types of polarisation?

A radar system is to have a maximum range of 100 km. What is the maximum pulse repetition frequency it can use?

A Doppler radar operates at a frequency of 10 GHz. Calculate the Doppler frequency produced by a target moving at 1 m/s.

At what distance do the “near” and “far” fields around a conductor carrying an alternating current have the same value? Justify your answer.

Write down the physical meaning of the four S-parameters describing a two-port network.

What three parameters determine the characteristic impedance of a microstrip transmission line?