Microwave engineering miscellaneous Easy Questions and Answers

Microwave engineering miscellaneous

Consider the following statements regarding feed which is the Key component of a reflector antenna as it has a decisive bearing on the overall-performance:
1. For a horn-feed antenna the reflector focus must coincide with horn-feeds phase centre, which for a wide-flare horn lies in the plane of horn aperture.
2. The feed must have minimal radiation outside the angular aperture of reflector.
3. In print focus or cassegrain systems, the main or sub-reflectors should be in Fraunhofer zone of the feed antenna.
Which of the statements are correct?

In microwave power measurements using bolometer, the principle of working is the variation of:

1. Inductance with absorption of power
1. Resistance with absorption of power
1. Capacitance with absorption of power
1. Cavity dimensions with heat generated by the power

In microwave radar, pulse repetition frequency is used to resolve range and doppler ambiguities using:

(A) In some applications, the TM01 mode in circular waveguide is preferred to the TE01 mode or TE11 mode.
(R) TM01 mode not only overcomes the problem of rotation of polarisation in circular waveguide but also requires a smaller diameter.

1. Both A and R are true and R is correct explanation of A
1. Both A and R are true but R is not a correct explanation of A
1. A is true but R is false
1. A is false but R is true

(A) In an oscillation zone of reflex klystron an increase in the reflector voltage results in lighter oscillation frequency.
(R) Electron bunches pass through the interaction gap before the retarding field is at a maximum and an increased reflector voltage results in the induced current lagging in voltage.

1. Both A and R are true and R is correct explanation of A
1. Both A and R are true but R is not a correct explanation of A
1. A is true but R is false
1. A is false but R is true