Important Short Questions and Answers: Microwave Passive Components

MICROWAVE PASSIVE COMPONENTS

1)What is Gyrator?

Gyrator is a two port device which provides a relative phase shift of 180 degree for transmission from port 1 to port 2 as compared to the phase for transmission from Port2 to port 1.

2)What are the composition of ferrites

Ferrites are ceramic like materials. These are by sintering a mixture of metallic oxides Properties

Specific resistivity‟s may be used as much as 1014 greater than that of metals Dielectric constants around 10 to 15 or greater Relative permeability is 1000 . Examples of ferrite devices: Isolator Circulator Phase shifters, Modulators, Power limiters

3)What are the high frequency limitation in conventional tubes

The high frequency effects in conventional tubes are

i) Circuit reactance like Inter electrode capacitance and Lead inductance

ii)Transit time effect

iii)              Cathode emission 

iv)            Plate heat dissipation area 

v)Power loss due to skin effect, radiation and dielectric loss.

4) What is Faraday’s rotation law?

If a circular polarized wave is made to pass through a ferrite rod which has been influenced by an Axial magnetic field B, then the axis of polarization gets tilted in clockwise direction and amount of tilt depends upon the strength of magnetic field and geometry of the ferrite.

5. What is the S-matrix of 3 port circulators?

6)Give the significance of Rat race junction

The rat race is particularly used for combining 2 signals or dividing a single signal into 2 equal halves

7)What are ferrite? Why its needed in circulator

Ferrites are non metallic meterials with resistives nearly 10 ¹⁴ times greater than metals and also the dielectric constant is in between 10 ^-15 and relative permeability of the order of 1000

8)Mention the application of gyrator and isolator

Gyrator :

(i)                In can be in radar antenna as a duplexer

 (ii)                         It will handle a low power . hence they are used as low power devices Isolator:

(i)                Isolator are generally used to improve the frequency stability of microwave generators, such as klystrons and magnetrons in which the reflection from the load affects the generating frequency

8)Name the microwave passive devices which make use of faraday rotation

ü Isolator

ü Gyrator

ü Circulator

9)What are properties of S- Matrix

ü Zero diagonal elements for perfect matched networks

ü Symmetry of reciprocal network

ü Unitary property

ü Phase shift property

10)           What are matched terminators

ü Low power co axial termination

ü Resistance strip

ü Standard mis matches

11)           Define isolator?

An isolator or uniline is two port non reciprocal devices, which produce a minimum attenuation to wave in one direction and very high attenuation in the opposite directio

12) Draw the Structure of Two hole Directional coupler

13) Draw the diagram for H – plan tee?

14 )What is H-Plane Tee?

It is a wave guide tee in which the axis of the slide arm is shunting the E- field or parallel to the H-field of the main guide.

15 ) Name some uses of waveguide twists?

(i) waveguide twists are used  to change the plane of polarization of a propagating wave.

(ii)  Waveguide twists are helpful in converting vertical to horizontal polarizations or vice versa.

16 ) Give the applications of directional coupler

1.         Unidirectional power measurement

2.         SWR measurement

3.         Unidirectional wave launching

4.         Reflectometer

5.         Balanced duplexer.

17 ) What are waveguide corners, bends and twists?

These wave guide components are normally used to change the direction of guide through an arbitrary angle