When a line short circuited at far end, the minimum voltage occurs at

A branched duplexer funds use in narrow bandwidth applications.

TR tube stands for transmit-receive tube and ATR tube stands for antitransmit receive tube.

Both these tubes are used in branched duplexer.

TE₀₁ mode is unaffected because its horizontally oriented electric field is every where perpendicular to the conducting strips.

Wavelength should be less than cutoff wavelengths.

Therefore frequency should be higher than cutoff frequency for minimum attenuation.

It is somewhat similar to TWT and can deliver microwave power over a wide frequency band.

It has an electron gun and a helix structure. However the interaction between electron beam and RF wave is different than in TWT.

The growing RF wave travels in opposite direction to the electron beam.

The frequency of wave can be changed by changing the voltage which controls the beam velocity.

Moreover the amplitude of oscillations can be decreased continuously to zero by changing the beam current.

It features are:

1. Frequency range - 1 GHz to 1000 GHz.

2. Power output - 10 mV to 150 mW (continuous wave) 250kW (pulsed).

It is used as signal source in transmitters and instruments.

When a circular waveguide is rotated by 90°, the configuration remain the same.

A Klystron is a vacuum tube used for generation/amplification of microwaves.

An electron beam is produced by oxide coated indirectly heated cathode and is focussed and accelerated by focussing electrode.

This beam is transmitted through a glass tube. The input cavity where the beam enters the glass tube is called buncher.

As electrons move ahead they see an accelerating field for half cycle and retarding field for the other half cycle.

Therefore, some electrons are accelerated and some are retarded. This process is called velocity modulation.

The velocity modulation causes bunching of electrons. This bunching effect converts velocity modulation into density modulation of beam.

The input is fed at buncher cavity and output is taken at catcher cavity.

In a two cavity klystron only buncher and catcher cavity are used. In multi cavity klystron one or more intermediate cavities are also used.

The features of a multicavity klystron are :

1. Frequency range - 0.25 GHz to 100 GHz

2. Power output - 10 kW to several hundred kW

3. Power gain - 60 dB (nominal value)

4. Efficiency - about 40%.

A multicavity klystron is used in UHF TV transmitters, Radar transmitter and satellite communication.

At high frequencies transit time is large as compared to the period of microwave signal.

Same antenna is used for transmission and reception.

A parallel tuned circuit has an infinite impedance if R is zero.

A quarter wave line short-circuited at far end behaves as a parallel tuned circuit.