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537 questions and answers

945 views

Write a short note on Bathe hole coupler.

Bathe hole coupler has a single centre offset hole in the common broad wall of the two guides and the coupling between port 1 and 3 is controlled by the offset of the hole i.e., the angle θ between the axis of the two guides determines the amount of coupling.

1132 views

What is the advantage of heterojunction bipolar transistor (HBT) over BJT? Describe the advantage of operational mechanism of HBT.

The advantage of heterojunction bipolar transistor over BJT is High speed switch device and enhancement of output power.

1088 views

Derive the expression for the condition for negative differential mobility of transferred effect on devices.

The generation of negative resistance in a Gunn diode is explained by the valley current. The passive electronic device absorbed or dissipated power and active devices generated the power. Power across the passive devices is I2R and across the active devices is -I2R.

1335 views

Distinguish between group velocity and phase velocity.

If there is modulation in the carrier, the modulation envelope actually travels at velocity slower than that of carrier alone and of course slower than speed of light. The velocity of modulation envelope is called the group velocity Vg.

1565 views

Discuss the operating principle of Faraday’s rotation isolator.

In 1845 Michael Faraday demonstrated that the plane of polarization of a linearly polarized light is rotated when it passes through ferrite materials along the direction of applied magnetic field. This is true for microwave also.

1354 views

Can a circulator be used as an isolator? If so, how? Difference between circulator and isolator

Circulator can be separated into two classes, 4 port waveguide circulators based on Faraday rotation of waves propagating in a magnetized material and 3 port Y junction circulators based on cancellation of waves propagating over two different paths near a magnetized material. A circulator can also be used as an isolator.

944 views

Find out the expressions for the different components of electric and magnetic fields inside a rectangular waveguide for TE mode of propagation. Hence find out the expression for the guide wavelength and propagation constant.

In order to study transmission lines electromagnetically, one should know the laws governing time varying electromagnetic fields. The interaction between charges and their mutual energy is expressed in terms of four vectors E and B, D and H. The first pair defines the factor on a charge density ρ moving with vector v given by;