# Electromagnetics [GATE (Graduate Aptitude Test in Engineering) Electronics]: Questions 75 - 78 of 96

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## Question 75

Electromagnetics
Gain and Directivity

Appeared in Year: 2016

### Question

MCQ▾

An antenna pointing in a certain direction has a noise temperature of . The ambient temperature is . The antenna is connected to a pre-amplifier that has a noise figure of and an available gain of over an effective bandwidth of 12 MHz. The effective input noise temperature for the amplifier and the noise power at the output of the preamplifier, respectively, are

### Choices

Choice (4)Response

a.

b.

c.

d.

## Question 76

Electromagnetics
Polarization, Phase and Group Velocity

Appeared in Year: 2015

### Question

MCQ▾

The electric field of a plane wave propagating in a lossless non-magnetic medium is given by the following expression

The type of the polarization is

### Choices

Choice (4)Response

a.

Right Hand Elliptical

b.

Linear

c.

Left Hand Elliptical

d.

Right Hand Circular

## Question 77

Electromagnetics
Return Loss
Edit

Appeared in Year: 2019

### Question

Radiation resistance of a small dipole current element of length l at a frequency of 3 GHz is 3 ohms. If the length is changed by 1 % , then the percentage change in the radiation resistance, rounded off two decimal places, is … % . (Carry One Mark Each)

## Question 78

Electromagnetics
Wave Equation

Appeared in Year: 2016

### Question

MCQ▾

The electric field of a uniform plane wave travelling along the negative z direction is given by the following equation:

This wave is incident upon a receiving antenna placed at the origin and whose radiated electric field towards the incident wave is given by the following equation:

The polarization of the incident wave, the polarization of the antenna and losses due to the polarization mismatch are, respectively,

### Choices

Choice (4)Response

a.

Circular (clockwise) , Linear,

b.

Circular (anticlockwise) , Linear,

c.

Linear, Circular (clockwise) ,

d.

Circular (clockwise) , Linear,

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