ISRO Scientist or Engineer Electronics 2015

A Cassegrain reflector antenna has a sub-reflector whose geometrical shape is:

The beam-width and the directivity of an antenna are:

A lossless transmission line with characteristic impedance $$Z_0 = 50$$ ohm is 30 m long and operates at 2 MHz. Theline is shorted at the load, if the phase velocity = 0.6 times the velocity of light, the input impedance of the line is:

Two microwave sub-systems having respective return loss of 10 dB and 20 dB are cascaded together, the return loss at the input of the integrated system is:

A parabolic reflector antenna used for reception of data is 1 meter in diameter and operates at 30 GHz. The far field distance of this antenna for a quadratic phase error of 22.5 degree is:

A potential field is given by $$\phi = 2 xy^2 - 3 y^2z$$. If $$\hat{x}, \hat{y}, \hat{z}$$ are the unit vectors along x, y and z directions respectively, the field intensity at (0, 1, 0) is:

The VSWR of a microwaveunit is 1.5, the return loss is:

In two wire transmission line, two consecutive voltage minima are found at 20.6 caaee 25.6 cm. The operating frequency is:

A TEM mode transmission line is having distributed circuit parameters as R = 1 ohm/m, L = 200 nH/m, G = 300 $$\mu$$S/m, C = 60 pF, the line is:

A plane wave $$E = 100 \sin(\omega t - 10 x) V/m$$ in a loss less medium with $$\mu = 4 \mu_o, ε = ε_o$$ strikes another medium with 90 degree angle of incidence having $$\mu = 9 \mu_o, ε = ε_o$$, the reflection co-efficient is: