GATE EC Electromagnetics questions

A short-circuited stub is shunt connected to a transmission line as shown in the figure is. If $Z_{0}=50 \mathrm{ohm}$, the admittance $Y$ seen at the junction of the stub and the transmission line is

A rectangular metal wave guide filled with a dielectric material of relative permittivity $\varepsilon_{r}=4$ has the inside dimensions $3.0 \mathrm{~cm} \times 1.2 \mathrm{~cm}$. The cut-off frequency for the dominant mode is

Two identical antennas are placed in the $\theta=\pi / 2$ plane as shown in the figure. The elements have equal amplitude excitation with $180^{\circ}$ polarity difference, operating at wavelength $\lambda$. The correct value of the magnitude of the far-zone resultant electric field strength normalized with that of a single element, both computed for …

The phase velocity for the $\mathrm{TE}_{10}$ – mode in an air-filled rectangular waveguide is ( $c$ is the velocity of plane waves in free space)

In an impedance Smith chart, a clockwise movement along a constant resistance circle gives rise to

The $\text{VSWR}$ can have any value between

The electric field on the surface of a perfect conductor is $2 \mathrm{~Vm}$. The conductor is immersed in water with $\epsilon=80 \epsilon_{0}$. The surface charge density on the conductor is $\left(\epsilon_{0}=10^{-4} /(36 \pi) \mathrm{F} / \mathrm{m}\right)$

Distilled water at $25^{\circ} \mathrm{C}$ is characterized by $\sigma=1.7 \times 10^{-1} \mathrm{mho} / \mathrm{m}$ and $\epsilon=78 \; \epsilon_{0}$ at a frequency of $3 \; \mathrm{GHz}.$ Its loss tangent $\tan\delta$ is $\left(\epsilon=10^{-9} /(36 \pi) \mathrm{F} / \mathrm{m}\right)$

A plane wave is characterized by $\overline{\mathrm{E}}=\left(0.5 \hat{x}+\hat{y} e^{jz} / 2 \right)e^{jzet – jkz}.$ This wave is

The dominant mode in a rectangular waveguide is $\text{TE10,}$ because this mode has

The phase velocity of waves propagating in a hollow metal waveguide is

If a plane electromagnetic wave satisfies the equation $\frac{\partial^{2} \mathrm{E}_{\mathrm{x}}}{\partial \mathrm{z}^{2}}=\mathrm{c}^{2} \frac{\partial^{2} \mathrm{E}_{\mathrm{x}}}{\partial \mathrm{t}^{2}}$, the wave propagates in the

A transmission line is distortionless if

In a uniform linear array, four isotropic radiating elements are spaced $\frac{\lambda}{4}$ apart. The progressive phase shift between the elements required for forming the main beam at $60^{\circ}$ off the end-fire is

A medium wave radio transmitter operating at a wavelength of $492 \mathrm{~m}$ has a tower antenna of height $124 \mathrm{~m}$. What is the radiation resistance of the antenna?

A uniform plane electromagnetic wave incident normally on a plane surface of a dielectric material is reflected with a VSWR of $3.$ What is the percentage of incident power that is reflected?

A material has conductivity of $10^{-2} \mathrm{mho/m}$ and a relative permittivity of $4.$ The frequency at which the conduction current in the medium is equal to the displacement current is

If the diameter of a $\frac{\lambda}{2}$ dipole antenna is increased $\operatorname{from} \frac{\lambda}{100}$ to $\frac{\lambda}{50}$, then its

A $\text{TEM}$ wave is incident normally upon a perfect conductor. The $\mathrm{E}$ and $\mathrm{H}$ fields at the boundary will be, respectively,

The magnitudes of the open-circuit and short-circuit input impedance of a transmission line are $100 \; \Omega$ and $25 \; \Omega$ respectively. The characteristic impedance of the line is,