Consider the Friis' transmission equation $P_R=\left(P_T G_T G_R \lambda^2\right) /(4 \pi D)^2$, where $P_R$ and $P_T$ are the received and the transmitted powers, respectively.

$G_T$ and $G_R$ are the gain of transmitting and receiving antennas, respectively, $D$ is the distance between the transmitting and receiving antennas, and $\lambda$ is the wavelength in free space.

Given: $G_T=G_R=1.0, \lambda=0.30 \mathrm{~m}$ and $P_T=+10 \mathrm{dBm}$.

Choose the distance (D), in km , from the following options at which the received power, $P_R=-90 \mathrm{dBm}$ ?

The electric field of a monochromatic plane wave travelling in a lossless isotropic and homogenous medium is given by

$$ \vec{E}(z, t)=E_0[\hat{x} \cos (\omega t-k z)+\hat{y} \sin (\omega t-k z)] $$

in a right-handed orthogonal co-ordinate system.

Which of the following is the correct polarization of the electromagnetic wave?

Which option(s) represents/ represent the dielectric loss tangent of a substrate?

The cutoff frequency (in GHz ) for the dominant $\mathrm{TE}_{10}$ mode of an air-filled rectangular waveguide of inner dimension 0.28 inch $\times 0.14$ inch is $\_\_\_\_$ .

(rounded off to two decimal places).