Recent questions and answers in Antennas

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 transmitte...

A dipole antenna has a $\sin \theta$ radiation pattern where the angle $\theta$ is measured from the axis of the dipole. The dipole is vertically located above an ideal g...

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

For an $8$ feet $(2.4 \mathrm{~m})$ parabolic dish antenna operating at $4 \; \mathrm{GHz}$, the minimum distance required for far field measurement is closest to$7.5 \ma...

A trasmitting antenna radiates $251 \mathrm{~W}$ isotropically. A receiving antenna, located $100 \mathrm{~m}$ away from the transmitting antenna, has an effective apertu...

The average power of an omni directional antenna varies as the magnitude of $\cos \theta$, where $\theta$ is the azimuthal angle. Calculate the maximum Directive Gain of ...

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 an...

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 t...

Consider a linear array of two half-wave dipoles $\mathrm{A}$ and $\text{B}$ as shown in the figure is. The dipoles are $\frac{\lambda}{4}$ apart and are excited in such ...

The radiation resistance of a circular loop of one turn is $0.01 \; \Omega$. The radiation resistance of five turns of such a loop will be$0.002 \; \Omega$$0.01 \; \Omega...

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 differenc...

Consider a lossless antenna with a directive gain of $+6 \mathrm{~dB}$. If $1 \mathrm{~mW}$ of power is fed to it the total power radiated to the antenna will be$4 \mathr...

Two identical and parallel dipole antennas are kept apart by a distance of $\frac{\lambda}{4}$ in the H-plane. They are fed with equal currents but the right most antenna...

An antenna, when radiating, has a highly directional radiation pattern. When the antenna is receiving, its radiation patternis more directiveis less directiveis the samee...

For a dipole antennathe radiation intensity is maximum along the normal to the dipole axisthe current distribution along its length is uniform irrespective of the lengtht...

At $20 \; \mathrm{GHz}$, the gain of a parabolic dish antenna of $1$ meter diameter and $70 \%$ efficiency is$15 \mathrm{~dB}$$25 \mathrm{~dB}$$35 \mathrm{~dB}$$45 \mathr...

Two dissimilar antennas having their maximum directivities equal,must have their beamwidths also equalcannot have their beamwidths equal because they are dissimilar anten...

The beamwidth-between-first null of uniform linear array of $\mathrm{N}$ equally-spaced (element spacing $=d$ ), equally-excited antennas is determined by$\mathrm{N}$ alo...

In a broad side array of $20$ isotropic radiators, equally spaced at a distance of $\frac{\lambda}{2}$, the beam width between first nulls is$51.3$ degrees$11.46$ degrees...

In the radiation pattern of a $3$-element array of isotropic radiators equally spaced at distances of $\frac{\lambda}{4}$ it is required to place a null at an angle of $3...

An antenna with a directive gain of $6\text{ dB}$ is radiating a total power of $\text{16 kW}$. The amplitude of the electric field in free space at a distance of $\text{...