A material has conductivity of 10-2 mho/m and a relative permittivity of 4. The frequency at which conduction current in the medium is equal to displacement current is
Conduction current density J = wD
J = σE σE = ωD = 2p fD
A transmission line is feeding 1 watt of power to a horn antenna having a gain of 10 dB. The antenna is matched to the transmission line. The total power radiated by the horn antenna into the free space is
Pradiated = Gain of Antenna x Input power = G.I
10 log1010 . 1 10 watt.
An end fire array consisting of several half-wave lengths of directive gain 40, then find the width of major lobe
Poynting vector is associated with which of the following?
P = E x H
A uniform plane EM wave incident normally on a plane surface of a dielectric material is reflected with a VSWR of 3. What percentage of incident power that is reflected?
Preflected = |δ|2 Pincident
|δ|2 = 0.25 .
A 10 GHz signal propagates in a waveguide with a phase velocity of 4 x 108 m/s. If the signal produces standing wave in the guide, then the distance between successive minimal will be
f = 10 GHz, v = 4 x 108 m/sec,
The incidence from dielectric medium 1 (ε1) into dielectric medium 2 (ε2), Brewster angle θB and the corresponding angle of transmission θt for will be respectively
Brewster angle θ = tan-1
A medium of relative permittivity εr2 = 2 forms an interface with free space. A point source of EM energy is located in the medium at a depth of 1 meter from the interface. Due to the total internal reflection, the transmitted beam has a circular cross-section over the interface. The area of the beam cross section at the interface is given by
A transmission line of characteristic impedance z0 = 50 Ω. Phase Velocity = 2 x 108 m/sec, and length l = 1 m is terminated by a load z1 = (30 - j 40) ohms. The input impedance of the line for a frequency of 100 MHz will be
A circular waveguide carries TE11 mode whose radial electric-field is given by
Er = E 0J1 (r) sin φ V/m
where 'r' is the radial distance in cm, from the waveguide axis. The cut-off wavelength of the mode is
A uniform plane wave travelling in air is incident on the plane boundary between air and another dielectric medium with εr = 4. The reflection coefficient for the normal incidence is
A transmission line has characteristics impedance of (75 + j 0.01) Ω and is terminated in a load impedance of (70 + j 50) Ω. The transmission coefficient will be
Transmission coefficient .
Maximum effective aperture of an antenna which is operating at a wavelength of 3 meters and has a directivity of 100
The distance between maxima and minima of a standing wave is
A TV. transmitting aerial is fixed on top of a 150 metre tower located on a mountain 1200 m height. The range of transmitter is
1 = 1.44[ht + ht]
A vertical wire of 1 meter length carries a current of 1 A at 10 MHz. The total radiated power is nearly
P = I2 . R (1)2 . 73 73 watt.
Here, vertical wire will be considered as dipole.
The length of half-wave antenna is at 30 MHz
For a 400 kHz transmission line having L = 0.5 mH/km, C = 0.08 mF and negligible R and G, the characteristic impedance will be
f = 400 kHz, L = 0.5 mH, C = 0.08 mF
Which one of the following statement is not a correct for a plane wave with = 0.5e-0.1x cos (106t - 2x)az A/m?
P = E x H P = EH, θ = 90º
η = 120p = 377 Ω.
Beamwidth (between first nulls) will be for an antenna at 3 MHz with directivity of 100
the time average Poynting vector is
Calculate the wave number in waveguide having dimensions 4 x 2 cm at 3 GHz
For a transmission line with homogeneous dielectric the capacitance per unit length is 'c', the relative permittivity of the dielectric is 'εr' and velocity of light in free space is 'v' the characteristic impedance z0 is equal to
The I/P impedance of a short circuited quarter wave long transmission line is
Because for irrotational, ∇ x = 0.
A dipole antenna of λ/8 length has an equivalent total loss resistance of 1.5 Ω. The efficiency of the antenna is
Rr = 80p2 , Re = 1.5 Ω,