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In cell phone antennas are
The law J = σE, where J is current density, σ is electrical conductivity and E is field strength is
Purpose of antenna is
Antenna is a __________ element
Which of the following antennas is λ /4 length?
Which of the following is λ/2 length?
In a rectangular waveguide if operating frequency is greater than cut off frequency then propagation constant is
In a rectangular waveguide ZTE . ZTM 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 reflection coefficient will be
A λ/8 section of transmission line is determined of load impedance of (2 – j 5) Ω. If characteristic impedance of line is 10 Ω. Then input impedance of line is
Whenever a wave is incident on a perfect conductor then the reflection coefficient is
A conductor carries 10 A current in + x direction and is lying in a field having a flux density 0.2 T directed along + z direction. The magnitude of force per metre length and direction are
Equipotential surfaces about a point charge are in which one of the following forms?
Which one of the following statement is correct?
A waveguide operated below cut off frequency can be used as
Unit of e is __________ .
ZL = 200 Ω and it is desired that Zi = 50 Ω The quarter wave transformer should have a characteristic impedance of
For TE or TM modes of propagation in bounded media, the phase velocity is
An electron in a homogeneous magnetic field and having velocity perpendicular to the direction of field moves
When a particular mode is excited in a waveguide, these appears an extra electric components in the direction of propagation. The resulting mode is
Ferromagnetic materials
The L/C has the dimension of
An electric charge Q is placed in a dielectric medium which of the following quantities are independent of the dielectric constant ε of the medium
The thin parallel wires are carrying current along the same direction. The force experienced by one due to the other is
Laplacian of a scalar function v is
A (75 – j 40) W load is connected to a co-axial line of z0 = 75ω at 6 MHz. The load matching on the line can be accomplished by connecting
Polystyrene has a relative permittivity of 2.7. If the wave is incident at an angle θi of 30° from air into polystyrene, the angle of transmission will be nearly
The cut off wavelength λc for TE20 mode for a standard rectangles waveguide is
The dimension of flux density is
A piece of copper and another piece of Germanium are cooled from 30°C to 80 K. The resistance of
For a hollow waveguide, the axial current must necessarily be
Consider the following; for a loss-less transmission line we can write, Zin = – jz0 for a shorted line with l = λ/8Zin = ± j ∞ for a shorted line with l = λ/4Zin= jz0 for an open line with l = λ/2Zin = 0 for a matched line of any length Select the […]
The current distribution along a travelling wave antenna can be written in the form
For a wave propagating in air filled rectangular waveguide.
It is desired to reduce the reflection at an air porcelain by use of 7/4 plate (for Porcelain μ = 40, and εr = 7). The thickness of the polystyrene plate required at 10 GHz will be
When the phase velocity of an EM wave depends on frequency in any medium, the phenomenon is called
A plane EM wave is travelling in an unbound loss less dielectric having μy = 1 and εy = 4, the time average Poynting vector of the wave is 5 W/m3 . The phase velocity vp (assuming velocity of light as 3 x 108 m/sec) is
When a plane wave is incident normally from dielectric ‘1’ (μ0, ε1) onto dielectric ‘2’ (μ0, ε2) the electric field of the transmitted wave is 2 times the electric field of the reflected wave. The ratio ε2/ε1 is
For an elliptically polarized wave incident on the interface of a dielectric at the Brewster angle the reflected wave will be
A rectangular waveguide (2.29 x 1.02) cm operates at a freq. of 11 GHz in TE10 mode. If the maximum potential gradient of the signal is 5 kV/cm, then the maximum power handling capacity of the waveguide will be