ZL = 200 Ω and it is desired that Zi = 50 Ω The quarter wave transformer should have a characteristic impedance of
Z0 = Zi . ZL
A broadside array consisting of 200 cm wavelength with 10 half-wave dipole spacing 10 cm. And if each array element feeding with 1 amp. current and operating at same frequency then find the half power beamwidth
A broadside array operating at 100 cm wavelength consist of 4 half-wave dipoles spaced 50 cm apart. Each element carries radio frequency current in the same phase and of magnitude 0.5 A. The radiated power will be
P = n . I2 . Rr, where Rr = 80p2 Ω.
n = 4.
Refractive index of glass is 1.5. Find the wavelength of a beam of light with a frequency of 1014 Hz in glass. Assume velocity of light is 3 x 108 m/sec in vacuum.
Given, μ = 1.6, f = 1014 Hz, v = 3 x 108 m/sec.
The function f(x - vot) represent which of the following?
f(x - vot) represents in +ve direction while f(x + vot) represents a progressive wave in -ve direction.
The input impedance of short-circuited line of length l where λ/4 < l < λ/2, is
l < λ/4, ZL = 0
, if Zd comes +j kZC then inductive,
If Zd comes -j kZC then capacitive.
for 0 ≤ l ≤ 1/4, λ ≤ l ≤ 3λ/4 will be inductive.
A wave is propagated in a waveguide at frequency of 9 GHz and separation is 2 cm between walls find cut off wavelength for dominant mode.
Find the radiation resistance of an antenna of length λ/10 meter?
Charge needed within a unit sphere centred at the origin for producing a potential field,
q = 120p coulomb, r = 1 meter.
A rectangular metal waveguide filled with a dielectric of relative permittivity εr = 4, has the inside dimensions 3 x 1.2 cm, the cut off frequency for the dominant mode is
for dominant mode.
A wave is propagated in a waveguide at frequency of 9 GHz and separation is 2 cm between walls Calculate group velocity for dominant mode.
Vg . Vp = C2
For F1 layer the maximum ionic density is 2.3 x 104 electrons per cc. The critical frequency for this layer will be
fc = 9Nmax .
Which one of the following does represents the electric field lines for the TE02 mode in the cross section of a hollow rectangular metallic waveguide?
TE02 m = 0, n = 2
in x direction no propagation, only in y, and normal to the waveguide, tangential component is continuous.
The velocity of electromagnetic wave in a good conductor is
, for good conductor εr >> 1.
Radiation intensity of a dipole depends strongly on frequency. If at a frequency f, the intensity of radiation is 'I'. Then at a frequency of f/2, the intensity will be
I ∝ f.
Consider a 300 Ω, quarter wave long at 1 GHz transmission line as shown in figure. It is connected to a 10 V, 50 Ω source at one end is left open circuited at the other end. The magnitude of the voltage at the open circuit end of the line is
γ = a + jβ a = 0 γ = jβ
v = VI e-rz + VR erz
No change in the voltage at the open end it will same,
vr = 10 volt.
The phase angle corresponding to λ/4 in a standing-wave pattern is
A hollow rectangular waveguide has dimensions a = 2b. Calculate the amount of attenuation, if the frequency is 3 GHz, and b = 1 cm.
Since, wave is attenuated hence β = 0
and Take, dominant mode m = 1,
n = 0
Calculate the directivity of an antenna for θE = 30º, θH = 60
Most antenna consisting of a 50 meter long vertical conductor operates over a perfectly conducting ground plane. It is base fed at a frequency of 600 kHz. The radiation resistance of the antenna in ohms 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
ZL = 75 - J . 40, ZC = 75 W, f = 6 mHz
Given ZL is capacitive, so proper matching, load must be inductive.
A plane wave is characterized by the wave is
Because, magnitude is different (0.5, 1) and phase is 90º
The electric field on the surface of a perfect conductor is 2V/m. The conductor is immersed in water with ε = 80 ε0. The surface charge density on the conductor is ((ε0 = 10-9/36p)F/m)
A wave is propagated in a waveguide at frequency of 9 GHz and separation is 2 cm between walls calculate the phase velocity for dominant mode.
Vg . Vp = C2
A plane electromagnetic wave travels in dielectric medium of relative permittivity 9. Relative to free space, the velocity of propagation in the dielectric is