58201. Antenna efficiency of antenna is, if radiation resistance is 370 Ω and loss resistance is 100 Ω

58202. At a particular time it is observed that the frequencies of F layer at Delhi is 3 MHz the maximum electron density is

58203. The effective length of an λ/2 antenna (Given Rr = 73 Ω and (Ae)max = 0.13 λ2 and η = 120 p is __________ .

58204. Calculate cut off frequency for dominant mode in rectangular waveguide if dimensions are a = 2, b = 1 cm.

58205. The input impedance for a half dipole if radii of both the antenna is 4 and 8 meter respectively

58206. A rectangular waveguide measures 3 x 4.5 cm internally and has a 10 GHz signal propagated in it. Calculate the guide wavelength for dominant mode.

58207. A rectangular waveguide measures 3 x 4.5 cm internally and has a 10 GHz signal propagated in it. Calculate the cut off frequency for dominant mode.

58208. Find the flux crossing the plane surface defined by 0.5 ≤ r ≤ 3.5 m and 0 ≤ z ≤ 3 m. if

58209. An isolated sphere in air has a radius equal to meter, its capacitance is

58210. Find cut off wavelength for mode TE11 in a circular waveguide having radius 2 cm. Assume K'a = 1.841

58211. The refractive index of E layer, if angle of incidence is 30°

58212. The sinusoidally time varying vector field
is

58213. A transmission line having 50 Ω impedance is terminated in a load of (40 + j 30) Ω. The VSWR is

58214. Distilled water at 25°C is characterized by σ = 1.7 x 10-4 mho/m and ε = 78 ε0 at a frequency of 3 GHz. Its loss tangent is (ε = 10-9/36p F/m)

58215. The input impedance of short-circuited line of length l where l < λ/4

58216. If the height of transmitting and receiving antenna in a LOS system are 49 meter and a 9 meter respectively then the distance up to which communication may be possible is about

58217. In a line VSWR of a load is 6 dB. The reflection coefficient will be

58218. The refractive index of E layer at frequency of 81 N

58219. ∇ . = 0 is frequently known as

58220. A rhombic antenna is a

58221. Which of the following relations is valid?

58222. Diffraction of electromagnetic waves

58223. The magnetic field intensity vector of a plane wave is given by (x, y, z, t) = 10 sin (5000t + 0.004x + 30 ), where denotes unit vector in y direction the wave is propagating with a phase velocity.

58224. A line of characteristic impedance z0 ohms, phase velocity VP = 2 x 108 m/sec and length l = 2 m is terminated by a load impedance zL Ohms. The reflection coefficients at the input end and load end are respectively for a frequency of 50 MHz will be

58225. When a particular mode is excited in a waveguide, these appears an extra electric components in the direction of propagation. The resulting mode is

58226. An antenna has a gain of 44 dB. Assuming that the main beam of the antenna is circular in cross-section the beamwidth will be

58227. Fill up the blanks using suitable alternative: Since 1986, there ......... no earthquakes here?

58228. In cellphone communication base antennas are connected to other base antennas in

58229. The I/P impedance of a long short circuited section of a loss less transmission line is

58230. Which of the following relations is correct?

58231. For frequencies upto 1650 kHz __________ antenna is used

58232. Due to which of the following reasons, the ground wave eventually disappears, as one moves away from the transmitter?

58233. A loop antenna may be of

58234. Velocity of the wave when it passes from air into sphere

58235. The ratio of the directivity of an end fire antenna to that of a broadside antenna is

58236. If the electric field intensity associated with a uniform plane electromagnetic wave travelling in a perfect dielectric medium is given by
E(z, t) = 10 cos (2p x 107t - 0.1 p z) volt/metre, then the velocity of the travelling wave is

58237. The absorption of radio waves by atmosphere depends on

58238. For transmission-line matching over range of frequencies, it is best to use a

58239. Microwave signals transmitted towards the sky are

58240. Radiation intensity does not depend upon

58241. Δ2V = - r /E is known as __________ equation

58242. A vertical earthed antenna is resonant when its physical height is equal to

58243. Which of the following is a vector quantity?

58244. The L/C has the dimension of

58245. The value of VSWR is taken as ∞ when the line is

58246. The wavelength of an electromagnetic wave after reflection at angle on a surface

58247. A higher value of Standing Wave Ratio indicates

58248. An end fire array consisting of several half-wave lengths of directive gain 40, then Find width of major lobe for broadside

58249. A wavelength of 1 mm could be expected in

58250. The numerical value of directivity of current element of half-wave dipole is 1.76 and 2.15 dB respectively. The directive gain of half-wave dipole over current element will be