72151. For transmission of waveform a dielectric medium of permittivity ε1 into a dielectric medium of lower permittivity ε2 , (ε1 > ε2) the critical angle of incidence θc (relative to the interface) is given by
72152. The line of sight communication requires that transmit and receive antennas to face each other. If the transmit antenna is vertically polarized, for the best reception the receive antenna should be
72153. An antenna has 40 Ω resistance and 60 Ω radiation resistance. The efficiency of the antenna is
72154. The duration of sunspot cycle is
72155. Electromagnetic cavity resonators (energy storage devices) are used in
72156. Waveguides are generally used above
72157. Maximum power transfer will take place in a practical antenna if (XL = Load Reactance, XA Antenna Reactance)
72158. Which type of fading causes serious distortion of modulated signal?
72159. Tropospheric scatter is used with frequencies in the
72160. A Yagi antenna has a driven antenna
72161. The minimum height of outer atmosphere is
72162. 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
72163. A square corner reflector is used in
72164. The wave in wave guide has
72165. While determining antenna height for terrestrial microwaves links, the effect of refraction from the atmosphere is taken care of by considering the effective curvature of the earth to be
72166. A T.V. station works at 300 MHz and radiates 100 kW of power. This signal received at a distance of 200 km will be
72167. The power gain of a half-wave dipole with respect to an isotropic radiator is
72168. In an impedance smith chart, a clockwise movement along a constant resistance circle gives rise to
72169. When the phase velocity of an EM wave depends on frequency in any medium the phenomenon is called
72170. The main disadvantage of the two-hole directional coupler is
72171. The radiation pattern of a parabola antenna is
72172. In microwave communication links, when fading due to rain attenuation occurs then technique adopted for solving the problem would include
72173. Due to which of the following reasons a lightning conductor on top of a building is made into a pointed spike?
72174. The virtual height of an ionospheric layer is __________ true height
72175. The divergence of a vector is a scalar, while the curl of a vector is another
72176. An open wire transmission line having a characteristic impedance of 600 ohms is terminated by a resistive load of 900 Ω. The standing wave ratio will be
72177. The skip distance is the maximum distance upto which ionospheric reflection is possible.
72178. Maxwell's divergence equation for the magnetic field is given as
72179. Which antenna is a wideband antenna?
72180. The radiation pattern of loop antenna is
72181. Maxwell's curl equation for the static electric field E can be expressed as
72182. The unit of ∇ x H is
72183. The relative permittivity of the ionosphere at ratio frequencies is
72184. Tropospheric scatter propagation is not subject to any fading.
72185. The attenuation in waveguide above to cut off frequency
72186. VSWR is related with reflection co-efficient as
72187. When a current carrying conductor is brought into magnetic field, the force that moves the conductor depends upon
72188. A square corner reflector is used in which of the following?
72189. The moment of inertia of a triangular section with base ‘b’ and height’h’about an axis through the centre of gravity and parallel to the base is given as
72190. If the resultant of two forces has the same magnitude as either of the forces,then the angle between the forces is
72191. The direction of vectors gives the direction of propagation of electromagnetic waves
72192. According to maximum power transfer theorem, the maximum power is absorbed by one network from another network when
72193. A medium is divided into regions I and II about x = 0 plane, as shown in the figure below. An EM wave with electric field is incident normally on the interface from region-I. The electric field E2 in region-II at the interface is
72194. The static electric field in a conductor is
72195. The propagation constant of a transmission line is
72196. In a perfect conductor the incident and reflected wave combine to produce
72197. MUF is highest in periods of greatest sunspot activity.
72198. A transmission line has primary constants R, L, G and C and secondary constant z0 and γ = (a + Jβ). If the line is loss less, then
72199. Which of the following is multiband HF receiving antenna?
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