127. A folded-di gole antenna used with television receivers has a terminal impedance of___ohms at its resonance frequency.
A.75
B.300
C.50
D.150
128. In any transmitting antenna system, efficiency primarily depends upon
A. ohmic losses of various conductors
B. radiation resistance
C. ground conductivity
D. atmospheric conditions
129. The demodulation of the sound signals in a TV receiver is accomplished by
A. linear detector
B. product detector
C. discriminator
D. envelope detector
130. The service area of a TV transmitter for satisfactory reception is determined by ? zone.
A. line-of-sight
B. diffi-action
C. tropospheric
D. regional tropospheric
131. The service range of a TV transmitter is determined by the height
A. of the transmitting aerial
B. of the transmitting and that 'receiving antenna
C. of the transmitting and that receiving antenna and power transmitter
D. and gain of the transitting and receiving antenna and power of the transmitter
132. The function of the serrations in the composition video waveform is to
A. equalize the charge in the integrator before the start of vertical retrace
B. help veritcal synchronization
C. hele horizontal synchronization
D. simplify the generation of the vertical sync pulse
133. The gain of a simple half-wave dipole over an isotropic radiator is of the order of ?dB.
A.2
B.6
C.7
D.8
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