Question

Broadcasting antennas are generally
A. Vertical type
B. Both vertical and horizontal type
C. Omni directional type
D. Horizontal type

Answer 1

Hint: An antenna or aerial, used with a transmitter or receiver, is the contact between radio waves travelling across space and electric currents flowing through metal conductors. When transmitting, a radio transmitter sends an electric current to the antenna's terminals, which the antenna then emits as electromagnetic waves (radio waves). An antenna receives some of the strength of a radio wave and converts it to an electric current at its terminals, which is then transferred to a receiver to be amplified. Antennas are an important part of any radio system.

Complete step by step solution:
The antenna's job is to capture radio waves from preferred television stations and convert them into small radio frequency alternating currents that are fed into the television's tuner, which extracts the signal. The antenna is connected to the television through a transmission line, which is a specialised wire intended to transport radio current. Antennas in the past utilised a flat wire known as 300 ohm Twin Lead. Today's standard is 75 ohm coaxial wire, which is less sensitive to interference and connects into a F or Belling-Lee connection on the back of the TV (depending on area).
An omnidirectional antenna emits equal radio power in all directions perpendicular to an axis, with strength changing with angle to axis and decreasing to zero on axis. This radiation pattern is doughnut-shaped when graphed in three dimensions. An isotropic antenna, on the other hand, radiates the same amount of power in all directions (a spherical radiation pattern). Because vertically placed antennas emit equally in all horizontal directions and the power radiated declines down with elevation angle, little radio energy is targeted towards the sky or down toward the ground and squandered.
Therefore the correct option is (D).

Note:
The monopole antenna, which consists of a vertical rod conductor placed atop a conducting ground plane, and the vertical dipole antenna, which consists of two collinear vertical rods, are the most popular omnidirectional antenna designs. The quarter-wave monopole and half-wave dipole are both popular because they feature vertical radiation patterns that consist of a single wide lobe with greatest radiation in horizontal directions.