Correct Answer - Option 1 : Automobiles, spacecraft
correct option is 1
Concept:
Wire Antennas:
Short Dipole Antenna
Dipole Antenna
Loop Antenna
Monopole Antenna
In automobiles, for nondirectional radio communication on the surface of the earth, where the direction to the transmitter or the receiver is constantly changing we use vertical whip antennas. the whip antenna is a monopole antenna. (option 1 is correct)
For very high gain applications we use yagi-uda antenna, microstrip patch array, aperture array, slotted waveguide array. (option 3 is incorrect)
A horn antenna or microwave horn is an antenna that consists of a flaring metal waveguide shaped like a horn to direct radio waves in a beam. Horns are widely used as antennas at UHF (ultra-high frequency) and microwave frequencies, above 300 MHz. (option 4 is incorrect)
Military aircraft and missiles are the largest application of conformal antennas. (option 4 is incorrect)
