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The ground rods create a ground plane under the antenna which increases the gain. The ground rods may extend horizontally from the base, but in antennas fed by coaxial cable as shown here they are usually sloped downward to increase the radiation resistance of the antenna from the 36 ohms of a quarter wave monopole closer to 50 ohms, so the ...
Isotron is the trade name for a shortwave antenna marketed by Bilal Co. for use as an amateur radio transmitting antenna for restricted spaces. [1] It is physically short as compared to a dipole antenna for a given frequency. It consists of a coil placed between two angled sheet metal plates.
The J-pole antenna is an end-fed omnidirectional half-wave antenna that is matched to the feedline by a shorted quarter-wave parallel transmission line stub. [5] [1] [6] For a transmitting antenna to operate efficiently, absorbing all the power provided by its feedline, the antenna must be impedance matched to the line; it must have a resistance equal to the feedline's characteristic impedance.
The rhombic antenna is a directional wire antenna used on MF and HF bands for shortwave reception. The antenna consists of a wire suspended above the ground in the shape of a rhombus , terminated at one end by a resistor equal the the wire's characteristic impedance, about 400 to 600 ohms, and at the other end connected to the feedline to the ...
English: Diagram of a corner reflector antenna. It consists of a half wave dipole antenna mounted in front of two flat rectangular reflectors joined at an angle θ which is usually 90°. The reflector is usually made of rods parallel to the dipole element. Corner reflector antennas have gain of 12-15 dBi, high front-to-back ratio, and wide ...
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A beam waveguide antenna is a type of complicated Cassegrain antenna with a long radio wave path to allow the feed electronics to be located at ground level. It is used in very large steerable radio telescopes and satellite ground antennas, where the feed electronics are too complicated and bulky, or requires too much maintenance and alterations, to locate on the dish; for example those using ...