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Small rhombic UHF television antenna from 1952. Its broad bandwidth allowed it to cover the 470 to 890 MHz UHF television band. A rhombic antenna is made of four sections of wire suspended parallel to the ground in a diamond or "rhombus" shape. Each of the four sides is the same length – about a quarter-wavelength to one wavelength per ...
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 receiver. The rhombic is a travelling wave antenna, Each segment of the rhombus has a radiation ...
the upper half of a vertical full-wavelength loop antenna mounted on the ground (not to be confused with the visually similar but electrically different half-square antenna described below, under array antennas, [r] nor to be confused with the halo antenna, described next). The full loop is cut at two opposite points along its perimeter, and ...
The radiation patterns of a vertical half-wave dipole, an omnidirectional antenna. The horizontal and vertical polar patterns are projections of the 3 dimensional pattern onto horizontal and vertical planes, respectively. An omnidirectional antenna radiates equal signal strength in all horizontal directions, so its horizontal pattern is just a ...
The vertical plane is used to plot an antenna's relative field strength perpendicular to the ground (which directly affects a station's coverage area) on a polar graph. Normally, the maximum of 1.000 or 0 dB is at the side (unless there is beam tilt ), which is labeled 0°, to 90° at the top and −90° at the bottom.
The thick, black, vertical line is the feed cable, ending in a small black box that contains a trimmer capacitor that with the gamma arm length, impedance matches the antenna feedpoint. A halo antenna , or halo , is a center-fed 1 / 2 wavelength dipole antenna , which has been bent into a circle, with a break directly opposite the feed ...
The antenna's main lobe, its direction of greatest sensitivity, is to the right, off the end of the wire that is terminated in the resistor. The Beverage antenna consists of a horizontal wire one-half to several wavelengths long, suspended close to the ground, usually 3 to 6 m (10 to 20 feet) high, pointed in the direction of the signal source.
The Adcock antenna is an antenna array consisting of four equidistant vertical elements which can be used to transmit or receive directional radio waves. The Adcock array was invented and patented by British engineer Frank Adcock and since his August 1919 British Patent No. 130,490, the 'Adcock Aerial' has been used for a variety of ...