Acorner reflector antenna is a type ofdirectional antenna used atVHF andUHF frequencies.[1][2] It was invented byJohn D. Kraus in 1938.[3][4] It consists of adipoledriven element mounted in front of two flat rectangular reflecting screens joined at an angle, usually 90°.[1] Corner reflector antennas have moderategain of 10–15 dB,[2] highfront-to-back ratio of 20–30 dB, and widebandwidth.
Corner reflector antennas are widely used for UHFtelevision receiving antennas,point-to-point communication links and data links forwireless WANs, andamateur radio antennas on the 144, 420, and 1296 MHz bands.[2] They radiatelinearly polarized radio waves and can be mounted for either horizontal or vertical polarization.
The corner reflectorantenna should not be confused with acorner reflector, a passive device used to reflect radio waves back toward the source.
The flat reflecting surfaces can be metal sheets, but are more often made of wire screen or rod elements parallel to the driven element, to reduce weight and wind loads on the antenna.[2] The spacing of the rodsD should not be more than 0.06 (6%) of thewavelength. The angleθ between the sides is most commonly 90°.[1] The gain increases as the angle narrows, but the increase below 90° is minimal, and requires longer reflector screens be used. However, angles down to 45° have been used.[2]
The spacing(S) of the driven element in front of the point where the reflectors meet is approximately0.5 λ but is not very critical; for 90° antennas the gain doesn't vary more than 1.5 dB forS between0.25 λ and0.75 λ.[1][2] Theradiation resistance of the dipole increases with this spacing, so the spacing can be adjusted to match the driven element to the feed line.[2] Bowtie driven elements are often used for wide bandwidth applications like television antennas.[1]
The antenna can be regarded as a form of directive antenna with a gain intermediate between a planereflective array antenna and aparabolic antenna. Corner reflector antennas are particularly suitable in applications where a broadband directional antenna around one to1+1⁄2 wavelengths in size is needed.[5] A parabolic dish this size has no advantage in gain over the corner reflector, so its simplicity of design and construction make it attractive.
Several different variations of the antenna are used
