Corner reflector antenna

Physical design

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. The spacing of the rods D should not be more than 0.06 (6%) of the wavelength. The angle θ between the sides is most commonly 90°. 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.

The spacing (S) of the driven element in front of the point where the reflectors meet is approximately but is not very critical; for 90° antennas the gain doesn't vary more than 1.5 dB for S between and . The radiation resistance of the dipole increases with this spacing, so the spacing can be adjusted to match the driven element to the feed line. Bowtie driven elements are often used for wide bandwidth applications like television antennas.

The antenna can be regarded as a form of directive antenna with a gain intermediate between a plane reflective array antenna and a parabolic antenna. Corner reflector antennas are particularly suitable in applications where a broadband directional antenna around one to wavelengths in size is needed. A parabolic dish this size has no advantage in gain over the corner reflector, so its simplicity of design and construction make it attractive.

Variations

Several different variations of the antenna are used

• The single driven element can be replaced by a Yagi array. UHF Yagi television antennas very often use a corner reflector. These antennas actually function more like two separate antennas: the corner reflector and driven element serves to provide broad bandwidth gain at the lower end of the UHF band, while the Yagi array is cut to give extra gain at the high end of the band.
• Monopole versions for use at lower frequencies have been built by placing vertical reflecting screens behind a vertical monopole antenna.

References

References

1. Kraus, John D., US patent 2270314, [https://patents.google.com/patent/US2270314 Corner reflector antenna], filed January 31, 1940; granted January 20, 1942.