Rhombic antenna

A Rhombusantenne is a diamond-shaped directional antenna. It was invented in the 1940s by Edmond Bruce and Harald Friis.

This type of antenna usually requires a lot of construction area, but offers due to its simple construction, high efficiency, since the transmission energy is emitted in a relatively flat and narrow leg. The Rhombusantennen come mainly in the frequency range of the shortwave used.

Construction

Rhombusantennen differ in two variants. The open end version, which radiates bidirectionally, and the closed variant more frequently used, which radiates unidirectional and at the end requires a terminating resistor.

The antenna basically consists of two symmetric fed horizontally extending wires are spread, and combined again. The arm length should be at about three times the longest wavelength. The height is about half a wavelength above ground. Instead of a terminating resistor, however, a so-called absorption line of resistance wire can be used with a minimum of 6 times the wavelength, at the end of a sip resistor is connected.

The transmitter power is supplied mostly with an open strip line that represents the best solution for Rhombusantennen because they can be built with an impedance of 600 ohms, which corresponds approximately to that of the antenna.