Wire grid antenna

Image of the Wire grid antenna.

The wire-grid array was first described by Kraus back in the 1960's as a Backward Angle-Fire Array Antenna consisting of a grid situated parallel and close to a flat conducting sheet or ground plane. When fed at the centre the antenna radiates broadside, but by feeding the grid at an edge and adjusting the dimensions of the grid cells, a squint from broadside can be achieved. Though various authors have discussed this antenna (the wire-grid as well as a microstrip version of the topology) there is still some confusion around the operation mechanism of the antenna. When the grid is located a fair distance from the ground plane (around a quarter of a wavelength) the antenna may be compared to an array of dipole elements above a ground plane, with the cell-dimensions chosen such that the array elements are resonant at the operating frequency and correctly phased to achieve the desired radiation characteristics.

By adjusting the cell dimensions and the height of the array above the ground plane one can achieve high gain over a moderate band with beam-steering possibilities as-well as a degree of impedance control. This usually requires a complex feed structure but can also be achieved by using this very simple structure.