An investigation of slot radiators in rectangular metal plates

The radiation from slots cut in conducting surfaces of limited extent is discussed. Equatorial plane patterns of an axial half-wave slot in a rectangular metal plate are measured in the X band. The experimental results compare favourably with the calculated patterns on the assumption that the plate can be represented by a thin elliptic cylinder or ribbon of infinite length. It is observed that, if the length of the plate is equal to or greater than its width, the pattern is within a few per cent of the corresponding theoretical pattern for a plate of infinite length. The admittance of the slot in the plate was also measured and compared with the computed conductance. The agreement is seen to be quite good.