Impedance properties of X-slot array as a function of displacement on broad face of rectangular waveguide

A pair of narrow slots crossed at right angles and located at the proper point on the broad wall of a rectangular waveguide will radiate a circularly polarized wave. The impedance properties of a slotted waveguide antenna with an array of such X-type slots of arbitrary length and offset in a guide wall of finite thickness are investigated and studied. Experimental measurements were conducted to study the impedance properties of an X-type slot and its array with different angles between the arms. It is observed that the conductance presented by the X-slot and its array is much larger than that presented by the corresponding longitudinal shunt slots. In design of an array at the higher end of the passband frequencies of a rectangular waveguide using longitudinal slots, the small value of conductance presented by such a slot limits the array design. This limitation can be reduced to a great extent if X-type slots are used as the array elements in slotted waveguide antennas