An iris-excited slot radiator in the narrow wall of rectangular waveguide

The inclined, narrow-wall slot radiator has been used extensively in antenna arrays. The slot is easily machined and handles high power. The inclination of the slot, however, produces an undesirable cross-polarized radiation component. This cross polarization, coupled with the variation of the slot admittance with frequency, causes pattern deterioration and loss in array efficiency. A noninclined, narrow-wall slot radiator has been developed. This slot is excited by two compound irises which produce an inclination of the electric field as it passes the slot. The field inclination replaces the slot inclination, thereby eliminating the cross-polarized component. Although the power handling capability of the slot is limited by the iris structure, the slot has improved conductance characteristics. Variation of slot excitation in both amplitude and phase has been produced by varying the iris dimensions. The iris-excited, narrow-wall slot radiator has application to receiving and to low-power transmitting arrays.