ANALYSIS OF AN UNTILTED WIRE-EXCITED SLOT IN THE NARROW WALL OF A RECTANGULAR WAVE-GUIDE BY INCLUDING THE ACTUAL EXTERNAL STRUCTURE

The admittance of an untilted slot in the narrow wall of a rectangular waveguide is calculated by including the actual external structure, T he slot is excited by two tilted thin wires inside the waveguide, The slot is also allowed to extend into the two broad walls of the wavegui de to make it sufficiently long for resonance to occur, The external s lot admittance is evaluated by using a spectrum of two-dimensional sol utions, a method which can handle the arbitrary cross section of the e xternal structure. The analysis predicts that if both the slot and the wires are tuned to resonance, the transmission coefficient gets const ant phase over a wide-frequency band, The results also show that reson ance can be obtained for any slot length by adjusting the wire length, and this relation between the lengths is presented. The distance betw een the slot and the wires needed to maximize the radiated power is al so shown, Some results are confirmed by measurements.