Field distribution and radiation field of finite axial slots on circular waveguides

The field distribution on a finite axial slot is determined from that of a semi-infinite axial slot, using a multiple reflection technique. It involves enforcing the continuity of the transverse field components, at the common boundaries between the solid and the slotted sections of the waveguides, to determine the mode coefficients of reflected and transmitted waves. The steps for determining these coefficients are similar to the case of a semi-infinite axial slot, but are repeated at both slot ends to express the slot field in terms of higher-order reflections. For practical waveguides, of radius a > 0.35 ¿¿, only the first-order reflections are significant and are used to compute the slot field for various slot parameters. Using the known slot fields, the radiation fields of a single slot and an array of axial slots are also determined.