Employing irises and septums to excite the centreline longitudinal slot antennas

Abstract

A suitable method is introduced to excite the centreline longitudinal slot antennas. For each slot, an iris and a rectangular septum are employed at the opposite sides of the slot such that they have offset from the waveguide centreline. It is shown that to form a high performance slotted array antenna consists of the centreline longitudinal antennas, employing antenna elements where each of them is excited only by an iris or a septum is not advisable. So, employing an iris and a septum all together is proposed to excite the centreline longitudinal slot antennas. This enables one to have a better control over the characteristics of the proposed slot antennas. The performed study indicates that the proposed slot antennas can be modelled as a shunt admittance on a transmission line. In order to demonstrate the effectiveness of the proposed slot antennas, a two-by-three planar array is designed, constructed and tested. The efficacy of the proposed slot antennas is verified by the simulation and the measurement results. K E Y W O R D S butterfly lobes, centreline longitudinal slots, computer-aided design, iris excited centreline longitudinal slot antenna, septum excited centreline longitudinal slot antenna, slot antennas

Employing the dumbbell-shaped longitudinal slot antennas in the planar slotted antenna arrays

“…It has been found that in the proposed dumbbell-shaped slot antennas, the septum length depends on the iris depth. To derive the appropriate septum length versus the iris depth, the procedure which has been offered in [49] was followed. Figure 2 shows the applicable septum length versus the iris depth.…”

“…First, two standing wave slotted arrays consist of four waveguides and each waveguide contains four slots that have been designed and simulated. For the first array, all the antenna elements are centerline round-ended slots [49]. For the second array, the radiated elements are the proposed dumbbell-shaped slot antennas.…”

“…For designing the arrays, the equivalent normalized self-admittance of the isolated slots (for both round-ended and dumbbell-shaped) must be known for every combination of the slot length and iris depth. For the round-ended slot, some universal curves have been derived that enable one to easily find the equivalent normalized self-admittance of the isolated slots [49]. Similarly, For the dumbbell-shaped slot antennas, it has been found that the equivalent normalized self-admittance of the isolated slots can be represented by some universal curves.…”

“…For designing the arrays, the equivalent normalized self-admittance of the isolated slots (for both round-ended and dumbbell-shaped) must be known for every combination of the slot length and iris depth. For the round-ended slot, some universal curves have been derived that enable one to easily find the equivalent normalized self-admittance of the isolated slots [49].…”

“…1) has been employed while the slot length and the iris depth in the model were swept from 17 to 23.5 mm and 2 to 10 mm, respectively. Then, the equivalent normalized shunt admittances, the resonant length, and resonant conductance of the dumbbell-shaped slot antennas for every combination of the slot lengths and iris depths were derived [49]. Figure 10 shows the resonant length times the free space wavenumber versus the iris depth.…”