Millimeter-Wave Antenna of a Travelling-Wave Long Sinusoidal Slot in the Narrow Face of a Rectangular Waveguide

Abstract

A travelling-wave long sinusoidal slot in the narrow face of a millimeter-wave (Ka-Band) rectangular waveguide is investigated. To the best of our knowledge, a slot of this shape is applied to the narrow face of a rectangular waveguide for the first time at this frequency range. The analytical study is based on the magnetic current model. Experimentally, far-field and S-parameters are measured and a good match is obtained between analytical and measured patterns. Frequency scan rates and velocity ratios of the structure are calculated. The effect of the sinusoidal slot's geometrical parameters (amplitude, period and number of periods) on the radiation patterns is also investigated. The drawback of the sinusoidal radiator is its cross-polarized beam that is not convenient for antenna applications. These co and cross-polarized beams scan in two different angle regions. To filter/suppress the cross-polarized beam, a grid polarizer is mounted to the sinusoidal slot and a 15 dB suppression level is reached. S-parameters measurement shows that the antenna efficiency increases remarkably after the application of the grid polarizer to the slot.

A travelling-wave antenna with continuous linear slot in the narrow face of a Ka-band rectangular waveguide and its comparison with the sinusoidal slot

“…Some results were also compared with those of the transversal field component (E ∅ ) of the SSWA, which was investigated in a previous study [10]. Some results were also compared with those of the transversal field component (E ∅ ) of the SSWA, which was investigated in a previous study [10].…”

“…The radiated far-zone fields of a travelling wave linear slot in a narrow face of a rectangular waveguide will be formulated as given in [10]. Formulation starts with definition of a fictitious magnetic current ⃗ I m in the slot [4,5].…”

“…Some of the results will also be compared to the E ϕ beam results of the SSWA 2 [10], which can be seen in Figure 7. Some of the results will also be compared to the E ϕ beam results of the SSWA 2 [10], which can be seen in Figure 7.…”

“…The calibration steps of the VNA for slotted waveguide antennas are as follows. The calculation method is as described in [10]. Then the VNA was fully calibrated.…”

“…Another interesting topic that is investigated in this paper is a comparison of the linear slot to another one: a sinusoidal slot, which was investigated in a previous study by the author [10]. In that paper it was shown that the sinusoidal slotted waveguide antenna (SSWA) has 2 beams, which are in 2 different polarizations.…”