True-Time-Delay Mechanical Phase Shifter in Gap Waveguide Technology for Slotted Waveguide Arrays in Ka-Band

Abstract

This paper proposes a novel all-metal mechanical phase shifter in gap waveguide technology. The phase shifter is aimed at providing beam-scanning capabilities to conventional slot array antennas along the elevation plane. To validate experimentally the beam-steering functionality, a 4×8 slot-array antenna has been designed and fabricated, along with the phaseshifting mechanism. The whole antenna consists of two pieces: a lower rotatable block, which changes the length of concentric Groove Gap Waveguides, and an upper fixed block, where the slot-array antenna is placed. Experimental results validate the proposed concept, having obtained steering angles of up to 25 • , with gain levels around 20 dBi with an antenna efficiency close to 90%. A reflection coefficient below −10 dB is achieved for a wide range of rotation angles from 29.5 GHz to 30.5 GHz. The proposed phase shifter is completely scalable to any array size and its true-time-delay nature enables wide steering ranges for closely-spaced slot arrays with wideband radiation performance.

Low-Loss Mechanically Tunable Resonator and Phase Shifters in Groove Gap Waveguide Technology

“…Despite achieving literally unlimited phase shift, high powerhandling, and relatively low insertion loss, the proposed phase shifter in the previous section (as well as those presented in [11], [12]) have an important practical limitation. In the presented structures, the input or output port is mounted on a moving conductive plate.…”

“…Therefore, the overall path of the guided wave, and thereby the phase of the transmitted wave from Port 1 to Port 2 is changed. It is very important to note that in contrast to the phase shifters presented in [11], [12], in this configuration both input and output ports are stationary, thus no need for flexible cables or expensive rotary joints. It is also worth highlighting that, in this structure, when the middle plate is displaced for a distance x, the variation of the waveguide's length l is twice that, i.e., l = 2 x.…”

“…This is because changing the length of a waveguide to achieve a mechanically tunable resonator or phase shifter, while a theoretically trivial method, its practical implementation is not as trivial, and may result in the leak of EM power from the structure and need for a movable output port. To address this issue, recently an array of mechanical phase shifters based on changes in the length of a vertical GGWG has been proposed in [11] and [12]. However, the work is thoroughly focused on the realization of an array of phase shifters for feeding a waveguide slot array antenna, resulting in the following limitations and complexities: 1) To achieve a phase shift, the lower metallic surface and as a result, the input feed port needs to be rotatable.…”

A Review on Improved Design Techniques for High Performance Planar Waveguide Slot Arrays

“…Such antennas are good candidates for mm-wave bands because of their several important advantages compared with antennas with linear polarization, such as combating multipath interferences or fading, no strict orientation requirement between transmitting and receiving radiators and polarization mismatch reduction. Additionally, dual band (with two non-adjacent working bands) [66,67] and dual linear polarization WSAs [66,68] are interesting candidates for 5G applications, which also call for wideband [69][70][71][72], high-gain [73][74][75] and beam-steerable [76,77] antennas.…”

Near Field Sensing Applications with Tunable Beam Millimeter Wave Antenna Sensors in an All-in-One Chip Design

“…Alternatively, LC circuits [37], phase shifters [38,39], and phase shifters with diodes can be used to achieve beam angle switching [40][41][42][43]. The main beam can be mechanically steered using hardware devices such as motors or drivers with control software [44] to steer the radiation field pattern emitted by the guided antenna.…”