Switchable T-Slot for Dual-Circularly-Polarized Slot-Array Antennas in Ka-Band

Abstract

This paper presents two slotted array antennas working in the Ka-band with switchable circular polarization capability. The first prototype is a series-fed slotted-waveguide linear array composed of ten T-shaped slots. The second antenna is a two-dimensional array with 2×2 T-shaped slots fed by a corporate distribution network. In both cases, a reflection coefficient below −10 dB has been experimentally observed within the targeted frequency band between 29.5 and 30.5 GHz. Good polarization purity is achieved for both polarization senses and in both prototypes. The fundamental contribution of the paper is to propose a simple mechanism to switch the circular polarization sense in a low-cost, low-profile and high-efficient antenna. The design and experimental results confirm that the solution is suitable for both one-and two-dimensional arrays in the millimeter-wave band.

Cost-Effective Design of Polarization and Bandwidth Reconfigurable Millimeter-Wave Loop Antenna

“…In addition, the proposed antenna offers three polarization modes compared to two in [ 12 ], employs a simple switching mechanism compared to that utilized in [ 13 ], and needs only two PIN diodes compared to four in [ 14 ]. On the other hand, the studies in [ 15 , 16 , 17 , 18 ] are focused on polarization reconfigurable mmWave arrays, which naturally require a more complex design in terms of feed network and switching mechanisms for many antennas. However, the presented single-loop antenna offers wider impedance and CP bandwidths than those reported in [ 15 , 16 , 17 ] and a slightly narrower impedance bandwidth compared to [ 18 ].…”

“…Prototypes of polarization reconfigurable mmWave antennas have been reported in several studies [ 12 , 13 , 14 , 15 , 16 , 17 , 18 ]. For example, a K-band polarization reconfigurable patch antenna has been proposed in a layered structure using RF-MEMS to switch between two polarization modes, LHCP and LP, over impedance bandwidths of 11.8% and 3%, respectively, with a peak gain of ~3.9 dBic [ 12 ].…”

“…On the other hand, a 2 × 2 mmWave polarization reconfigurable patch antenna array has been reported by utilizing two PIN-diode pairs to switch between dual CP modes with respective impedance and AR bandwidths of 11% and 4% with an efficiency of 51% [ 15 ]. Besides, linear, and square arrays with 10 and 2 × 2 T-shaped slot elements have been reported with respective impedance bandwidths of 3.3% and 10%, where two mechanically switchable CP senses have been achieved over an AR bandwidth of 3% for both arrays [ 16 ]. Similarly, full polarization reconfigurability has been achieved using a phased array of 8 × 12 Butterfly elements with 4 feeding ports that switch the polarization by utilizing the required excitation amplitude and phase [ 17 ].…”

“…In addition, a figure of merit was introduced and used to compare the performance to those in earlier studies. However, in [ 15 , 16 , 17 , 18 ], polarization reconfigurability has been achieved by utilizing a substantial number of elements in conjunction with customized feeding networks that naturally increase the cost and complexity compared to a single antenna configuration.…”

Single-Layer Sequential Rotation Network in Gap Waveguide for a Wideband Low-Profile Circularly Polarized Array Antenna

“…For example, metallic waveguides using crossed [3], [4], inclined [5], [6], Y-shaped [7], T-shaped [8], [9], ringshaped [10] or L-shaped slots [11], [12] are some of the options commonly used to achieve the 90 • phase shift be-FIGURE 1: Fabricated antenna with each of the layers that make it up slipped. tween the two orthogonal polarizations.…”