Low-Complexity Wideband Circularly Polarized Modular Scalable Phased Array for Vehicular Satellite Communication

This paper presents a low-complexity wideband circularly polarized (CP) array in X-band for vehicular satellite communication. The array comprises dual-polarized corner-fed patch elements for achieving wide bandwidth. The active elements are integrated in a modular manner using interposers that enables the scalability of the array and simplicity of routing RF signals, as well as dc bias and digital control lines on the array surface. The building block of the scalable array is a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2 \times 2$ </tex-math></inline-formula> subarray of dual-polarized patch elements and an interposer with an 8-channel beamformer integrated circuit mounted on it. The interposer circuit simplifies the routing of dc and digital lines on the surface of larger arrays, lowers the cost of fabrication, and makes the array debugging simple. To show the scalability of the design, an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8 \times 8$ </tex-math></inline-formula> array made of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$16 \; 2 \times 2$ </tex-math></inline-formula> arrays is designed, fabricated, and tested both in free space and the presence of a laminated moonroof glass. The array exhibits a minimum measured realized CP gain of 26.7 dBi and 25.8 dBi over the band 10.7–12.7 GHz in free space and the presence of the laminated glass, respectively. The array beam is steerable over the range of ±40° in all directions, both in free space and in the presence of a laminated moonroof glass. Remarkably, the array is shown to maintain its high gain, bandwidth, axial ratio, and scan range when operated behind laminated moonroof glass, making it suitable for its installation inside vehicles for satellite communication without necessitating any alterations to the array or the vehicle’s exterior design.