An Ultra-Wideband 45° Linearly Polarized Tightly Coupled Antenna Without Collector Loading

This paper proposes a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$45^{\circ}$</tex> linear polarization tightly coupled array antenna with an operating frequency covering <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{S}$</tex> to Ku bands. By improving the antenna shape, no collector resistor loading is achieved while eliminating the common mode resonance in the band. The VSWR of this antenna element is less than 2.5 in most frequency bands of the working bandwidth. The tightly coupled structure between adjacent elements effectively offsets the inductance brought by the floor to expand the antenna bandwidth, and the horizontally placed square resistance film effectively suppresses the resonance point in the frequency band. Finally, an <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$8\times 8$</tex> antenna array is designed, which has VSWR <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$&lt; 3$</tex> in the entire frequency range except for a few edge elements, and a VSWR <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$&lt; 3.5$</tex> when scanning to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$45^{\circ}$</tex>.