Ka-Band $4 \times 4$ Butler Matrix-Based Switched Beamformer Supporting Uniform Eirp Beams in Single-/Dual-Port Excitations

This paper presents a Ka-band <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$4 \times 4$</tex> Butler matrix-based switched beamformer supporting uniform EIRP beams in single-/dual-port excitations. The switched beamformer is composed of a reconfigurable switched beamforming network based on a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$4 \times 4$</tex> Butler matrix which can generate total 7 beams, and bi-directional transmit-receive (TRX) channels with attenuators. The switched beamformer can support uniform EIRP beams in all possible modes by equalizing magnitudes at each antenna port in the dual-port excitation mode. Measured gain and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{O P}_{1 d B} /$</tex> element in TX mode are <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{3 0 d B}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{1 3. 6}$</tex> dBm, respectively. In RX mode, measured electronic gain and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{I P}_{1 d B}$</tex> /element are <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{4} \mathbf{d B}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$-\mathbf{2 2} \mathbf{d B m}$</tex>, respectively, and the noise figure is below 7 dB at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$27.8-31.5 \text{GHz}$</tex>. To our knowledge, this is the first <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$4 \times 1$</tex> switched beamformer addressing the issue of non-uniform magnitudes in the dual-port excitation mode.