Abstract
A new $1\times $ 4 phase distribution network (PDN) featuring a fully controllable progressive phase shift between outputs is proposed for continuous beam-scanning arrays. The PDN is made up of two parts: a modified $2\times $ 4 Butler matrix integrated with four phase shifters (PSs), and a tunable power divider (TPD) whose power division ratio can be controlled over a wide tuning range. The synthesis equations show that the relative phase shift between PDN outputs can be fully controlled by the TPD and embedded PSs without using an external single-pole quad-throw (SP4T) switch. The proposed PDN is demonstrated at 2.4 GHz as the feed network of a 4-element linear array. The experimental results display a fully controllable progressive phase shift (from −180° to 180°) between PDN outputs over a 20% bandwidth with good performance of matching, power division, and relative phase shifts. A spatial coverage of 116° with the feature of continuous beam scanning and negligible dc power consumption is achieved. Benefitting from the single-input topology, a planar 16-element phased array for 2D beam scanning is then realized by simply stacking and cascading five instead of eight PDN modules. It removes the high-cost and bulky SP16T switch. Experimental results demonstrate the uniqueness of the proposed designs.
Highlights
Beam-forming networks (BFNs), an essential part in beam switching and beam scanning phased arrays, have become the core subsystem in fifth-generation (5G) communication systems and beyond [1]
The experimental validation starts from the circuit responses (S-parameters), followed by the radiation patterns of a 4-element linear quasi-Yagi array fed by the phase distribution network (PDN)
The measured input and output return losses are better than 11 dB while an average transmission coefficient of -10 dB, indicating a 4 dB extra loss sourced by the PDN, is observed over a 20% FBW (2.16 – 2.64 GHz)
Summary
Beam-forming networks (BFNs), an essential part in beam switching and beam scanning phased arrays, have become the core subsystem in fifth-generation (5G) communication systems and beyond [1]. Better spatial resolution with a low beam-cross level is achieved to fulfill seamless coverage From another point of view, the Nth-order Butler matrix still requires an additional single-pole multiple-throw (SPNT) switch to select the excitation port from the common input. A cascade connection of two 90° PSs presented in Sec. III.A is adopted to fulfill PSx and PSy. The measured responses show a good matching (|S11| -10 dB) with an average insertion loss of 1.7 dB and a phase error less than 16° over the bandwidth from 2.1–2.7 GHz. The experimental validation starts from the circuit responses (S-parameters), followed by the radiation patterns of a 4-element linear quasi-Yagi array fed by the PDN.
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