Pin-Diode Based Low-Loss Multi-State Electrical Phase Shifter for Sub-6 GHz Base Station

This paper presents an electrical phase shifter (EPS) based on pin-diodes for adjusting the electrical tilt (e-tilt) angle of base station. The EPS is located in front of the array antenna feed at the base station and plays a role in adjusting the beam direction by changing the input phase of the antenna. The loaded type EPS has very low insertion loss and is designed to enable up to 4-states changes with wide bandwidth by using an impedance transformer and matching structure. On the other hand, the switched type EPS is designed to have a large phase change of 80° and improved bandwidth by adding radial stubs and defected ground structure (DGS). As a result, the proposed EPS was designed with low loss characteristics and capable of 6-states phase adjustment in 20° steps from 0° to 120° by combining the loaded type and switched type EPS. In addition, a test board including a bias circuit and a dip switch for controlling pin-diodes was manufactured, and measured using a vector network analyzer. To measure only the loss of EPS itself, loss compensation de-embedding was performed to exclude the connector losses. The validity of the proposed EPS was verified by confirming that the measured values matched well with the simulation results, which is expected to be widely used in base stations requiring e-tilt in the future.