Bi-directionally fed phased array antenna with variable impedance phase shifter for ISM band

We propose a novel phased array antenna that is fed bi-directionally from feeding points of both ends (bi-directional phased array antenna: BiPA). The BiPA works with less phase shift than mono feeding one. We use variable impedance phase shifter (VIPS) used in the BiPA. The phase shifter consists of π-connected three variable capacitors. The directivity of the BiPA is simulated, and the calculated values are ±25° in beam angle, -11.5 dB in side lobe at 2.45 GHz with control voltage range of DC 0 to 3.5 V. The improvement to reduce the side lobe to -18.5 dB is also considered.