Time-Modulated Antenna Array with Beam Steering Based on Single-Pole Double-Throw Switches and Four-State Phase Shifters

Beam steering in antenna arrays is usually accomplished acording to the phased array concept with phase-shifters incorporated into the feeding network. The steering resolution typically depends on the number of phase-shifter states, i.e., larger number of states enables finer resolution. For instance, a typical phased array with four-state phase-shifters provide the steering resolution of 30° only. This paper shows that beam-steering resolution as fine as 1° can be obtained even with four-states phase-shifters when the time-modulated antenna array approach in adopted. This aproach is based on periodic time modulation of the antenna array excitation signals. The time-modulated antenna array presented in this paper incorporates four-state phase shifters and single-pole double-throw switches which are used to periodically modulate the excitations. The beam-steering angle depends on the delays applied to the switch-controlling signals. The concept presented in this paper is examined by electromagnetic simulations of a sixteen-element patch antenna array.