Design of a new low-cost miniaturized 5.8GHz microwave motion sensor

Abstract

The designed low-cost 5.8GHz microwave motion sensor uses a new type of non-isolated branch bridge as the distribution of the transmit signal, local oscillator signal, and receive signal. The bridge is terminated with a pair of reverse configuration diodes to complete balanced mixing. The antenna of the sensor is a shared microstrip patch antenna for receiving and sending. The local oscillator signal and the transmission signal come from the same oscillator. Except for the non-isolated bridge, the distribution of the local oscillator and the transmission does not require an additional power distribution network. The antenna port and oscillator port of the bridge are non-isolated ports, and the two ports connected to the diode are isolated. The new electric bridge has good symmetry and maintains the balance of the traditional electric bridge mixer. The volume of the microwave motion sensor using this new type of bridge mixer is only 18mm*20mm*1.5mm.