Rattlesnake Antenna System [Education Column]

A rattlesnake antenna system (RAS), inspired by the hunting behavior of rattlesnakes, is proposed. It can automatically align the main beams of the directive antennas at both the transmitting (Tx) and receiving (Rx) sites, and then perform distant data transmission/reception. Each of the transmitting and receiving sites consists of an antenna module, an RF module, a state-control module, a motor-driver module, and a stepper motor. The functionalities, design, and assembly of these modules are detailed in this paper. The antenna module is composed of three square patch-antenna elements, and functions as a beacon antenna, two sensing antennas, and a high-gain transmitting or receiving antenna, depending on the states of the associated switches. The beacon antenna at one site, having a wider angular coverage, provides a beacon signal for the two sensing antennas at the other site. Connecting the sensing antennas to power detectors and a difference circuit, the auto-aiming subsystem can thus locate the direction of the other site, and trigger the stepper motor to rotate accordingly. After aligning the two sites with each other, the antenna module acts as a high-gain antenna for high-quality and long-range data transmission/reception. The detailed design concept and operational principles of the antenna modules, and the operational procedures of the rattlesnake antenna system, are also presented. A prototype system was built and tested, and the auto-aiming and long-range communication functionalities were successfully demonstrated.