Harmonic Sensor Node with Single-Port Unidirectional Dualband Antenna Extracting Sensor-Voltage from Link-Channel Characteristics

In this paper, we propose a sensor node using a unidirectional harmonic antenna that can acquire remote sensor information without complex digital circuits. The antenna suitable for the harmonic sensor node is characterized by utilizing a wideband E-shaped element to suppress pattern degradation at harmonic frequencies. First, through basic investigations where the sensor is modeled as a variable voltage source, we demonstrate that sensor voltage information can be remotely detected based on the transmission zero frequency. Next, using a sensor node incorporating a temperature sensor and energy harvesting circuit as an example, we show that the temperature in a remote location can be detected from the stopband frequency, thereby verifying the effectiveness of the proposed method. These findings are validated through harmonic balance analysis, electromagnetic field simulations, and RF circuit simulations.