Alternating Current Sensing Slot Antenna

Dual operations of AC current sensing and Bluetooth transmission using a reconfigurable slot antenna are described here. The novel current sensing setup comprises of a tunable antenna connected to a current transformer and AC/DC converter to create a smart AC current sensing mechanism. The tunable antenna consists of a double-layer slot antenna on a thin, flexible substrate with a tuning circuit consisting of capacitive-coupled biasing tracks on the backside. Capacitive coupling isolates circuits at DC while providing connectivity at radio frequency (RF). Tracks act as the capacitors for the tuning biasing circuit. A double-sided copper clad Mylar substrate is etched to produce the slot antenna on one side and the biasing circuit using inexpensive Varactor diodes on the other side. The antenna tunes over a wide frequency range of approximately 2:1. The antenna is able to sense currents by providing a frequency response when connected to the sensing system. The current sensing antenna can also detect the operational or non-operational states of the appliances and devices. This low-cost setup of antenna on a flexible substrate can assist in detecting the power and current monitoring in household electrical devices providing an energy-efficient solution while also operating as a transmitter via Bluetooth. The measured reflection coefficients and radiation patterns are in a good agreement with the simulated results and noticeably clear sensing of current is achieved.