Modeling and Characterization of Electrically Small Ultrawideband Antenna for Headstage-Based Wireless Neural Signal Recording System

Diagnosis of neural diseases can be performed using microsystems that record neural signals collected simultaneously after neural simulations. Headstage and homecage-based recording systems can be implanted on small freely-moving animals to test such system which requires miniaturized, lightweight, and high gain antennas in order for the small animals to carry them easily while also decreasing loss during data transmission. This paper proposes a 15\times 15 mm2 slot antenna with a 50~\Omega microstrip excitation line. The slot antenna is created by the addition of slots in the ground plane which is a common miniaturization method as it results in ultrawideband operating frequency. A lumped component-based model along with a 3D EM model of the modified SMA connector used for the measurement and headstage model is also developed to observe the effect on the antenna performance. The antenna achieved an operating frequency of 4.25 - 9.4 GHz and a bidirectional radiation pattern with gain ranging from 2.24 to 4.35 dBi. The proposed antenna is also circularly polarized and achieves 80.6% - 90.8% radiation efficiency over the operating BW. It can transmit a maximum of 20 dBm of power over the operating frequency without exceeding the FCC-imposed SAR limit. Based on the performance, the antenna is suitable for headstage and homecage-based neural signal recording systems with IR-UWB transmitter for high data rate transmission.