Monolithic Integration of X-cut Leaky SAWs and Electrically Small Antennas for RF Passive Wireless Sensors

In this work, an on-chip, bulk X-cut Lithium Niobate (LN) platform for the fabrication of monolithical integrated radio frequency (RF) front-ends passives and sensors is presented. Lithographically defined shear horizontal (SH
0
) Leaky Surface Acoustic Wave (LSAW) resonators and Electrically Small Antennas (ESA) are co-designed and manufactured on the same substrate with a single-step fabrication process.SH
0
LSAW resonators demonstrated an electromechanical coupling $\left( {k_t^2} \right)$ of 40%, a mechanical quality factor at resonance (Q
m
) of 300, and a figure of merit (FOM) of 90 around 400 MHz. The fabricated ESA exhibits a compact form-factor of only 1 cm
²
, operates around 600 MHz in a grounded configuration, and is projected to present a gain of -2 dBi at 900 MHz. These results match the simulated electromagnetic performance and this platform promises strong prospects for miniaturized, monolithic, low-cost wireless sensor nodes for long-range IoT applications.