Integrated 5.7 GH size antenna for wireless sensor networks

We report on design, fabrication and characterization of chip-size antennas for operation at 5.7 GHz and use in wireless sensor networks. Application of wafer-level chip-scale packaging (WLCSP) techniques like adhesive wafer bonding and through-wafer electrical via formation, combined with the selected antenna types (patch and folded patch) allows on-chip integration and is the main novelty of our work. A short-range wireless link between two systems both equipped with an 8/spl times/8 mm/sup 2/ patch antenna (measured characteristics: 5.705 GHz central frequency, 90 MHz bandwidth @ -10 dB, 0.3 dB gain, 18 % efficiency) realized on a high-resistivity silicon (HRS) substrate is demonstrated. A folded-patch antenna built on two stacked glass substrates allows size reduction down to 4.5/spl times/4/spl times/1 mm/sup 3/ and has a projected efficiency of 60%.