Development of Miniaturized 300-MHz Frequency Band Antenna with H-Bridge Power Amplifier for Wireless Sensor Node

摘要

We have developed a miniaturized 300-MHz band loop antenna based on the concept of Litz wire with a H-bridge class-D power amplifier for small wireless sensor nodes. Although 300-MHz frequency band transmission has several advantages, such as long-distance communication, the antenna with high efficiency needs to have large area. If an antenna is integrated on a small wireless sensor node, the efficiency of the antenna as well as the power amplifier have to be increased by decreasing the power loss. In this study, we applied the concept of Litz wire to an antenna to decrease the resistance of the antenna and developed a H-bridge type class-D power amplifier. Six loop antenna layers connected in parallel with area of 17 mm x 8 mm and thickness of 1.6 mm was fabricated in a multilayer printed circuit board. The power of-34 dBm at 310 MHz at 1 m away from the antenna was achieved with a high efficiency H-bridge power amplifier. In this case, the calculated communication length is about 150 m.