Design of Small Printed Multiband Loop Antennas for Short Range Wireless (SRW) Applications

Abstract

Worldwide application of wireless IoT and telemetry solutions are more cost effective (require lower manufacturing and logistic cost) and more immune against interferences, if they are inherently able to operate in multiple frequency bands. Switched current high impedance PA configurations driving high impedance printed antennas with very few discrete components have very low cost and yields good efficiency in the 0…+10dBm power range. However, one major bottleneck is the difficulty of the high impedance multiband antenna design.
In this paper, investigation, design and measured results of multiband, high impedance, small, printed UHF loop antennas are presented. The built antenna are inherently tuned with only two discrete capacitors to properly terminate the applied high impedance, highly efficient switched current power amplifier (PA) in the targeted two UHF bands. The presented design method is applicable for more than two band operations and for higher frequency bands as well.