Diode‐switched thermal‐transfer printed antenna on flexible substrate

Abstract

Diode‐switching that can be used to introduce frequency agility into antennas produced by thermal transfer printing is demonstrated. The particular example is a triangular Sierpinski fractal pattern with two PIN diodes to switch between operation optimised for the 800 MHz ultra‐high frequency (UHF) band (diodes on) and 2400 MHz ISM band (diodes off). Our measured results show an improvement in S 11 in the UHF band from −2 to −28 dB and from −7 to −30 dB at 2400 MHz, when switching the diodes appropriately. The measured bandwidth is 200 (1000) MHz, and the measured directivity is 3.1 dB (5.2 dB) while the measured gain is −5.2 dB (6.7 dB) for the diodes on (off).