Fabrication and experimental validation of a reconfigurable fractal Ka-band microstrip antenna with ADS-based rectifier feasibility analysis for RF energy harvesting

Abstract

In this paper a reconfigurable fractal microstrip antenna for broadband RF energy harvesting at Ka band is presented along with a study of the feasibility of the rectifier using ADS. The proposed antenna is intended to cover the band of 25–35 GHz, and features a slot loaded fractal radiator with two switching paths (D1 and D2) for controlling the effective surface current distribution. The antenna was designed on Rogers RT/Duroid 5880 material with compact size of 20 × 24 × 0.55 mm 3 and successfully tested with the help of the reflection-coefficient response. The measured S11 results show multiple matched resonances, reaching −19.89 dB at 27.10 GHz, −19.49 dB at 28.50 GHz, −16.29 dB at 30.10 GHz, −29.04 dB at 32.80 GHz, and −25.52 dB at 34.80 GHz. The radiation performance simulation shows that the antenna efficiency is high in both the base and individual switching states, with 86% being the minimum efficiency, and 91.55% the maximum average efficiency for both switching paths turned on. The antenna also has an average peak gain of ∼8.5 dBi, peak gain of more than 10 dBi at higher Ka-band, circularly polarized gain in the useful operating band and a cross-polarization discrimination of ∼23 dB. The feasibility of the conversion of RF to DC was tested by designing a rectifier at Ka band, doing this harmonic-balance simulation with a load of 300Ω, in ADS.A Ka-band rectifier design was made in ADS using a 300Ω load for an RF to DC conversion feasibility test. The predicted rectifier efficiency of the simulated was 92% at 32 GHz and 25 dBm with an output voltage of about 16 V at 32 GHz and 30 dBm. The work features a small and reconfigurable Ka-band antenna front end where the rectification pathway is created with the help of simulation. The work shows a small and reconfigurable Ka-band antenna front end along with a simulated rectification path for future low power IoT and wireless sensor energy harvesting systems.