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The proposed triple band notch antenna is a coplanar waveguide fed radiator with incorporated notching resonators etched for achieving the desired band rejection. Sequential design of UWB antenna is presented for different frequency band rejections. Three different notch antennas are proposed having single band rejection for each antenna. The optimized antenna is achieved by accumulating the three stop band resonators in a single design. The mutual coupling effect of the proposed resonators are investigated in details. Proposed antenna operates from 2.4 to 11 GHz. The introduction of C-shape slot at main radiator, CSRR at ground plane and inverted U-shape slot at the center of the patch results in narrow band rejection of WiMax (3.5 GHz), WLAN (5.8 GHz) and satellite service band (8.2 GHz), respectively. The antenna prototype measures 31 × 30 mm 2 . Measured and simulated results fulfil the performance criteria for the proposed antenna.

For the first time, the design and implementation of a fully-integrated wireless information and power transfer system, operating at 24 GHz and enabling battery-less sensor nodes, is presented in this paper. The system consists of an RF power source, a receiver antenna array, a rectifier, and a batteryless sensor node which communicates via backscatter modulation at 868 MHz. The rectifier circuits use commercially available Schottky diodes to convert the RF power to DC with a measured efficiency of up to 35%, an improvement of ten percentage points compared with previously reported results. The rectifiers and the receive antenna arrays were jointly designed and optimised, thereby reducing the overall circuit size. The battery-less sensor transmitted data to a base station realised as a GNU Radio flow running on a bladeRF Software Defined Radio module. The whole system was tested in free-space in laboratory conditions and was capable of providing sufficient energy to the sensor node in order to enable operation and wireless communication at a distance of 0.15 metres.

This paper presents the design and implementation of efficient & compact flexible rectennas (antenna + rectifier) for wireless power transfer to wearable IoT sensor nodes at 24 GHz. Two different rectifier configurations i.e. shunt and voltage doubler have been analyzed for performance comparison. Experimental results of complete rectenna have also been demonstrated for conformal surfaces. The proposed flexible rectifiers is fabricated through conventional PCB manufacturing method. Measured RF-DC conversion efficiency of 31% and DC voltage of up to 2.4 V is achieved for 20 dBm input power across an optimal load resistance of 300Ω at 24 GHz.