Abstract-In this paper, two compact patch antenna designs for a new application -outdoor RF energy harvesting in powering a wireless soil sensor network -are presented. The first design is a low-profile folded shorted patch antenna (FSPA), with a small ground plane and wide impedance bandwidth. The second design is a novel FSPA structure with four pairs of slot embedded into its ground plane. Performance of both antennas was first simulated using CST Microwave Studio. Antenna prototypes were then fabricated and tested in the anechoic chamber and in their actual operating environment -an outdoor field. It was found that the FSPA with slotted ground plane achieved a comparable impedance bandwidth to the first design, with an overall size reduction of 29%. Simulations were also carried out to investigate the effects of different design parameters on the performance of the proposed slotted ground plane FSPA.

In this paper the suitability of using a printed circuit board (PCB) microstrip patch receiving antenna for a novel application -RF energy harvesting to power a wireless soil sensor network deployed in an outdoor environment -is investigated. The performance of a conventional circular microstrip patch antenna using different microwave laminate substrates is evaluated in terms of return loss, radiation efficiency, and gain. Based on a chosen PCB material as the antenna substrate, an enhanced gain circular patch with a ring shaped parasitic radiator is presented. Simulations have been carried out using CST Microwave Studio to examine the antenna's performance both in free air and in the presence of different soil conditions.

Several important measurement uncertainties and errors associated with test receivers and preamplifiers in a radiated emission test system are rigorously investigated. It is found that some defective RF connectors can have abnormal insertion loss (∼0.8 dB in our study) at certain frequencies. Signal synchronization between the signal generator and the test receiver is found to be an important factor in cable attenuation measurements, and an uncertainty of about 0.8 dB is recorded between using and not using signal synchronization. The measurement uncertainty associated with the preamplifier gain variation is found to be as large as 0.47 Db, when the temperature changes from the room temperature (25°C) to 35°C or to 15°C. The results obtained in this study provide additional knowledge to the existing measurement standards used in the industry. They also have important implications for practical measurements in seeking to fulfil industrial measurement standards.

This article presents an efficient method of modeling reverberation chambers (RCs) based on proportional dimensions. The motivation of this work is to predict the performance of a large‐size RC based on a proportionally reduced‐size scale model. Electromagnetic dimensional scale model in RC is explained, and the theory is deduced from Maxwell equation. Good agreements between simulation and measurement results have been observed and discussed. The large‐size RC simulation result fulfills the requirement in terms of electric field standard deviation based on the scaled model. It showed that using the scaled model to estimate a large‐sized RC is feasible, thus reducing the simulation time and saving computing power. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:838–841, 2015