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A method has been proposed to simultaneously enhance the gain (14 dB), bandwidth (BW) (12.84% of the operating central frequency) and efficiency (94%) of a microstrip patch antenna. The antennas have been designed based on the patch size improvement technique to improve the fabrication tolerance. The designed prototypes have been fabricated by conventional low cost printed circuit board etching method and tested at X‐band (8–12 GHz) and 60 GHz band (57–66 GHz) frequencies. Antennas’ overall performance is maintained across their operating frequency range. The tested antennas for 60 GHz band convince the requirements for multi‐gigabits/s data rate wireless local area network and wireless personal area network applications recommended by IEEE 802.11ad and IEEE 802.15.3c standards. In all cases the simulation and the measured results are in good agreement.

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ABSRACT: A method has been proposed to increase the size of rectangular microstrip patch antenna (RMPA) for mm-wave and terahertz frequencies to increase the fabrication tolerance. The method is experimentally tested on a RMPA designed at 56 GHz frequency where both the simulation and measured results are in good agreement. Moreover, the antenna's overall performance is also improved.ABSTRACT: A substrate integrated waveguide six-port directional coupler is designed and characterized. The circuit exploits a very compact size and good reflection and transmission characteristics, as it exhibits both return loss and isolation higher than 15 dB over a 13% bandwidth. The device is made by connecting all ports to a single junction which mixes all signals. Some prototypes have been built and experimental results show a very good agreement with simulations.

In this paper, ultra-wide patch antenna arrays have been presented at 60 GHz band (57.24-65.88 GHz) with improved gain and beam-width capabilities for remote detection of respiration and heart beat rate of a person with Doppler radar principle. The antennas measured and simulation results showed close agreement. The breathing rate (BR) and heart rate (HR) of a 31-year-old man have been accurately detected from various distances ranging from 5 to 200 cm with both single-antenna and dual-antenna operations. In the case of single-antenna operation, the signal is transmitted and received with the same antenna, whereas in dualantenna operation, two identical antennas are employed, one for signal transmission and the other for reception. It has been found that in case of the single-antenna operation, the accuracy of the remote vital sign monitoring (RVSM) is good for short distance; however, in the case of the dual-antenna operations, the RVSM can be accurately carried out at relatively much longer distance. On the other hand, it has also been seen that the visual results are more obvious with higher gain antennas when the radar beam is confined just on the subject's body area.