This paper describes the design rules of a compact microstrip patch antenna with polarization reconfigurable features (right-handed circular polarization (CP)/left-handed CP). The basic antenna is a circular coplanar-waveguide (CPW)-fed microstrip antenna excited by a diagonal slot and the CPW open end. This device is developed for short-range communications or contactless identification systems requiring polarization reconfigurability to optimize the link reliability. First, experimental and simulated results are presented for the passive version of the antenna excited by an asymmetric slot. A reconfigurable antenna using beam-lead p-in diodes to switch the polarization sense is then simulated with an electrical modeling of the diodes. Finally, the efficiency reduction resulting from the diode losses is discussed.
Planar Goubau line (PGL) structures on high-resistivity silicon are adapted to the 57-64 GHz frequency band. Simulations and measurements show a lower attenuation than with the coplanar line is obtained. Very low losses are attained with a measured average attenuation of 0.064 dB/mm on the whole band. To allow this measurement, coplanar-PGL transitions have been optimized.
Abstract-The Radio Frequency IDentification (RFID) Low Frequency (LF) serial loops structure is proposed to improve TAGs detection when a TAG coil-antenna rotates by any angle, due to the tagged pebble moving. The detection zones of two types of TAGs (the token and glass TAG) and two types of reader coils, in function of the TAG size, TAG orientation and shape of the reader coils are tested. The effect of the proposed multi-coil inductively coupled is confirmed by measurement using a commercial LF RFID system.
In this paper, a new LF/HF RFID reader loop antenna design is proposed and tested, in order to increase detection areas of the tags. The studied structure is a Twisted Loop Antenna (TLA) which is based on a modified distribution and orientation of the magnetic field lines. Our structure fruitfully uses the complementary antenna principle in a coplanar configuration. This offers more possibilities of tag detection whatever the tag position and orientation. The antenna performances are evaluated by optimizing the equivalent mutual inductance between reader antenna and tag antenna. Results are presented firstly in simulation (MATLAB and HFSS electromagnetic calculator) and secondly by experimental tests at different distances and misalignments, for the two possible tag orientations: parallel and perpendicular.
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