Smart planar inverted‐F antenna for broadband applications

Abstract

A single‐feed dual‐band stacked‐patch Planar Inverted‐F Antenna (PIFA) is integrated with a RF switch array at one side of its shorting straps to make a tunable PIFA. The L‐band switch yields 0.45‐dB insertion loss (IL) and 10‐dB isolation bandwidth (BW) of >100% at 1.2 GHz. The tunable PIFA yields 13% frequency tunability BW at 800 MHz band and 21% BW at the 1.9‐GHz band. The measured radiation patterns are broad beams with low backlobes, as compared to those of a standard PIFA. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 389–393, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11226

Epitaxially grown ferroelectric thin films for agile devices

“…(i) semi-conducting devices, like diodes, especially varactors and PIN used for instance in filters and antennas [1][2][3][4]; the advantages are low voltage and short commutation time, but they suffer from important losses (several dB in the GHz range) and large power consumption. Also MMIC technology FET transistors, with very low power consumption, are used as on-off switches in digital circuits [5], but their insertion losses are high; (ii) Micro Electro Mechanical Systems (MEMS), processed in the shape of cantilevers or bridges, give access to switches or variable capacitors, used in agile filters [6] or phase shifters [7]; their insertion losses are low, but the technology of their integration in microwave devices is quite complex; (iii) magnetic materials (mainly yttrium iron garnet [8] or ferromagnetic materials [9]) use the variation of magnetic permeability under application of an external magnetic field; their main drawbacks are long response time and large size; (iv) liquid crystals, in their nematic phase, exhibit a dielectric anisotropy that changes under an applied electric field: this property has been used to built agile phase shifters and capacitors [10][11][12]; however their insertion losses are still too high [13]; (v) ferroelectric compounds are currently very attractive materials for applications in electrically tunable high-frequency devices [14], as these materials are characterized by nonlinear dielectric properties [15] and then exhibit an electric field dependent dielectric permittivity (") driven by a DC voltage [16].…”