The term "ultrawideband" (UWB) in antenna research has become a buzzword over the past decade.

Space-charge depth profiles in various electret polymers have been measured in both the time and the frequency domain using thermal pulses and waves, respectively. A comparison of the two techniques on corona-charged polytetrafluoroethylene showed that the thermal-pulse method yielded similar results as the thermal-wave technique, but approximately 20–50 times faster. The article discusses sensitivity limitations as well as possible applications, including the real-time monitoring of space-charge decay under UV irradiation.

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A compact quadruple band microstrip patch antenna with two rectangular notches is proposed and analysed for multiband applications. The proposed antenna structure is obtained from reference patch antenna by providing two rectangular notches on the radiating patch and their effects are investigated in terms of return loss, radiation pattern, current distribution and voltage standing wave ratio (VSWR). The proposed structure is simulated using electromagnetic solver Ansoft's high frequency structure simulator (HFSS) and results are in good agreement with measured results.ABSTRACT: This letter presents planar microstrip branch-line (BL) couplers with improved phase and amplitude stability bandwidth along with significant size reduction. The prototypes are designed to operate at 433 MHz frequency band suitable for ISM 433 MHz applications. The prototypes with symmetric polygonal modification (SPM) and asymmetric polygonal modification (ASPM) offer a wide quadrature phase bandwidth of 37.8% and 35.5% respectively, over which the phase imbalance is within 908658. In SPM all four transmission lines of the BL coupler have been symmetrically modified to bring in 75.99% size reduction compared to the conventional design. Further asymmetric modification has been performed to bring an additional 12.34% size reduction, compared to symmetric, and providing an overall size reduction of 78.95% compared to conventional BL coupler. The prototypes are able to offer compactness without compromising much on the matching, transmission and isolation parameters.

High-resolution, large-area three-dimensional mapping of polarization profiles in electret polymers was carried out by means of a fast thermal pulse technique with a focused laser beam. A lateral resolution of 38 μm and a near-surface depth resolution of less than 0.5 μm was achieved. At larger depths, fast thermal diffusion in the metal electrode rather than the laser spot size becomes the limiting factor for the lateral resolution.