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The identify friend or foe antenna is a complement to many radar antennas which allows the discrimination between friendly and hostile targets by receiving identification data. Such antenna must synthesize both a sum and a difference pattern in azimuth to allow target discrimination and must point to the target being inquired, either by mechanical or electronic scanning in azimuth. In this paper, to attain optimal electronic scanning, an array of antennas lying on a generic planar curve is considered. A multi-objective optimization based on the invasive weed optimization algorithm is then applied to the shape of such curve, aimed at maximizing performances. Whereas a conventional linear array of 6 elements can effectively scan ±30°, with respect to broadside, the proposed array, notwithstanding the same number of elements and overall length, can scan ±45° and still synthesize effective sum and difference patterns. [ABSTRACT FROM AUTHOR]

In this paper an antenna array operating in circular polarization in the C-band is presented. The array is based on the sequential rotation architecture, applied to six elements, and arranged in hexagonal shape. Thanks to its geometry, the array is suitable for tiling of surfaces as well as for regular solid arrangement. Satisfying experimental validation of a prototype based on the proposed design is observed, with a peak gain of 10.4 dB at 5.8 GHz maintained within 3 dB over a 500 MHz band, a 10 dB return loss bandwidth of 500 MHz, and a 3dB axial ratio bandwidth of almost 400 MHz, meaning 6.5% of fractional bandwidth. [ABSTRACT FROM AUTHOR]

In this paper, a wide band monopole antenna with a shaped profile is presented. Shaped profile and end-caps allow for a compact antenna with respect to wavelength. Antenna is designed to be as isotropic as possible and with low phase deviation from spherical wave front to allow accurate detection of the direction of arrival of an unknown signal when used in radiogoniometry applications. [ABSTRACT FROM AUTHOR]

This paper presents an efficient highfrequency analysis framework for studying diffraction occurring at irises, or baffles, in the arms of a Fabry-Perot optical interferometer, relevant to the design and operation of interferometric detectors of gravitational waves like LIGO and Virgo. [ABSTRACT FROM AUTHOR]