Abstract-A compact, low profile, dual polarized, ultra wideband, frequency selective surface is proposed. It is designed by using two similar metallic array structures separated by dielectric material FR4. The simulated reflection bandwidth (with transmission < −20 dB) for TE incident wave is 8 GHz from 2.87 GHz to 10.87 GHz corresponds to 116%. The unit cell dimension and periodicity are of the order of 0.37λ at the centre frequency. The overall thickness of the proposed FSS is 1.8 mm.The proposed FSS has higher order of band-stop response and good angular stability. The measured transmission response of FSS is very close to simulated response. Design expressions for the resonance frequencies are proposed, and the calculated results are found to be in good agreement with the simulated ones. Finally, a parametric analysis of the proposed FSS is presented.

Abstract-Three hexagonal patch antennas are designed for circular polarization and experimentally validated. These antennas are labeled; simple hexagonal patch, hexagonal patch with slotted ground and hexagonal patch with parasitic element. The measured impedance bandwidths of the three antennas are 2% for the simple patch, 5.2% for the patch with slotted ground and 6.35% for the antenna with parasitic element. The axial ratio (measured) obtained is 4.73% for the patch with slotted ground and 3.33% for the hexagonal patch antenna with parasitic element. The measured radiation patterns of these antennas are found to be in good agreement with the simulated radiation patterns. The average gain of all the three antennas is also evaluated. A frequency selective surface (FSS) is proposed with dimensions smaller than that of a conventional FSS structure. The measured gain improvement with the proposed FSS is around 3 dB in the operating band.

A CPW‐feed prototype slot antenna for ultra‐wideband applications is proposed. The slot is made by etching on the ground plane, the union of two elliptical structures placed at right angles. The fractal shape antenna is excited by two stepped CPW feed. To enhance the gain, a compact ultra‐wideband frequency selective surface (FSS) structure is designed and implemented. The measured impedance bandwidth of antenna with and without FSS is nearly same and equal to 9.0 GHz from 3.6 to 12.6 GHz. The measured peak gain varies from 3 to 5 dB without FSS and from 5 to 12.5 dB with FSS. Measured results are found in good agreement with the simulated results. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1498–1502, 2014

Abstract-In this paper, an ultra wideband antenna employing a defected ground structure is presented. The radiating element is a circular patch on which a fractal based geometry is inscribed in the form of slots and excited by a tapered feed-line for impedance matching. The antenna has an impedance bandwidth of 8.2 GHz (117% at centre frequency of 7 GHz) and a peak gain around 6 dB. To improve the impedance bandwidth and gain, a Swastika shape Electromagnetic band gap (EBG) structure is proposed. The unit cell of the proposed EBG has a compact size of 3 mm×3 mm and is obtained by introducing discontinuities in the outer ring of the Cross-Hair type EBG. The stop band (−20 dB) achieved with this EBG is 3.6 GHz (7.5 GHz-11.1 GHz) which is 1.6 GHz more than that achieved by a standard mushroomtype EBG of the same size and same number of elements. After application of the proposed EBG, there is an improvement of 12% in the impedance bandwidth while the peak gain increases by about 2-3 dB. The radiation of the antenna shows a dumb-bell shaped pattern in the E-plane and Omni-directional pattern in the H-plane. All the measured results are in good agreement with simulated results.

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