A new antenna, designed on a PET substrate and\ud implemented by inkjet printing using a conductive ink, is\ud proposed as a passive tag antenna for UHF Radio Frequency\ud Identification (RFID). The operating bandwidth of the proposed\ud antenna is very large, since it encompasses all worldwide UHF\ud RFID bands, and extends well beyond at both edges. Moreover, it\ud has a very simple geometry, can be easily tuned to feed many of\ud the commercial RFID chips, and is very robust with respect to\ud realization tolerances. The antenna has been designed using a\ud general purpose 3D CAD, CST Microwave Studio, and measured\ud results are in very good agreement with simulations. The\ud proposed passive RFID tag meets both the objectives of low-cost\ud and size reduction

The Elliott's procedure for the design of a waveguide longitudinal slot array has been extended to the case of dielectric-covered planar slot arrays. A protective dielectric cover is required in many different applications of waveguide slot arrays, especially in aerospace and satellite applications. The results of the synthesis procedure have been validated against a commercial FEM software

A design procedure for circularly polarized waveguide slot linear arrays is presented. The array element, a circularly polarized radiator, consists of two closely spaced inclined radiating slots. Both the characterization of the isolated element and the evaluation of the mutual coupling between the array elements are performed by using a method of moments procedure. A number of traveling wave arrays with equiphase excitations are designed and then analyzed using a finite element method commercial software. A good circular polarization is achieved, the design goals on the far field pattern are fulfilled and high antenna efficiency can be obtained

Microstrip patch antennas are widely employed in several applications, thanks to their low profile, low cost, and easy manufacturing. However, the demand for new technologies providing compactness and high performance poses a long-lasting challenge for the antenna designer. Traditional methods for bandwidth improvement and size reduction have some drawbacks, tied mostly to poor radiation performance or troublesome implementation. In this letter, a novel, simple, but effective patch antenna layout exploiting the customizable form factor guaranteed by 3-D printing (or other fabrication techniques) is presented. An appropriate modification in the vertical profile of the radiator is introduced. Specifically, without loss of generality, a cylindrical shape has been selected as a proof of concept. The proposed solution allows to increase the impedance bandwidth from 2.9% of a standard flat microstrip patch to 9%. Additionally, the projected antenna resonant size can be reduced up to 38% compared to its flat counterpart.

The robustness of wearable UHF-band planar inverted-F antennas (PIFAs), with respect to body-antenna separation and human tissue dispersion, is addressed through numerical investigations. The main goal is gaining physical insights into the relationship between the grounded antenna performance and the distribution of the electric and magnetic energy densities in the antenna near-field region close to the ground plane border. A criterion for choosing a proper shape of the antenna ground plane is suggested, which can improve the antenna robustness with respect to the random variations of the body-antenna coupling scenario, but with a minimal impact on the antenna size