Linear-to-circular polarization transformer based on the employment of electrically small antennas

"In this contribution, we propose the use of electrically small antennas for the design of a new setup to increase power transmission through a sub-wavelength aperture. A linear-to-circular polarization transformer based on this concept is also presented. We show that the proposed structure placed at the end of an open-ended circular waveguide is able to change its linear polarization to a circular one. The overall structure is designed to efficiently radiate a circular polarized field at theGPS L1 frequencies (around 1575.42 MHz) with a realized gain greater than 5 dBi.

Patch antenna generating structured fields with a Moebius polarization state

The term «structured light» has been recently introduced to indicate a whole series of studies related to the shaping of the amplitude and phase distributions of an optical beam, in order to obtain unusual properties. This concept has, then, found applications at microwave frequencies but limited to the generation of electromagnetic fields with a non-zero orbital angular momentum (OAM). In this letter, inspired by the recent realization of an optical beam with a Möbius strip polarization state, we investigate about the possibility of generating an electromagnetic field with such a peculiar behavior, by using standard microwave structures. In particular, in order to obtain the required amplitude and phase patterns, we propose to use a single multi-mode patch antenna and, through analytical and full-wave numerical results, we prove the effectiveness of our approach

Linear-to-Circular Polarization Transformer using Electrically Small Antennas

"In this contribution, a linear-to-circular polarization transformer based on the employment of electrically small antennas is presented. The proposed setup consists of a circular metallic disk with a sub-wavelength aperture through which two sets of connected circularly polarized electrically small antennas are placed. We assume to use such a structure to close an openended linearly polarized circular waveguide in order to change the polarization from linear to circular. The proposed setup works around 1.627 GHz and exhibits 8 MHz of 3-dB axial ratio bandwidth

Design of a multifunctional SRR-loaded printed monopole antenna

In this article, we present the design and the operation principles of a printed monopole antenna loaded with two identical split-ring resonators (SRRs). The idea is to use the SRRs not only to miniaturize the antenna dimensions but also to introduce multiple resonances, which can be properly selected by using electronic switches placed across the four gaps of the two SRRs. The physics behind the operation of the proposed antenna as well as the design procedure are presented in details and the expected multifrequency operation is demonstrated and supported by proper full-wave numerical simulations. By properly combining the ON\\\/OFF status of the four switches, in fact, it is possible to either change the operation frequency and\\\/or the shape of the radiation pattern of the printed monopole or even add new operation frequencies. The proposed SRR-loaded printed antenna, thus, may find applications in mobile communications requiring pattern diversity and multiple operation frequencies. (c) 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 22:552557, 2012

Design of a circular polarized horn filtenna using complementary electrically small resonators

"We present a circular polarized (CP) filtering antenna (filtenna) consisting of a regular conical horn and a novel polarization transformer. The proposed linear-to-circular polarization transformer is obtained by using complementary electrically small resonators etched on a metallic sheet. This structure behaves both as a polarization transformer and a filter allowing to reduce the impedance bandwidth of the conical horn to avoid additional noise in satellite receiving systems. The proposed antenna, operating at X-band, exhibits a CP realized gain of 17.5 dBic.

Power-selectivity horn filtenna loaded with a nonlinear SRR

In this contribution, we present the design of a power-selectivity horn filtenna based on the use of a nonlinear Split Ring Resonator (SRR). In particular, in order to obtain a nonlinear behavior of the SRR, we load its external gap with a pair of Schottky diodes, which require a not negligible power level to be activated. Inserting the resulting nonlinear resonator inside the throat of a horn antenna, we show that both matching and radiating properties exhibit or do not exhibit a notched-band, depending on the operating power level

Dual-circularly polarized topological patch antenna with pattern diversity

Recently, the topological properties of composite vortices, i.e., the superposition between vortex modes of a different order, have proven effective in manipulating the radiation properties of patch antennas and making them suitable for new operative scenarios. In this paper, we exploit these properties to design a multi-antenna system exhibiting both pattern- and polarization-diversity. The low mutual coupling and the possibility to steer two orthogonal polarized elds in different directions, make this radiating element an optimal candidate for antenna diversity or MIMO systems and, thus, for increasing signal quality or channel capacity of a communication system