Leaky wave antenna with amplitude controlled beam steering based on composite right/left-handed transmission lines

An antenna comprising two different composite right/left-handed transmission line structures is proposed which enables easy beam steering at an operation frequency of 10 GHz. The composite right/left-handed transmission lines are based on planar, periodically arranged via free unit cells, implemented in microstrip technology. Both transmission lines exhibit the infinite wavelength phenomenon which occurs at 9.72 GHz and 9.89 GHz, respectively. Thus, operating the different leaky wave structures at 10 GHz, radiation with azimuth angles of &plusmn;8&deg; and &plusmn;17&deg; can be achieved depending on the selected input port. In order to obtain a tunable main beam direction, the radiation patterns of both structures are superimposed by feeding them simultaneously. The influence of each guiding structure, and hence the direction of the main beam, can be controlled via the feeding amplitude. As a result of this, the beam can be steered between &plusmn;17&deg; with a gain of up to 10 dBi. The guiding structures are arranged in parallel with a clearance of <i>a</i>=12.2 mm which is less than half of the wavelength in free space. This allows in a further step the attachment of additional guiding structures in order to increase the tunable angle range or creating an antenna array with a small beamwidth in the elevation plane without the occurrence of grating lobes. An antenna prototype was fabricated and validated by measurements

Design and analysis of an isotropic two-dimensional planar Composite Right/Left-Handed waveguide structure

A two-dimensional isotropic Composite Right/Left-Handed (CRLH) waveguide structure is proposed which is designed for operation in <i>X</i>-band. The balanced structure possesses left-handed behaviour over a large bandwidth from 7.5 GHz up to its transition frequency at 10 GHz. Above this region, the unit cell behaves in a right-handed manner up to 13.5 GHz. Operating the structure within these bands yields a frequency dependent index of refraction ranging from &minus;2.5 &le; <i>n </i> &le; 0.8. Isotropic characteristics are obtained between 8.5 GHz &le; <i>f </i> &le; 12 GHz resulting in &minus;1.5 &le; <i>n</i> &le; 0.8. The planar CRLH structure is designed based on transmission line theory, implemented in microstrip technology and optimized using full-wave simulation software. An equivalent circuit model is determined describing the electromagnetic behaviour of the structure whose element values are obtained by even and odd mode analysis. The design of the unit cell requires an appropriate de-embedding process in order to enable an analysis in terms of dispersion characteristics and Bloch impedance, which are performed both

Local and non-local equivalent potentials for p-12C scattering

A Newton-Sabatier fixed energy inversion scheme has been used to equate inherently non-local p-${}^{12}$C potentials at a variety of energies to pion threshold, with exactly phase equivalent local ones. Those energy dependent local potentials then have been recast in the form of non-local Frahn-Lemmer interactions.Comment: 15 pages plus 9 figures submitted to Phys. Rev.

Realisation of Via-free Microstrip Composite Right/Left-Handed Transmission Lines

Three via-free microstrip composite right/left handed (CRLH) unit cells are presented, which enable easy and low-cost fabrication of transmission lines exhibiting the infinite wave length phenomenon. All guiding structures are designed in an entirely printed circuit technology based on the transmission line theory and its equivalent circuit. Supported by EM simulation software the unit cells are optimized to operate at a frequency of 10 GHz. Appropriate experiment boards were fabricated and the measurements obtained from a microwave vector network analyzer are compared to the simulated results. Furthermore, an approach is worked out to determine the dispersion characteristics of the unit cells without the need of an equivalent circuit. The introduced and applied method allows to calculate dispersion relations directly based on simulated and measured ABCD parameters. Left and right-handed regions are pointed out by the dispersion diagram and the so-called infinite wavelength phenomenon is exhibited