A three-dimensional backward-wave network matched with free space

A backward-wave slab based on a capacitively and inductively loaded three-dimensional transmission-line network is designed in such a way that impedance-matching with free space is obtained. To enable field propagation from free space to the network and vice versa, the use of a transition layer is proposed. Matching of the designed network with free space and negative refraction occurring at the slab interfaces are confirmed with full-wave simulations.Comment: 8 pages, 5 figure

Experimental verification of the key properties of a three-dimensional isotropic transmission line based superlens

Design and experimental realization of a three-dimensional superlens based on LC-loaded transmission lines are presented. Commercially available components and materials are used in the design. Transmission properties of the designed structure are studied experimentally and the observed lens properties are compared with analytical predictions. Backward-wave propagation and amplification of evanescent waves in the prototype structure are verified both analytically and experimentally.Comment: 12 pages, 10 figure

Experimental verification of broadband cloaking using a volumetric cloak composed of periodically stacked cylindrical transmission-line networks

Cloaking using a volumetric structure composed of stacked two-dimensional transmission-line networks is verified with measurements. The measurements are done in a waveguide, in which an array of metallic cylinders is inserted causing a short-circuit in the waveguide. The metal cylinders are cloaked using a previously designed and simulated cloak that hides the cylinders and thus enables wave propagation inside the waveguide.Comment: 8 pages, 3 figure

Broadband cloaking with volumetric structures composed of two-dimensional transmission-line networks

The cloaking performance of two microwave cloaks, both based on the recently proposed transmission-line approach, are studied using commercial full-wave simulation software. The cloaks are shown to be able to reduce the total scattering cross sections of metallic objects of some restricted shapes and sizes. One of the studied cloaks is electrically small in diameter, and the other is electrically large, with the diameter equal to several wavelengths.Comment: 6 pages, 7 figure

Impedance-matched microwave lens

A microwave lens with highly reduced reflectance, as compared to conventional dielectric lenses, is proposed. The lens is based on two-dimensional or three-dimensional transmission-line networks that can be designed to have an effective refractive index larger than one, while having almost perfect impedance matching with free space. The design principles are presented and an example lens is studied using commercial simulation software.Comment: 11 pages, 8 figure

On Impedance Bandwidth of Resonant Patch Antennas Implemented Using Structures with Engineered Dispersion

We consider resonant patch antennas, implemented using loaded transmission-line networks and other exotic structures having engineered dispersion. An analytical expression is derived for the ratio of radiation quality factors of such antennas and conventional patch antennas loaded with (reference) dielectrics. In the ideal case this ratio depends only on the propagation constant and wave impedance of the structure under test, and it can be conveniently used to study what kind of dispersion leads to improved impedance bandwidth. We illustrate the effect of dispersion by implementing a resonant patch antenna using a periodic network of LC elements. The analytical results predicting enhanced impedance bandwidth compared to the reference results are validated using a commercial circuit simulator. Discussion is conducted on the practical limitations for the use of the proposed expression.Comment: 4 pages, 7 figure