Inductive Grid Research Articles

4-layer inductive grid FSS at 45° incidence

Transmission/reflection-band centre ratios of about 1.3 can be attained with multiple layers of inductive or capacitive grids, or with single-layer arrays of more complex elements. The copolar losses and the linear crosspolar performance of a 4-layer inductive grid and a 2-layer array of concentric rings are compared to illustrate some of the problems that can arise experimentally.

The application of double grids as Fabry-Perot interferometers

Presents a theory describing the diffraction properties of a double grid, composed by two perfectly conducting, rectangular hole inductive grids lying in closely separated parallel planes. Investigations concerning the interferometric nature of the double grid operated in long wavelength radiation are discussed. In particular, a multiple scattering approach is used to explain the positions of the interference resonances and to determine the optimal design parameters for a double grid Fabry-Perot interferometer.

Inductive Grids in the Region of Diffraction Anomalies: Theory, Experiment, and Applications

We describe briefly a rigorous theory for the diffraction of a plane wave by inductive grids having circular apertures pierced in doubly periodic fashion in a thick, perfectly conducting screen. We compare the theory with measurements made at millimetric wavelengths both for normal incidence and off-axis (in the region of strong polarization effects). We discuss the conclusions to be drawn from the calculations and measurements on the use of such grids as filters which pass short wavelengths, particularly in relation to their possible application in the field of solar energy.

On the theory and solar application of inductive grids

A brief description is given of the rigorous formulism of Chen, which describes the diffraction by perfectly-conducting inductive grids. The formulism is used to prove several general properties of grids, including the relevant form of the Reciprocity Theorem. The theory is used to investigate the equivalent circuit model proposed by other authors for thin grids, and also to derive a monomodal model of the type first proposed by Chen. The latter model is shown to be useful even in the region where more than one spectral order propagates.

A Study of an Array of Square Openings

The diffraction theory for the transmission of electromagnetic fields through a grid in a dielectric is derived and experimentally checked in the visible wavelength region. In the far infrared, an approximate mathematical representation is found to describe the grids in dielectrics. The empirical equations in the far infrared are combined with the electrical circuit transmission line analog for inductive grids. Detailed structure of the transmittance vs wavenumber curves are presented.

A flush-mounted leaky-wave antenna with predictable patterns

This paper describes the design and the measured performance of a large, flat antenna consisting of an inductive grid spaced over a conducting surface. The analysis employs the transverse-resonance method to determine the radiating properties of the structure. This analytical technique is shown to predict very accurately the amplitude and phase of the illumination along the aperture of the antenna. An antenna was built with an 18- by 24-inch aperture and tested over the frequency band from 7-to-13 kmc. The results of these tests confirm the theoretical predictions in every detail. A pencil beam from the antenna scans in the H-plane (perpendicular to the antenna) from 20\deg to 60\deg from the normal to the aperture as the frequency changes from 7-to-13 kmc. The H-plane beamwidth remains virtually constant over most of this band. The first H-plane sidelobe or shoulder is at least 29 db below the main lobe from 7-to-10 kmc, and at least 23 db below from 10-to-13 kmc. All H-plane sidelobes beyond three or four beamwidths on either side of the main lobe are at least 40 db below the main lobe everywhere in the 7-to-13 kmc band. At the design frequency the measured pattern agrees with the theoretical pattern within a fraction of a db down to 40 db below the peak of the main lobe, even though the gain of the antenna at this frequency is only 33 db.