Harmonic-Suppressed Miniaturized-Element Frequency Selective Surfaces With Higher Order Bandpass Responses

Abstract

In this reprot, we introduce a new technique for designing miniaturized-element frequency selective surfaces (MEFSSs) with bandpass responses and no spurious transmission windows over extremely large bandwidths. The proposed, harmonic-suppressed MEFSSs consist of multiple metallic and dielectric layers. Each metallic layer is in the form of a two-dimensional arrangement of capacitive patches or an inductive wire grid with extremely sub-wavelength periods. Harmonicfree operation in these structures is achieved by using multiple, closely-spaced capacitive layers with overlapping unit cells to synthesize a single, effective capacitive layer with a larger capacitance value. This allows for reducing the unit cell size of a conventional MEFSS considerably and moving the natural resonant frequencies of its constituting elements to considerably higher frequencies. Consequently, the spurious transmission windows of such MEFSSs, which are caused by these higher-order harmonics, can be shifted to very high frequencies and an extremely broad frequency band free of any spurious transmission windows can be obtained. Using this technique, an MEFSS with a second-order bandpass response is designed to operate at 3.0 GHz with 20% fractional bandwidth and be free of spurious transmission bands up to 27.0 GHz. A prototype of this harmonic-free MEFSS is fabricated and experimentally characterized in the lab. Measurement results confirm harmonic-free operation of the proposed FSS for incidence angles in the ±60• range for both the TE and TM polarizations of incidence.

Design of narrow‐band dielectric frequency‐selective surfaces for microwave applications

“…This result is in agreement with previously published practical FSS radomes wich are tipically comprised of hundreds of elements and similar sizes [33]- [35].…”

Angularly Stable Frequency Selective Surface Combined With a Wide-Scan Phased Array

“…Considering that the elements are much smaller than the wavelength, the behavior of each layer can be represented as a shunt impedance (capacitive or inductive), with respect to a plane-wave propagation, over a large frequency range [8]. The design of a MEFSS suppressing harmonic responses was presented in [9], and achieved stable behavior for oblique incidence in the principal planes. The thickness was electrically small, less than λ/10, rather than a multiple of λ/4, resulting in lower losses.…”

“…The thickness was electrically small, less than λ/10, rather than a multiple of λ/4, resulting in lower losses. Nevertheless, in [9] or in other more recent designs [10] the FSS was only characterized and tested under plane-wave illumination.…”

A Transplantable Frequency Selective Metasurface for High-Order Harmonic Suppression

“…In [7][8][9], band-pass frequency selective surfaces with stop-band characteristics are reported. They use artificial absorbing coating, resistive high-impedance surface, and other techniques to achieve the harmonic absorbing properties.…”