Frequency response

About: Frequency response is a research topic. Over the lifetime, 25705 publications have been published within this topic receiving 332249 citations.

Single-Layer High-Order Miniaturized-Element Frequency-Selective Surfaces

Abstract: A new miniaturized-element frequency-selective surface is presented in this paper. This frequency-selective surface is made up of a 2-D periodic array of metallic loop and a wire grid of the same period printed on either side of a very thin substrate. Unique features of the new design include localized frequency-selective properties, high-order frequency response achieved by a single substrate, lack of passband harmonics in the frequency response, and very low frequency response sensitivity to the incidence angle. High-order frequency response is accomplished through the application of a thin substrate that allows considerable couplings between the elements on the two sides of the substrate. The layers' couplings in conjunction with each layer characteristics are designed to produce a high-Q bandpass frequency response, in addition to a transmission zero. It is shown that by inserting variable capacitors in the gap between the metallic loops, the center frequency of the passband can be tuned over nearly an octave. In addition, using a cluster of loops as the unit cell and modifying the parameters of the loops within the cluster, a dual-band characteristic from a single-layer miniaturized-element frequency-selective surface can be achieved. A prototype sample of the miniaturized-element frequency-selective surface, whose unit cell can be as small as lambda0 /12, is fabricated to verify the design performance through a standard free-space measurement setup. The transmission characteristic of the structure is measured and compared with numerical simulation results.

Frequency response and electronic testing for constant-temperature hot-wire anemometers

Abstract: The author aims to identify theoretically and to measure electronically the basic dynamic performance parameters of the constant-temperature hot-wire anemometer It is found that a well designed anemometer behaves as a third-order control system which allows for a two-parameter optimization of its dynamic response The cut-off frequency of the anemometer and related dynamic parameters can be estimated by means of electronic square- and sine-wave tests

Characterization of a coherent optical RF channelizer based on a diffraction grating

Abstract: A coherent optical RF channelizer has been constructed and characterized. The optical channelizer is based on a free-space optical diffraction grating, and utilizes coherent optical heterodyne detection to translate all of the frequency channels to a common intermediate frequency (IF). The designed optical channelizer has a 1-GHz channel spacing, and a nominal 5-GHz IF and can offer an instantaneous bandwidth greater than 100 GHz. The channelizing receiver has been characterized for its frequency response, crosstalk, and spur-free dynamic range, and the results are in a good agreement with the theoretical values.

On the theory of self-resonant grids

Abstract: An approximate theory is developed to predict the frequency response of a self-resonant grid. The grid is comprised of capacitive and inductive elements and exhibits a band-stop resonance. The analysis is based upon the derivation, from physical considerations, of an equivalent circuit representation of the grid structure. Predicted results compare well with measured data.