Method and apparatus for multilayer frequency selective surfaces
First Claim
1. A method for designing a multiple layer structure for transforming an electromagnetic signal having a specified polarization, the electromagnetic signal being directed through each layer of the multiple layer structure, and the method comprising the steps of:
- (a) specifying a frequency for the electromagnetic signal and an angle of incidence of the electromagnetic signal on the multiple layer structure;
(b) providing a stacked plurality of frequency selective surface layers, a first layer being on top and one or more lower layers positioned beneath it, each layer having adjustable parameters to provide a desired transformation response and each lower layer having a rotational orientation with respect to a corresponding layer immediately above each lower layer, each layer transforming the electromagnetic signal as it passes through the layer; and
(c) adjusting the parameters and rotational orientation of at least one layer so that a chosen set of polarization modes of the electromagnetic signal do not couple as the electromagnetic signal passes from one layer to a next layer.
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Abstract
A method for designing a multiple layer frequency selective surface structure. An overall response for the structure is specified. The desired response may be modeled as a filter response. Parameters for each of the layers making up the structure that provide the overall response are determined based on the polarization modes between the layers being decoupled. To provide for decoupling, the individual layers are rotated with respect to each other. The overall response of the structure is then calculated and compared to the desired response. Adjustments are made in the parameters of each layer until the calculated response is equal or nearly equal to the desired response.
25 Citations
43 Claims
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1. A method for designing a multiple layer structure for transforming an electromagnetic signal having a specified polarization, the electromagnetic signal being directed through each layer of the multiple layer structure, and the method comprising the steps of:
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(a) specifying a frequency for the electromagnetic signal and an angle of incidence of the electromagnetic signal on the multiple layer structure;
(b) providing a stacked plurality of frequency selective surface layers, a first layer being on top and one or more lower layers positioned beneath it, each layer having adjustable parameters to provide a desired transformation response and each lower layer having a rotational orientation with respect to a corresponding layer immediately above each lower layer, each layer transforming the electromagnetic signal as it passes through the layer; and
(c) adjusting the parameters and rotational orientation of at least one layer so that a chosen set of polarization modes of the electromagnetic signal do not couple as the electromagnetic signal passes from one layer to a next layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A multiple layer frequency selective structure comprising:
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an upper frequency selective surface layer receiving an electromagnetic signal, the upper frequency selective surface layer having a port I mode decoupling angle and a port II mode decoupling angle; and
one or more lower frequency selective surface layers disposed beneath the upper frequency selective surface layer in a stacked configuration;
each lower frequency selective surface layer having a port I mode decoupling angle and a port II mode decoupling angle; and
each lower frequency selective surface layer having a layer rotational orientation to the layer immediately above the lower layer,wherein the layer rotational orientation of each lower layer being such that the port I mode decoupling angle of each lower layer is within a desired tolerance of the port II mode decoupling angle of the layer immediately above each lower layer. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A method for designing a multiple layer structure to obtain a desired response, the multiple layer structure having an upper frequency selective surface layer and one or more lower frequency selective surface layers, each lower layer having a rotational orientation with a corresponding layer immediately above each lower layer, and the method comprising the steps of:
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(a) specifying a desired overall response for the multiple layer structure;
(b) specifying a scattering matrix for each layer;
(c) calculating a port I mode decoupling angle and a port II mode decoupling angle for each layer based on the scattering matrix for each layer;
(d) adjusting the rotational orientation of each lower layer so that the port I mode decoupling angle of each lower layer is within a desired tolerance of the port II mode decoupling angle of the corresponding layer immediately above each lower layer;
(e) calculating an overall response for the multiple layer structure;
(f) comparing the calculated overall response with the desired response; and
(g) repeating steps (b) through (f) until the calculated overall response is within a desired tolerance of the desired response. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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Specification