Multi-resonant, high-impedance electromagnetic surfaces

• US 6,774,867 B2
• Filed: 12/23/2002
• Issued: 08/10/2004
• Est. Priority Date: 10/04/2000
• Status: Expired due to Fees

• Current Assignee: Wemtec Inc.
• Original Assignee: E-Tenna Corporation
• Inventors: Diaz, Rodolfo E., McKinzie, William E. III
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): Dinh, Trinh Vo
• Application Number:
  US10/327,842
• Publication Number:
  US 20030122729A1
• Time in Patent Office: 596 Days
• Field of Search: H01/Q 1.502, 343/909, 343/770, 343/767, 343/748, 343/788, 343/842, 343/866, 343/911.R, 343/700.MS
• US Class Current: 343/909
• CPC Class Codes: H01Q 15/008 said selective devices having Sievenpipers' mushroom elements
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
• CPC Class Codes: H01Q 9/0442 with particular tuning means

Abstract

An artificial magnetic conductor is resonant at multiple resonance frequencies. The artificial magnetic conductor is characterized by an effective media model which includes a first layer and a second layer. Each layer has a layer tensor permittivity and a layer tensor permeability having non-zero elements on the main tensor diagonal only.

Claims

1. An artificial magnetic conductor (AMC) resonant with a substantially zero degree reflection phase over at least two resonant frequency bands, the artificial magnetic conductor comprising a frequency selective surface characterized by a plurality of Lorentz resonant frequencies in transverse permittivity at independent, non-harmonically related, predetermined frequencies different from the resonant frequency bands, wherein the frequency selective surface has a transverse permittivity ε

_1t defined by ${\mathrm{\varepsilon <br><br>}}_{1<br><br>x}={\mathrm{\varepsilon <br><br>}}_{1<br><br>y}=\frac{Y<br><br>\left(\mathrm{\omega <br><br>}\right)}{j<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{\omega <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\varepsilon <br><br>}}_0<br><br>t},$

wherein Y(ω

) is a frequency dependent admittance function for the frequency selective surface, j is the imaginary operator, ω

corresponds to angular frequency, ε

₀ is the permittivity of free space, and t corresponds to thickness of the frequency selective surface.

2. The AMC of claim 1 wherein the frequency selective surface has a normal permeability μ

_1z defined by ${\mathrm{\mu <br><br>}}_{1<br><br>z}=\frac{Z<br><br>\left(\mathrm{\omega <br><br>}\right)}{\mathrm{j\omega <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\mu <br><br>}}_0<br><br>t},$

wherein Z(ω

) is a frequency dependent impedance function, j is the imaginary operator, ω

corresponds to angular frequency, μ

₀ is the permeability of free space, and t corresponds to thickness of the frequency selective surface.