MULTIPLE BAND FREQUENCY SELECTIVE REFLECTORS

• US 3,842,421 A
• Filed: 02/15/1973
• Issued: 10/15/1974
• Est. Priority Date: 02/15/1973
• Status: Expired due to Term

• Current Assignee: Space Systems/Loral Incorporated (Loral Space and Communications Incorporated)
• Original Assignee: Edward S. Jewell, James V. Rootsey
• Inventors: Rootsey, James V., Jewell, Edward S.
• Primary Examiner(s): Lieberman, Eli
• Application Number:
  US05/332,666
• Time in Patent Office: 607 Days
• Field of Search: 343/756,909,779,837
• US Class Current: 343/909
• CPC Class Codes: H01Q 15/0033 used for beam splitting or combining, e.g. acting as a quasi-optical multiplexer H01Q19/191 and H01Q19/195 take precedence
• CPC Class Codes: H01Q 15/24 Polarising devices; Polarisation filters H01Q15/12, H01Q15/22 take precedence
• CPC Class Codes: H01Q 19/193 with feed supported subreflector splash plate feeds H01Q19/134
• CPC Class Codes: H01Q 5/45 using two or more feeds in association with a common reflecting, diffracting or refracting device

Abstract

Polarization independent resonant elements are arrayed in a common plane to form a frequency selective reflective surface for electromagnetic energy. By employing an interspersed array of multiple frequency elements, sufficiently decoupled to permit independent operation, reflections in multiple bands are possible. This makes it possible to operate the reflector at two widely separated frequencies or, by critical separation in terms of frequency, to operate the reflector as a broadband device.

Claims

1. In a resonant electromagnetic energy reflector structure having a plurality of polarization insensitive resonant elements, said elements being in a common plane and in sufficient number to render said plane electrically active at the frequency of resonance of said elements, the improvement comprising:

interspersing spaced polarization insensitive resonAnt elements of a plurality of resonant frequencies, said elements being configured and spatially rotated to minimize the electrical coupling between elements of different resonant frequencies.

2. The improvement of claim 1 wherein said plurality of resonant frequencies is two, and said resonant elements comprise crosses of one size interspersed between crosses of a larger size, said crosses of said one size being oriented at about 45* with respect to said crosses of said larger size.

3. The improvement of claim 1 wherein said plurality of resonant frequencies is two, and said resonant elements comprise crosses resonant at a first frequence interspersed with rings resonant at a second frequency.

4. The improvement of claim 1 wherein said plurality of resonant frequencies is three and said resonant elements comprise rings resonant at a first frequency interspersed between crosses resonant to a second frequency and an array of crosses resonant to a third frequency located so that each ring encloses a cross, said crosses inside said rings being oriented at about 45* with respect to said crosses resonant to said second frequency.

5. The improvement of claim 1 wherein said resonant elements comprise conductive forms on an insulating substrate and said elements produce frequency selective energy reflection.

6. The improvement of claim 1 wherein said resonant elements comprise apertures in a conductive surface and said elements produce frequency selective energy transmission.

7. A resonant electromagnetic energy reflector structure comprising:

a first array of polarization insensitive elements dispersed substantially uniformly over a common plane, said elements being resonant at a first frequency, and a second array of polarization insensitive elements spaced from said first array and also dispersed substantially uniformly over said plane, the elements in said second array being resonant at a second frequency and interspersed uniformly among the elements of said first array, said reflector structure being characterized in that the elements of said second array are spatially rotated to be sufficiently de-coupled electromagnetically from the elements of said first array to permit operation of the reflector at discrete frequencies represented by the resonant frequencies of the two arrays.

8. A resonant electromagnetic energy reflector structure as claimed in claim 7, wherein said two resonant frequencies are sufficiently closely spaced as to produce a reflector having a broad frequency response characteristic.

9. A resonant electromagnetic energy reflector structure as claimed in claim 7, wherein said first and second arrays comprise crosses, said second array crosses being smaller and oriented at about 45* with respect to those of said first array.

10. A resonant electromagnetic energy reflector structure as claimed in claim 7, wherein said first array comprises crosses and said second array comprises rings.