Frequency selective reflector system

Claim 2

A self-supporting reflector adapted to pass signals at frequency f 1 and reflect signals at a higher frequency f 2 comprising: a plurality of conductive square grids having equal length connecting legs of conductive material, at least some of said legs including a conductive ring of a diameter approximately one-third wavelength long at the frequency f 2 to reflect signals at frequency f 2 , said legs being of a selected length and construction such that the inductive reactance presented by said legs at frequency f 1 equals the capacitive reactance of said rings at frequency f 1 giving parallel resonance and said reflector passes signals at frequency f 1 with low attenuation.

Claim 3

The combination claimed in claim 1 wherein each of said legs includes said ring centered along the length thereof.

Claim 4

The combination claimed in claim 1 wherein each of said legs includes a plurality of rings.

Claim 5

A reflector adapted to pass signals at frequency f 1 and reflect signals at a higher frequency f 2 comprising: a first plurality of conductive rings arranged in rows and columns, said rings being of a diameter approximately one-third wavelength long at said frequency f 2 , a second plurality of rings surrounding alternate rings of said first plurality of rings with said second rings of a diameter approximately one-third wavelength at a frequency sufficiently lower than f 1 that the inductive reactance presented by each of said second plurality of rings equals the capacitive reactance presented by an associated ring of said first plurality of rings at the frequency f 2 to cause said signals at f 1 to pass said reflector with low attenuation.

Claim 6

A reflector adapted to pass signals at frequency f 1 and reflect signals at a higher frequency f 2 comprising: a first plurality of conductive rings arranged in rows and columns, said rings being of a diameter approximately one-third wavelength long at said frequency f 2 , a second plurality of rings surrounding alternate rings of said first plurality of rings with said second rings of a diameter approximately one-third wavelength at a frequency sufficiently lower than f 1 that the inductive reactance presented by each of said second plurality of rings equals the capacitive reactance presented by an associated ring of said first plurality of rings at the frequency f 2 to cause said signals at f 1 to pass said reflector with low attenuation.

Claim 7

A dual frequency band antenna system with low grating lobes comprising: a first reflector having a focal axis and a first focus point, a first feed means located at said focus point adapted to couple signals at a first frequency f 1 , a second curved surface reflector having a focal axis substantially coincident with the focal axis of said first reflector and being positioned along the focal axis of said first reflector between said first reflector and the focus point of said first reflector, said second reflector having a focus point substantially along said focal axis of said first reflector at a point between said first and second reflectors, a second feed means located at the focus point of said second reflector adapted to couple signals at a frequency f 2 higher than said first frequency f 1 , said second reflector including conductive rings one-third wavelength in diameter at frequency f 2 with the ring centers spaced one-half wavelength apart at frequency f 2 for providing reflection of signals at a frequency f 2 and a plurality of conductive members of a selected length positioned with respect to said rings for presenting an inductive reactance at said frequency f 1 equal to the capacitive reactance presented by said rings at frequency f 1 causing said reflector to pass signals at frequency f 1 .

Claim 8

A dual frequency band antenna system with low grating lobes comprising: a first reflector having a focal axis and a first focus point, a first feed means located at said focus point adapted to couple signals at a first frequency f 1 , a second curved surface reflector having a focal axis substantially coincident with the focal axis of said first reflector and being positioned along the focal axis of said first reflector between said first reflector and the focus point of said first reflector, said second reflector having a focus point substantially along said focal axis of said first reflector at a point between said first and second reflectors, a second feed means located at the focus point of said second reflector adapted to couple signals at a frequency f 2 higher than said first frequency f 1 , said second reflector including conductive rings one-third wavelength in diameter at frequency f 2 with the ring centers spaced one-half wavelength apart at frequency f 2 for providing reflection of signals at a frequency f 2 and a plurality of conductive members of a selected length positioned with respect to said rings for presenting an inductive reactance at said frequency f 1 equal to the capacitive reactance presented by said rings at frequency f 1 causing said reflector to pass signals at frequency f 1 .

Claim 9

The combination claimed in claim 5 wherein said antenna system is a Cassegrain antenna system where said first reflector is the main parabolic reflector and said second reflector is a hyperbolic subreflector.

Claim 10

The combination claimed in claim 5 wherein alternate rings of said plurality of rings are surrounded by a second ring of a diameter approximately one-third of a wavelength in diameter at a frequency lower than f 1 .

Claim 11

The combination claimed in claim 5 wherein said second reflector includes a square grid of conductors with the legs including a conductive ring of one-third wavelength diameter at frequency f 2 .

Claim 12

A frequency selective reflector comprising: a plurality of conductive rings approximately one-third wavelength in diameter at a desired frequency f 2 and a plurality of conductive members of a selected length and configuration positioned with respect to said rings for presenting in the region of said rings an inductive reactance at a desired pass frequency f 1 equal to the capacitive reactance presented by said rings at frequency f 1 to cause said reflector to pass signals at frequency f 1 with low attenuation.

Claim 13

A frequency selective reflector comprising: a plurality of conductive rings approximately one-third wavelength in diameter at a desired frequency f 2 and a plurality of conductive members of a selected length and configuration positioned with respect to said rings for presenting in the region of said rings an inductive reactance at a desired pass frequency f 1 equal to the capacitive reactance presented by said rings at frequency f 1 to cause said reflector to pass signals at frequency f 1 with low attenuation.