US 4,785,266 AGranted

Dielectric rod polarizer having wedge shape polarizing portions

AssigneeThe Marconi Company Limited

InventorsPaul Newham, Bernard J. Andrews

Life of this patent

Estimating the term…

Loading patent…

Abstract

A microwave polarizer is provided in the form of a wedge at the termination of a rod of dielectric material. Preferably the wedge tapers exponentially in order to provide a good impedance match. Circularly polarized radiation propagating along the rod experiences a differential phase shift at the wedge. This phase shift may be arranged to be 90.degree., so that linearly polarized radiation exits from the wedge. A continuous circular or square guide is used to contain the dielectric rod so that simultaneous orthogonal signals can be converted to or from circular polarizations. Such a wedge termination may be provided at the end of a splashplate or polyrod antenna feed, for a satellite communication system, where right-handed circular polarization is used on the up-link and left-handed circular polarization is used on the down link. The conventional orthomode transducer may be dispensed with, thereby enabling the sub-reflector to be located closer to the main reflector, thus reducing blockage and increasing the bandwidth.

Claims7

Dependent claims

A radio frequency polarizer, comprising:

(a) a rod of dielectric material elongated along a length direction,
(b) said rod having a body portion and at least one end portion, said body portion having a cross-section transverse to said length direction and said cross-section having a width direction transverse to said length direction,
(c) said end portion having a length along said length direction and a wedge formation comprising a reduction of rod dimension in said width direction only,
(d) a tubular waveguide elongated along a length direction and containing said rod therein, said length direction of said rod coinciding with said length direction of said tubular waveguide,
(e) said tubular waveguide having a cross-section for carrying orthogonal plane-polarized waves, and said cross-section of said body portion conforming to and being a close fit in said cross-section of said tubular waveguide,
(f) said cross-section of said tubular waveguide being constant throughout said length of said wedge formation, said wedge formation being non-critically positioned longitudinally along and within said tubular waveguide, and
(g) said wedge formation of said rod of dielectric material effecting a differential phase-shift between orthogonal components of each of said orthogonal plane-polarized waves for conversion between plane and non-plane polarization.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/070,063Filed 6 Jul 1987 · continuation
Priority: GB 842110220 Aug 1984
Granted: 15 Nov 1988
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

H01Q 13/24
Non-resonant leaky-waveguide or transmission-line antennas; Equivalent structures causing radiation along the transmission path of a guided wave:…
H01P 1/172
For producing a continuously rotating polarisation, e.g. circular polarisation: using a dielectric element
H01Q 13/0241
Waveguide horns: radiating a circularly polarised wave
H01Q 19/08
Using refracting or diffracting devices, e.g. lens: for modifying the radiation pattern of a radiating horn in which it is located