Patent ID: 6839037
Filing Date: 2005-01-04
Classification: H01P

Abstract:
1. A dual probe waveguide structure for use in a LNB (low noise block) for receiving a left (L) and a right (R) circularly polarised electromagnetic radiation signal and for converting the circularly polarised signals into linearly polarised signals, the waveguide structure comprising a waveguide housing of a substantially symmetrical cross section, said waveguide housing having a front aperture and a rear waveguide wall, wherein the waveguide wall is provided by a ground plane of a circuit board disposed at the end of the waveguide, a septum disposed within the housing and coupled to the rear waveguide wall and the housing to separate the waveguide into two waveguide compartments, one compartment for receiving and converting the left circular polarisation signal into a first linearly polarised signal and the other compartment for receiving and converting the right circular polarised signal into a second linearly polarised signal orthogonal to the first linearly polarised signal, a first probe extending into said first waveguide compartment from the rear waveguide wall and a second probe extending into the second rear waveguide compartment from the second waveguide wall the first and second probes each having a free end, the probes being oriented and arranged such that the free ends of the probes are disposed in proximity to the waveguide wall or septum in each respective compartment such that the probes capacitively couple into the magnetic field of the primary or fundamental waveguide mode in the waveguide compartment.