Wave transmission lines and networks – Plural channel systems – Having branched circuits
Patent
1994-05-02
1997-04-08
Lee, Benny T.
Wave transmission lines and networks
Plural channel systems
Having branched circuits
343756, 333 21A, 333137, H01P 1161, H01P 1165
Patent
active
056191731
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a dual polarisation waveguide probe system for use with a satellite dish for receiving signals broadcast by a standard satellite which includes two signals orthogonally polarised in the same frequency band. In particular, the invention relates to a waveguide for use with a low-noise block receiver into which two probes are disposed for coupling from the waveguide desired broadcast signals to external circuitry.
DESCRIPTION OF THE RELEVANT PRIOR ART
In one prior art arrangement the two probes are axially separated along the length of the waveguide. Because the desired signals are orthogonally polarised to each other, the two probes are also located in the waveguide at 90.degree. to each other. In this arrangement a reflective post is located between the two probes, but parallel to the first probe and spaced therefrom by a quarter wavelength distance assuming a maximum field and optimum coupling to the probe. With this structure the geometry is such that the probe output terminals on the outside of the waveguide are at 90.degree. to each other. This provides a mechanical problem in connecting the probe outputs directly to a planer printed circuit board. A further problem is that inadequate connection between probe and printed circuit board could cause increased losses at the frequencies involved which are about 10-11 GHz.
In a second prior art arrangement the two probes are located at the same axial position along the waveguide, but are at 90.degree. to each other by virtue of being printed on the circuit board and are separated by a isolation patch, also printed on the circuit board, to provide the necessary isolation between the collected signals. With this arrangement the circuit board effectively splits the waveguide into two parts and this results in increased mechanical complexity. In addition, this arrangement of the two probes at the same axial location does not provide as good an isolation between the orthogonal signals as does the axially separated probe arrangement.
In another prior art arrangement the two probes are located at 90.degree. at the same axial location in a single waveguide section. With this structure the output terminals of the probes are also at 90.degree. to each other around the outside of the waveguide and suffers from the same disadvantages as the first prior art arrangement. It also suffers from some of the disadvantages of the second prior arrangement, namely that the provision of the two probes at the same axial location does not provide as good an isolation between the orthogonal signals as does the axially separated probe arrangement.
An object of the present invention is to obviate or mitigate at least one of the aforementioned disadvantages.
This is achieved by providing a waveguide which allows two co-axial or printed probes disposed in the same plane to be used in such a manner that one probe receives linearly polarised energy of one sense and the other probe receives linearly polarised energy of the orthogonal sense.
The waveguide may be circular or non-circular cross-section, for example, square. It also may be of uniform cross-section along its length or the cross-section may vary slightly. In a preferred embodiment the cross-sectional is symmetrical, i.e. circular or square.
In one embodiment a single cylindrical bar is used as the reflector means which reflects one sense of polarisation and passes the orthogonal signal with minimal insertion loss, and then reflects the rotated orthogonal signal. In an alternative embodiment a separate reflector means may be used for each probe, both reflector means being parallel and spaced apart in the same longitudinal plane and being separated from their respective probes by .lambda./4 (a quarter of the wavelength of interest).
A reflection rotator is also formed using a similar cylindrical bar which is orientated at 45.degree. to the incident linear polarisation with a short circuit spaced approximately a quarter wavelength (.lambda./4) behind it. This structure splits the incident energy in
REFERENCES:
patent: 4596047 (1986-06-01), Watanabe et al.
patent: 5374938 (1994-12-01), Hatazawa et al.
Baird Andrew P.
Flynn Stephen J.
King Gerard
Cambridge Computer Limited
Lee Benny T.
LandOfFree
Dual polarization waveguide including means for reflecting and r does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Dual polarization waveguide including means for reflecting and r, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dual polarization waveguide including means for reflecting and r will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2399912