Waveguide coupler

Details Waveguide coupler Waveguide coupler

1999-10-15

2001-11-06

Pascal, Robert (Department: 2817)

Wave transmission lines and networks

Plural channel systems

Having branched circuits

C333S02100R, C333S137000

Reexamination Certificate

active

06313714

ABSTRACT:

FIELD OF THE INVENTION
The present invention pertains to a waveguide coupler. More particularly, the present invention pertains to a square symmetric orthomode waveguide coupler for wide band cellular applications.
BACKGROUND OF THE INVENTION
Modern communication techniques have increased the amount of high frequency radio communication significantly. By way of examples, cellular phones and Internet communication have added a considerable number of high frequency radio transmissions. Cellular phones and Internet communication involve transmission of signals from a ground location to a satellite, and retransmission of the signals from the satellite to another ground location either directly or by way of one or more other satellites. The usage is compounded, since both cellular phones and Internet communication involve two-way communication. The satellite functions of up link signal reception and down link signal transmission within a coverage area using reflector antenna systems require feed systems capable of supporting dual frequency and dual sense polarization. The down link signal transmission is generally at a fairly high power, and so requires low power loss. In addition, the ability to cover a band of from 17.5 GHz to 20 GHz is needed. As a result of all this, wider bandwidth is highly desirable.
SUMMARY OF THE INVENTION
The present invention is a square symmetric orthomode waveguide coupler which allows broad band down link dual sense polarization transmission at one frequency band, while simultaneously accepting up link dual sense polarization signal transmission at another frequency band. The present invention takes advantage of the increased separation distance with respect to frequency between the dominant TE
01
rectangular waveguide mode and that of the next higher order rectangular waveguide mode relative to that of the separation distance and frequency between the dominant TE
11
circular waveguide mode and the next higher order circular waveguide mode. Consequently, the square symmetric orthomode coupler of the present invention can operate over a wider frequency band then can a circular symmetric orthomode coupler. Furthermore, the rectangular waveguide circular polarized TE
01
mode created by the square symmetric orthomode waveguide coupler of the present invention can in turn be used to create broad band circularly polarized dominant TE
11
modes in a circular waveguide of the same bandwidth.
A first embodiment of the waveguide coupler of the present invention has a substantially square cross-section of a width which tapers from a first width at a first end to a second, smaller width at a second end. Each side of the square waveguide coupler is provided with a turnstile port to couple signals throughout the entire lower frequency band to or from a first waveguide connected to the first end of the waveguide coupler. In addition, signals throughout the higher frequency band can be coupled through the waveguide coupler from the first waveguide to a second waveguide connected to the second end of the waveguide coupler, and signals within the covered frequency band can be coupled from the second waveguide to the first waveguide.
In a second embodiment, the waveguide coupler of the present invention includes a first waveguide coupling section having a first end with a substantially circular cross-section and a second end with a substantially square cross-section. This second embodiment also includes a second waveguide coupling section having a substantially square cross-section with a width which tapers from a first width at a first end to a second, smaller width at a second end and with a turnstile port in each side thereof. This second waveguide coupling section is thus of a design similar to the design of the first embodiment of waveguide coupler. The first end of this second waveguide coupling section is connected to the square end of the first waveguide coupling section, preferably through a square intermediate section extending from the first waveguide coupling section square end. Signals throughout the entire lower frequency band can be coupled to and from the turnstile ports to a circular waveguide connected to the circular end of the first waveguide coupling section. In addition, signals throughout the entire higher frequency band can be coupled through the waveguide coupler from the circular waveguide to a second, square waveguide connected to the second end of the second waveguide coupling section, and signals within the covered frequency band can be coupled from the second, square waveguide to the first, circular waveguide.


REFERENCES:
patent: 3978434 (1976-08-01), Morz et al.
Farr, Mode Converter (Abstract) (No. 576,842), vol. 659, p. 587, Official Gazzette, Jun. 10, 1952.*
“Wide-Band Communication Satellite Antenna Using a Multifrequency Primary Horn;” Hiroyuki Kumazawa, Masaki Koyama and Yoshio Kataoka;IEEE Transactions on Antennas and Propagation, May 1975; pp. 404-407.

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