Bell Telephone Laboratories

At&t Bell Laboratories

Chung-Li Ren

Han-Chiu Wang

Michael J Gans

Adolf J Giger

Francis G Joyal

Matthew V Thompson

In an angle diversity receiving system, the primary and diversity signals are produced by a waveguide signal separator coupled to a single receiving antenna. The separator operates by converting selective higher order modes in the antenna into fundamental modes that will propagate in its two output waveguides. The result is a robust system that operates over a frequency band wide enough to cover both the 4 GHz and 6 GHz common carrier bands with both horizontally and vertically polarized signals, and that can use a wide variety of antennas.

Angle diversity signal separator using mode conversion

An insertion filter is described for existing waveguide without modification. The filter includes a resilient bifurcated dielectric member (11) which conforms to the internal geometry of the waveguide (21). The dielectric member secures the position of a dielectric resonator (15) and a tuning screw (17) and retains their relative positions. A stud (18) is mounted on one of the bifurcations of the dielectric member to compensate electrically for the presence of the member in the waveguide while the dielectric resonator attenuates waveguide energy in a prescribed frequency band.

Filter for existing waveguide structures

Bandstop (FIGS. 1-3) and bandpass (FIGS. 4, 5) filters are presented utilizing broad and narrow wall resonator coupling in a rectangular waveguide (11 and 37) at a common cross sectional reference plane. For the bandstop filter, the resonators (12, 13) are resonant at a common frequency f.sub.0 to provide a two-pole bandstop response in a filter of minimal longitudinal dimensions. For the compact bandpass filter, each tone rejection is provided by a pair of resonators (31, 35) coupling to the electromagnetic field signal at two points one from a broad wall and the other from a narrow wall of the waveguide (37) but displaced by some multiple of a half wavelength. Another pair of resonators (33, 34) are in common cross sectional plane relationship to the first pair but located on a wall of different width to provide rejection of a tone at the other end of the passband. The use of resonators with different resonant frequencies at a common cross sectional plane avoids possible interresonator coupling. Additional pairs of resonators (e.g., 32, 36) may be interleaved with these resonator locations. Each resonator (e.g., 13) is associated with an aperture (e.g., 19) and has its major portion extending into a housing (e.g., 18) located exterior to the waveguide (e.g., 11).

Waveguide filter employing common phase plane coupling

A 90 degree phase stepper is described comprising a tandem array of three, 3 db hybrid couplers where the first and third couplers are of one variety (either 90 degree or 180 degree couplers) and the second is of the other variety. A pair of variable phase shifters are located in the two wavepaths connecting the first and second couplers, and a single variable phase shifter is included in one of the two wavepaths connecting the second and third couplers. Each phase shifter introduces either a zero or a 180 degree phase shift. By the appropriate selection of phase shifts, the phase of the output signal can be stepped in 90 degree increments. The stepper is designed for use in the signal combining circuit of a space diversity system. It is an advantage of the circuit that all of the received signal is preserved.

Ninety degree phase stepper

A waveguide bandstop filter is described. Two ceramic dielectric disc resonators each having a resonant frequency f.sub.0 and separated by 3/4.lambda.go, where .lambda.go is the wavelength at f.sub.0, are each disposed in individual apertures in the waveguide wall. The substantial portion of each resonator is exterior to the waveguide cavity and surrounded by a metallic housing which isolates each resonator from each other. The resonators are oriented so that a coupling arrangement exists between the electromagnetic energy propagating through the waveguide and each resonator so that a resonant mode is excited therein at frequency f.sub.0.

Waveguide filter employing dielectric resonators

A launching and/or receiving network is disclosed capable of coupling radio signals in a first frequency band, e.g., 2 GHz into and/or out of an existing antenna system without perturbing the signals being transmitted in other frequency bands, e.g., 4, 6 and/or 11 GHz. The first frequency band signal is launched through an evanescent mode waveguide filter which is both coupled to the flared sidewall of a feedhorn through an H-plane, T-junction, and provides a very broad stopband for the signals in the other frequency bands being launched in the feedhorn. To minimize mode conversion for the signals in the other frequency bands, a dummy evanescent mode waveguide filter is connected at one end thereof to the feedhorn facing the first frequency band launching network and at the other end thereof to a matched load through a waveguide section. A second launching and/or receiving network can be similarly coupled to the feedhorn in a plane normal to the first network to permit a different orthogonally polarized beam, at the first frequency band, to be simultaneously transmitted and/or received by each of the two networks.

Growing community of inventors

Andover, MA, United States of America

Chung-Li Ren