US 5,471,177 AGranted

Octave band gap diplexer

AssigneeHughes Aircraft Company

InventorsThomas Hudspeth, Fritz Steinberg

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Abstract

A diplexer (14) has a first rectangular waveguide (38) extending from a front port (16) to a back wall (70), the back wall having a rectangular opening (72) therein constituting a section of a second rectangular waveguide (20) and serving as a back port (18) of the diplexer. A first spectral region of electromagnetic power communicates between the front port and a side port (28), and a second spectral region of electromagnetic power communicates between the front port and the back port. A center frequency of the second spectral region is greater than a center frequency of the first spectral region by a factor greater than or equal approximately to two. The side port includes an aperture (126) disposed in a sidewall (42) of the first waveguide, a third waveguide (32), and a coupling element (128) extending from the third waveguide through the aperture into the first waveguide for coupling electromagnetic power at the first spectral region between the first and the third waveguides. Coupled resonators (112, 124) disposed within the third waveguide provide a bandpass filter characteristic at the first spectral region, and inhibit propagation of electromagnetic power at the second spectral region between the first and the second waveguides. Within the inner conductor are two spaced apart cylindrical elements (100, 112) constituting plates of a capacitor (102).

Claims19

Dependent claims

A diplexer having a front port and a back port and a side port for communicating a first spectral region of electromagnetic power between said front port and said side port and a second spectral region of electromagnetic power between said front port and said back port, wherein a center frequency of said second spectral region is greater than a center frequency of said first spectral region by a factor greater than or equal approximately to two, the diplexer comprising:

a first waveguide and a second waveguide each having a rectangular cross section and supporting a transverse electric mode of electromagnetic wave, said first waveguide having a cut-off frequency below said first spectral region, said second waveguide having a cut-off frequency below said second spectral region and above said first spectral region;
a back wall terminating said first waveguide, said back wall having an opening through which said second waveguide extends for communicating with said first waveguide, said opening having cross sectional dimensions smaller than corresponding cross sectional dimensions of said first waveguide, said opening serving as said back port, said back wall serving as a shorting element to inhibit propagation of radiation at said first spectral region into said second waveguide, an end of said first waveguide opposite said back wall serving as said front port;
and
wherein said side port comprises an aperture disposed in a sidewall of said first waveguide, a third waveguide, and a coupling element extending from said third waveguide through said aperture into said first waveguide for coupling electromagnetic power at said first spectral region between said first and said third waveguides;
and
tuning means disposed within said third waveguide for inhibiting propagation of electromagnetic power at said second spectral region between said first and said third waveguides.

3 more elements

Dependencies are inferred from the claim text.