AU706590B2

AU706590B2 - Waveguide-coaxial converter

Info

Publication number: AU706590B2
Application number: AU37946/95A
Authority: AU
Inventors: Keiichi Umezu
Original assignee: NEC Corp
Current assignee: NEC Corp
Priority date: 1994-11-28
Filing date: 1995-11-20
Publication date: 1999-06-17
Anticipated expiration: 2015-11-20
Also published as: TW301815B; CA2163323C; CA2163323A1; AU3794695A; JPH08154008A; EP0715368A1; CN1041583C; CN1127435A

Description

iA WAVEGUIDE-COAXIAL CONVERTER BACKGROUND OF THE INVENTION 1. Field of the Invention: The present invention relates to a waveguidecoaxial converter used in connecting a coaxial line and a square waveguide used in a communication device, and particularly to waveguide-coaxial converter provided with a connector for a coaxial line connection at a prescribed portion of a square waveguide.

2. Description of the Related Art: Waveguide-coaxial converters having a low-pass filter for eliminating higher harmonics are known in S' the art. The configuration of one example of such a waveguide-coaxial converter is shown in Fig. 1, which 15 shows a coaxial low-pass filter 8 connected by means of a connector 2 to a wide outer wall portion in the vicinity of the terminal portion of a square waveguide 1, or as shown in Figs. 2A and 2B, which show a waveguide low-pass filter 9 having fine sorted blocks 20 10 provided on the inner wall of the waveguide.

However, as in the case of the coaxial type shown in Fig. 1, waveguide-coaxial converters of the abovedescribed prior art having an independent coaxial lowpass filter 8 provided on the wide outer wall surface of the waveguide-coaxial converter results in a bulky shape, and this presents difficulties in miniaturization. Further, in the case of the waveguide low-pass filter 9 shown in Figs. 2A and 2B, the necessity for precise machining of the fine blocks 10 results in difficulties in manufacturing.

SUMMARY OF THE INVENTION The object of the present invention is to provide a waveguide-coaxial converter having low-pass filter functions that features simple and compact construction.

According to one aspect of the present invention there is provided a waveguidecoaxial converter comprising: a square waveguide having a passage formed therein to penetrate a side wall thereof and communicate with a cavity thereof; a connector positioned in a portion of said passage such that a core conductor of a substantially uniform thickness passes through said passage, and is directed toward said cavity; S: 15 a low-pass filter made up of a plurality of joined conductors of differing impedance, and positioned at a portion of said core conductor of said passage; and a columnar insulative support member having an outer diameter equal to the diameter of said passage, passing through said passage and secured to said square waveguide, said core conductor extending through said low-pass filter, and protruding from °the inner wall of said square waveguide and into said cavity a distance matching a pass band, said core conductor connector and said low-pass filter being secured inside said insulative support member.

The above and other objects, features, and advantages of the present invention will become The next page is page 4 [R:\LIBpp]02239.doc:JJP EDITORIAL NOTE NUMBER 37946/95 THIS SPECIFICATION DOES NOT CONTAIN A PAGE NUMBERED "3" 4 apparent from the following description based on the accompanying drawings which illustrate examples of preferred embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view showing a waveguidecoaxial converter of the prior art with an added coaxial low-pass filter; Fig. 2A and Fig. 2B are a sectioned frontal view and a plan view, respectively, of one portion of a prior-art waveguide-type low-pass filter; Fig. 3 is a sectional view of an embodiment of a waveguide-coaxial converter according to the present invention, and Fig. 4 is an enlarged partial view of Fig. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to Fig. 3, according to an embodiment of the waveguide-coaxial converter of the present invention, a connector 2 for connection to an unshown exterior coaxial line is arranged at a prescribed 20 position on the outer wall of a square-waveguide 1, the waveguide at the position of arrangement of this connector having a greater wall thickness, and a passage being formed that communicates with a cavity 12 in the square waveguide 1. In addition, a columnar 5 insulative support, for example a Teflon support 5 made from PTFE (Polytetrafluoroethylene; commercial name: Teflon) having an outer diameter equal to the diameter of the passage 11 is inserted into the passage 11 and secured to the square waveguide 1.

One end surface portion of the Teflon support 5 is directed toward the connector 2, the other end surface portion directly contacts the inner wall of the square waveguide opposing the passage 11, and in the interior of the Teflon support 5 are secured a.low-pass filter 3 and an antenna conductor 4 protruding from the inner wall of the square waveguide and into the waveguide cavity 12 a distance exactly matching the pass band, the low-pass filter 3 and the antenna conductor 4 being formed in a unit with the core conductor of the connector 2. The antenna conductor 4 extracts those microwaves propagated inside the square waveguide 1 that are in the pass band of the low-pass filter 3, and the position, shape and material of the antenna conductor 4 20 are matched to the above-described pass band.

As shown in Fig. 4, the low-pass filter 3 is constructed by connecting alternating high-impedance portions 6 and low-impedance portions 7 arranged in the axial direction of the coaxial line in the passage position of the core conductor of the connector 2. The difference between the high-impedance portions 6 and 6 low-impedance portions 7 is determined by the shape and construction of the conductor for their employed frequencies, and can be freely set in accordance with the pass-band.

Because the core conductor of the connector 2 combines both a low-pass filter 3 and antenna conductor 4, and moreover, because the low-pass filter 3 and antenna conductor 4 are held by a Teflon support arranged inside the square waveguide i, a waveguidecoaxial converter of this type of configuration is more compact overall and has a simpler structure and fewer parts than the construction shown in Fig. 1 in which a low-pass filter is added. In addition, this construction is easier to manufacture than a waveguide-type *e*e 15 low-pass filter such as is shown in Fig. 2.

o The present invention is not limited to the above-described embodiment and allows a variety of S"modifications. For example, the insulative support may be formed from materials that do not affect microwaves other than that of the Teflon support 5, and the shape and construction shown in Fig. 3 and Fig. 4 need not be adopted as long as the material of the support is strong and secure. In addition, the structure of the low-pass filter 3 joined to the core conductor of the connector 2 is not necessarily restricted to the structure shown in the figures.

7 While a preferred embodiment of the present invention has been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.

-8- The claims defining the invention are as follows: 1. A waveguide-coaxial converter comprising: a square waveguide having a passage formed therein to penetrate a side wall thereof and communicate with a cavity thereof; a connector positioned in a portion of said passage such that a core conductor of a substantially uniform thickness passes through said passage, and is directed toward said cavity; a low-pass filter made up of a plurality of joined conductors of differing impedance, and positioned at a portion of said core conductor of said passage; and a columnar insulative support member having an outer diameter equal to the diameter of said passage, passing through said passage and secured to said square waveguide, said core conductor extending through said low-pass filter, and protruding from the inner wall of said square waveguide and into said cavity a distance matching a pass 15 band, said core conductor connector and said low-pass filter being secured inside said insulative support member.

2. A waveguide-coaxial converter according to claim 1 wherein the end surface of said insulative support member on the side of said cavity directly contacts the inner wall of said square waveguide.

3. A waveguide-coaxial converter substantially as herein described with reference to Figs. 3 and 4.

DATED this twenty-second Day of March, 1999 NEC Corporation Patent Attorneys for the Applicant SPRUSON FERGUSON [R:\LIBp]02239.doc:JJP