EP2296218A1

EP2296218A1 - Uncalibrated metal diaphragm antenna diplexer

Info

Publication number: EP2296218A1
Application number: EP10176357A
Authority: EP
Inventors: Paolo Vigano'
Original assignee: TVC SpA
Current assignee: MICROWAVEFILTERS & TVC S.R.L.
Priority date: 2009-09-15
Filing date: 2010-09-13
Publication date: 2011-03-16

Abstract

An antenna diplexer of an uncalibrated metal diaphragm type, comprising an outer casing (2) made of a metal conductive material therewithin is arranged a metal reed element longitudinally extending with respect to said diplexer and thereon are formed a plurality of diaphragm elements (6) defining resonating cavities (7) therebetween, on said casing (2) being moreover provided signal input/output guides (8, 9) and a T-shape joint (5), characterized in that the first/last resonating cavity (7a) is formed at said input/output guide (8, 9).

Description

BACKGROUND OF THE INVENTION

The present invention relates to an improved antenna diplexer of an uncalibrated metal diaphragm type.
The field of the invention is that of the so-called antenna diplexers, which are devices for conveying microwave signals from a transmitter to an antenna and, respectively, from an antenna to a receiver.
In particular, in an uncalibrated metal diaphragm antenna diplexer, it is necessary to properly compensate for the size tolerances which could negatively affect, mainly at a diaphragm measurement level, the diplexer performance (with respect to the bandwidth, and mating, and central frequency requirements, and so on ...).
At present, the number of filter cavities depends on the overall size of the diplexer, which is in turn related to the size of the system said diplexer is coupled to.
Thus, because of the above reason, given a diplexer preset standard size, the diplexer performance are firstly set, thereby the diplexer operating performance cannot be further improved.

SUMMARY OF THE INVENTION

Accordingly, the main object of the present invention is to provide a novel metal uncalibrated diaphragm diplexer, which, with respect to prior like diplexer arrangements, has a very improved selectivity and bandwidth, the diplexer size being the same.
The above mentioned object as well as yet other objects are achieved by the inventive diplexer as claimed in claim 1.
Preferred embodiments of the invention are disclosed in the accompanying claims.
With respect to prior uncalibrated metal diaphragm diplexers, the inventive diplexer provides the advantage that it may include, the distance between the diplexer input/output parts being the same, an increased number of resonating cavities.
Thus, it is possible to achieve either a greater diplexer selectivity or, alternatively, an enlarged band, the selectivity being the same.
Moreover, the inventive diplexer is adapted to easily compensate for its constructional tolerances, while holding a very good operating performance, thereby the inventive diplexer may be made in a very simple manner and at a very low cost.

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned objects, advantages and features of the present invention will become more apparent hereinafter from the following detailed disclosure of a preferred embodiment of the invention, which is illustrated, by way of a non limitative example, in the figures of the accompanying drawings, where:

Figure 1 shows an example of an uncalibrated metal diagram diplexer of the prior art;
Figure 2 is a perspective view showing a schematic diagram of the diplexer according to the present invention;
Figure 3 is a top plan view showing the inventive diplexer of figure 2;
Figure 4 is a further perspective view showing a detail of a bent portion of the diplexer shown in figure 2;
Figures 5 and 6 show the enlarged detail A of figure 3, respectively with an enlarged and narrowed configuration of the waveguide sidewalls, at its T joint; and
Figure 7 is another perspective view showing the inventive diplexer in its assembled condition.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In figure 1, a prior diplexer has been generally indicated by the reference number 1. Such a prior diplexer comprises a metal casing 2 forming the diplexer rectangular waveguide, said casing including crank or bent portions 3 and 4 of the transmitter and receiver respectively, and a T joint 5 for connecting the diplexer to the antenna.
As shown, at the bent portions 3 and 4, related input/ output guides 8 and 9 are further provided on said casing 2.
Said casing 2 also includes a conductive metal reed element, longitudinally extending with respect to the diplexer, thereon the diplexer diaphragms 6 defining therebetween the filter resonating cavities 7 are formed.
As it should be apparent, in the above prior diplexer, the first resonating cavity 7a of the corresponding filter (either a receiving or a transmitting filter, as shown by the dashed line in figure 1) formed by the first diaphragm 6a is arranged at the end of the crank construction (either downstream or upstream of the latter, depending on the transmitting or receiving branch of the filter).
Thus, the diplexer spaces occupied by the crank or bent portions 3 and 4 do not contribute to improving the filter performance, since these spaces are "passive" spaces from a signal processing standpoint.
Accordingly, the prior diplexer performance are just limited to those provided by the resonating cavities arranged between the crank 3 (or 4) and the T joint 5.
In figure 2, the inventive diplexer has been generally indicated by the reference number 10, and also comprises a quadrangular metal conductive material casing 2, including signal input/ output guides 8 and 9, and a T joint 5.
Said casing 2 further includes a conductive material reed element, with a plurality of diplexer diaphragms 6, therebetween resonating cavities 7 are formed.
According to the invention, the first (or last) resonating cavity 7a is formed at said signal input/ output guides 8 and 9, said first (or last) resonating cavity 7a being defined at the height of the iris pattern 11 provided on the coupling section of the corresponding guides 8, 9 in the waveguide 2, as is clearly shown by the dashed line in figure 3.
More specifically, as shown in figure 4, the iris pattern 11 interconnecting the guides 8, 9 and cavity 7a is arranged on the longitudinal axis 12 (or on an axis parallel to said longitudinal axis) of said guide 8 or 9, in turn perpendicular to the longitudinal axis 13 of the diplexer casing 2.
Thus, differently from the prior diplexer of figure 1, in the interspace between the T joint 5 and guide 8, instead of a prior crank 3 (or 4) the first (or last) resonating cavity 7a is arranged.
Consequently, in that same useful space of the filters, an additional resonating cavity is formed, which may be used either for increasing the filter selectivity, or for enlarging the passband, the selectivity being the same.
In this latter case, in particular, the diplexer construction of figure 2 may be adapted to compensate for, the size being the same, the size errors caused by mechanical machining operations.
To render the longitudinal size of the diplexer individual filters compatible with the interaxes of distance b.c between the respective waveguides 8, 9 and the T joint 5 (Fig. 3), and to meet the required offband reflection conditions of the individual filters, the distance or width between the sidewalls 18 and 19 of the waveguide, at the level of the T joint 5, is selected so as to properly change.
More specifically, and as it is clearly shown in figures 5 and 6, it is possible to either provide walls 14, 15 separated from one another by a distance a' greater than the distance a existing between the filter construction walls 18 and 19, or further walls 16, 17 spaced by a distance a" less than said distance a.
In particular for a set longitudinal size of the two diplexer filters with a related cavity built-in in the diplexer bent portions or cranks:

if the interaxes b.c between the filter waveguides are less than the rated interaxes to provide a set electric performance of the T joint 5, then it will be necessary to increase the width of the waveguide at said T joint by providing walls 14 and 15 spaced by a distance a' larger than that a existing between the filter walls 18, 19;
if, on the contrary, the interaxes b.c are larger than the set or rated value thereof, with respect to the length available for the T joint 5, then the width of the waveguide on that same joint will be narrowed, by providing, to that end, walls 16, 17 at a distance a" less than the distance a existing between said filter walls 18 and 19.

Thus, the optimum electric lengths for each branch of said T joint 5 will be easily fitted to the available interaxes measurement, by either increasing or reducing the waveguide widths at the level of said T-joint.

Claims

An antenna diplexer of an uncalibrated metal diaphragm type, comprising an outer casing (2) made of a metal conductive material therewithin is arranged a metal reed element longitudinally extending with respect to said diplexer and thereon are formed a plurality of diaphragm elements (6) defining resonating cavities (7) therebetween, on said casing (2) being moreover provided signal input/output guides (8, 9) and a T-shape joint (5), characterized in that the first/last resonating cavity (7a) is formed at said input/output guide (8, 9).
An antenna diplexer, according to claim 1, characterized in that said first/last resonating cavity (7a) is interconnected to said input/output guides (8, 9) at an iris pattern (11) thereof.
An antenna diplexer, according to claim 2, characterized in that said iris pattern (11) is arranged on a longitudinal axis (12) of said guides (8, 9), or on an axis parallel to said longitudinal axis, and being perpendicular to the longitudinal axis (13) of said antenna diplexer casing (2).
An antenna diplexer, according to one or more of the preceding claims 1 to 3, characterized in that said antenna diplexer further comprises a variable width wave guide (a', a") at said T joint (5) the width thereof may be changed with respect to the width (a) of the diplexer filters.
An antenna diplexer, according to claim 4, characterized in that said antenna diplexer comprises moreover, at said T joint (5), side walls (14, 15) spaced by a distance (a') larger than the distance (a) of the walls (18, 19) of said filters.
An antenna diplexer, according to claim 4, characterized in that said antenna diplexer comprises moreover, at said T joint (5), side walls (16, 17) spaced by a distance (a") less than the distance (a) existing between said walls (18, 19) of said filters.