| Title of Invention | A PLANAR WAVE GUIDE BASED COMPARATOR FOR MONOPULSE APPLICATION IN PARTICULAR IN KA BAND |
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| Abstract | A planar waveguide based comparator for monopulse application In particular in Ka band, comprises a basic building block of planar waveguide Tee junction, the e-plane junction arm being provided with an impedence matching means (Im), at least four input ports for connecting the output ports of an antenna, and at least three output ports for outputting signal relating to difference azImuth, difference elevation and sum of the inputted signal via the input ports, the device features restricting the thickness of the comparator ( c) below 20mm at Ka frequency. |
| Full Text | 2 FIELD OF THE INVENTION This invention relates to a planar wave guide based comparator for monopluse application. BACKGROUND OF THE INVENTION Monopulse is a method of determining the angular location of a source of radiation or of a target that re radiates a part of the energy incident upon it. Monopulse tracking technique is of two types i) phase comparison and ii) amplitude comparison. In amplitude comparison monopulse technique, an angle information is obtained by amplitude comparison of signals from quadrant outputs of an antenna or adjacent antennas. A comparator when connected to the output ports of the antenna generates a 'sum signal' by combining in phase the energy received from all the four quadrants forming the antenna. 'Difference signal' is obtained by combining the signal in adjacent quandrants 180° out of phase. On the axis, the difference signal is zero, since all the quandrants receive equal power. If an error in positioning the antenna in the target direction is present, a finite difference signal exists. The amplitude of the difference signal is proportional to the position error. A comparator is thus a very important and an integral part of an antenna for monopluse application. It is basically an assembly of wave- guide Tee junctions suitably arranged as shown in Fig. 1 to provide a sum and two difference outputs. A waveguide Tee junction, also called a magic Tee, is a combination of E plane Tee and H plane Tee as shown in Fig. 2. Waveguide dimensions in the comparator are chosen to support only TEio mode propagation. E field in the arm 1 is normal to a field in the arm 4. There is, therefore, no direct 3 transmission between the arms I fit 4 when these are symmetrically placed. The characteristics of E-plane and H-plane Tees are such that when the waves enter the arms 2 & 3, the output of the arm 4 is proportional to the phase difference of the inputs through the arms 2 & 3. Output of the arm 1 is proportional to the phase sum of the inputs through the arms 2 & 3. If the arms 2 & 3 are terminated in matched loads and no reflection takes place within the junction, the power fed through either arm 1 or 4 will result in equal power division (-3 dB) to the arms 2 & 3. Reflections, however, do take place at the junction because of discontinuities, and affects the performance. Thus, a proper matching is necessary to avoid reflection at the junctions. OBJECTS OF THE INVENTION An object of the invention is to propose a planar wave guide based comparator for monopulse application. Another object of this invention is to propose a planar wave guide based comparator having thickness Yet another object of this invention is to propose planar wave guide based comparator which is compact and can be adapted for integration to appropriate antenna for monoptuse application. Further, object of this invention is to propose planar wave guide based comparator highly suitable for application where volume and weight are constraint as in airborne vehicles. 4 BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS FIG. 1 - shows a monopluse comparator of prior art, FIG. 2 - shows a wave guide magic Tee-injection according top the prior art. FIG. 3 - shows a planar waveguide magic Tee junction according to the present invention. FIG. 4 -shows the planar wave guide comparator. DETAILED DESCRIPTION OF A PREFERRED ENBODIEMNT OF THE INVENTION As shown in fig - 2, a magic Tee normally has vertical projection along the E plane arm, which increases it's is overall thickness. In certain applications, where space and weights are practical constraints, thickness has to be kept at minimum. This calls for configurating a planar version of a magic Tee and a comparator. A planar version of magic tee for use in a comparator to meet the specifications for example, amplitude and phase imbalance, isolation between the direct and the coupled ports and broad-band matching, requires an impedance matching technique. As shown in Fig - 4, a planar waveguide version of a comparator (c) for mono-pulse application at Ka-band has been provided with Tee-junction. The basic building block is a planar waveguide Tee junction as shown in Fig - 3. An impedance matching means (Im) at the E-plane junction arm has been provided 5 for hardware realization of a planar version of the comparator (c). The comparator (c) has four input ports where antenna output ports are to be connected for mono-pluse application. The comparator (c) has three output ports for sum, difference azimuth and difference elevation. The most salient feature of the comparator is its planar version, total thickness being less than 20 mm at Ka frequency band. There is scope for further reduction in thickness depending on practical requirements. 4. TYPICAL TEST RESULTS OF COMPARATOR: I) Frequency : Ka-Band n) Amplitude imbalance among output ports : +/- 0.3dB HI) Phase imbalance among output ports ; +/- 3.0 degree IV) VSWR at Centre frequency) : V) Isolation between a) Sum and Difference Azimuth port : Better Than - 30dB b) Sun and difference Elevation port : Better than -30dB c) Difference ports : Better than - 30dB c) 6 WE CLAIM 1. A planar waveguide based comparator for monopulse application in particular in Ka band, comprising :- - a basic building block of planar waveguide Tee junction, the E- plane junction arm being provided with an impedence matching means (Im); - atfeast four input ports for connecting the output ports of an antenna; and - atleast three output ports for outputting signal relating to difference azimuth, difference elevation and sum of the inputted signal via the input ports, the device features restricting the thickness of the comparator (c) below 20 mm at Ka frequency. 2. A planar waveguide based comparator for monopulse application in particular in Ka band as substantially described herein with reference to the accompanying drawings. A planar waveguide based comparator for monopulse application In particular in Ka band, comprises a basic building block of planar waveguide Tee junction, the e-plane junction arm being provided with an impedence matching means (Im), at least four input ports for connecting the output ports of an antenna, and at least three output ports for outputting signal relating to difference azImuth, difference elevation and sum of the inputted signal via the input ports, the device features restricting the thickness of the comparator ( c) below 20mm at Ka frequency. |
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00121-kol-2005 correspondence-1.1.pdf
00121-kol-2005 correspondence.pdf
00121-kol-2005 description(complete).pdf
00121-kol-2005 description(provisional).pdf
121-KOL-2005-CANCELLED PAGES 1.1.pdf
121-KOL-2005-CANCELLED PAGES.pdf
121-KOL-2005-CORRESPONDENCE.pdf
121-KOL-2005-DESCRIPTION (COMPLETE) 1.1.pdf
121-KOL-2005-EXAMINATION REPORT.pdf
121-KOL-2005-GRANTED-ABSTRACT.pdf .pdf
121-KOL-2005-GRANTED-CLAIMS.pdf
121-KOL-2005-GRANTED-DESCRIPTION (COMPLETE).pdf
121-KOL-2005-GRANTED-DRAWINGS.pdf
121-KOL-2005-GRANTED-FORM 1.pdf
121-KOL-2005-GRANTED-FORM 2.pdf
121-KOL-2005-GRANTED-FORM 3.pdf
121-KOL-2005-GRANTED-FORM 5.pdf
121-KOL-2005-GRANTED-LETTER PATENT.pdf
121-KOL-2005-GRANTED-SPECIFICATION-COMPLETE.pdf
121-KOL-2005-PETITION UNDER RULE 137.pdf
121-KOL-2005-REPLY TO EXAMINATION REPORT 1.1.pdf
121-KOL-2005-REPLY TO EXAMINATION REPORT.pdf
| Patent Number | 255770 | ||||||||
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| Indian Patent Application Number | 121/KOL/2005 | ||||||||
| PG Journal Number | 13/2013 | ||||||||
| Publication Date | 29-Mar-2013 | ||||||||
| Grant Date | 21-Mar-2013 | ||||||||
| Date of Filing | 21-Feb-2005 | ||||||||
| Name of Patentee | SAMEER | ||||||||
| Applicant Address | Kolkata Centre, Society for Applied Microwave Electronics Engineering & Research R & D Laboratory of Dept. of Information Technology Plot-L2, Block-GP, Sector-V Salt Lake Electronics Complex Kolkata 700 091 | ||||||||
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| PCT International Classification Number | G02B 6/00 | ||||||||
| PCT International Application Number | N/A | ||||||||
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