1、STD-SI BS EN bL5O-1-ENGL IT77 = Lb2LibbS 0587Lb Li7 i BRITISH STANDARD Methods of measurement for waveguides Part 1. Decoupling and rotation of the plane of polarization The European Standard EN 61580-1 : 1996 has the status of a British Standard ICs 33.120.10 NO COPYING WITHOUT BSI PERMISSION EXCEP
2、T AS PERMITTED BY COPYRIGm LAW BS EN IEC 1580-1 : 1996 61580-1 : 1997 STD-BSI BS EN bL5BO-1-ENGL 1997 mpLb2qbb9 05871b 785 W BS EN 61580-1 : 1997 This British Standard, having been prepared under the direction of the Electrotechnical Sector Board, was published under the authority of the Standards B
3、oard and comes into effect on 15 February 1997 O BSI 1997 Committees responsible for this British Standard The preparation of this British Standard was entrusted by Technical Committee EPLJ46, Cables, wires and waveguides, RF connectors and accessories for communication and signaiiing, to Subcommitt
4、ee EPL/4X?, RF connectors and waveguides, upon which the following bodies were represented AEA Technology BEAMA Electrical Cable and Conductor Accessory Manufacturers British Non-Ferrous Metals Federation British Telecommunications plc Federation of the Electronics Industry Ministsy of Defence Natio
5、nal Supervisory Inspectorate Society of Cable Television Engineers Amendments issued since publication Amd. No. I Date 1 Text affected The following BSI references relate to the work on this standard Committee reference EPL/46/2 Draft for comment 96/203427 DC ISBN O 680 26937 X STD-BSI BS EN bLSB-2-
6、ENGL 1997 Lb29bbS 0587370 qT7 W BS EN 61580-1 : 1997 Contents Committees responsible National foreword page Inside front cover u Foreword 2 Text of EN 6158Cbl 3 * * UI O BSI 1997 i STDmBSI BS EN bL580-L-ENGL i777 lb2Ybb7056TLZ 333 BS EN 61580-1 : 1997 National foreword This British Standard has been
7、 prepared by Subcommittee EPIJ46/2 and is the English language version of EN 61580-1 : 1996 Methods of memurmmt for waveguides - Part 1: Decoupling and rotation of #.e plane of polurization published by the European Committee for Electrotechnical Stanh-on (CENELEC). It is identical with IEC 1580-1 :
8、 1996 published by the International Electrotechnical Commission Compliance with a British Standard does not of itself confer immunity from legal obligations. (IEC). Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN title page, pages 2 to 10, an in
9、side back cover and back cover. O BSI 1997 STD-BSI BS EN bLSBO-L-ENGL 1997 lbZqbb9 0587372 27T EUROPEAN SIANDAFUI NORIME EUROPENNE EUROP - optional amplifier, e.g. TWT (not shown); - frequency meter; - low pass filter; - scalar network analyser with appropriate detectors; - precision orthomode trans
10、ducer; - precision load for waveguide under test; - waveguide variable attenuator, e.g. rotary vane attenuator; - recorder; - directional coupler; - isolators; - waveguide transitions if required. NOTES 1 The polarization isolation of the precision orthomode transducer should be at least 10 dB bette
11、r than the expected decoupllng level of the waveguide under test. 2 The return loss of the waveguide load should be at least 40 dB. 3 The alignment of the Waveguide under test onto the orthomode transducer should be of the hlghest precision, to avoid masking the results by the level generated by the
12、 mlsaltgnment. 4 lhe flanges should be clean, and free of dirt or scratches which may affect the results of the measurement. 2.3 Procedure 1) The test equipment is set up as shown in figure 1. 2) The equipment allows for the stabilization of the frequency that can be tuned using a frequency meter. 3
13、) The rotary vane attenuator (RVA) is set to the expected level of decoupling of the waveguide under test (WUT). 4) The output of the RVA, point A, is connected to the detector directly at point B and the RF is switched on. 5) The scalar analyser is set to measure the radio of input power (through t
14、he directional coupler) to that in detector at point B. 6) Calibration lines are recorded using the RVA. 7) The RF is switched off. 8) The calibration Set-up is disconnected, and the RVA is set back to a reading of O dB. The waveguide port at point A is connected to one polarization port of the orth
15、omode transducer, and the waveguide port at point B is connected to the other port of the orthomode transducer (OMT). The RF is switched on. 9) The decoupling can be measured and plotted directly. 2.4 Expression of results The decoupling can be read as a function of frequency directly from the recor
16、ded plot. 3 Measurement of cross-polarization 3.1 Principle The cross-polarized energy generated in a waveguide under test can be measured by comparing the energy level in the orthogonal polarization at the end of the waveguide under test to the energy incident in a defined polarization into the wav
17、eguide under test. 3.2 Test equipment The test equipment is set up as shown in figure 2. Major test equipment items are listed as follows: - sweep oscillator covering appropriate RF band; - optional amplifier, e.g. TWT (not shown); - frequency meter: - lower pass filter; - scalar network analyser wi
18、th appropriate detectors; - two precision orthomode combiners; - recorder; - directional coupler; - two waveguide loads, of return loss level better than 40 dB; - isolators; - waveguide transitions if required. NOTES 1 The two orthomode transducers should have polarization Isolation of at least 10 d
19、B better than the expected polarization level of the waveguide under test (WUT). 2 The alignment of the two orthomode transducers onto the WUT must be of the highest precision, to avoid masking the cross-polarization level of the WUT by the level generated by the misallgnment. 3 All flanges should b
20、e clean and free of particles, to allow preclse mating of the tlange surfaces. 4 The two orthomode transducers should be oriented In exactly the same plane. e.g. with the horizontal port polarization in the horizontal plane, if the wavegulde under test will allow this. For example, a circular wavegu
21、ide with a sliding flange arrangement would require this alignment process, whereas a square waveguide cannot be aligned in this way. 5 During the tests, the waveguide loads should be attached to the free ports of the two orthomode transducers. The return loss of the load should be not less than 40
22、dB. 3.3 Procedure 1) The equipment is set up as shown in figure 2. 2) The equipment is switched on and allowed to stabilize. The frequency band is set using the frequency meter. 3) Input power at point A is connected to one of the ports of the OMT, for example vertical polarization. 4) The RVA is se
23、t to the expected level of the cross-polarization of the waveguide under test. STD-BSI BS EN b150-1:ENGL 1777 1b2Libb 58777 851 Page 6 EN 61580-1 : 1996 5) The detector at point B is connected to the vertical port of the other OMT. The scalar analyser is set up to display the swept frequency receive
24、 level. Calibration lines are recorded using the RVA. 6) The detector at point B is transferred from the vertical polarization port of the OMT to the horizontal polarization port. The RVA is adjusted to read zero. 7) The scalar analyser is adjusted to provide a convenient display, and a recording of
25、 this display is made on top of the calibration chart previously taken. 8) The plot shows the swept cross-polarization level of the waveguide under test for an input signal polarized in the vertical plane. 9) The waveguide input to the OMT is then transferred from the vertically polarized port to th
26、e horizontally polarized port and the RVA is again set to the expected level of cross- polarization generated by the waveguide under test. 10) The scalar analyser will now be displaying the calibration level in the horizontal polarization port. Calibration lines are recorded using the RVA. 11) The d
27、etector at point B is then transferred from the horizontal port back to the vertical port of the OMT, and the RVA setting is returned to zero dB. 12) The display can be observed on the scalar analyser, and a recording of this display is made on top of the calibration chart previously taken. 13) The
28、plot shows the swept cross-polarization level of the waveguide under test for an input signal polarized in the horizontal plane. 3.4 Expression of results The two charts will show the cross-polarization behaviour of the waveguide under test, one for a vertically polarized swept signal and the other
29、for a horizontally polarized swept signal. The two levels will not necessarily be identical because of the different alignment of either of the polarizations to the effective distortion plane of the waveguide under test, and also the different phasing relation between the geometrical imperfections a
30、nd finite cross- polarization behaviour of the two OMTs. 4 Measurement of the plane of polarization 4.1 Principle If the waveguide incorporates a swivel flange arrangement, it is then possible to rotate the waveguide assembly under test in the above test procedure in order to optimize the generated
31、cross-polar levels in both polarizations, since in the general case they will be different. This is only possible with circular waveguides. In square, or other waveguides, this optimization is not possible, and the levels are determined by the characteristics of the particular unit under test. If ne
32、cessary, mechanical alterations on the cross-sectional shape of the WUT can be used for optimization. 4.2 Test equipment The test equipment will be the same as that described in section 3.2. NOTE - The same cautionary notes as those described above In 3.2. In addition, when the swivel flanges are lo
33、osened to allow rotation of the Waveguide, the flange must be loosened slightly and reiightened evenly to avoid inconsistent results due to orthogonal modes being generated at the joint. STDIBSI BS EN bL58O-1-ENGL 1777 Lb24bb7 1587178 778 = Page 7 EN 61580-1 : 1996 4.3 Test procedure I) Follow the p
34、rocedure outlined in section 3.3 above until step 7. At this point the display is showing the generated level of cross-polar energy for a vertically polarized input signal. 2) Evenly and slightly loosen the swivel flange bolts connecting the waveguide under test to the detector end OMT. Rotate the O
35、MT until the lowest level of cross-polar energy is observed. Evenly tighten the swivel flange bolts. 3) Move to the input end OMT, and then evenly and slightly loosen the swivel flange bolts to the input end of the waveguide under test. Rotate the OMT until the lowest level of cross-polar energy is
36、observed. Evenly tighten the flange bolts. 4) Return to the detector end OMT, and make a mark (pencil or ink) on the flange to indicate the orientation of the OMT with respect to the waveguide. 5) After the test Set-up to measure the generated level of cross-polar energy for a horizontally polarized
37、 input signal. 6) Evenly and slightly loosen the detector end OMT swivel flange bolts. Rotate the OMT until the lowest level of cross-polar energy is observed. Evenly tighten the swivel flange bolts. 7) Mark (pencil or ink) on the flange to indicate the orientation of the OMT with respect to the wav
38、eguide under test. 8) Compare this mark with that made in step 4) above. 9) Evenly and slightly loosen the flange, and set the OMT orientation to half-way between the two marks. Evenly tighten the flange bolts. 4.4 Expression of results The two OMTs are now set at the optimum position with respect t
39、o the cross-polar performance of the waveguide under test. The polarization rotation angle can be found by halving the angular separation of the marks previously made at the receive end swivel flange of the waveguide under test. Note that due to the possible distortion in the waveguide under test, t
40、he two OMTs may now no longer be in the same plane. STD-BSI BS EN bLSBOL-ENGL 1777 Tb24bb7 05873-77 b24 + Transducteur mode orthogonal - Gnrateur RF RF generator Page 8 EN 61580-1 : 1996 Charge Coupleur Coupler Frquencemtre Frequency meter I Atnuateur Attenuator Wtecteurs Analyseur scalaire eVou enr
41、egisteur Scalar analyser Figure 1 - Appareillage dessai pour le dcouplage Test Set-up for decoupling Page 9 EN 61580-1 : 1996 r p- IA Transducteur Transducteur mode orthogonal - WUT - mode orthogonal Orthogonal I Orthogon a I transducer Isolateur isolator transducer .- Low pass filter Frquencemtre F
42、requency meter Dtecteurs f Analyseur scalaire eou enregisteur Scalar analyser and/or recorder Figure 2 - Appareillage dessai pour mesurer ia polarisation crolsh du guide dondes Test Set-up for measuring waveguide cross-polarization STD-BSI BS EN b158U-L-ENGL L777 lb24bb7 0587181 282 BS EN 61580-1 :
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