BS EN 61580-1-1997 Methods of measurement for waveguides - Decoupling and rotation of the plane of polarization《波导管测量方法 偏振平面退耦和循环》.pdf

1、BRITISH STANDARD BS EN 61580-1: 1997 IEC 1580-1: 1996 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 33.120.10BSEN 61580-1:1997 This British Standard, having been prepar

2、ed under the directionof the Electrotechnical Sector Board, was published underthe authority of the Standards Board and comes intoeffect on 15 February 1997 BSI 12-1998 The following BSI references relate to the work on this standard: Committee reference EPL/46/2 Draft for comment 96/203427 DC ISBN

3、0 580 26937 X Committees responsible for this British Standard The preparation of this British Standard was entrusted by Technical Committee EPL/46, Cables, wires and waveguides, RF connectors and accessories for communication and signalling, to Subcommittee EPL/46/2, RFconnectors and waveguides, up

4、on 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 Ministry of Defence National Supervisory Inspectorate Society of Cab

5、le Television Engineers Amendments issued since publication Amd. No. Date CommentsBS EN 61580-1:1997 BSI 12-1998 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 Text of EN 61580-1 3BSEN 61580-1:1997 ii BSI 12-1998 National foreword This British Standard has

6、been prepared by Subcommittee EPL/46/2 and is the English language version of EN61580-1:1996 Methods of measurement for waveguides Part 1: Decoupling and rotation of the plane of polarization published by the European Committee for Electrotechnical Standardization (CENELEC). It is identical with IEC

7、1580-1:1996 published by the International Electrotechnical Commission (IEC). A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself con

8、fer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi and ii, theEN title page, pages 2 to 6 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in

9、the amendment table on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 61580-1 August 1996 ICS 33.120.10 Descriptors: Waveguides, decoupling and rotation of plane of polarization English version Methods of measurement for waveguides Part 1: Decoupling and rotation of the

10、plane of polarization (IEC 1580-1:1996) Mthodes de mesure appliques aux guides dondes Partie 1: Dcouplage et rotation du plan de polarisation (CEI 1580-1:1996) Meverfahren fr Hohlleiter Teil 1: Entkopplung und Rotation der Polarisationsebene (IEC 1580-1:1996) This European Standard was approved by C

11、ENELEC on 1996-07-02. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national stan

12、dards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and not

13、ified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland a

14、nd United Kingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1996 Copyright reserved to CENELEC members Ref. No. EN 61580-1:

15、1996 EEN61580-1:1996 BSI 12-1998 2 Foreword The text of document46B/206/FDIS, future edition1 ofIEC 1580-1, prepared by SC46B, Waveguides and their accessories, ofIEC TC 46, Cables, wires, waveguides, R.F. connectors, and accessories for communication and signalling, was submitted to the IEC-CENELEC

16、 parallel vote and was approved by CENELEC as EN61580-1 on1996-07-02. The following dates were fixed: Contents Page Foreword 2 1 Scope 3 2 Measurement of decoupling 3 2.1 Principle 3 2.2 Test equipment 3 2.3 Procedure 3 2.4 Expression of results 3 3 Measurement of cross-polarization 4 3.1 Principle

17、4 3.2 Test equipment 4 3.3 Procedure 4 3.4 Expression of results 4 4 Measurement of the plane of polarization 5 4.1 Principle 5 4.2 Test equipment 5 4.3 Procedure 5 4.4 Expression of results 5 Figure 1 Test set-up for decoupling 6 Figure 2 Test set-up for measuring waveguide cross-polarization 6 lat

18、est date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 1997-04-01 latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 1997-04-01EN 61580-1:1996 BSI 12-1998 3 1 Scope This par

19、t of IEC1580 is applicable to waveguides which can propagate two orthogonal polarizations of the same waveguide mode. In this way, the waveguide type is generally restricted to square or circular cross-section, such as waveguide with an octagonal cross-section. The objective of the three test proced

20、ures given below is to characterize the cross-polar properties of waveguides. When a single mode of defined polarization is generated at the source end of the waveguide under test, geometrical imperfections will induce a depolarization to occur as the signal propagates along the waveguide. This depo

21、larization will be a limiting factor on the usefulness of the waveguide in supporting two independent polarizations. As a result, it is necessary to quantify the generated cross-polarization in the waveguide under test. The measurement procedures attempt to do just that. Testing can be performed on

22、waveguide runs or on a single waveguide. Tests may be performed in the field not just in the laboratory. Three procedures are briefly described, which include the following: a) Measurement procedure for the decoupling, defined as the orthogonally polarized signal level reflected from the waveguide u

23、nder test when terminated with a matched load. b) Measurement procedure for the generated cross-polarized level when a single polarization signal is injected into a waveguide under test. c) Measurement procedure for establishing the effective angle of rotation of the electric field in the waveguide

24、under test. 2 Measurement of decoupling 2.1 Principle The test procedure consists of injecting a signal with a defined polarization into the waveguide under test. The decoupling is the level of the signal that is reflected back into the orthogonal polarization of an orthomode transducer, often calle

25、d a polarization duplexer, relative to the input signal. Either single or swept frequency measurements can be made. 2.2 Test equipment The test equipment is set up as shown inFigure 1. The test equipment items are as follows: sweep oscillator covering required RF band; optional amplifier, e.g.TWT (n

26、ot shown); frequency meter; low pass filter; scalar network analyser with appropriate detectors; precision orthomode transducer; precision load for waveguide under test; waveguide variable attenuator, e.g. rotary vane attenuator; recorder; directional coupler; isolators; waveguide transitions if req

27、uired. NOTE 1The polarization isolation of the precision orthomode transducer should be at least 10dB better than the expected decoupling level of the waveguide under test. NOTE 2The return loss of the waveguide load should be at least40 dB. NOTE 3 The alignment of the waveguide under test onto the

28、orthomode transducer should be of the highest precision, to avoid masking the results by the level generated by the misalignment. NOTE 4 The 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

29、inFigure 1. 2) The equipment allows for the stabilization of the frequency that can be tuned using a frequency meter. 3) 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 dire

30、ctly at point B and the RF is switched on. 5) The scalar analyser is set to measure the radio of input power (through the 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 th

31、e RVA is set back to a reading of 0 dB. The waveguide port at point A is connected to one polarization port of the orthomode 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 pl

32、otted directly. 2.4 Expression of results The decoupling can be read as a function of frequency directly from the recorded plot.EN61580-1:1996 4 BSI 12-1998 3 Measurement of cross-polarization 3.1 Principle The cross-polarized energy generated in a waveguide under test can be measured by comparing t

33、he energy level in the orthogonal polarization at the end of the waveguide under test to the energy incident in a defined polarization into the waveguide under test. 3.2 Test equipment The test equipment is set up as shown inFigure 2. Major test equipment items are listed as follows: sweep oscillato

34、r covering appropriate RF band; optional amplifier, e.g. TWT (not shown); frequency meter; lower pass filter; scalar network analyser with appropriate detectors; two precision orthomode combiners; recorder; directional coupler; two waveguide loads, of return loss level better than 40 dB; isolators;

35、waveguide transitions if required. NOTE 1The two orthomode transducers should have polarization isolation of at least 10dB better than the expected polarization level of the waveguide under test (WUT). NOTE 2The alignment of the two orthomode transducers onto the WUT must be of the highest precision

36、, to avoid masking the cross-polarization level of the WUT by the level generated by the misalignment. NOTE 3All flanges should be clean and free of particles, to allow precise mating of the flange surfaces. NOTE 4The two orthomode transducers should be oriented in exactly the same plane, e.g.with t

37、he horizontal port polarization in the horizontal plane, if the waveguide under test will allow this. For example, a circular waveguide with a sliding flange arrangement would require this alignment process, whereas a square waveguide cannot be aligned in this way. NOTE 5During the tests, the wavegu

38、ide loads should be attached to the free ports of the two orthomode transducers. The return loss of the load should be not less than 40dB. 3.3 Procedure 1) The equipment is set up as shown inFigure 2. 2) The equipment is switched on and allowed to stabilize. The frequency band is set using the frequ

39、ency 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 set to the expected level of the cross-polarization of the waveguide under test. 5) The detector at point B is connected to the vertical port of the other OMT. The scal

40、ar analyser is set up to display the swept frequency receive 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

41、adjusted to provide a convenient display, and a recording of 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

42、is then transferred from the vertically polarized port to the 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 po

43、rt. Calibration lines are recorded using the RVA. 11) The detector 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

44、 on top of the calibration chart previously taken. 13) The 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,

45、 one for a vertically polarized swept signal and the other 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 differe

46、nt phasing relation between the geometrical imperfections and finite cross-polarization behaviour of the two OMTs.EN 61580-1:1996 BSI 12-1998 5 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 wavegu

47、ide assembly under test in the above test procedure in order to optimize the generated 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 th

48、e levels are determined by the characteristics of the particular unit under test. If necessary, 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 section3.2. NOTEThe same cautionary

49、 notes as those described above in3.2. In addition, when the swivel flanges are loosened to allow rotation of the waveguide, the flange must be loosened slightly and retightened evenly to avoid inconsistent results due to orthogonal modes being generated at the joint. 4.3 Test procedure 1) Follow the procedure 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 swiv