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1、BRITISH STANDARD BS 5640-2: 1978 IEC 597-2: 1977 Aerials for the reception of sound and television broadcasting in the frequency range 30 MHz to 1 GHz Part 2: Methods of measurement of electrical performance parameters UDC 621.396.67 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 13:08:54 GM
2、T+00:00 2006, Uncontrolled Copy, (c) BSI BS 5640-2:1978 This British Standard, having been prepared under the direction of the Electronic Equipment Standards Committee, was published under the authority of the Executive Board on 30 November 1978 BSI 04-2000 The following BSI references relate to the
3、 work on this standard: Committee reference EEL/25/4 Draft for comment 76/20789 DC ISBN 0 580 10434 6 Cooperating organizations The Electronic Equipment Standards Committee, under whose direction this British Standard was prepared, consists of representatives from the following Government department
4、 and scientific and industrial organizations: British Broadcasting Corporation* British Electrical and Allied Manufacturers Association (BEAMA) British Radio Equipment Manufacturers Association Cable and Wireless Limited Cable Television Association of Great Britain Electrical, Electronic, Telecommu
5、nications Plumbing Union Electricity Supply Industry in England and Wales Electronic Components Industry Federation* Electronic Engineering Association* Institution of Electronic and Radio Engineers* Ministry of Defence Post Office* Scientific Instrument Manufacturers Association The organizations m
6、arked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this British Standard Aerial Manufacturers Association British Aerial Standards Council Confederation of Aerial Industries Home Office Independent Broad
7、casting Authority Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 13:08:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5640-2:1978 BSI 04-2000i Contents Page Cooperating organizationsInside front cover National forewordii 1Sc
8、ope1 2Object1 3Methods of measurement1 4Measuring site3 5Measuring procedures4 6Reference aerials (under consideration)5 Figure 1 Example of circuit arrangement for gain measurements, with the aerial under test used as a receiving aerial, disposition p), or as a transmitting aerial, disposition q)6
9、Figure 2 Schematic circuit arrangement for measuring system loss7 Figure 3 Schematic circuit arrangement for measuring cable attenuation7 Figure 4 Schematic circuit arrangement for measuring system loss8 Figure 5 Variation of the voltage Vr with the relative aerial height h/28 Publications referred
10、toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 13:08:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5640-2:1978 ii BSI 04-2000 National foreword This British Standard has been prepared under the direction of the Electronic Equipment Standards Committee. It is identical
11、with Publication 597-2 “Aerials for the reception of sound and television broadcasting in the frequency range 30 MHz to 1 GHz” Part 2 “Methods of measurement of electrical performance parameters”, published by the International Electrotechnical Commission (IEC). Terminology and conventions. The text
12、 of the International Standard has been approved as suitable for publication, without deviation, as a British Standard. Some terminology and certain conventions are not identical with those used in British Standards; attention is especially drawn to the following. Wherever the word “standard” appear
13、s, referring to this standard, it should be interpreted as “British Standard”. Cross-reference. For the following International Standard referred to in the text, there is a corresponding British Standard; this is as given below: NOTEThe reference to IEC 107:1960, for which there is no corresponding
14、British Standard, constitutes informative matter only and since no mandatory requirements are involved, the validity of this British Standard is not affected. However, the method of measurement referred to in 3.1 of this British Standard is described under section forty (clauses 115 and 116) of the
15、second edition of IEC Publication 107-1:1977. It is intended to revise BS 3549:1963 “Methods for measuring and expressing the performance of television receivers” to align with this new edition of IEC 107-1. A British Standard does not purport to include all the necessary provisions of a contract. U
16、sers of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. International StandardCorresponding British Standard IEC 597-1:1977BS 5640 Aerials for the reception of sound and television broadcas
17、ting in the frequency range 30 MHz to 1 GHz Part 1:1978 Electrical and mechanical characteristics (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 8, an inside back cover and a back cover. This standard has been updated (see copyri
18、ght date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 13:08:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5640-2:1978 BSI 04-20001 1 Scope This standard applies to linearl
19、y polarized aerials for domestic use in the frequency range 30 MHz to 1 GHz. 2 Object This standard specifies the conditions and methods of measurement of electrical performance parameters of aerials for the reception of sound and television broadcasting. 3 Methods of measurement 3.1 Reflection coef
20、ficient For most purposes, either the magnitude of the reflection coefficient or the standing wave ratio as a function of frequency for the range for which the aerial has been designed, will give sufficient information. The one may be derived from the other or they may be independently determined fr
21、om the aerial impedance either by calculation or by reading a Smith impedance chart. The same precautions as indicated in Sub-clause 4.2 shall be taken into account. The reflection coefficient can be calculated from measurements made by means of, for example, a slotted line, a frequency sweep method
22、 (see IEC Publication 107, Recommended Methods of Measurement on Receivers for Television Broadcast Transmissions, Sub-clause 3.5) or a reflectometer method. 3.1.1 Graphical presentation The magnitude of the reflection coefficient or the standing wave ratio (SWR) or return loss ratio (RLR) shall be
23、given as a function of frequency, the measured points being clearly indicated. The specified resistive load for which the aerial has been designed shall be stated. 3.2 Gain Gain shall be expressed as defined in Sub-clause 3.2 of IEC Publication 597-1, Aerials for the Reception of Sound and Televisio
24、n Broadcasting in the Frequency Range 30 MHz to 1 GHz, Part 1: Electrical and Mechanical Characteristics, and calculated from measurements made on site as detailed in Sub-clause 4.1. By the law of reciprocity, an aerial (other than an active receiving aerial) will exhibit equivalent characteristics
25、whether it be tested as a receiving or as a transmitting aerial. Either method may be used when measuring gain and directivity. Gain shall be measured by either the substitution method, Sub-clause 3.2.1 a) and b), or by the reciprocity (identical aerials) method, Sub-clause 3.2.2. 3.2.1 Gain measure
26、ments by the substitution method a) The aerial together with its mounting system, shall be placed on a site as indicated in Clause 4 and exposed to an incident plane electromagnetic wave, having a polarization corresponding to the design of the aerial. The aerial output power delivered to the specif
27、ied resistive load shall be compared with the power from a substituted reference dipole or transfer standard aerial. b) The aerial, together with its mounting system, shall be placed on a site as indicated in Clause 4 and connected to a radio frequency source with an impedance equal to the specified
28、 resistive load. The power delivered to the terminals of this aerial, to produce a certain field strength at a distant receiving aerial, shall be compared with the power which must be supplied to a reference dipole or transfer standard aerial to produce the same field strength at the same distant re
29、ceiving aerial. In using the above methods a) or b) a resonant half-wave dipole will normally be used as a reference aerial in measuring gain, but it is frequently necessary to use a more directional aerial and this has been defined in Sub-clause 3.13 of IEC Publication 597-1. A transfer standard ae
30、rial must have accurately known and consistently reproducible gain, directivity and cross-polarization characteristics. It must be completely specified in dimensional working drawings, with full mechanical specification to permit it to be reproducibly constructed whenever required. Where an unbalanc
31、ed transmission system is used, a suitable balance to unbalance transformation shall be made between the dipole and the transmission system; the transformation loss shall be taken into account. The magnitude of the reflection coefficient of the reference aerial to the transmission system shall not e
32、xceed 0.1 at the measuring frequencies. 3.2.2 Gain measurement by the reciprocity method Two identical aerials of the type to be tested are necessary. One is used as the transmitting aerial and the other as the receiving aerial. Each aerial is mounted with its designed mounting system on a mast as d
33、escribed is Sub-clause 5.1. During each measurement both aerials are at the same height above the ground, facing each other. Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 13:08:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5640-2:1978 2 BSI 04-2000 With the following notation: As = the m
34、easured loss, in decibels Gi = the gain, in decibels, relative to an isotropic aerial d = the distance between the phase centres of the two aerials 2 = the wavelength corresponding to the measuring frequency Gd = the gain, in decibels, relative to a half-wave dipole it can be shown that, provided th
35、e influence of ground reflections is negligible, the measured loss between these two aerials is equal to: In practice, d can be assumed to be approximately equal to the distance between the feed-points of the two aerials. The gain relative to an isotropic aerial can therefore be evaluated from a los
36、s measurement as follows: Relative to a half-wave dipole, the gain will be: 3.2.3 Graphical presentation Gain shall be presented in graphical form as a gain-frequency plot in the bandwidth of interest. Any discrete measuring frequencies shall be clearly indicated on the graph, and the specified resi
37、stive load shall be stated. The type and location of the reference aerial used in the measurement shall be stated on the graph. The gain, as defined in Sub-clause 3.2 of IEC Publication 597-1, shall be determined using a loss-less half-wave dipole as the reference, and shall be expressed in decibels
38、. NOTEIf by agreement between manufacturer and purchaser the gain is expressed, as indicated in the note to Sub-clause 3.2 of Publication 597-1, in any other way, or using any other reference standard, or in reference to any directions of azimuth other than that of the main lobe, these facts shall b
39、e clearly stated on the graph and in the performance data sheet. 3.3 Directivity pattern The measurement of directivity pattern shall be made on a site as specified in Sub-clause 4.1 in a uniform electromagnetic field, with a polarization corresponding to that of the aerial during measurement. 3.3.1
40、 Graphical presentation The directivity pattern may be presented as a polar diagram, using a decibel scale relative to maximum measured voltage. However, a linear voltage scale can be used, and in either case the pattern can be displayed in cartesian co-ordinates if required. The measured points sha
41、ll be clearly indicated on the graph, down to the specified percentage of the main lobe, the percentage being stated. When a continuous plot has been made, this shall be stated. The measuring frequency and the orientation of the aerial with respect to the directivity pattern shall be clearly indicat
42、ed on the diagram. 3.4 Directivity protection The directivity protection, as detailed in Sub-clause 3.3 of IEC Publication 597-1, shall be determined from the directivity pattern made for the frequency range specified in Sub-clause 3.6.2 of that publication. 3.5 Cross-polarization protection In meas
43、urements on cross-polarization protection, the orthogonal component of radiation from the transmitting aerial is significant and cannot be ignored. Measuring procedures for cross-polarization protection, both in the direction of maximum gain, and as a cross-polarization directivity protection patter
44、n for other directions of azimuth are considered in Sub-clause 5.3. 3.6 Impedance The impedance of the aerial together with its mounting system can be measured by any suitable method. Baluns may be needed when dealing with symmetrical aerials. 3.6.1 Graphical presentation The impedance of the aerial
45、 shall preferably be plotted on a Smith impedance chart with the frequency as parameter, the measured points being clearly indicated. This impedance shall be referred to the specified resistive load for which the aerial has been designed. 3.7 Feeder pick-up measurements Under consideration. NOTEIt i
46、s recommended that coaxial cables be connected to aerial terminal devices through a balun in order to minimize feeder pick-up. Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 13:08:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5640-2:1978 BSI 04-20003 4 Measuring site A suitable measuring
47、site shall be of sufficient size and have surroundings which are substantially free from reflecting objects. It should be noted that the dimensions of the site will be comparatively large when measurements are to be made at the lower frequencies and when high gain or physically large aerials are bei
48、ng tested. 4.1 Gain and directivity pattern measurement The following applies to those measurements of gain and directivity where the aerial to be measured is used as a receiving aerial. In order to avoid errors in the measurements due to excessive variations in phase and amplitude in the space occu
49、pied by the aerial under test, the minimum distance between the aerials shall be determined from one of the two following requirements. The requirement which specifies the greater distance shall be met. a) The variation in phase at the measuring site, in a plane perpendicular to the direction of propagation, occurring across a distance equal to the greatest physical dimension of the aerial under measurement, shall not exceed ;/8 radians. To achieve this requirement, the distance between the two aerials shall be at least, where b1 and b2 are the largest dimensions of