1、AECMA STANDARD NORME AECMA AECMA NORM Edition approved for publication 28 February 2005 prEN 2591 -221 Edition P 1 February 2005 Comments should be sent within six months after the date of publication to AECMA-STAN ICs: Descriptors: ENGLISH VERSION Aerospace series Elements of electrical and optical
2、 connection Test methods Part 221 : Voltage Standing Wave Ratio (VSWR) Srie arospatiale Luft- und Raumfahrt Organes de connexion lectrique et optique Mthodes dessais Partie 221 : Ratio dOndes Stationnaires Elektrische und optische Verbindungselemente P rfverfa h ren Teil 221 : Stehwellenverhltnis Th
3、is Xerospace Series“ Prestandard has been drawn up under the responsibility of AECMA-STAN (The European Association of Aerospace Industries - Standardization). It is published for the needs of the European Aerospace Industry. It has been technically approved by the experts of the concerned Domain fo
4、llowing member comments. Subsequent to the publication of this Prestandard, the technical content shall not be changed to an extent that interchangeability is affected, physically or functionally, without re-identification of the standard. After examination and review by users and formal agreement o
5、f AECMA-STAN, it will be submitted as a draft European Standard (prEN) to CEN (European Committee for Standardization) for formal vote and transformation to full European Standard (EN). The CEN national members have then to implement the EN at national level by giving the EN the status of a national
6、 standard and by withdrawing any national standards conflicting with the EN. Electrical Domain I I Copyright 2005 O by AECMA-STA/ Copyright Association Europeene des Constructeurs de Materiel Aerospatial Provided by IHS under license with AECMANot for ResaleNo reproduction or networking permitted wi
7、thout license from IHS-,-,-Page 2 prEN 2591-221:2005 Foreword This standard was reviewed by the Domain Technical Coordinator of AECMA-STANS Electrical Domain. After inquiries and votes carried out in accordance with the rules of AECMA-STAN defined in AECMA- STANS General Process Manual, this standar
8、d has received approval for Publication. Contents Page 1 Scope 2 Normative referen ces . 3 Preparation of specimens . 4 Apparatus 5 Proced Ure . . 6 Requirement . 7 Detail to be specified Annex A (normative) Definition of S parameters Copyright Association Europeene des Constructeurs de Materiel Aer
9、ospatial Provided by IHS under license with AECMANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Page 3 prEN 2591-221 :2005 1 Scope This standard specifies a measurement method of VSWR, in the required frequency bandwith of coax contacts or connectors with characte
10、ristic impedance. It shall be used together with EN 2591-100. The measurement is carried out according to vectorial method using ?Y parameters (see definition in Annex A). 2 Normative references The following referenced documents are indispensable for the application of this document. For dated refe
11、rences, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 2591 -1 00, Aerospace series - Elements of electrical and optical connection - Test methods - Part 100: General 3 Preparation of specimens Method ?A? T
12、his method is applicable when exist accurate adapter in the series of connectors or contacts to tested. The sampling shall include, for each specified cable, one section of coaxial cable with device under test in both ends. The section is constituted as follow (see Figure 1): - 60 cm k 2,5 mm of coa
13、xial cable - 1 male coaxial device - 1 female coaxial device 1 2 3 Key 1 Male coaxial device 2 Female coaxial device 3 Coaxial cable; Lg. = 60 cm f 2,5 mm Figure 1 1) Published as AECMA Prestandard at the date of publication of this standard Copyright Association Europeene des Constructeurs de Mater
14、iel Aerospatial Provided by IHS under license with AECMANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Page 4 prEN 2591-221:2005 Method “B” This method is applicable when exist accurate adapter in the series of connectors or contacts to tested. The sampling shall
15、include for each specified cable, one section of coaxial cable with standard connectors in both end, and device under test in the middle of the section of the cable. The section is constituted as follow (see Figure 2): - 60 cm k 2,5 mm of coaxial cable divided in 2 (2 x 30 cm) - 1 male coaxial stand
16、ard connector (SMA, Nor TNC type . . .) - 1 female coaxial standard connector (SMA, Nor TNC type . . .) - 1 male coaxial device - 1 female coaxial device 1 2 3 4 4 Key 1 Coaxial (Std) male connector 2 Device under test 3 Coaxial (Std) female connector 4 Coaxial cable; Lg. = 2 x 30 cm f 2,5 mm Figure
17、 2 4 Apparatus The apparatus shall comprise: Measure equipment include (see Figure 3): - vector network analyser - calibration kit - standard precision adapters - a 75 SZ kit of transformation, to perform measurement from 50 SZ network analyser, when it is necessary. Copyright Association Europeene
18、des Constructeurs de Materiel Aerospatial Provided by IHS under license with AECMANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Page 5 prEN 2591-221 :2005 5 Procedu re 5.1 Cali bration Select measure frequency range and sampling points number. Carry out the compl
19、ete calibration of network analyse, Part 1 and Part 2 (Y Parameters, SI, SI, Sz1 and S,) Using calibration kit according to instructions specified by network analyser manufacturer. 5.2 Measurement Method A Connect the section in measure on network analyser, using if necessary, standards accurate ada
20、pters, and perform the measurement. The VSWR of one connector is determined by using the temporal response (time domain) and a function called “GATE” to isolate the connector, which must be connected to the standard precision adapter. Method B Connect the section in measure on network analyser, usin
21、g if necessary standards accurate adapters, and perform measurement. The VSWR of the two mated connectors is determined by using the temporal response (time domain) and a function called “GATE” to isolate the two mated connectors from the coaxial cable. 6 The Voltage Standing Wave Ratio (VSWR) does
22、not exceed specified values on the product standard. Req u i remen t 7 Detail to be specified The following items shall be specified: coaxial cables part number standard coaxial connectors part number network analyser, manufacturer, type and serial number frequency range sampling point number standa
23、rd precision adapter part number measurement impedance (50 Q or 75 Q) for coaxial contact, connection length wiring instruction and tooling for thread coupling connectors, the coupling torque of the coupling ring Copyright Association Europeene des Constructeurs de Materiel Aerospatial Provided by I
24、HS under license with AECMANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Page 6 prEN 2591-221:2005 Key 1 Vector network analyser 2 RF generator and 3” parameter test set Legend Precision hermaphroditic connectors Standard Precision Adapters Hermaphrodite Standard
25、 Coaxial I nt e rface Connector Interface Device Under Test Interface Figure 3 Copyright Association Europeene des Constructeurs de Materiel Aerospatial Provided by IHS under license with AECMANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Page 7 prEN 2591-221 :20
26、05 Annex A (nor mat ive) Definition of S parameters A.l Consider an E.M.F. source, E, measured in V, with an internal impedance Z, and a load impedance Z. Effective Power of a Sinusoidal source The applied power P dissipated in Z is defined as IEl %e(z) (Z+Z,) EZ (Z*+Zg E* *) 1 = Iz+z,I P=%e(VI*) =
27、%e P is a maximum when Z = Z, * (balanced load). This maximum power is known as the effective or RMS nota - Root Mean Squared power for a given source (E, Z,) and can be expressed as In general, when Z has a different value to Z, we define P as z-z, * P= 4 IEl 1 1-Iz+/, 1 where z-z, * z+z, is known
28、as the Power Reflection Coefficient. The power dissipated in Z can be expressed as the difference of two powers, and when the source (E, Z,) power is maximum and when Z Z, the amount of power reflected towards the source is equal to Copyright Association Europeene des Constructeurs de Materiel Aeros
29、patial Provided by IHS under license with AECMANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Page 8 prEN 2591-221:2005 A.2 Waves - Incident and Reflected (Kurokawa Waves) Let us define an impedance, Z, in terms of a potential difference, V, and a current I. We al
30、so define an Incident Wave, a, and a Reflected Wave, b, with respect to a Reference Resistance, R, as follows: - the power dissipated in Z= P = laI2 - lbI2 - the effective power generated by the source (E, R,) = P, = laI2 Expressing a and b in terms of V, I, R, gives: V+R, I V-R, I a= 2JR, 2 If Z is
31、 supplied by the source (E, R,) we can state that E = V+ R,.Iwhich automatically validates i,= la1 . NOTE - - R, is known as the Reference Resistance for the “waves“ a and b The word wave is written inside speech marks because a and b do not show the typical electromagnetic behaviour associated with
32、 classical waves -they are rather Power Waves The definition of a and b is independent of that fact that the dipole 2 is fed by a source of an internal resistance R, The power dissipated in 2 is independent of the characteristics of the source and is always equal to la12-lb12 The ratio of the waves
33、b to a is equal to (when V= 2.4 - - - b Z-R, a Z+R, _- - which is the Reflection Coefficient of the impedance 2 with respect to the reference resistance R,. Copyright Association Europeene des Constructeurs de Materiel Aerospatial Provided by IHS under license with AECMANot for ResaleNo reproduction
34、 or networking permitted without license from IHS-,-,-Page 9 prEN 2591-221 :2005 A.3 S Parameters of a quad pole Let us apply the precedent definition to the input and output of a quad pole device. This time we define an incident and reflected wave, al and bl, for the input side and incident and ref
35、lected wave, a2 and b2, for the output side, relative to the input and output reference resistances, RI and R2. We can state that the system is linear and we can therefore re-write the above equations to express on variable in function of two of the other unknowns. These S Parameters are also known
36、as the system distribution parameters and characterise the quad pole in function of its input and output reference resistances, RI and R2. NOTE These S Parameters define the quad pole at a given frequency A.4 Physical Signification and Interest of S Parameters A.4.1 Physical significance of SI, If S
37、I1 = bl/al, where a2 = O, then a2 is equivalent to V2 = - R2.12, the output of the quad pole is therefore closed loop on R2 and if Z, is the input impedance of Q, then in these conditions, we can state that VI = Zell and SI1 is the input reflection coefficient with respect to RI when the output impe
38、dance = R2. Copyright Association Europeene des Constructeurs de Materiel Aerospatial Provided by IHS under license with AECMANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Page 10 prEN 2591-221:2005 A.4.2 Physical significance of S22 In the same way, if SZ2 = b2/
39、u2 then when al = O, the input is closed loop on RI and under these conditions if Z, is the output impedance, we obtain SZ2 is the input reflection coefficient with respect to R2 when the input impedance = RI. The S, parameters are therefore defined as the Reflection Coefficients. A.4.3 Physical sig
40、nificance of S21 If SZ1 = b2/ul then when u2 = O, the output is closed loop on R2 and therefore s -2= 1 a1 i“ R2 V2-R2r2 VI +RI Il If we assume that the quad pole Q is supplied by a source (E, RI) then E = VI + R1.Il and V2 = - R2.12 The quad pole being supplied by a source of impedance RI and with
41、a load R2 will have a S Parameter S2, proportional to a voltage gain called the System Transmission Coefficient. If we take the square of SZ1 then we obtain where IS2112 is the Composite Power Gain. Copyright Association Europeene des Constructeurs de Materiel Aerospatial Provided by IHS under licen
42、se with AECMANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Page 11 prEN 2591-221 :2005 A.4.4 Physical significance of Sq2 We can do a similar calculation as above and we will find that, for a quad pole (2 supplied by a source (E, R2) and whose input is closed loo
43、p on RI, the SI2 parameter is defined by Sz1 is called the Inverse Transmission Coefficient. These S Parameters are used to characterise the junctions in high frequency applications because they possess a number of advantages: - these parameters are measurable at RI and R2. In practice we choose sta
44、ndard values for resistances RI and R2 such as 50 ohms or 75 ohms. It is much easier to measure variables over a known resistance than on an open circuit (Z Parameters) or in a short circuit (Y Parameters). - in closing each side of the circuit allows frequency sweeping. - as the termination resista
45、nces RI and R2 are dissipative, the risks of instability during the analysis of the active quad pole are decreased (which is not the case for open or short-circuits). - a simple device already exists to separate a and b waves at high frequencies. This device is the directional coupler. Copyright Association Europeene des Constructeurs de Materiel Aerospatial Provided by IHS under license with AECMANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
