NORME INTERNATIONALE CEI IEC INTERNATIONAL STANDARD 60512 23 7 Première édition First edition 2005 01 Connecteurs pour équipements électroniques – Essais et mesures – Partie 23 7 Essais d''''écrantage et[.]
Montage d’essai
Analyseur de réseaux Générateur Récepteur
Ecran externe de montage d'essai
Figure 3 – Exemple de montage de mesure pratique
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The maximum coupling lengh L c, max allowed on the highest frequencies f max n f is r2 r1 max c, max c, f f n n = π ε ± ε f
The maximum coupling length (\$L_c\$) is measured in meters, while the highest frequency (\$f_{max}\$) is expressed in hertz (Hz) The speed of light is approximately 300 Mm/s The relative permittivity of the dielectric for the inner system, represented as \$\varepsilon_{r1}\$, is determined by the connector and connecting cable over the length \$L_c\$ In contrast, \$\varepsilon_{r2}\$ denotes the relative permittivity of the dielectric in the outer system.
NOTE The condition means that the phase constant of the cable multiplied with the length is less than 1.
DUT (Device under test) Test jig outer screen
Figure 3 – Example of a practical measurement set-up
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The Device Under Test (DUT) serves as the connector for an assembled cable Due to the specific setup used, the test results consist of a combination of the connector attached to the cable and its male and female adapters Two adapters are required: one is located within the test setup to connect the tested connector to the receiver at the proximal end, while the other is positioned outside the test setup to connect the assembled cable to the receiver at the distal end.
Connectors are essential coupling components, ideally using a well-shielded coaxial connector, preferably of the SMA type, instead of a cable, along with an impedance matching network if needed All pins of the connectors are connected in parallel to create a quasi-coaxial system.
Connecteur D (femelle) (avec broches en parallèle) Plage L
Capot arrière en acier étamé (soudé au connecteur D)
Figure 4 – Exemple de raccord, adapté à un DES particulier
A network analyzer is connected to the test setup using well-shielded coaxial cables The generator links to the external circuit, which consists of the DES within the test setup and the setup's shield The receiver connects to the internal circuit formed by the assembled cable Since most analyzers have only two ports, a coaxial switch is necessary to alternate the receiver's connection between the proximal and distal ends of the internal circuit When measurements are taken at the proximal end, the distal end must be properly terminated with a well-shielded termination.
(dans l'inverseur) et vice versa Au moment de l'inversion, les circuits de terre (boucles) ne doivent pas être touchés pour ne pas modifier les courants perturbateurs de terre
In this testing method, current flows along the outer shield of the connector and returns along the outer shield of the test setup A very low leakage current flows through the test circuit cables to the network analyzer, due to the presence of toroidal ferrites located just outside the test setup.
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The device under test (DUT) is a cable assembly connector, and the test results are derived from the combination of this connector with the cable and two necessary adapting connectors (male and female).
The test jig features two connection points: one inside for linking the tested connector to the receiver at the near end, and another outside for connecting the cable assembly to the receiver at the far end.
The adapters are the appropriate mating connectors, with a well-screened coaxial connector
– preferably an SMA type connector – instead of a cable – and an impedance matching network (if necessary) All pins of the adapters are connected into parallel, to form a quasi- coaxial system
D-connector (female) (with pins in parrallel) L-pad
Tinned steel backshell (soldered to D-connector)
Figure 4 – Example of an adapter, suitable for a particular DUT
A network analyzer is integrated into the setup using well-shielded coaxial cables, with the generator linked to the outer circuit that includes the Device Under Test (DUT) and the test jig's screen The receiver connects to the inner circuit, which consists of the cable assembly Since most analyzers feature only two ports, a coaxial switch is necessary to alternate the receiver port between the near-end and far-end of the inner circuit When conducting measurements at the near-end, it is essential to terminate the far-end with a properly shielded termination.
(in the switch) and vice versa When switching, the ground circuits (loops) shall remain unaffected so as not to change the disturbing ground currents
This test method involves current flowing along the outer screen of the connector and returning through the outer screen of the test jig The design minimizes spurious current in the test circuit cables leading to the network analyzer, thanks to the ferrite toroids positioned just outside the test jig.
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Figure 5 – Schéma du circuit de mesure
Ressources
Les mesures doivent être réalisées en utilisant un analyseur de réseau ou sinon un générateur de signal discret et un récepteur de mesure sélectif
The measurement equipment includes the following components: a) a network analyzer with an adequate frequency range, or alternatively, a signal generator that matches the characteristic impedance of the quasi-coaxial system of the tested cable, along with an impedance matching connector Additionally, it may be supplemented by a power amplifier or a low-noise amplifier if required for very low transfer impedance, ensuring that the background noise of the test setup is minimized.
A) The measurement is set at 10 dB B) A time-domain reflectometer (TDR) is utilized, featuring a system rise time of less than 200 ps, or a 5 GHz network analyzer equipped with FD/TD capabilities C) Two connectors are required, as illustrated in Figure 4 The impedance matching network, essential for the proximal and distal ends of the internal circuit to the receiver, is calculated accordingly.
Si l'impédance du système interne Z 1 est inférieure à 50 Ω (la résistance d'entrée du récepteur), les formules ci-dessous sont utilisées
La configuration est représentée à la figure suivante:
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The measurements shall be performed using a network analyzer or alternatively, a discrete signal generator and selective measuring receiver
The measuring equipment required includes a network analyzer with an adequate frequency range or a signal generator that matches the characteristic impedance of the quasi-coaxial cable system under test, potentially using an impedance adapter This setup may also require a power amplifier and/or a low noise amplifier for measurements involving very low transfer impedance, ensuring that the noise floor is at least 10 dB lower than the measurement Additionally, a time domain reflectometer (TDR) with a system rise time of less than 200 ps is necessary for accurate testing.
The 5 GHz network analyzer features both frequency domain (FD) and time domain (TD) capabilities, complemented by two adapters as illustrated in Figure 4 Additionally, an impedance matching network is included to ensure proper matching between the near- and far-end of the inner circuit to the receiver, with calculations provided for optimal performance.
If the impedance of the inner system Z 1 is less than 50 Ω (the receiver input resistance) the formulas below are used
The configuration is depicted below:
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Le gain de tension, k m du circuit est:
En partant du récepteur (50 Ω) vers le DES (Z 1 ) s 1 s p p 1 p
En partant du DES (Z 1 ) vers le récepteur (50 Ω)
Si l'impédance du système interne Z 1 est supérieure à 50 Ω (la résistance d'entrée du récepteur), les formules ci-dessous sont utilisées
La configuration est représentée à la figure suivante:
Le gain de tension, k m du circuit est:
En partant du récepteur (50 Ω) vers le DES (Z 1 )
En partant du DES (Z 1 ) vers le récepteur (50 Ω) s s p p p DR m, 50 50
= Ω d) un montage d'essai, qui est une enveloppe complètement écrantée dont les deux moitiés
For easy access, metal bands should be used to connect the components The assembly size must accommodate the DES and one of the connectors It is recommended to equip all test wires of the assembled measurement cables with toroidal ferrites for optimal performance Additionally, a coaxial inverter with 1-2 access points is required.
Préparation du spécimen et du calibreur
For specimen preparation, the following details must be adhered to according to the specific specification: a) preparation of the connector (DES) and the necessary assembled cable; b) appropriate fittings between the measuring equipment (50 Ω) and the impedance of the connector contacts in parallel, as well as the shielded cable conductors in parallel.
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The voltage gain, k m of the circuit is:
Going from the receiver (50 Ω) to the DUT (Z 1 ) s 1 p p 1 p
= + Going from the DUT (Z 1 ) to the receiver (50 Ω)
If the impedance of the inner system Z 1 is greater than 50 Ω (the receiver input resistance) the formulae below are used
The configuration is depicted below:
The voltage gain, k m of the circuit is:
Going from the receiver (50 Ω) to the DUT (Z 1 )
= + Going from the DUT (Z 1 ) to the receiver (50 Ω) s s p p p DR m, 50 50
The test jig must be a fully screened enclosure with easily accessible halves connected by metal finger-strips, designed to accommodate the Device Under Test (DUT) and one adapter Additionally, it is advisable to equip all test leads of the measurement cable assemblies with clip-on toroid ferrites A 1-2 port coaxial switch is also required for the setup.
4.3 Preparation of the specimen and the calibrator
For specimen preparation, the following specifications must be adhered to: a) the connector (DUT) and the required cable assembly must be prepared; b) adapters should be matched between the measuring equipment (50 Ω) and the impedance of the connector contacts in parallel, as well as the conductors of the screened cable in parallel, as illustrated in Figure 4.
Licensed to MECON Limited for internal use in Ranchi and Bangalore, supplied by Book Supply Bureau By applying jaw ferrites, they will be reinforced at low frequencies by taking a certain number of turns of coaxial cables through the ferrite toroids.
Conditionnement
L'essai est réalisé dans les conditions atmosphériques normales conformes à la
Aucune correction de température n'est nécessaire.
Régularité d'impédance
The impedance consistency of both the external and internal circuits must be tested in both frequency and time domains This includes measuring the system's rise time with a step function below 200 ps (TDR) or utilizing a 5 GHz bandwidth network analyzer to differentiate reflection points in the frequency/time domain conversion Such measurements in the time domain are essential for identifying impedance steps within the setup.
The reflection loss in both the external and internal test circuits should be less than 10 dB across the entire specified frequency range for measuring screen effectiveness.
Affaiblissement opérationnel des câbles de connexion et du DES
The operational attenuation of the power coaxial cables between the network analyzer and the Device Under Test (DUT) must be considered Additionally, the operational attenuation of the DUT itself should also be taken into account This is essential for accurately assessing the screens and eliminating the effects of filters that may be present in the connectors.
Pour obtenir ces affaiblissements opérationnels, il convient que le générateur à la Figure 3 soit connecté par le câble d'alimentation coaxial à l'extrémité proximale du circuit interne
The receiver is connected via a coaxial power cable to the distal end of the internal circuit It is important to measure the operational attenuation across the specified frequency range.
Cette mesure comprend également l'affaiblissement du raccord d'adaptation d'impédance inséré en final Ceci doit être pris en compte lors de l'évaluation de l'impédance de transfert efficace.
Procédure
In a line injection circuit, both the transfer impedance \( Z_T \) and the capacitive coupling impedance \( Z_F \) simultaneously influence the equivalent transfer impedance \( Z_{TE} \) Therefore, it is essential to conduct both proximal and distal measurements.
The voltage ratio between the internal and external circuits should be measured across the entire frequency range, ideally using a logarithmic frequency sweep at the same frequency points as the calibration procedure.
Licensed to MECON Limited for internal use in Ranchi and Bangalore, this document is supplied by the Book Supply Bureau To enhance performance at lower frequencies, clip-on ferrites should be applied by threading several turns of the test circuit coaxial cables through the ferrite toroids.
The test is performed under standard atmospheric conditions in accordance with
No temperature correction is needed
The impedance regularity of both the outer and inner circuits must be evaluated in both the frequency and time domains, ensuring that the system rise time for step function measurements is below 200 ps (TDR).
A 5 GHz bandwidth in a Network Analyzer is essential for accurately identifying reflection points in both the frequency and time domains The time domain measurement plays a crucial role in detecting impedance steps within the setup.
The return loss in the outer and inner test circuits must be at least 10 dB lower in magnitude than the screening effectiveness values across the frequency range of the measurements.
5.3 Operational attenuation of the connecting cables and the DUT
When testing the device under test (DUT) with a network analyzer, it is crucial to consider the operational attenuation of both the coaxial feeding cables and the DUT itself This consideration ensures that only the screens are verified, effectively eliminating the influence of any filters that may be integrated into the connectors.
To achieve the desired operational attenuations, the generator depicted in Figure 3 must be linked via the coaxial feeding cable to the near end of the inner circuit (left adapter) Meanwhile, the receiver should be connected to the far end of the inner circuit (right adapter) using the same coaxial feeding cable.
The operational attenuation should be measured over the whole specified frequency range
That measurement also includes the attenuation of the final inserted impedance matching adapter That has to be taken into account when evaluating the effective transfer impedance
In a line injection circuit, the transfer impedance \$Z_T\$ and the capacitive coupling impedance \$Z_F\$ simultaneously influence the Device Under Test (DUT), leading to an equivalent transfer impedance \$Z_{TE}\$ Therefore, it is essential to conduct both near-end and far-end measurements.
The voltage ratio between the inner and outer circuits should be measured across the entire frequency range, ideally using a logarithmic frequency sweep at the same frequency points utilized during the calibration process.
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La stabilité de fréquence pour une heure doit être supérieure à 10 –5 pour l'équipement d'essai
Le balayage doit être logarithmique de manière que:
F start est la fréquence spécifiée la plus faible;
F stop est la fréquence spécifiée la plus élevée; n est le nombre de points de fréquence;
K est l'augmentation de fréquence logarithmique
Sauf spécification contraire, le nombre minimal de points de fréquence à soumettre aux essai doit être de:
– 200 points dans la gamme 1 MHz à 10 MHz;
– 400 points dans la gamme 1 MHz à 100 MHz;
– 800 points dans la gamme 1 MHz à 1 000 MHz
6 Evaluation de l'impédance de transfert efficace
U 1 est la tension d'extrémité proximale (n) ou distale (f) mesurée sur le DES;
U 2 est la tension envoyée au circuit externe; f n
The equivalent transfer impedance, denoted as Z TE, can be measured either proximally (n) or distally (f) The term f n a meas refers to the attenuation measured at the proximal (n) or distal (f) end in decibels (dB) Additionally, a cal represents the composite loss of the connection cables and the device under test (DUT), which includes the impedance matching adapter inserted at the end, expressed as a positive dB value Lastly, k m indicates the voltage gain of the impedance matching circuit.
Z 2 est l’impédance caractéristique du circuit externe (injection)
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The frequency stability for 1 h shall be better than 10 –5 for the test equipment
The sweep shall be logarithmic so that
F start is the lowest specified frequency;
F stop is the highest specified frequency; n is the number of frequency points;
K is the logarithmic frequency increment
Unless otherwise specified the minimum number of frequency points to be tested shall be:
– 200 points in the range 1 MHz to 10 MHz;
– 400 points in the range 1 MHz to 100 MHz;
– 800 points in the range 1 MHz to 1 000 MHz
6 Evaluation of the effective transfer impedance
U 1 is the induced near-end (n) or far-end (f) voltage measured at the DUT;
U 2 is the voltage fed into the outer circuit; n f
Z TE represents the equivalent transfer impedance for near-end (n) or far-end (f) measurements The term n f a meas refers to the attenuation measured in decibels (dB) at either the near end or far end The composite loss, denoted as a cal, includes the losses from connecting cables and the device under test (DUT), along with any inserted impedance matching adapters, which contribute positively in dB Additionally, k m signifies the voltage gain of the impedance matching circuit.
Z 2 is the characteristic impedance of the outer (injection) circuit
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When this test is specified in the particular specification, the following information must be provided: a) the lower and upper frequencies within which the measurements should occur; b) the value of Z TE in ohms; c) additional instructions for the construction of the connection or fastening device.
Technical data sheets or test reports must include all details outlined in Article 5, specifically the following information: a) the title of the test, the date, and the names of the operators; b) the testing equipment used along with the dates of the last and next calibrations; c) a description of the test setup (including diagrams if possible) for the fixtures, assembly, and wiring; d) additional information about the network analyzer, such as brand, type, and specifications; e) values and observations, preferably presented in graphical form.
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When the detail specification mandates this test, it is essential to specify the lower and upper frequency range for measurements, the value of Z TE in ohms, and any additional instructions for constructing the adapter or fixture.
Objet
La présente annexe donne des lignes directrices pour la transposition de l'impédance de transfert efficace mesurée en affaiblissement d'écrantage.
Définition de l'affaiblissement d'écrantage d'un écran de connecteur
En tenant compte du fait que l'impédance du circuit externe lors des essais d'écran de câble est spécifiée comme étant 150 Ω, la relation suivante entre l'affaiblissement d'écrantage et
Z TE est proposée pour les écrans de connecteur: (Z TE