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Introduction (or Why Make Transmission Line Measurements?)

Introduction (or Why Make Transmission Line Measurements?). A transmission line (or cable) transfers electrical energy from one point to another. Time delay and Attenuation (distortion and losses) are also important parameters for high speed busses. Attenuation.

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Introduction (or Why Make Transmission Line Measurements?)

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  1. Introduction (or Why Make Transmission Line Measurements?) • A transmission line (or cable) transfers electrical energy from one point to another. • Time delay and Attenuation (distortion and losses) are also important parameters for high speed busses.

  2. Attenuation • Lossy lines are becoming increasingly important in high speed • Yet, there is much confusion in the industry about the origin of the losses and how to account for their effects in practical ways.

  3. Attenuation (cont.) • The power loss in a cable. It is due to heating loss because of conductor resistance and skin effects. • Dielectric loss caused by poor dielectric materials. • The total loss is expressed in decibels (dB) per unit length of cable (ratio between two amounts of power existing at two points) dB = 10 log P1/P2

  4. Attenuation (cont.)

  5. Attenuation (cont.) • The most important effect arising from a lossy transmission line is rise time degradation. • The losses behave in a way that causes higher frequency components of the signal to be attenuated more than low frequency components

  6. RG223

  7. K02252D

  8. Connectors cascade • compare between 4 connectors cascade (1 male-male,1 male- female and 2 female- female) to 2 connectors cascade (1 female-male and 1 female-female) and 1 female- female

  9. Cascade of connectors Attenuation [db] Vs. freq [Hz] 1 adaptor 2 connectors 4 connectors

  10. Cascade - conclusion • As expected, connector in serial cause signal decrease • While concatenate a few elements, minimize number connectors

  11. Two cables and connector manipulation • Cable rg58 measurement • 2 Cables rg58 plus connector between • Two rg58 attenuation by mathematical multiple on single cable

  12. Two cables and connector manipulation Attenuation [db] Vs. freq [Hz] 1 rg58 cable 2 rg58 without any connector 2 rg58 with connector

  13. Two cables and connector manipulation conclusions • As we can see , the multiply by 2 of the single 1m cable characters an attenuation of 2m cable. • The lower curve present the influence of the connector . • It’s better to use one single long cable than two cascade of short cables.

  14. Good/Bad cables, connectors and relationship • Rg58 with / without connectors • Sucoflex100 (8274/4E) with/without connectors. • Substrate a different and comparison

  15. Good/Bad cables, connectors and relationship Good cable 2 cable + connector Bad cable Bad cable + connector Attenuation [db] Vs. freq [Hz]

  16. Attenuation [db] Vs. freq [Hz] Manipulation on the couple of curves above ( substract the attenuation ,show that there is no relationship between good cale + connector VS. bad cable + connector.

  17. Conclusion- • The quality of the cable does not relate to the connector influence, • The attenuation behaves in serial effect. • Assumption – the gap between the diff curve result from measure mistakes.

  18. Elements location • cable – connector – cable • connector –cable – cable • cable – cable – connector

  19. Location of the elements in cascade Attenuation [db] Vs. freq [Hz]

  20. element location - conclusions • There has no different in arrangement of elements • As known , VNA measures and calculates the DUT (passive elements) between the calibration edges as whole component and ignore the inner order.

  21. Measurement sensitivity • Flexibility. • Connection tightening between elements.

  22. Flexibility based on the vendor parameters . Little radius Big radius Attenuation [db] Vs. freq [Hz]

  23. Connection tightening between elements Tight connection with Newton key Tight connection with hand Weakly connection Attenuation [db] Vs. freq [Hz]

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