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What is the Return loss and VSWR ? How are they related? please explain.

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تم إضافة السؤال من قبل Mohamed Abaker Ezeldin Mohamed , IT help desk technician , Sudan Radio and Television Broadcasting
تاريخ النشر: 2014/10/30
Mohamad Sony
من قبل Mohamad Sony , Head

hubungan mereka adalah nila dari rugi2 transmisi, adapun VSWR adalah efisiensi daya yang di transmisikan dari sumber daya dan return loss adalah perbedaan antara daya yang di trnsmisikan dengan daya yg di refleksikan.

Fadi Ezzeddin
من قبل Fadi Ezzeddin , Engineering Manager , Syrian radio and TV organization

Due to mismatches in impedance within the connector, some of the signal is reflected. The ratio of the input to the reflected signal is called the Voltage Standing Wave Ratio (VSWR).

VSWR= {1+(Pr/Pi)-1}/{1-(Pr/Pi)-1}

Where Pi is the incident power and Pr is the reflected power.

 This ratio can also be measured in dB, and expressed as Return Loss.

In telecommunications, return loss is the loss of power in the signal returned/reflected by a discontinuity in a transmission line or optical fiber. This discontinuity can be a mismatch with the terminating load or with a device inserted in the line. It is usually expressed as a ratio in decibels (dB);

where RL(dB) is the return loss in dB

Return loss is related to both standing wave ratio (SWR) and reflection coefficient (Γ). Increasing return loss corresponds to lower SWR. Return loss is a measure of how well devices or lines are matched. A match is good if the return loss is high. A high return loss is desirable and results in a lower insertion loss.

Return loss is used in modern practice in preference to SWR because it has better resolution for small values of reflected wave.

Return Loss= 20*log10(VSWR+1/ VSWR-1) dB

AbdulAziz Abdullah Jaman ALHABASHEY
من قبل AbdulAziz Abdullah Jaman ALHABASHEY , Owner , RAYDAN Engineering Consultants (Telecoms)

 

 

In telecommunications, return loss is the loss of power in the signal returned/reflected by a discontinuity in a transmission line or optical fiber. This discontinuity can be a mismatch with the terminating load or with a device inserted in the line. It is usually expressed as a ratio in decibels (dB);

 The SWR (Satndinding Wave Ratio)  is usually thought of in terms of the maximum and minimum AC voltages along the transmission line (hence VSWR or Voltage Standing Wave Ratio).

For example, the VSWR value1.2:1 denotes an AC voltage due to standing waves along the transmission line reaching a peak value1.2 times that of the minimum AC voltage along that line.

 

VSWR = Vmax/Vmin

 

There is a relationship between the Power and the Voltage as follows:

 

P=VR

 

 

 

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