Application of VSWR bridge

Simplified measurement method of impedance

Application

The impedance of inputs and outputs of RF circuits are demanded to be 50 ohm. It is possible to verify the impedance using an impedance analyzer or other method. But these methods need so much cost.

MVS300 provides an easy and a low cost way to verify it.

Solution

Principle of the measurement

Using VSWR bridge, we can measure a return loss t hat is a reflected power from a DUT. In a circuit system whose the impedance is 50 ohm and the matching is enough taken, the reflection is hardly generated and the return loss becomes larger.
On the other hand, in the case of that the DUT por t is a short circuit, the power is reflected almost all and the return loss becomes near 0dB.
If the return loss is under -14dB, the transmit ra te is assumed over 95%, and the impedance is generally assumed to be 50 ohm and a matching is given.

Principle of the measurement

1. Connect the MSA338TG/MSA438TG and MVS300B, and tak e a normalize in the frequency range to be measured. Keep the DUT terminal open.
2. Connect the DUT and measure the return loss.

*Please refer the manual of MVS300B for more detail

System configuration

• Spectrum Analyzer MSA438TG
• Spectrum Analyzer MSA338TG
• VSWR Bridge MVS300

*MICRONIX Corporation reserves the right to make changes in design, specification and other information without prior notice.

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