To Measure the Return Loss, Percentage Reflection and Vswr Ratios for the Given Loads

Objective:

To measure the return loss, percentage reflection and VSWR ratios for the given loads.

Theory:

Network analyser is used to examine reflections on a transmission line due to the given loads. The network analyser has a built-in generator, so the radio itself will not be needed in order to make the measurements. The network analyser generates the RF signal, sends it down the line and measures the reflected power, comparing it to the forward power.

Equipments used:

• Network analyzer
• BNC F-F (female to female)
• BNC 50 ohms terminator
• BNC Mismatch terminator
• Ntype M- BNC- F

Procedure:

1. First we would set the center and span frequency of network analyzer selecting the freq button on the spectrum analyser. The centre freq being 450MHZ and span being 0MHZ.
2. Now select the measure button and select S11 for calculating return loss.
3. Now calibrate the Network analyzer to 0db by selecting the cal button the analyzer.
4. Then select the marker and place it on 450 MHZ
5. After that we would attach the open circuit at the end of the cable and measure the return loss at marker freq and note it on the table.
6. Repeat step 4 for short circuit.
7. Repeat step 4 for 50 ohms load.
8. Repeat step 4 for 25 ohms load.
9. Now we would calcite the percentage of reflected power and not it down on the table for each respective load.

10.Now we would calculate the VSWR ratio and note it on the table.

RESULTS:

Discussion:

Return loss of unmatched load as obtained is higher than the matched load which actually or practically should had been the opposite. The reason for this could be that the unmatched load is greater than the matched load who’s value is 50 ohms.

Formal lab report

Applied Electromegnetics

Submitted to:                                                Submitted by:

S.M. Nurul Morshed                                    Manpreet Kaur (N01192018)