Question

Explain how you could measure the insertion loss, coupling, and directivity of a directional coupler. Draw a block diagram and give step-by-step procedures. Include sample results for a source with an output of 0 dBm (measured at the input to the directional coupler) and specifications as follows:

- insertion loss: 0.5 dB

- coupling: 25 db

- directivity: 35 dB

Answer 1

To measure insertion loss, coupling, and directivity of a directional coupler, follow these steps: 1. Measure the power at the input and output of the coupler to calculate the insertion loss. 2. Measure the power at the output of the power meter connected to the coupled line to determine the coupling. 3. Measure the power at the output of the main line and the coupled line to find the directivity. Sample results for a source with an output power of 0 dBm are: insertion loss = 0.5 dB, coupling = 25 dB, directivity = 35 dB.

Step-by-step explanation:

Measuring the insertion loss, coupling, and directivity of a directional coupler can be done using various techniques and equipment. Here is a step-by-step procedure:

1. Measuring Insertion Loss:

Insertion loss is the ratio of power that gets lost when a signal passes through the coupler. To measure insertion loss:

1. Connect the input of the coupler to a signal source with an output power of 0 dBm.
2. Measure the power at the output of the coupler using a power meter.
3. Calculate the difference between the input power and the output power to determine the insertion loss.

2. Measuring Coupling:

Coupling is the ratio of power transferred from the main line to the coupled line. To measure coupling:

1. Connect the main line of the coupler to a signal source with an output power of 0 dBm.
2. Connect a power meter to the coupled line of the coupler.
3. Measure the power at the output of the power meter.
4. Calculate the difference between the input power and the output power to determine the coupling.

3. Measuring Directivity:

Directivity is the ratio of power coupled from the main line to the coupled line compared to the power coupled from the coupled line to the main line. To measure directivity:

1. Connect the main line of the coupler to a signal source with an output power of 0 dBm.
2. Measure the power at the output of the main line using a power meter.
3. Disconnect the main line and connect the power meter to the coupled line.
4. Measure the power at the output of the power meter.
5. Calculate the difference between the two power measurements to determine the directivity.

Sample Results:

For a signal source with an output power of 0 dBm, the measured values may be as follows:

• Insertion Loss: 0.5 dB
• Coupling: 25 dB
• Directivity: 35 dB