VNA based UWB echo signal Experiment Part 2.

Objective

1. Measurement for building a safe experimental environment.
2. Reproduced to build the experimental environment and determine the MUTUAL coupling signal in the experimental environment.
3. Comparison of the reflective properties of wood and metal materials.
4. Construction of time-of-flight calculations in UWB reflection signals under VNA-based systems.

Materials

• VNA device, KEYSIGHT 5063A ENA
• N Male to SMA Female Connector
• Coaxial Cable
• UWB antenna, provided by Gary (Shenzhen), bandwidth 3 - 20GHz
• Metal plate, as a wave full reflection obstacle, size 34cm
• Wood plate,

Table 1. The VNA Setup for Measuring

Option	Value
RF Power	-5dBm
IF Bandwidth	70kHz
Averaging	64
Start Frequency	100kHz
Stop Frequency	6.5GHz
Number of Frequency Points	10001

Table 2. Coaxial Cable Parameters

Parameter	Value
Type	SS405
Length	30cm
Impedance	50 Ohm
Capacitance	96 pF/m
Shielding Effectiveness	110 dB

Method

Setup Diagram

Fig 1.  Experimental setup overview diagram, using the VNA device to transmit a frequency swept signal from Port1, after the medium reflection from Port2 to get the echo signal, using the VNA to measure the scattering parameters and calculate the obtained signal of the transmitted signal

Mutual Coupling Signal

Mutual coupling signal refers to the phenomenon where electromagnetic fields from one circuit or antenna influence the behavior of another nearby circuit or antenna. It occurs when the electromagnetic fields generated by one element couple or interact with the other elements in the vicinity.

To get the mutual coupling signal, fix the antennas in a fixed position with a spacing of 8 cm (it can also vary), make sure no object is nearby, and measure the S21 signals. Convert it to a time signal called mutual coupling signal (Sa(t)).

$$Sa(t)=\sum _i^N{S}_{21}\ast A_{\text{gaussian}}\ast \cos ({\omega }_{i}t+{\varphi }_i)$$

Procedure

1. Start the VNA device.
2. Set up the VNA measurement parameters.
3. Connect antenna to the coaxial cable.
4. Measure the mutual coupling signal based on the methods mentioned above.
5. Set the wood plate at different distances from VNA, 5cm - 25cm.
6. Get S11 and S21 scattering parameter from the wood plate at different distances from VNA.
7. Analyze raw data and compare the data with metal plate reflection signal data from experiment 1.

Results

Mutual Coupling Signal

Metal Plate vs. Wood Plate echo signal

Conclusion and Future Experiment Plan