Isolator | Phraygun

Isolators

Objective

To ensure that each isolator can send an RF signal in one direction, either forward direction or reverse direction.

Proof of Concept

Calibrate port 1 of the Nano VNA from 800 MHz to 1000 MHz with 5 segments which will give you 505 points. Once the VNA is calibrated connect the isolator in forward bias and perform a sweep while graphing the S21 Gain. Then connect the isolator in reverse bias and perform another sweep while graphing the S21 Gain.

Pass criteria: Forward Direction: -2 dB < Gain <= 0 dB
Reverse Direction: -30 dB< Gain <= -15 dB
Fail criteria: Forward Direction: Gain > 0
Reverse Direction: Gain > -15

Methods

Need to ensure that the isolator can sufficiently send a one way RF signal within the 915 MHz ISM frequency band. We began this test by performing a 2 port calibration such that the calibration plane was established at CH0 of the VNA for a frequency range of 800 MHz to 1000 MHz with 5 segments of 505 points. We then measured each isolator’s forward direction performance by connecting the isolator’s in to CH0 and the isolator’s out to CH1. Then we measure each isolator’s reverse direction performance by connecting the isolator’s out to CH0 and the isolator’s in to CH1. For both forward and reverse direction perform a frequency sweep while graphing the S21 Gain. The gain of each isolator in the 915 MHz band resulted in a forward direction of less than 0dB and reverse direction of less than -15 dB.

Results

Our ideal gain for all of the isolators in forward direction would be 0 dB and for reverse direction it would be negative infinity. However reaching negative infinity and 0 dB would be nearly impossible to achieve, which is why we picked -20 dB as our passing criteria for the reverse direction and 0dB for the forward direction. After observing the results, all of the isolators have passed. The findings from this test shows us that we will be able to properly send a one way RF signal.

Isolator 1