Coaxial Cable | Phraygun

Coaxial Cables

Objective

To ensure that each coaxial cable can transfer RF signals thru the cables.

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 coaxial cable and perform a sweep while graphing the S11 Return Loss.

Pass criteria: -1 < Return Loss <= 0
Fail criteria: -1 => Return Loss > 0

Methods

Need to ensure that the coaxial cables can sufficiently transfer RF signals thru the cables that are within the 915 MHz ISM frequency band. We began this test by performing a 1 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 cable’s performance by connecting each of the coaxial cables to port 1 and performing a frequency sweep while graphing the S11 Return Loss. The return loss of each patch antenna in the 915 MHz band resulted in less than -1 dB.

Results

Our ideal return loss for all of our coaxial cables would 0 dB because in an open circuit the return loss would be 0 dB. However, this is nearly impossible to achieve which is why our passing criteria is between 0 dB and -1 dB because we want the return loss as close to 0 dB as possible but a negative -1 dB would still be okay for our case. After observing our results, we found that all the coaxial cables passed this test. The findings from this test show that each of the coaxial cables are between the -1 dB and the 0 dB, which means that all of our cables work.

Cable 1