Re: Wimo 13cms aerial VSWR
Ed,toggle quoted messageShow quoted text
Hardly a recommendation....I use an HP 5753C and S parameter test set. The price was good!
Calibration is done at the end of the test cable using professional SOT calibration and a good test cable.
I purposely said that the cheapies didn’t allow ‘measurement’ at 2.3GHz, but the indications can still be useful.
It’s all down to how good the directivity is of whatever the ‘device’ is that is discriminating the direction of signal ‘flow’.
It goes without saying that when the VNA is not directly connected to the antenna feedpoint, and a coax cable is used, then it is necessary to calibrate at the antenna end of the connecting cable, using a good, known, cal kit SOT set.
I find it useful to test with various good quality Attenuators at the end of the cable. The attenuators are terminated in a short (or open) to minimise fringing effects. 3 and 6dB attenuators should read close to twice their attenuation. 10dB and higher will probably show increasing error. Calibrated mismatches are harder to find but can be made, but will need calibrating with a known, good VNA.
I hope that helps?
73 de Sam
On Friday, November 15, 2019, 4:17 pm, Ed G3VPF <g3vpf@...> wrote: