Dear Group,
I'd like to have some advice regarding the typical practice when connecting an antenna (aerial for US purists) to a spectrum analyzer.
I suppose the dangers are
- DC levels
- ESD / static charge of the antenna
- power outside the band you're currently watching (eg you zoom in on some detail and reduce input attenuation to reduce the noise level and simultaneously fry the mixer because you were hit by a radar signa)
- thunder strike
I should add that the perspective is not to use a 2.4 GHz rubber duck antenna but do scalar analysis of a 10 meter amateur affair.
The prospective protections are:
- a DC block
- attenuators
- diode limiters
The analyzer would be a 70000 series with 70904A 2.9 GHz RF section. It has both DC and AC coupled modes.
I know how to watch for mixer overload.
Again, any advice on how it should be done?
Best regards,
sr75pro
I'd like to have some advice regarding the typical practice when connecting an antenna (aerial for US purists) to a spectrum analyzer.
I suppose the dangers are
- DC levels
- ESD / static charge of the antenna
- power outside the band you're currently watching (eg you zoom in on some detail and reduce input attenuation to reduce the noise level and simultaneously fry the mixer because you were hit by a radar signa)
- thunder strike
I should add that the perspective is not to use a 2.4 GHz rubber duck antenna but do scalar analysis of a 10 meter amateur affair.
The prospective protections are:
- a DC block
- attenuators
- diode limiters
The analyzer would be a 70000 series with 70904A 2.9 GHz RF section. It has both DC and AC coupled modes.
I know how to watch for mixer overload.
Again, any advice on how it should be done?
Best regards,
sr75pro
I would not use a limiter if I needed to measure distortion. I'm not sure about the 70000 series, but typically 1 watt CW is the max input into most analyzers. Not sure about peak power. Unless you are very close to a transmitter, you probably won't see that kind of power. If you are not concerned about distortion and you are close to a strong transmitter, then a limiter should be OK.
A limiter and attenuator should control most ESD events. I've also seen inert gas tubes used (neon, argon) to control voltage spikes. Not sure how well they work for ESD. For thunder strike a good set of earplugs should suffice
Anyway, those are some of my ideas, but it appears that you have thought this through pretty well already.