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Help on understanding the power detector


o.a.aldhaibani 2021/11/02 08:51

Dear All,

I am just trying to understand how this nanovna working!!
Anyone know please which power detector been used or how it works? i can see the coupler but, after that where receiving/ returning signal gose? I am a bit confuse tbh.

Thanks in advance

Omar

Jim Lux 2021/11/02 11:11

On 11/2/21 8:51 AM, o.a.aldhaibani@ljmu.ac.uk wrote:
> Dear All,
>
> I am just trying to understand how this nanovna working!!
> Anyone know please which power detector been used or how it works? i
> can see the coupler but, after that where receiving/ returning signal
> gose? I am a bit confuse tbh.


Generically, all these small VNAs have the detector in software. They
down convert to an audio frequency, then mix to baseband and detect to I/Q.

o.a.aldhaibani 2021/11/03 06:52

Thanks indeed for the reply Jim.
Just one more question please, a SA612A chip(Double-balanced mixer) has been used which is covering up to 500MHz and the sweeping is up to 3.8GHz!! so how is that possible, please?

Thank you

Omar

Jim Lux 2021/11/04 04:17

On 11/3/21 6:52 AM, o.a.aldhaibani@ljmu.ac.uk wrote:
> Thanks indeed for the reply Jim.
> Just one more question please, a SA612A chip(Double-balanced mixer)
> has been used which is covering up to 500MHz and the sweeping is up to
> 3.8GHz!! so how is that possible, please?


Just because you're outside the datasheet specs doesn't mean it stops
working :)

It just doesn't meet the guaranteed specs.

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