Hi,

I am working on a MIFA Wifi microstrip antenna design. As I connect the nano VNA to the antenna feed I do not see change in S11.
Not really sure what is happening here.
below are the screenshots for my design, the connections and VNA view,

Consider recalibrating your vna across the band 1-3GHz to see if you can see a S11 resonance at a different frequency to your expected 2.4GHz.I suspect that your meandered antenna lines are too close to each other and you are getting unwanted coupling between these parallel sections of the antenna which is maybe de-tuning your antenna.If the resonance is too low in frequency,use a scalpel to reduce the length of the meandered antenna by for example 1mm and then remeasure.Carry on reducing antenna length until resonance occurs at 2.4ghz.If resonance is too high in frequency,you need to add copper tape,maybe add 10mm in length and then cut back with scalpel until resonance occurs at 2.4ghz.

Your expected centre frequency for the antenna was 2.4GHz but I suspect
that due to the meandered antenna lines being very close,only one track
width apart,that unwanted coupling is occurring and detuning the
antenna.Recalibrate the vna across the band 1-3 GHz to determine where
resonance of the antenna is actually happening and once you know that can
then go forward to retune to 2.4GHz.
On Fri, 4 Jun 2021, 04:02 , <asharma@bewhere.com> wrote:

> Hi,
>
> I am working on a MIFA Wifi microstrip antenna design. As I connect the
> nano VNA to the antenna feed I do not see change in S11.
> Not really sure what is happening here.
> below are the screenshots for my design, the connections and VNA view,
>
>
>
>
>
>
>
>

and you HAVE TO calibrate exactly at the cable end!! (or you measure nuts)

greetz sigi dg9bfc

Am 04.06.2021 um 09:58 schrieb Ian Bradley:

> Your expected centre frequency for the antenna was 2.4GHz but I
> suspect that due to the meandered antenna lines being very close,only
> one track width apart,that unwanted coupling is occurring and detuning
> the antenna.Recalibrate the vna across the band 1-3 GHz to determine
> where resonance of the antenna is actually happening and once you know
> that can then go forward to retune to 2.4GHz.
> On Fri, 4 Jun 2021, 04:02 , <asharma@bewhere.com
> <mailto:asharma@bewhere.com>> wrote:
>
> Hi,
>
> I am working on a MIFA Wifi microstrip antenna design. As I
> connect the nano VNA to the antenna feed I do not see change in S11.
> Not really sure what is happening here.
> below are the screenshots for my design, the connections and VNA view,
>
>
>
>
>
>