how to solve wifi problems with ios 6 + 6.0.1 + 6.2 ?

Hello all, I have a problem with my iPhone 4 and wifi since updating to ios 6. Before that I had no problems with wifi.

The wifi connection is very bad. only within 1 meter of the conector I can connect with wifi.

Also the update to ios 6.0.1 and ios 6.1 gave no solutions.

I've tried all the tips on the internet. network settings are reset, iphone reset etc.

Now there is still no solution I am distraught. Does anyone have any tips???