[Discuss-gnuradio] My SHIELDING is wrong?

[Songsong Gee]

I have electrodes to be tested their characteristics

Here is a picture of them,

https://picasaweb.google.com/lh/photo/UY9fJGfk2iayEBafvniVbg?feat=directlink

And I connected them to USRPs via SMA-SMA cable

https://picasaweb.google.com/lh/photo/0wJ84tU_Y0veX6svcWBeMw?feat=directlink

However, there is a problem!

I want to know characteristics of just CIRCLE part, except a rod part.

In my experience, this rod part acts as an antenna! Thus, I cannot figure out exactly

So, I make a shield around the rod part. This shield is made with Aluminum foil which is used for cooking.

https://picasaweb.google.com/lh/photo/kMx24c0PLaQdhfo2-t00MQ?feat=directlink

And I expect that the rod part rarely sense electromagnetic wave and thus only the circle part can receive a signal

The result is like this:

Result without SHIELDING

https://picasaweb.google.com/lh/photo/JBWG6A0NzhbLgcto44_B0w?feat=directlink

Result with SHIELDING

https://picasaweb.google.com/lh/photo/H9RItzjpfemHy-OR2eQhQg?feat=directlink

That's very weird.

As my knowledge, if there is SHIELDING, the sensitivity of an antenna should get worse.

But, in my experiment, this SHIELDING helps communication!

I have any idea of it. I got confused

Did I make shielding wrong?