When bypass capacitors removed circuit still performing?

[usman_mahfooz]

When bypass capacitors are removed and transmission line is open and RF is coming out with only 3 dB isolation. Following image shows what i am trying to say. Can somebody comment how it's possible. Is it because of coupling?
f=3 Ghz
Circuit is on a PCB substrate and pcb is lightly tightened on the base of a flat heat sink.
Another thing is when i press different poins on the pcb etched are the response changes at the output by 2 --6 dB.
**broken link removed**

 

[volker_muehlhaus]

This is the parasitic capacitance between the two open ends.

 

[ckshivaram]

stray capacitance effect cause this problem if there is no good isolation

 

[tony_lth]

Did you see the bottom of the gap? Does it have copper?
You can simulate it in HFSS.
And the grounded difference caused different attenuations.