Why a ground loop a problem, not a ground plane(patch attena)?
It is only an antenna if the size of the structure starts to approach about 1/10 th of the wavelength of your frequency of interest.  For example 1 GHz is about 30cm, so ground structures bigger than 3cm start to assist in radiation.  However they are not good radiators unless you are impedance matched to them to transfer maximum power.  So in general a weak EMI signal at 1GHz would not radiate well because they are usually low power and they are not impedance matched to transfer maximum power to the patch of ground.  And the rule of thumb of having more ground almost always beats out any incidental radiation that might leak out.