The key here is the "Suggested layout" diagram in the .pdf file. The
transmitter ground is connected to the ground plane, so the 50 ohm
microstrip line is one conductor of the feedline and the upper surface
of the ground plane is the other. There will be very little radiation
from the feedline because return current will flow on the ground plane
directly beneath the top side trace.

Right at the antenna is the only place where the microstrip line will
physically move away from the ground plane -- the other conductor of the
feedline. So only that part will radiate. Typically, you'd have a
conductor which goes vertically straight up from the end of the
microstrip line to the patch. Only that very short part of the feed
system will radiate.

Roy Lewallen, W7EL

redhat wrote:
i was talking about this u-strip antenna
http://export.farnell.com/productima...d/42265868.jpg
,where the center pad is the feed but has no ground pad (the other pads
are for mounting),here is the datasheet:
http://rocky.digikey.com/WebLib/Yage...-118-00918.pdf
so, when you mount it to the pcb and connect it to a microstrip line
for example, the antenna ground (internal) will not be connected to the
circuit's ground
http://www.geocities.com/aezzat3/antenna.jpg
so , this means that the ciircuit's ground will radiate and not all the
power will be fed to the antenna. is that right?
Regards