help me to simulate a loop antenna operating at 434mhz
We have to start by asking what simulation tools you might have available?
For a 434Mhz loop antenna, you can get very accurate results using an integral-equation Method-of-Moments simulation. This is based on the NEC2 and NEC4 engines in the public domain that came from original publically funded work at Lawrence Livermore University.
A widely used commercial, though relatively affordable tool is NEC4Win.
4NEC2 is a free open source simulator that is very capable and widely used.
here --> http://www.softpedia.com/get/Science-CAD/4nec2.shtml
You will find examples of loop antennas, but you must expect to play with and gain some experience at using it first. Fortunately, there is lots of help, and step-by-step explanations easily searched out. Good luck with it.