can anybody tell me if there are any antenna design tools availbale for PCB or simple antennas for 868 915 Mhz bands. or does any body have a design for good omin directional antenna's for these bands
Hi,
You can also use Ansoft Ensemble or HFSS for antenna simulations. Ensemble is like Sonnet, but HFSS is 3D program and you can simulate any structure with HFSS. If you are looking for omni directional antenna, you have to use a dipole antenna.
You must enter right parameters for EM simulation, every increase numbers of cells increase time of simulation several times.
EM algoritms like FDTD (XFDTD,ZELAND,CST MWS,ANSOFT) are very robust and you must have very fast processor or processors.
If you are beginer try with algorithm based on Method of Moments. One programm based on this algorithm is NEC, it's faster several times then FDTD based programms.
Sonnet 8.52 is a good tool for planar antennas. It is very simple, and this version is very fast. I advice to use it. You can download the light version and see how it works.