here it is .. radius 7 mm , height 4.45 mm , r/h=1.57 ratio ... the feeder was calculated as being d1=3mm , d2=0.85 mm with a ratio of d1/d2=3.49 .. could you please tell me what is the best dielectric that i should use where should the feeder be situated and what parameters should i change to achieve the desired dual band frequencies 800 Mhz , 1.8 Ghz ( or at least the best posibil result that gets close to what i want ) .. thanks for your help , i really appreciate it