thanks man, infact i am using radiation boundary lambda/4 on either side except downward , i tried many other examples for ISM band (2.45 GHz) there i get fine results but when extend my design and shift my frequency on 100 MHz all the results become wrong , u please do some favour for me just do something with the design and bring gain and directivity more than one and efficiency greater than 50% , it will be enough for me , as i tried many thing on this but i could not get right results , please i will be very thankful for you and also i am uploading my changed project file please in which i have made the ground plane finite conductor , check it please.....