A high-gain omnidirectional printed antenna

Hello all,
Does anyone have a good idea for a high-gain(peak gain>6dBi) omnidirectional printed antenna in ISM band?
THS!

liutengji

Please check the following link.

https://www.edaboard.com/viewtopic.p...585&highlight=

You could achieve this with four colinear dipoles and have a little design margin as well. The array would be about two and a half wavelengths long.