I am using the following antenna to form an array that can radiate two different patterns with appropriate switching.http://www.amotech.co.kr/__Data/_uploads/antenna/01%20GPS%20Antenna/GPS_Patch_Pin%20Type/Datasheet_YDRA-A25-1575%20(Rev%200).pdf
First mode is called anti-jam mode and we request highest directivity as possible. I am ok with this.
Second mode is normal mode and we want a radiation similar to stand-alone antenna, Which is 5 dB peak gain and 90-100 degree HPBW. Despite all my trials I havent been able to achieve this mode. When I activate one element of the array, gain reduces significantly due to mutual coupling, when I activate two elements, hpbw decreases. Increasing element spacing reduces coupling however axial ratio deteriorates this time. How I can I achieve those two beamform properly?
I am using FEKO and can upload feko files upon request.