Hello,
I design 868MHz IFA antenna. It should be placed in one corner of 160x160mm PCB. Small part of GND under the antenna structure is destinated for antenna GND. On the rest part of PCB will be elements and also GND. So can I set whole surface of PCB as a metal (copper)? Are the simulations done OK? What did I wrong?
I attach my design and results. View attachment 868MHz.rar
Ok, this should work. But from my experience, increased distance between antenna radiator and ground gives an antenna impedance that is easier to match. Have you tried a cutout in the ground below the antenna?