Hands up, who gets antenna gain? Like why 2dBd is better than 3dBi and why 8dBi might not be a good choice after all? This whole antenna gain topic might be quite confusing. Not only there are 2 units dBi and dBd (since blame marketing for that!) but also one must realize that antenna does not really have a gain like an amplifier or transistor. If 100mW will be put into antenna it will never radiate more than a 100mW. Truth to be told, it will always radiate less than that!