I'm interested in omnidirectional antennas or maybe I should say antennas that don't care too much if you move/rotate them. Now how would you build a good antenna for a specific frequency range. (e.g 1920-2170MHz or 2401-2473MHz or 87.5-108MHz)
And what's the magic behind getting the best dbi?
I heard that the antenna height is very important and that the ideal antenna height is the wavelength divided by two, is that correct?
Also: Could you use two antennas and wire them together for better results?
And does it matter if you roll up or bend an antenna? (Is there a limit, maximum angle or so?)
Edit: One more thing, I found an antenna that claims to be optimized for
890 - 960 MHz / 1710 - 2150 MHz. How is that possible? Does it really not pick up 960-1710MHz?