Two port antenna isolation effect

Question

I wonder and imagine if one antenna systems having two ports for two different working frequencies (so two different antenna elements included inside of it), what is the port isolation importance in respect to impedances of the two ports? With another words, Is bad isolation between the ports able to change the impedances of each other where coaxial cables are connected? If so, how level of isolation might do such a thing?

Thx

Answer 1

Port isolation could impact a few things:

• Impedance matching. Poor impedance matching and poor isolation could certainly lead to reflections. Poor match and poor isolation could lead to other complex problems like poor cross-polarization, distorted beams, etc.
• Radiation efficiency. Pour isolation but a good match would lead to poor radiation efficiency: the antenna can't radiate any power if the other port is absorbing it.
• Component damage. If you were transmitting high power into port 1 and you have poor isolation, it could damage the components on port 2.

The level of isolation needed is application dependent.