FEKO Help. Apply a Specific Excitation current to an array of wire antenna

New to FEKO. Thanks for the help in advance. I've come up with excitation currents for a Dolph-Chebyshev distribution of excitation currents for a 7 element linear phased array.

I wish to simulate this array with the specific normalized currents to get the radiation pattern.

I-3 = .263
I-2 = .5672
I-1 = .8735
I0 = 1
I1 = .8735
I2 = .5672
I3 = .263

When I change the voltage in a port for an element, it changes the impedance of the line too, so I don't know how to work around so I can get the above currents.

Hope that makes sense.

Thanks