No, it is not plastic. It is an actual PC board with copper traces. I scratched of some of the coating to see the copper. Also the wires solder directly to the board (antenna).Same principle as the MaxUAV, DBlite antennas. Forgot about this configuration - this would make trying to change the resonant multiple even less feasible so my guess is that if it is anything other than plastic, it just a parasitic element that is too narrow to be useful (pattern wise - you increase the horizontal width of the beam by making the antenna wider).