Practical fluorescent light tube antenna design: A feasibility study

A reconfigurable monopole array antenna consists of one or a few driven monopole elements, surrounded by passive monopole elements that can be switched to be connected to ground. Thus, the antenna radiation pattern can be discretely adjusted by choosing different subsets of parasitic monopole elements connected to ground. This switching can be performed by PIN diodes. Here we will look at the alternative of using commercially available fluorescent light tubes. These fluorescent light tubes will become active, that is form plasma monopole antennas, when switched on. For a practical application we need to investigate the RF excitation of such plasma antennas and we need to find a way to tune the resonance frequency for a fixed length fluorescent tube. It is found that creating a magnetic frill excitation in a ground plane works well and that we can tune the resonance frequency by lowering or extending the tube in or from the ground plane while shielding the lowered part of the fluorescent tube.