Inductive Coil Sensor Distance Issues

So I've made an inductive coil, loop sensor. The sensor is a resonator circuit that connects to my Arduino Uno Rev 3. I am doing a self calibration through code that will find the resonant frequency and the voltage on the coil at which point it holds these values. What I'm having trouble with are the following item.

  1. The sensing distance of the coil is not as good as when I was using an independent power supply. (I'm assuming this is due to the low current output of the Arduino). In which case I need a way to get more current out of the board while stilll being able to use the Arduino to calibrate the resonator circuit. Would it be as simple as placing a power supply with a higher voltage somewhere? If so how could I prevent it from killing the Arduino? i. If the current is the issue how could I effectively get the Arduino to work well with an additional power supply. Keep in mind the Arduino is pushing the frequency on the coil as well as the voltage right now. I need to maximize the read distance for the resonantor.