Can I run an extra wire between the two earth or ground rods?... I've now tried this and while it increases antenna efficiency by not including the ground rod resistance in the return current path the wire does act as an antenna for local RF noise and a small amount of noise gets back in. If you were to extend the spacing I would recommend that you add extra ground rods along the ground wire to improve the grounding to reduce the noise pickup. I'm going to try that on my antenna to see if it takes it back to the truly quiet noise floor again.