Both the length and the spacing of the elements of an aerial are important when seeking to achieve resonance with the incoming frequency. I suspect that your suggestion might well degrade the signal, rather than enhance it. Further, if it did work, it would tend the increase the directional focus of the aerial, rather than boost off-axis signals.
Good quality aerials are fairly cheap. Since you're obviously prepared to work up a ladder anyway, it would make far more sense to simply install a decent one:
http://www.maplin.co.uk/p/nikkai-outdoor-tv-aerial-a20hg