The only thing that really matters with the antenna is that it is the same length. Thickness does not matter (except for the additional weight a thick wire would give).

There are kits (antenna kits that is) out there that provide for antenna replacements that are short whip type antennas that mount somewhere on the fuselage and look authentic. These are made long electrically by matching components internally. What this means is that the wavelength is matched electrically rather than by a physical length of wire.

The wavelength for a receive (or transmit for that matter) at 72 MHz is 13.6 feet. That is impractical. But, oddly enough, increments of that are acceptable provided they meet certain criteria.. they must be in increments of 1/4 wavelength but become somewhat less efficient than full wavelength.

The best and most efficient are full wavelength antennas, but we can't have 13 feet of wire hanging out the back of our models. So, quarter length or wavelength divided by 4 = quarter wavelength or 3.41 feet which is what we normally have on our receivers.

Probably more information than I really needed to provide, but perhaps this will help with a bit of understanding of antennas and lengths. This is why range is severly limited with a transmitter antenna not fully extended, but if a range check IS made, the antenna is down. This is because if it works with the antenna down, from say 200 feet away, you will have no problems with the antenna fully extended (theory.. other issues can cause problems, but this is basically true).

Hope this helps.

DS.