Remember that antennas needs a large area to receive the radio energy in the air and smaller antennas are always a compromise. A straight long wire are the best but you can curl it up to still make it tuned to a frequency and make it shorter but it will receive less signal. There is no way to make a small antenna work as good as a big antenna. But if a receiver are not good enough it could overload from a big antenna and could actually work better with a smaller antenna. Portable receivers are usually designed to be used with small antennas. Shortwave antenna size are usually restricted by the location and the area you have at your disposal and might anyhow force you to use compromised antennas.
/Ubbe
