It depends on the frequency range you are tuning.
A 45 ft. antenna will be more resonant at wavelengths somewhere around the 15 meter band -- around there it will probably be somewhat directional off the sides of the wire; but it still will pick up stations from other directions.
For most SW frequencies, your antenna will be fine where it is -- it will tend to be omnidirectional when picking up those longer wavelengths / lower frequencies.