This is the antenna I have found to be the most effective limited space radiator that I have ever used.
The main requirement is to get it positioned in the clear, away from buildings if possible. Having said that, it is possible to hang a groundplane from the limb of a tree, this also works very well. The diagram below shows the basic design:
The Formula for calculating the length of the Radiator is given by:
L in feet) = 234/(Frequency in Mhz)
There is a school of thought which holds the view that the RADIALS should be 5% longer than the Radiator, but I have found, together with others, that the Radials should be the same length as the Radiator.