Ground-plane verticals are widely used by amateurs but frequently it is not possible to install the classical 1/4-wave vertical with 1/4-wave radials. There are many variations that work around common problems. You can for example use shorter radials as shown in short radials in GP antennas , 88 kb, Antenna Compendium 6. You can also combine fewer and shorter radials with top loading as discussed in The lazy H vertical , 3,243 kb (a biggie!), Communications Quarterly Spring 1997. It also can be helpful to see the relationship between elevated and buried radial systems. This is discussed in another way to look at verticals , 145 kb, QEX Mar/Apr 1999.