```At 10:16 9/03/00 -0000, G3XDV wrote: ``````Due to its directivity, a short vertical monopole has a gain of 2.6dB over a dipole (4.77dBi versus 2.15dBi for a dipole). ```Careful! Surely this assumes perfect ground, doesn't it? Even at HF, I think most amateurs would prefer to use a vertical dipole than a ground-plane antenna. ```Good point. I have been breaking my mind about that for some while. But it seems to me that we take the inperfect ground into account already with the ground-loss resistance, so do we have to take it into account a second time ? eg : assume a 10m high vertical (radiation resistance 8.2 milli-Ohm) If we had a perfect ground (and loadingcoil) only the radiation resistance will limit the antennacurrent, so if we put 100W into the system we will have an antennacurrent of 110A (!) and radiate 100W, what due to the directivity of the antenna results in 183W ERP. Now we take the real-world case and assume a loss of 100 Ohm (environement + coil). If we put 100W into this system we will have an antennacurrent of ```1A and radiate 8.2mW (-42dB compared to the 'perfect case'). The question is if we can take the directivity of a perfect vertical ```(2.6dB) into account ? My opinion is that we have to take this gain into account, as the enviromental losses already played their part by limiting the antennacurrent. But the only way to find out what really happens is to measure the radiation pattern of the antenna, is the anyone with acces to a small airplane or helicopter ? 73, Rik ON7YD ```