```Peter wrote: ``````Question to PA0SE: Dick, did you choose 1.5mm of diameter or radius? Some programs are using "radius" other "diameter"... ``````I used diameter. AO requires the material to be put in. I choose copper, for which the program uses a conductivity of 1.7241E-08. ``````Here are the results from simulations with MININEC I'm including the maximum gain as the program reports at "x-direction" (g in dBi) ``````AO also provides gain figures of course but I refrained from including them in my report because they are not applicable to the surface wave by which the majority of contacts on LF are made. If you want to know field strength figures for the surface wave (both E- and H-field) you can use the "near field" option of AO or EZNEZ. As was explained by W7EL on an earlier occasion this in reality computes the sum of the near field and the surface wave. At a distance of 2 wavelength or more from the antenna the near field becomes so weak that for all practical purposes the result of the "near field" computation gives the surface wave. You can check the validity of the results by calculating E/H (E in V/m, H in A/M). The result should be near 120 * pi = 377. The method only gives E and H at selected points, not as a radiation pattern. I am happy that Peter's calculations of Rs agrees very well with mine using AO. However this should not be taken as a proof that the results must be true as both programs use the same algorithm. Refering to the last part of my second report (16.9.99 14.17) it is clear that top loads are hardly a substitute for height. Even raising the antenna from 10 to 15 m increases radiation resistance more than even the largest top load can do. This is easily understood as radiation resistance is proportional to height squared whereas the most a top load can do is doubling the radiation resistance. This also explains the fine signal from Steve, GW4ALG. His helium balloon raises the antenna to 20 m and that gives him a radiation resistance of almost 32 milli-ohm, even without any top load at all! 73, Dick, PA0SE ```