Ralph Holland: antenna simulation publications

From publications

Another hobby of mine (VK1BRH).

Most of the following simulations have been performed with computer simulation using EM tools such as NEC-2, which is available via anonymous ftp or at the NEC Unofficial home page. You can also obtain further information from the Applied Computational Electromagnetics Society (ACES). Tools such as MININEC, NEC, ELNEC etc are derived from common ancestors which use the Method of Moments as a basis. Other research continues[1].

This article describes how an effective ground system can be produced for a short vertical antenna. The article explores ground losses and elevated sradial systems. A case study is presented for a 3 radial elevated groundplane.
This article explores how spiral top-loading can be employed to significantly reduce the height of a resonant radiator. Experimental results show howa 1.5m vertical can be resonated between 1.6 and 3.5 MHz! An attempt has been made to quantify the system losses. When the technique is applied to a 10 m vertical the losses can be reduced to about 3 dB at 3.5 MHz.
This article shows how the impedance of a horizontal dipole is affected by the ground parameters and mounting height. Various plots are provided to show the effect of frequency and ground parameters. Two tables are provided detailing the r.f. loss resistance in circular copper conductors.
This article describes how the efficiency of a dipole can be improved byplacing it above a counterpoise. An optimimum height and separation is observed which can be used to obtain an improvement of approximately 40%in efficiency. The radiation pattern is also displayed.
  • Hybrid Antennas, Amateur radio, Ralph Holland, Amateur Radio, Vol65 No 1, Jan 1997, pp 10-14, WIA.
This article is a treatise on antennas that use a combination of vertical and horizontal polarisation. There is a comparison table where the pros and cons of a particular configuration can be weighed up against the constructionand location. Radiation patterns, complete with holes, are displayed in a three-dimensional plot and charts are provided showing the feedpoint impedance and total system efficiency for various soils.

Copyright (c), Ralph Holland - VK1BRH, 1997 - 2004