For years, antenna manufacturers and consultants have known that antennas mounted off the side of towers exhibit radiation patterns which are affected by the tower structure acting as a complex passive reflector. An "omnidirectional" antenna no longer creates an omnidirectional field In 1969, the engineers at The Antenna Specialists Company mounted a tower on a rotatable platform on their test range and measured side-mounted antenna patterns by rotating the entire tower. As more and more patterns were measured at different spacings on towers with different face dimensions, it finally was concluded that reasonable accuracy could only be obtained by modelling an exact installation. The many variables prevented interpolating results for an installation falling "between" two measured patterns The work done in the 1969-1970 period was archived for possible future reference As time progressed, computers integrated their way into all facets of business. The need to provide more detailed systems information grew, and the ability of systems engineers to perform was greatly tested. Fifteen years after the test range data was archived, the A/S Systems Engineering Department was tasked with the goal of writing software to predict these patterns. The result is ANTPLOT a program which, when compared to the real data on file for over two decades, will provide pattern predictions with reasonable accuracy. Since many other variables can affect the patterns, use of this data for system design is at your own risk
