It is possible using NEC to model a 3-meter, base-fed monopole with respect to its installation and operating conditions, and for NEC to calculate the groundwave field intensity vs. distance directly for those conditions.
The plots linked below show the results of such evaluations for the system configurations and conditions shown there.
From this evaluation (and much practical experience) it is clear that users installing their unlicensed AM transmitter and 3-meter whip elevated above earth level, and using a long, radiating "lightning" ground conductor to reach an r-f ground buried in the earth have a distinct advantage in the fields such a system will produce at a given distance when compared to the same system mounted with its base at earth level.
These increased fields are not the result of the height above earth of the 3-meter radiator, itself. They are the result of the increased radiation resistance of the elevated systems, which improves their radiation efficiency (other things equal). This can be seen in the values of the radiation resistance (Rr), gain in dBi, and field intensities shown for such elevated systems in the plots linked below.
http://i62.photobucket.com/albums/h85/rfry-100/Part15AMSystemComparison.gif
RF
The plots linked below show the results of such evaluations for the system configurations and conditions shown there.
From this evaluation (and much practical experience) it is clear that users installing their unlicensed AM transmitter and 3-meter whip elevated above earth level, and using a long, radiating "lightning" ground conductor to reach an r-f ground buried in the earth have a distinct advantage in the fields such a system will produce at a given distance when compared to the same system mounted with its base at earth level.
These increased fields are not the result of the height above earth of the 3-meter radiator, itself. They are the result of the increased radiation resistance of the elevated systems, which improves their radiation efficiency (other things equal). This can be seen in the values of the radiation resistance (Rr), gain in dBi, and field intensities shown for such elevated systems in the plots linked below.
http://i62.photobucket.com/albums/h85/rfry-100/Part15AMSystemComparison.gif
RF