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Old 20-Jan-2012, 8:22 PM   #21
GroundUrMast's Avatar
Join Date: Oct 2010
Location: Greater Seattle Area
Posts: 4,773
Originally Posted by sc2dave View Post
Sorry,all of these letters and numbers are 100% Greek to me.
Sorry about that, I offer the modeling software code for any who may be interested in it. I hope the attached graphics may be helpful in visualizing the changes to the radiation/receiving pattern as the antenna geometry is changed.

For those interested, 4NEC2 can be downloaded free of charge. The software makes the job of designing a workable antenna within the reach of those of us who lack a masters or doctorate degree in mathematics and electrical engineering.

In the last 'code' post, the dimensions of a 5/8 wave whip is about 1.87meters (SY DEL=1.868521 'Element Section Length in Meters). A loading coil is needed as well, located at the base of the antenna, it's calculated value is about 0.6 ÁH (SY COIL=6.125e-7 'Load Inductance, Henrys). This should be enough information to build an experimental 5/8 wave vertical antenna for use in the FM broadcast band. (Using the calculator at I estimate a coil 0.5" in diameter, 0.7" long and having 3 turns, will be very close to the needed value for the load coil.)

The modeling suggests that you would see about 2 or 3 dB better gain compared to a stock whip antenna.
If the well is dry and you don't see rain on the horizon, you'll need to dig the hole deeper. (If the antenna can't get the job done, an amp won't fix it.)

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Last edited by GroundUrMast; 22-Jan-2012 at 6:05 AM. Reason: Added load coil dimension estimate
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