Antenna Design
Antenna Design Software
Bottom-Loaded Vertical Antenna

Bottom-Loaded Vertical Antennas & Coil Design

Author: R.J.Edwards G4FGQ © 24th October 2002

This program calculates the base feed-point impedance and the loading inductance or capacitance required for resonance for a given vertical antenna height, diameter and operating frequency. The number of coil turns and wire gauge are also calculated for a given coil length and diameter.

The computed base feedpoint resistance does not include the resistance due to losses in the ground radials. If an estimate of that loss is available it should be added to Rin. Antenna height can be varied such that feedpoint resistance matches the impedance of coax lines (usually 50 or 75 ohms) after taking ground-loss resistance into account.

It is of interest that a vertical ground-mounted antenna has greatest low-angle gain when its height is approximately 0.63 wavelengths. The vertical radiation pattern begins to develop small high-angle lobes at greater heights, but there is still substantial low-angle radiation.

All input data can be varied in small increments from the keyboard.

Run this Program from the Web or Download and Run it from Your Computer
This program is self-contained and ready to use. It does not require installation. Click this link BotLoad2 then click Open to run from the web or Save to save the program to your hard drive. If you save it to your hard drive, double-click the file name from Windows Explorer (Right-click Start then left-click Explore to start Windows Explorer) and it will run.

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