Amateur Quarter Wave
Ground Plane Antenna Calculator

This calculator requires the use of Javascript enabled and capable browsers. This calculator is designed to give the vertical length (height) of a quarter wave ground plane antenna, and the length of each of the four radials (often called radiators) for the frequency chosen. The normal quarter wave ground plane antenna consists of a vertical radiator which is insulated and centered between 4 horizontal surrounding radials which extend out from the base of the antenna. Each radial is evenly spaced (90 degrees apart from each other) around the vertical element. Enter the desired frequency. Click on Calculate and the optimum length for that frequency will be displayed in meters, feet, and inches. To optimize the antenna for a frequency RANGE, do the calculations twice, once for the low end of the range and once for the high end; then average the two and plan to adjust the VSWR on both ends of the range as needed.

Required Data Entry
Desired Frequency Mhz
Calculated Results
Calculated Vertical Length Meters
Calculated Vertical Length Feet
Calculated Vertical Length Inches
Calculated Each Radial Length Meters
Calculated Each Radial Length Feet
Calculated Each Radial Length Inches
Updated 6.02.11

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