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Amateur 5 Side Loop Antenna Calculator

This calculator requires the use of Javascript enabled and capable browsers. This calculator is designed to give the horizontal length of a particular dipole antenna (often called a pentenna), or one side of it (and directional details), for the frequency chosen. The general appearance of this antenna is a supported pentagon shaped loop, parallel to the ground, closed on 4 sides and open in the selected directional side. It is a modified dipole for space and directional reasons. This design reduces the amount of space needed for the antenna but requires 5 support points instead of 3 for a typical dipole. It also becomes somewhat directional be that a benefit or a detriment. The angle of the loop at the support points is 72 degrees by default but can be modified slightly for best performance. Obviously the gap opening size will differ. Enter the desired frequency and select the desired calculation from the drop box. Click on Calculate and the optimum length for that combination will be displayed in feet and inches. In the case of the Gap selection, the length given is for the distance of the gap between the ends of the side lengths. Lengths are given in feet, inches and fractions of inches, and in meters. The center of each Tee should be joined to the end of each of the dipole main elements. 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
Select Antenna Calculation Length

Calculated Results
Calculated Selected Dipole Length
Calculated Support Point Angle
Updated 6.02.11

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