Calculator: Flower Pot Antenna

The “Flower Pot” antenna is a brilliant vertical coaxial dipole design popularized by VK2ZOI. Its biggest advantage is that it can be completely inserted inside a PVC pipe, making it mechanically robust, weatherproof, and very easy to “hide” (ideal for Gray Man tactical deployments or restrictive HOAs).

How it works

• It is electrically a center-fed half-wave dipole.
• Top Element (Radiator): The coaxial cable shield is removed, leaving only the center conductor with its dielectric.
• Bottom Element: The intact coaxial cable. The outer shield acts as the second half of the dipole.
• Choke Coil: An RF choke made by coiling the same coaxial cable on the PVC pipe just below the bottom element. It prevents RF from traveling down the rest of the cable to the radio.

Tactical Flower Pot Calculator

Enter the operating frequency. (The measurements consider a slight shortening due to the velocity factor of the cable and the dielectric effect of the PVC pipe).

Center Frequency (MHz)

CALCULATE

Cutting Results

Top (Stripped, core only) -- meters

Bottom (Intact shield) -- meters

RF Choke Coil:
Just below the "Bottom" measurement, wrap 6 to 9 tight turns of the same coaxial cable around the PVC pipe.

⛺ Emergency Deployment Guide (For Non-Techs)

• Setup: It is installed completely vertically. Because it’s enclosed in a PVC pipe, you can simply tie the pipe to a balcony, tree branch, or wooden fence.
• Recommended Height: The higher, the better the range. Just make sure the PVC pipe is rigid enough so it doesn’t bend too much in the wind.
• Isolators: The great advantage of this design is that the PVC pipe acts as a perfect insulator. No additional isolators are required.
• Feed Line (Coaxial): The antenna is built from the exact same cable that feeds it. Make sure to use 50-ohm cable (RG-58 is the easiest to coil on PVC). In this particular case, using 75-ohm TV cable (RG-6) will alter the measurements and make it hard to coil properly, so it’s not recommended for this specific model.