The flower pot antenna is a common DIY antenna for ham radio. It is an end fed 1/2 wave dipole typically made out of RG58 coaxial cable. This form provides the exact coil diameter, length and number of turns to create an inductive coil with self-resonance near the operating frequency of the antenna.

This design provides a mounting location for a panel mount SO-239 connector. The RG58 coax is soldered to the connector and then fed through and around the form. The coax should fit tightly in place on the form once it is wound.

The table below provides the element lengths after tuning with a nanoVNA, however these are just a guideline:

Band: 2m
Center Frequency: 146MHz
Coax Outer Length: 450mm (top edge of form to end of coax shield)
Coax Inner Length: 886mm (top edge of form to end of inner coax conductor)
Coil Turns: 9.5
Coil Self-Resonance: 139MHz

Band: 70cm
Center Freq: 446MHz
Coax Outer Length: 136mm (top edge of form to end of coax shield)
Coax Inner Length: 260mm (top edge of form to end of inner coax conductor)
Coil Turns: 3.5
Coil Self-Resonance: 439MHz

Band: 1.25m
Center Freq: 222MHz
Coax Outer Length: 289mm (top edge of form to end of coax shield)
Coax Inner Length: 562mm (top edge of form to end of inner coax conductor)
Coil Turns: 5.5
Coil Self-Resonance: 216MHz

Band: 6m
Center Freq: 52.2MHz
Coax Outer Length: 1275mm (top edge of form to end of coax shield)
Coax Inner Length: 2550mm (top edge of form to end of inner coax conductor)
Coil Turns: 13.5
Coil Self-Resonance: 49.6MHz