Fan Dipole Antenna Designer
Optimized for 10, 12, 17, 20, 40, and 80 meter bands within 65" span
Design Parameters
Results
| Band | Length per side (in) | Total length (in) | Notes |
|---|---|---|---|
| 80m 3.700 MHz | 721.0 | 1441.9 | Standard install |
| 40m 7.150 MHz | 373.1 | 746.2 |
Needs bending
Details
The 40m element is too long for your space. You'll need to bend the ends downward or zigzag to fit within 65 inches.
|
| 20m 14.175 MHz | 188.2 | 376.4 | Standard install |
| 17m 18.118 MHz | 147.2 | 294.5 | Standard install |
| 12m 24.940 MHz | 107.0 | 213.9 | Standard install |
| 10m 28.500 MHz | 93.6 | 187.2 | Standard install |
Construction Guide
Materials Needed
- 5 different lengths of insulated wire (see table above)
- 1 central insulator (plastic or ceramic)
- End insulators for each wire
- Coaxial cable (RG-58 or better) with PL-259 connector
- Balun (1:1 current type recommended)
- Support ropes or guy wires
Assembly Instructions
- 1 Cut all wires to the calculated lengths, adding 6 inches to each for connections.
- 2 Attach all wires to the central insulator, ensuring good electrical contact between them.
- 3 Connect the coaxial cable center conductor to one side and shield to the other side at the center.
- 4 Attach end insulators to each wire and secure to support points.
- 5 Keep wires separated by at least 4-6 inches along their length to minimize interaction.
Important Note
This design uses a shared feed point for all elements. For best results, you may need to adjust lengths slightly during tuning. The 40m element will be the longest and may need to be bent to fit within your available space.
Performance Tips
Height Matters
Install the antenna as high as possible, ideally at least 1/2 wavelength above ground for the lowest band (40m). At 20 feet, you'll get good performance on higher bands.
Tuning
Start with the calculated lengths, then trim each element in 1-inch increments to find the sweet spot for your location. Higher bands tune more easily than 40m.
Feed Point
Use a 1:1 current balun at the feed point to prevent RF on the coax shield. Keep the coax perpendicular to the antenna for several feet to minimize interference.