Ham Antenna Modeler

Pick an antenna and your bands. Get cut lengths, mounting height, and the azimuth pattern.

1. What are you building?

2. Which bands?

3. Environment

Ground Support height

Choose at least one band and hit Model it to see results.

Balun / unun quick reference — which one and why

Device	Transforms	Use it for
1:1 current balun / choke	50 Ω, no ratio change	Balanced ~50 Ω loads (dipole, inverted-V) and as a common-mode choke on any coax feed.
4:1 balun	200 Ω → 50 Ω	Off-center-fed dipoles (OCFD/Windom), folded dipoles, some loops near 200 Ω.
9:1 unun	~450 Ω → 50 Ω	Non-resonant end-fed random wires (long wire), unbalanced.
49:1 unun	~2450 Ω → 50 Ω	Resonant end-fed half-wave (EFHW).
Matching coil / L-network	cancels reactance	Non-resonant verticals such as the 5/8-wave — not a balun job.