The discone, one antenna, ten to one.

Almost every antenna is cut for one band. A discone is the exception: a disc sitting above a cone, apex down, that stays matched across roughly a ten-to-one frequency range from a single set of dimensions. It is the natural monitoring antenna — one mast, and you can hear the whole VHF/UHF picture.

How to use it

• Set the design frequency to the lowest frequency you need. The cone spokes are a quarter wave there, and that is what sets the bottom end.
• Pick your element material — it sets the velocity factor for the cone spokes.
• Cone half-angle controls the flare. 25–35° is the usual range; a wider flare gives a slightly broader match and a wider antenna.

What you get

• The cone spoke (slant) length, the cone base diameter, and how tall the cone stands.
• The disc diameter at the published 0.7 × cone base ratio, and the disc spoke length.
• The feed gap between the disc and the cone apex.
• A band-by-band list of what actually falls inside the covered span.

Tips

• Spokes work as well as sheet metal at these frequencies, weigh far less and survive wind. Eight in the disc and eight in the cone is the usual build; more only helps a little, and the count is not a design variable. What matters is that every spoke is the same length and evenly spaced — the symmetry is what keeps the pattern omnidirectional.
• Feed with 50 Ω coax: center conductor to the disc, braid to the cone apex. Run the coax straight down through or alongside the cone.
• Keep the feed gap small and even. It is what sets the top end of the range.

Good to know

Below the cone cutoff a discone still receives — which is why a scanner discone appears to hear HF — but it is no longer matched or efficient down there, and you should not transmit into it. Gain is around a dipole’s across the whole range. This is an antenna you choose for coverage, not for reach; if you need reach on one band, build a Yagi or a J-pole instead.