Radio Antenna Calculator 1–6000 MHz

Choose an Antenna, pick a frequency, cable type and wavelength, then click Calculate.

Two-Element Dipole

Thin-wire end-effect ~5% applied. Output uses your selected units only.
Choose options and click Calculate.
How it works (Dipole)

Two equal arms fed at center. Horizontal → horizontal pol; vertical → vertical. Use a 1:1 current choke balun with coax.

More: Feeding, matching & choking
  • Center-fed (split) dipole prefers a 1:1 current balun at the feedpoint.
  • If matching is needed, use an LC network or a tuner at the shack end (keep feedline losses low).
Horizontal Center conductor Shield/ground Insulate halves Vertical Center conductor Shield/ground Insulate halves Dipole wave radiation

Ground-Plane (3 Radials @ 45°)

Radials default to ¼-wave (+~5%) at 45° for ~50–60 Ω.
Choose options and click Calculate.
How it works (Ground-Plane)

Vertical radiator above sloped radials forms a monopole over image ground. Add a choke on the feedline.

More: Matching & choking
  • 5/8-wave radiators often need a small series inductor to cancel capacitive reactance.
Radiator 3 radials @ 45° Feed: center → radiator, shield → radials

Yagi–Uda Array

Driven shortened ~5%. Reflector ≈ 1.05× driven; directors taper shorter. Spacing ~0.15–0.20 λ.
Choose options and click Calculate.
How it works (Yagi)

Driven + reflector + directors form a forward beam. Split driven is insulated; center conductor to one half, shield to the other; add a 1:1 choke.

More: Feeding, matching & choking
  • Split driven: 1:1 current balun at feed.
  • Gamma/hairpin: still add a common-mode choke near feed.
  • Folded dipole: ~300 Ω → 4:1 balun.
Click Calculate to draw elements, spacings & feed

Parabolic Dish + Feed

Default 20 λ (~solid, good gain)
Dish D/f/d computed from F/D and diameter. Wavelength selection scales feed element example dimensions only. Feed sits on the concave/front side at the focus.
Choose options and click Calculate.
How it works (Parabola + Feed)

Dish focuses plane waves at the focus (receive) and collimates feed radiation out the aperture (transmit). Match feed beamwidth to F/D.

More: Feed choice, matching & choking
Aperture plane

J-Pole Antenna

Radiator is fixed at ½-wave (~5% shorten). Stub is ¼-wave. Spacing ≈ 0.02 λ. Tap ≈ 0.06 λ above the short.
Choose options and click Calculate.
How it works (J-Pole)

A ¼-wave shorted stub matches a ½-wave radiator to ~50 Ω. Coax taps near the bottom. Add a choke.

More: Tap, matching & choking
  • Feed: center → stub; shield → radiator. Slide tap to fine-tune SWR.
  • Short bar: connects stub bottom to radiator bottom.
Center → stub Shield → radiator Bottom short

Polarization quick guide

Vertical Antennas

Horizontal Antennas

Baluns & Chokes — What, Why, DIY

Balun vs. Choke (difference)

Balun (Balanced ↔ Unbalanced)

  • Converts between balanced (e.g., dipole) and unbalanced (coax) systems.
  • May provide impedance transformation (e.g., 4:1) and act as a common-mode choke.
  • Maintains opposite phases (~180°) on balanced outputs.
  • Types: transformer, coil, coax (sleeve), choke balun (current balun subtype).

Choke (Common-Mode Suppressor)

  • Blocks common-mode current on the outside of coax. 1:1 (no impedance change).
  • Prevents the coax from becoming an unintended radiator.
  • Place at the feedpoint, or within 1/4 λ down the line.

Why & when a choke is needed

Why & when a balun is needed

DIY examples

Ferrite snap-on choke (1:1)

8–12 snap-on beads (mix 31/43) at the feedpoint Stops common-mode current on the outside of coax
  • Use mix 31 for HF–VHF, mix 43/61 for VHF–UHF. More beads → higher choke impedance.
  • Place at the feedpoint (or ≤ 1/4 λ down the line).

Air-wound coax choke (coax coil)

Coil diameter (pick per band) Turns ≈ 0.2–0.25 λ of coax length
  • Aim total coax in the coil near 0.22 λ at the target frequency.

Toroid transformer baluns (1:1 & 4:1)

1:1 current balun (Guanella) — bifilar 4:1 transformer 50 Ω (coax) ~200 Ω (folded dipole)
  • 1:1 current balun: FT240-31/43 core, bifilar windings — great for dipoles → coax.
  • 4:1: matches higher-Z loads (e.g., folded dipole). Mind core mix & power limits.

Bands & Quick Guidance (1 MHz → 6 GHz)

Examples are typical for North America; allocations vary by country. Follow local laws/licensing.

Medium Frequency (MF) — 300 kHz–3 MHz

Includes AM broadcast & nav beacons.

  • Uses: AM broadcast (~530–1710 kHz), NDB beacons (~190–535 kHz), maritime.
  • Antennas: Long wires, loops, verticals with extensive radials.
  • Polarization: AM ground-wave: vertical; loops vary.

High Frequency (HF) — 3–30 MHz

  • Uses: Shortwave broadcast, CB (~27 MHz), amateur 80/40/20/15/10 m, over-the-horizon radar.
  • Antennas: Dipoles, end-feds, verticals, loops.
  • Polarization: Mixed; ionosphere can rotate polarization.
  • Examples: CB 26.965–27.405 MHz, 10 m 28–29.7 MHz.

Very High Frequency (VHF) — 30–300 MHz

  • Uses: FM broadcast 88–108 MHz, air band 118–137 MHz (AM), marine 156–162 MHz, land-mobile 150–174 MHz, 2 m 144–148 MHz, MURS 151–154 MHz.
  • Polarization: Land-mobile & marine voice: vertical. Airband: vertical.

Ultra High Frequency (UHF) — 300 MHz–3 GHz

  • Uses: UHF TV, public safety (varies), FRS/GMRS 462–467 MHz, 70 cm 420–450 MHz, ADS-B 1090 MHz, ISM 902–928/2.4 GHz.
  • Polarization: Land-mobile/public safety: vertical. ADS-B/ATC: vertical.

L-band — 1–2 GHz

  • Uses: GNSS (~1.2–1.6 GHz), satcom, telemetry, 23 cm amateur (where permitted).
  • Polarization: GNSS is RHCP; many terrestrial links linear.

S-band — 2–4 GHz

  • Uses: 2.4 GHz Wi-Fi/Bluetooth, some radars, satcom.
  • Polarization: Usually linear (V/H); MIMO variants exist.

“6 GHz band” — 5.925–7.125 GHz

  • Uses: Wi-Fi 6E/7.
  • Polarization: Usually linear; multi-pol MIMO common.