Ham Radio Antenna Calculators
Sixty-three antenna calculators covering every common — and plenty of uncommon — HF, VHF, and UHF antenna types — dipoles, Yagis, Moxon rectangles, cubical quads, delta loops, J-poles, end-fed half-waves, loading coils, traps, portable and mobile whips, classic named wire designs, phased beams and arrays, receive-only loops, and HOA/stealth builds. All calculations run in your browser with no data sent anywhere.
Half-Wave Dipole Length Calculator
Calculates each arm length and total span for a horizontal or inverted-V half-wave dipole. Applies the standard end-effect velocity factor for wire or tube elements.
Yagi Antenna Element Length Calculator
Generates a complete element length and spacing table for 2–11 element Yagis using DL6WU-based scaling, with boom correction for aluminium booms.
Moxon Rectangle Dimension Calculator (Cebik Equations)
All five Cebik dimensions (A–E) for any frequency. Includes wire cut lengths, frame size, and installation notes. Works for any HF or VHF band.
Cubical Quad Element Calculator
Full-wave loop dimensions for 1, 2, or 3-element quad antennas. Outputs side length, circumference, spreader arm length, and total wire required.
Full-Wave Delta Loop Calculator
Equilateral triangle loop dimensions — total wire, side length, apex height, base width, and phasing line for a two-element beam.
J-Pole Antenna Dimension Calculator
Radiating element length, matching stub length, and approximate feed tap position for any frequency. Works for 2m, 70cm, 1.25m, and HF J-poles.
EFHW Wire Length and UNUN Calculator
Half-wave wire length for any band, plus 49:1 UNUN winding specification for FT-140-43 or FT-240-43 toroid. Includes multi-band harmonic coverage.
Quarter-Wave Vertical and Radial Calculator
Vertical element length, radial lengths for angled or flat radials, and estimated feed point impedance for various radial configurations.
Base Loading Coil Calculator
Required inductance to resonate a short vertical or mobile whip, plus Wheeler formula coil winding specification.
Antenna Trap LC Calculator
Calculates inductance and capacitance for a parallel LC trap resonant at a specified frequency, with coil winding details.
Antenna Gain dBd ↔ dBi Converter
Convert between dBd (referenced to dipole) and dBi (referenced to isotropic). Also converts to ERP and EIRP given transmitter power.
Inverted-V Dipole Height and Span Calculator
Given apex height and desired arm angle, calculates horizontal span, tip height above ground, and effective arm length.
Antenna SWR Bandwidth and Q Calculator
Estimates SWR 2:1 bandwidth from element diameter and resonant frequency. Also converts between Q, bandwidth, and resonant frequency.
Yagi Stacking Distance and Gain Calculator
Optimum vertical and horizontal stacking distance for two identical Yagis, combined gain estimate, and power splitter notes.
Buddipole-Style Coil-Loaded Arm Calculator
Given your telescoping arm's physical length, estimates the loading coil reactance and inductance needed on each side to reach resonance.
Buddistick-Style Vertical Coil Calculator
Same coil-loading approach as the Buddipole calculator above, applied to a single vertical whip fed against a counterpoise.
AX1-Style Short Whip Coil Calculator
Coil reactance and inductance for a very short (1.5–2 ft) whip. Flags when the whip is short enough that radiation efficiency will be notably reduced.
Screwdriver Antenna Coil Position Calculator
Estimates the required coil reactance and inductance for a given band — use as the starting motor position before fine-tuning electrically.
Fixed-Coil Mobile Whip Calculator
Single-band fixed-coil mobile whip — same math family as the screwdriver calculator, but for a fixed (non-adjustable) coil wound once per band.
Bugstick Mobile Whip Coil Calculator
Budget manually-tapped mobile coil — same loading-coil approximation as the Hamstick and Screwdriver calculators, sized for a hand-set tap.
Tapped-Coil Base-Loaded Whip Calculator
Estimated tap position on a multi-band tapped base-loading coil — a starting point before sweeping SWR and adjusting the tap clip.
Tactical Whip Coil Calculator
Quick-deploy field whip loading estimate — same coil approach as the other mobile whip calculators, sized for rapid setup with a ground spike and counterpoise.
Slinky/Spring-Loaded Vertical Calculator
Loading estimate for a compression-spring-loaded vertical — use the result as a starting stretch length, then fine-tune by hand while watching SWR.
Isotron-Style Loading Calculator
Rough starting-point coil estimate for a capacitance-hat-plus-coil compact antenna. Actual designs require empirical tuning of plate spacing and coil taps together.
Dual-Band Mag-Mount Whip Calculator
Quarter-wave whip length for 2m, plus the 70cm third-harmonic frequency the same physical whip works on (with correspondingly higher SWR).
Ladder-Line Roll-Up J-Pole Calculator
Radiator and stub lengths for a twin-lead/ladder-line J-pole, using the same half-wave-plus-stub math as the copper-pipe J-pole with a ladder-line velocity factor.
Random Wire Length Checker
Flags proposed wire lengths that land within 5% of a problematic half-wave multiple on common HF bands, and suggests known-good "sweet spot" lengths.
Go-Kit EFHW Length Calculator
Half-wave wire length and minimum counterpoise length for the HF leg of an emergency/go-kit antenna, fed with a 49:1 unun.
W3DZZ 80m/40m Trap Dipole Calculator
Feedpoint-to-trap and trap-to-tip leg lengths for the classic 2-trap, 2-band W3DZZ, plus a suggested trap LC target.
Extended Double Zepp (EDZ) Calculator
Leg and total wire length for a center-fed 0.64-wavelength-per-leg Extended Double Zepp, fed with ladder line into a balanced tuner.
Cobweb 5-Band Element Calculator
Folded-dipole element span for each Cobweb band — each band's zigzag element is independent, so trim only the one you're adjusting.
Classic Windom Leg Calculator
Total wire length and the ~36%-offset single-wire feedpoint tap for the historical Windom, fed with one wire into a link-coupled tuner (no balun).
Full Sloper Length Calculator
Standard half-wave dipole length for a sloper — electrically identical to a flat-top dipole, with directionality coming from the mounting angle, not a different length.
Folded Dipole Length Calculator
Overall half-wave length for a folded dipole — the fold raises feedpoint impedance to ~280–300 ohms without changing the resonant length.
Double Bazooka Coax-Sleeve Calculator
Coax leg length (adjusted for your coax's own velocity factor) for a double bazooka, where the shield is the radiator and the center conductor is shorted at the far end.
Koch Fractal Dipole Calculator
Straight-dipole reference length versus the folded Koch physical span, plus the extra wire needed per leg for the first-iteration zigzag fold.
ZL Special Phased Beam Calculator
Rear/front element lengths, close-element spacing, and crossed phasing-line length for the classic close-spaced 2-element phased beam.
HB9CV Phased Beam Calculator
Reflector/director lengths and spacing for the compact HB9CV — same design family as the ZL Special, matched with a capacitor-tuned phasing harness.
Quagi (Quad + Yagi) Calculator
Reflector and driven quad-loop perimeters plus a tapered director-rod table for a Quagi, using the same ratios as this site's Quad and Yagi calculators.
Handheld Satellite Yagi Element Calculator
NBS thin-wire reflector/driven/director lengths for a tape-measure handheld satellite Yagi, tapered ~2% per additional director.
Eggbeater Satellite Antenna Calculator
Bent-element wire length, reflector screen diameter, and phasing-line length for a crossed-dipole Eggbeater with reflector screen.
Turnstile Antenna Calculator
Straight dipole element length and 90° phasing-line difference for a crossed-dipole turnstile fed in quadrature — no reflector needed.
Lindenblad Circular-Polarization Calculator
Dipole element length for a 4-dipole Lindenblad array — tilt each ~30° from horizontal, spaced 90° apart around the mast, fed in phase.
Axial-Mode Helix Calculator
Circumference, diameter, turn spacing, axial length, and estimated Kraus-approximation gain for an axial-mode helix at your chosen turn count.
Hentenna Loop Calculator
Vertical side length and top/bottom spacing for the folded-loop Hentenna. Feed tap position along the bottom wire is found empirically with an analyzer.
Skeleton Slot Loop Calculator
Slot height and width for an Orr-style skeleton slot loop. Feed tap position along one long side is found empirically, the same as the Hentenna above.
EH Antenna Cylinder Size Calculator
Starting cylinder length and gap dimensions only — there is no closed-form formula for the matching network, which must be tuned empirically on the bench.
CFA Starting-Size Calculator
Reasonable E-field cylinder and H-field plate starting dimensions. This is a size estimate only — it does not endorse the design's disputed efficiency claims.
Rhombic Antenna Calculator
Leg length, approximate tilt angle, and typical gain for a terminated rhombic at your chosen leg length in wavelengths.
Vee Beam Antenna Calculator
Leg length, included apex angle, and typical bidirectional gain for a Vee beam, fed at the apex with ladder line into a balanced tuner.
Bobtail Curtain Calculator
Vertical element length, half-wave spacing between the three self-phased elements, and total top-wire span for a Bobtail Curtain.
W8JK Phased Array Calculator
Element length and crossed-phasing-line spacing for the classic 2-element close-spaced W8JK bidirectional array.
Lazy H Stacked Dipole Calculator
Element length, collinear row span, and vertical stack spacing for a Lazy H — both rows fed in phase, unlike the W8JK's crossed feed.
Bruce Array Calculator
Bay length, jumper-drop length between bays, and total horizontal span for a folded zig-zag collinear Bruce array.
Sloping V Antenna Calculator
Leg length and suggested included angle for a Sloping V — a starting point before slanting both legs toward your target DX direction.
EWE Receive Loop Calculator
Post height, suggested post spacing, and starting termination resistor for a low-band EWE receive antenna. Optimize the resistor empirically against a known station.
Pennant Receive Loop Calculator
Apex height, suggested base width, and starting termination resistor for a triangular Pennant receive loop.
Flag Receive Loop Calculator
Loop height, suggested loop width, and starting termination resistor for a rectangular Flag receive loop — a close cousin of the Pennant and EWE.
Bisquare Loop Calculator
Full-wave loop perimeter and each of the four equal sides for a diamond-shaped Bisquare loop strung between two supports.
Spiral Loop Calculator
Full wire length and approximate spiral diameter for a compact spiral-wound small transmitting loop at your chosen turn count.
Gutter-Mounted Stealth Wire Calculator
Concealed wire length for a gutter-run stealth antenna — the gutter plays no electrical role and must not be used as the radiator itself.
Window Screen Antenna Calculator
Each panel length and total frame span for an antenna built invisibly into an ordinary window screen frame. Panel width isn't critical to resonance.
Flagpole Vertical Calculator
Quarter-wave element length and minimum recommended flagpole height for a vertical hidden inside a genuinely non-conductive (fiberglass) flagpole.