Moxon Rectangle Design Tool

Moxon antenna calculator: dimensions, plans, and tuning guide

Use this Moxon antenna calculator to generate the A–E dimensions for a classic 2-element Moxon rectangle from your design frequency and conductor diameter. Choose common amateur-radio bands or enter a custom frequency, then use the plans, construction notes, tuning steps, gain and radiation-pattern guidance below to turn the calculated geometry into a practical antenna.

Open calculator Browse band plans
Classic 2-element geometry

Moxon antenna calculator

Enter the design frequency and conductor diameter to calculate the standard A–E Moxon rectangle dimensions. Use the band preset only as a shortcut; the frequency field remains the actual design input.

Selecting a preset fills a practical starting frequency. You can overwrite it.
Use the frequency you actually want to optimize, not merely the band name.
Enter the outside diameter of the wire, rod, or tubing used for both elements.
If AWG is offered, convert gauge to physical diameter before calculation.
Changing output units must not alter the underlying calculation.
This choice is informational and must not silently change dimensions.
Default page scope for the classic 2-element Moxon rectangle.
The calculator interface is ready for the separate calculation engine integration.
Geometry

Moxon rectangle dimensions: what A, B, C, D, and E mean

Read the Moxon rectangle as a top-view outline of two folded elements. Dimension A is the full side-to-side width, not a half-element measurement. B and D are the folded tails on the driven element and reflector, while C is the open gap between their coupled tips. E is the total front-to-back depth and equals B + C + D.

Measure dimensions along the conductor centerline when practical, and keep both sides symmetrical. If tubing must be bent with a noticeable radius, preserve the intended electrical path length rather than treating a rounded corner as a sharp geometric point. The feedpoint sits at the center of the driven element; the strongest radiation is normally toward the driven-element side, away from the reflector.

Top-view Moxon rectangle A–E dimension diagram Technical diagram showing driven element at the front, reflector at the rear, center feedpoint, paired end gaps, dimensions A through E, and forward radiation. Forward radiation Feedpoint Driven element Reflector A B C D E
Label Meaning Construction note
A Overall side-to-side width Keep the driven element and reflector spans equal unless using a specifically modeled derivative.
B Driven-element tail Changing B strongly affects feedpoint reactance and the tuned condition.
C End gap / element gap One of the most sensitive dimensions because it controls end coupling and strongly affects the rear null.
D Reflector tail Influences reflector current and feedpoint resistance; adjust only in small, symmetrical steps.
E Overall front-to-back depth Derived from B + C + D; useful for support-frame and boom planning.
Reference values

Typical Moxon antenna dimensions by band

Band Design f Reference conductor A B C D E
40 m 7.15 MHz #14 Cu wire 15.11 m 2.44 m 0.41 m 2.94 m 5.78 m
20 m 14.17 MHz #14 Cu wire 7.62 m 1.22 m 0.22 m 1.48 m 2.92 m
11 m 27.205 MHz 2.0 mm wire 4.01 m 0.60 m 0.114 m 0.75 m 1.46 m
10 m 28.50 MHz #14 Cu wire 3.79 m 0.59 m 0.125 m 0.73 m 1.45 m
6 m 50.5 MHz 12.7 mm tube 2.13 m 0.281 m 0.101 m 0.410 m 0.792 m
2 m 145.9 MHz 4.76 mm rod 0.738 m 0.097 m 0.036 m 0.142 m 0.274 m
70 cm 435.6 MHz #12 Cu wire 0.247 m 0.032 m 0.012 m 0.048 m 0.092 m

Use this table as a scale reference, not as a substitute for the calculator. Moxon dimensions change with design frequency and conductor diameter, and the end gap C changes particularly quickly as the conductor becomes electrically thicker.

HF wire designs can tolerate larger absolute construction errors than UHF versions, but symmetry still matters. At 6 meters and above, bend radius, support material, connector placement, and feedline routing can shift resonance enough to require model-based refinement. For 915 MHz, use the calculator as a starting point and then continue to the modeling section rather than relying on a universal fixed-size plan.

Fundamentals

What is a Moxon antenna?

A Moxon antenna, usually called a Moxon rectangle, is a compact 2-element parasitic beam. It uses one driven element connected to the feedline and one unpowered reflector. Both elements are folded at the ends so their tips face each other across two small gaps. That folded geometry makes the antenna substantially narrower than a conventional full-width 2-element Yagi while retaining similar forward gain and producing unusually strong rejection to the rear.

A properly designed Moxon can also present a feed-point impedance close to 50 ohms, making direct connection to common coaxial cable practical when a suitable common-mode choke is used.

Moxon rectangle geometry

The outline looks like a rectangle with two breaks at the sides. The front half is the driven element: a long radiator with two tails folded backward. The rear half is the reflector: a slightly longer parasitic element with two tails folded forward. The open end gaps do not carry a DC connection, but they create strong capacitive end coupling.

Together with the ordinary parasitic coupling between the long parallel portions, this gives the Moxon its distinctive electrical behavior. Wire Moxons are common on HF, where spreaders or lightweight frames support the folded shape; aluminum rod or tubing is often more practical on 10 meters, 6 meters, 2 meters, and higher frequencies.

Driven element, reflector, and feedpoint

The driven element is split at its center and fed as a balanced radiator. The reflector is continuous and receives energy through electromagnetic coupling rather than a feedline. Current induced in the reflector has a magnitude and phase that reinforce radiation in the forward direction and cancel much of the energy toward the rear.

The two folded tip sections add another controlled coupling path, which is why the element gap is more critical than on a simple bent dipole. The design is normally symmetrical left-to-right, and the coax should leave the feedpoint in a way that minimizes common-mode current on the outside of the shield.

Operating principle

How does a Moxon antenna work?

The Moxon beam works by controlling both ordinary parasitic coupling and end coupling. RF current is applied at the center of the driven element. The driven element creates an electromagnetic field that induces current in the reflector, just as in a 2-element Yagi. Because the reflector is electrically longer and positioned behind the driven element, its induced current is delayed in phase. The two fields then add more strongly in the forward direction and cancel more strongly in the rear direction.

The folded tails add a second interaction. The driven-element tails and reflector tails face each other across the end gaps, creating capacitive coupling between the tips. Changing the tail lengths or the gap changes current magnitude and phase on the reflector. When the geometry is optimized, the rearward field from the two elements approaches a deep null while the forward field remains strong.

This is the main reason a Moxon rectangle can show a much better front-to-back ratio than a conventional 2-element Yagi without using a phasing line or a second driven feedpoint.

At the same time, the geometry can be adjusted so the feed-point resistance lies close to standard 50-ohm coax. The exact feed-point Z is not a single fixed value: resistance and reactance change with frequency, conductor diameter, geometry, height above real ground, nearby conductive objects, and construction details.

Around the design frequency, a well-built 50-ohm Moxon typically needs no impedance-transforming network, but a 1:1 current choke is still good practice to keep common-mode currents off the feedline.

The maximum forward radiation is on the driven-element side of the rectangle, away from the reflector. In a horizontally oriented Moxon, the main azimuth lobe is broad, so small pointing errors cost little signal. Rotating the entire rectangle by 90 degrees changes the polarization from horizontal to vertical; it does not reverse the forward direction.

Over real ground, height changes the elevation pattern and take-off angle through reflected waves, so the installed pattern can look different from a free-space model even when the antenna itself is correctly tuned.

Performance

Moxon antenna gain, front-to-back ratio, impedance, SWR, and radiation pattern

Moxon antenna gain

A classic 2-element Moxon is a compact beam, not a high-gain long Yagi. Well-optimized free-space models commonly fall around 5.8–6.1 dBi forward gain near the design frequency, roughly the same class as a conventional 2-element reflector-driver Yagi and only a few tenths of a decibel lower in many comparable designs.

Installed gain can appear much higher in an elevation cut because the direct and ground-reflected waves combine to form low-angle lobes. That number is not “extra antenna gain” in the free-space sense; it depends on height, ground conductivity, terrain, and take-off angle.

If maximum gain is the priority, a 3-, 4-, or longer Yagi will usually outperform a 2-element Moxon. The Moxon is chosen for its combination of compact size, broad forward beam, useful gain, and strong rear rejection.

Front-to-back ratio and rear null

The signature Moxon characteristic is the rear null. At the optimized design frequency, modeled 180-degree front-to-back ratio can exceed 30 dB and may become much deeper over a narrow frequency region.

Do not treat the highest modeled number as a guaranteed real-world specification. The null is sensitive to frequency, element symmetry, end-gap accuracy, nearby objects, and feedline common-mode current. Across a practical passband, the front-to-back ratio typically falls toward the band edges while remaining very useful.

For interference rejection, also inspect the entire rear quadrant rather than only the exact 180-degree point: a deep single rear null can coexist with quartering rear lobes in some directional arrays.

Feed-point impedance and 50-ohm coax

The Moxon shape can be optimized for different feed-point impedances, but the most common amateur design targets roughly 50 ohms so it can connect directly to 50-ohm coaxial cable. Around resonance, a carefully designed rectangle often shows feedpoint resistance in the 50–60 ohm region with small reactance.

The value changes across the band. A low SWR at the transmitter does not prove the radiation pattern is correct, because coax loss can hide mismatch and a feedline carrying common-mode current can alter both impedance and pattern. Use a current choke close to the feedpoint and measure at the antenna whenever possible.

Bandwidth, SWR, VSWR, S11, and resonance

Bandwidth depends strongly on frequency range, conductor diameter, and what performance limit you care about. A thicker conductor generally produces a broader impedance and pattern bandwidth than very thin wire. The frequency of minimum VSWR is useful, but the frequency of best rear rejection may not be exactly the same point.

During design, treat SWR or S11 as one part of a multi-parameter optimization that also includes feedpoint resistance, reactance, gain, and the radiation pattern. On 2 meters a properly proportioned Moxon can cover the amateur band comfortably; on a very wide band such as 6 meters, optimize for the portion and polarization you actually use.

Azimuth, elevation, polarization, and beamwidth

The free-space azimuth pattern of a horizontal Moxon has a broad forward lobe and a small rear lobe, often approaching a cardioid shape near the design frequency. A typical horizontal 2-element Moxon has a -3 dB beamwidth around 70–80 degrees, which makes aiming less critical than with a longer Yagi.

The elevation pattern is set mainly by mounting height and ground interaction. Modeling software can display azimuth pattern, elevation pattern, polarization components, antenna currents, F/B ratio, beamwidth, take-off angle, and radiation efficiency so the user can evaluate the actual installation rather than relying on one headline number.

Construction

How to build a Moxon antenna: step-by-step

A Moxon is mechanically simple, but it rewards accurate layout. The most common build failures are not exotic RF problems: they are unequal element halves, an incorrect or unstable end gap, conductive support material too close to the tips, a feedline that becomes part of the antenna, or dimensions copied from a design that used a different conductor diameter.

Start from one calculated geometry and preserve it as faithfully as the material allows.

Materials and tools

Component Recommended choices Selection note
Elements Copper wire for HF; aluminum rod/tubing for VHF/UHF; aluminum tubing for rotatable HF beams Use the same outside diameter assumed by the calculation.
Support Fiberglass spreaders, UV-stable rope, PVC used sparingly, or a nonconductive frame Keep lossy or conductive material away from high-current and closely coupled tip regions.
End-gap spacers Fiberglass rod, RF-inert plastic, non-stretch line, heat-shrink only where suitable Spacer must hold C accurately without electrically bridging the gap.
Feedpoint Weatherproof center insulator, stainless hardware, ring terminals or proper tube clamps Provide mechanical strain relief separate from the electrical connection.
Feedline 50-ohm coax sized for frequency and run length Add a 1:1 current choke at or very near the feedpoint.
Hardware Stainless fasteners; compatible aluminum hardware where appropriate Avoid corrosion-prone dissimilar-metal joints.
Test gear Antenna analyzer or VNA; ruler/tape; calipers for small antennas At UHF, use calipers and repeatable fixtures rather than visual estimates.

  1. Calculate the dimensions

    Choose the design frequency first, then measure the actual conductor diameter. Run the Moxon calculator and record A, B, C, D, and E in one unit system. Also record the derived driven-element length A + 2B and reflector length A + 2D.

    If you are building for a broad allocation, decide which part of the band deserves the best front-to-back ratio and match; do not assume “band center” is always the best operational target.

  2. Cut and prepare the elements

    Cut the driven element and reflector as two symmetrical structures. For flexible wire, leave a small practical allowance for end loops, clamps, or final trimming, but do not change only one side.

    For tubing or rod, account for the actual bend radius and any inserted joint length. Mark the conductor centerline and preserve the intended electrical length.

  3. Build the rectangle geometry

    Lay the driven element and reflector in the same plane with their long sections parallel. Set dimension A as the full side-to-side span and place the reflector behind the driven element. The left and right tails should mirror each other.

  4. Set the end gap C accurately

    The two end gaps are electrically important because they control the capacitive coupling between the folded tails. Set both gaps to the same value and keep the opposing tips aligned. Do not electrically connect the tips: the gap must remain open.

  5. Install the feedpoint and choke

    Split the driven element at its center and connect the coax center conductor to one half and shield to the other. Because the Moxon is a balanced antenna and coax is unbalanced, install a 1:1 current choke close to the feedpoint.

  6. Mount the antenna in the intended polarization

    For horizontal SSB/CW or weak-signal work, mount the Moxon with the long element sections horizontal. For vertical FM or repeater use, rotate the whole rectangle 90 degrees.

  7. Check geometry before applying RF

    Re-measure A, both B tails, both C gaps, both D tails, and E after the antenna is mounted. Verify that both sides are symmetrical and that the feedline exits the feedpoint cleanly rather than running along an element.

  8. Make the first analyzer sweep

    Measure the antenna as close as possible to its final height and surroundings. Sweep a frequency span wider than the intended operating range and save the starting curve before making any changes.

    Record the frequency of minimum SWR, the resistance and reactance at the design frequency, and—if your VNA supports it—the S11 trace or Smith chart.

Adjustment

How to tune a Moxon antenna after construction

Tune the finished antenna in conditions close to the final installation. A Moxon is a coupled two-element system, so changing one dimension can move several electrical parameters at once. The practical goal is not simply “1.0:1 SWR.” You want the desired resonance and feed-point impedance while preserving the geometry that produces the forward lobe and rear null.

  1. Raise the antenna away from the ground and large conductive objects. For final verification, use the intended mast height and polarization whenever possible.
  2. Make a baseline analyzer sweep wider than the operating band. Save or write down the frequency of minimum SWR, R + jX at the target frequency, and the overall shape of the curve.
  3. Inspect the physical geometry before trimming. Confirm equal left/right dimensions, correct reflector position, identical end gaps, and a feedline that is not running along an element.
  4. If the entire resonance is clearly low in frequency, shorten the electrically active geometry in very small, symmetrical increments. If it is high, lengthen the adjustable driven-element portions if the construction allows it.
  5. Use the driven-element tail B for fine control of feedpoint reactance. Change both B tails by the same amount, then repeat the sweep.
  6. If the resistance is materially wrong while reactance is near zero, make small symmetrical changes to reflector-tail length D or the broader geometry rather than trying to “fix” it with an arbitrary tuner.
  7. Treat the end gap C as a pattern-sensitive adjustment. It strongly affects end coupling and the frequency of the deepest rear null; do not use large gap changes merely to chase a prettier SWR number.
  8. After every physical change, restore symmetry and re-measure the entire intended band.
  9. When possible, perform a simple field-strength or on-air front/back check from a stable signal source. A perfect analyzer trace cannot prove that the rear null is intact.
  10. Lock the spacers and hardware only after the final sweep. Weatherproof the feedpoint, then repeat one last measurement.

Which Moxon dimensions affect tuning?

Parameter Primary practical influence Adjustment guidance
A — width Overall impedance and electrical size Treat as a structural dimension. Change only when the antenna is clearly scaled wrong or a model calls for it.
B — driven tail Feedpoint reactance / resonance behavior Useful for small symmetrical tuning corrections after the main geometry is correct.
C — end gap End coupling; location/depth of rear null; also affects impedance Critical. Adjust in very small equal steps and verify pattern as well as SWR.
D — reflector tail Reflector current and feedpoint resistance Small changes can move resistance and F/B behavior; keep both sides identical.
E — depth Composite geometry, E = B + C + D Usually a consequence of B/C/D changes rather than an independent tuning control.

If the antenna tunes only after very large dimensional changes, stop and check the assumptions. The element diameter may not match the calculation, the bend geometry may have shortened the current path, the support material may be detuning the tips, or the coax may be carrying common-mode current.

Correcting the cause is usually better than forcing a match with a tuner. A matching network can make the transmitter happy while leaving a poor radiation pattern unchanged.

Band-specific guidance

Moxon antenna plans, dimensions, and build notes by band

The same Moxon rectangle principle scales from HF into UHF, but the mechanical problem changes dramatically. On 40 and 20 meters the challenge is supporting long wire elements; on 2 meters and 70 cm the challenge is dimensional tolerance and feedpoint detail. Use the calculator for your exact frequency and conductor diameter, then use the band notes below to choose realistic materials, mounting, and tuning methods.

40 meter Moxon antenna

A full-size 40 meter Moxon is large, but still attractive when a conventional 2-element Yagi would be mechanically impractical. A representative #14 copper-wire design around 7.15 MHz is roughly 15.1 m (49.6 ft) wide and 5.8 m (19.0 ft) deep.

Most 40m Moxons are wire antennas stretched on fiberglass poles, ropes, trees, or a light perimeter frame rather than heavy rotatable aluminum beams. The driven-element tails and reflector tails must remain parallel, and both end gaps must be held at the same distance even when the wire moves in wind.

Height above real ground has a major influence on the elevation pattern and take-off angle. Do not tune the antenna lying on the ground and expect the final resonance to remain unchanged after raising it. Make the first serious analyzer sweep at operating height, use a current choke at the feedpoint, and route the coax away from the driven element.

20 meter Moxon antenna

The 20 meter Moxon is one of the most practical HF versions because it offers a useful directional pattern without the span of a full-size 2-element Yagi. A classic #14 wire example designed near 14.17 MHz is about 7.62 m (25.0 ft) wide, with a driven tail around 1.22 m, an end gap around 0.22 m, a reflector tail around 1.48 m, and total depth around 2.92 m.

Those figures are references only; recalculate when the wire diameter or target frequency changes. Portable 20m Moxons can use a central mast with fiberglass spreaders and lightweight wire, while permanent versions may use aluminum tubing or a more rigid frame.

For broad coverage of the 20m amateur band, choose a design frequency that balances SWR and front-to-back performance across the segment you use most. The deepest rear null is narrower in frequency than the forward-gain curve.

11 meter Moxon antenna

An 11 meter Moxon antenna is a compact directional option for the 27 MHz region. With 2 mm wire at 27.205 MHz, a calculated starting geometry is about 4.01 m wide and 1.46 m deep, with B near 0.60 m, C near 0.114 m, and D near 0.75 m.

A rotatable aluminum version will use a much larger conductor diameter, so do not copy the wire dimensions unchanged—enter the actual tube diameter in the Moxon antenna calculator.

Choose the design frequency around the channels or operating segment you actually use. The 11m allocation and permitted equipment vary by country, so transmitting frequency and power must be considered according to the applicable jurisdiction.

10 meter Moxon antenna

A 10 meter Moxon is small enough to build as a light rotatable beam while still being large enough that ordinary hand tools can achieve the required accuracy. A classic #14 wire reference at 28.50 MHz is about 3.79 m wide and 1.45 m deep.

Aluminum tubing is common for permanent builds, but tubing diameter changes the optimum tails and end gap, so recalculate instead of scaling a thin-wire plan.

The 10m amateur band is wide in percentage terms. A single design can provide a usable SWR range across a large portion of the band, but maximum front-to-back ratio will occur over a narrower range.

6 meter Moxon antenna

A 6 meter Moxon combines manageable size with a broad beam and strong rear rejection, making it useful for SSB/CW, local nets, and directional FM.

For a 50.5 MHz design using 12.7 mm (1/2 in) aluminum tubing, a representative geometry is about A = 2.13 m, B = 0.281 m, C = 0.101 m, D = 0.410 m, and E = 0.792 m.

The conductor is electrically much thicker than typical HF wire, so the gap is proportionally larger and should be calculated for the actual tubing diameter. Do not treat the entire 50–54 MHz band as one narrow operating range.

2 meter Moxon antenna

The 2 meter Moxon is one of the easiest versions to build and test. Around 145.9–146 MHz, a 4.76 mm (3/16 in) aluminum-rod design is roughly 0.738 m wide and 0.274 m deep, with a gap near 35 mm.

For horizontal weak-signal use, orient the long element sections horizontally; for FM simplex or repeater work, rotate the rectangle vertically. The forward direction remains from the reflector toward the driven element.

Keep the feedpoint mechanically small, use a VHF-suitable choke, and measure with the coax routed as it will be used. If you later combine 2m and 70cm elements in one structure, treat it as a dual-band design problem.

70 cm Moxon antenna

At 70 cm, the Moxon rectangle becomes physically small enough that the feed system and support material can be comparable to the critical dimensions. A 435.6 MHz reference using AWG #12 copper wire is about 247 mm wide, with B around 32 mm, C around 12 mm, D around 48 mm, and total depth around 92 mm.

A few millimeters of error in the gap or pigtail length is far more important here than on 20 meters. Use a compact connector, short balanced feed connections, and low-loss 50-ohm coax appropriate for UHF.

For satellite work, 70cm Moxons are often used as part of crossed or turnstile-style arrangements; those systems require phasing and matching beyond the single-rectangle calculator.

915 MHz Moxon antenna

A Moxon antenna at 915 MHz can be extremely compact, but this is the point where a simple scale drawing stops being a complete engineering description. Connector bodies, coax launch geometry, conductor shape, dielectric supports, PCB substrate, nearby enclosure walls, and even a few millimeters of exposed feedline can shift S11 and the radiation pattern.

Use the Moxon calculator to obtain a first-pass geometry only if the conductor diameter remains within the validated range of the chosen algorithm, then move the design into a full-wave model before cutting a final structure.

For PCB or strip implementations, round-wire MoxGen-style dimensions are not directly equivalent to flat copper traces because end capacitance and effective conductor width change. Optimize the trace width, gap, feed transition, and substrate together in the model.

Comparison

Moxon vs Yagi: which 2-element beam should you build?

Parameter Moxon rectangle Conventional 2-element Yagi
Element count 2: driven element + reflector 2: driven element + reflector
Physical span Folded ends reduce side-to-side span; compact rectangle Straight elements require a larger side-to-side span
Forward gain Typically around 6 dBi free space; often only slightly below a comparable 2-element Yagi Similar class; commonly a few tenths dB higher when both are optimized
Front-to-back ratio Can be exceptionally high near the design frequency Usually much lower for a simple 2-element design
Beamwidth Broad forward lobe; forgiving aiming Usually somewhat narrower
Feedpoint Can be designed close to 50 Ω for direct coax feed Depends strongly on element spacing/length; matching may be required
Construction Folded tails and two critical end gaps Simpler straight elements, but boom spacing must still be accurate
Best fit Compact directional antenna, rear-noise/interference rejection, broad forward coverage Simple directional beam when compact folded geometry or extreme rear null is not required

For two-element beams, the Moxon trades a very small amount of possible forward gain for a shorter element span, a broader main lobe, a convenient 50-ohm design option, and much stronger rejection to the rear.

A Yagi becomes the better choice when you need more forward gain and are willing to add directors. Once the comparison is a 2-element Moxon vs a 3-, 4-, or 5-element Yagi, the longer Yagi can provide substantially higher gain and a narrower beam.

Comparison

Moxon antenna vs dipole

Parameter Moxon antenna Half-wave dipole
Directionality Directional, one broad forward lobe Bidirectional broadside pattern
Forward gain Useful beam gain in the favored direction Lower peak gain but covers two opposite broadside directions
Rear rejection Strong when correctly tuned No dedicated rear null; front and back are essentially equivalent
Physical size Folded two-element rectangle Single half-wave element; mechanically simpler
Construction More parts, support points, and a critical gap Very simple wire or tubing radiator
Aiming Orientation matters; rotator may be useful Often fixed; broad coverage may be preferable
Portable use Excellent when directional coverage is worth the extra frame Usually easier and lighter for fast field deployment
DX / interference Useful when favoring one direction or nulling rear noise Excellent general-purpose antenna when broad bidirectional coverage is desired

A dipole is the baseline choice when simplicity, low weight, and broad coverage matter more than directionality. A Moxon adds a parasitic reflector and folded-end coupling to move more of the radiated energy into one broad forward sector while reducing energy in the opposite direction.

Choose a Moxon when you know where the desired stations are, want to reduce noise or interference from the rear, or need a compact beam that still has a wide pointing tolerance. Choose a dipole when you want signals from two broad directions or need the simplest portable antenna.

Advanced variants

2-element, 3-element, and 4-element Moxon antenna designs

Classic 2-element Moxon antenna

The standard Moxon rectangle has exactly two elements: a center-fed driven element and one parasitic reflector. Both ends are folded, creating the paired end gaps that define the Moxon geometry. This is the configuration calculated by the main Moxon rectangle calculator on this page.

The A–E equations and MoxGen-style empirical corrections are designed around this two-element current system, where the reflector and end coupling are optimized together for a useful 50-ohm feedpoint, broad forward lobe, and deep rear null.

3-element Moxon and Moxon/Yagi hybrids

A 3-element Moxon normally means a Moxon-style driven element and reflector with an added director, or another hybrid in which a compact Moxon pair forms the rear portion of a Yagi-like array.

The extra director can increase forward gain and narrow the beam, but it also changes current distribution, feedpoint impedance, optimum spacing, and sometimes the best dimensions of the original Moxon pair. There is no universal “3 element Moxon calculator” that can be created by adding one fixed director length to the A–E results.

A valid 3-element design needs a defined geometry and optimization target, ideally checked in NEC, 4NEC2, EZNEC, or MMANA-GAL.

4-element Moxon-derived arrays

A 4-element Moxon antenna is even farther from the classic calculator model. It may use a Moxon rectangle as the driven/reflector section plus two directors, or it may be a purpose-designed compact beam that borrows folded-element ideas without preserving the original Moxon current relationships.

Treat a 4-element design as a separate antenna model with its own dimensions, not as a scalar extension of the two-element rectangle.

Multiple bands

Dual-band and multiband Moxon antennas

A single-band Moxon is relatively predictable because one driven element, one reflector, and two end gaps dominate the current distribution. A dual-band or multiband Moxon adds conductors that can couple to each other, so simply nesting two calculator outputs on the same boom is not a guaranteed design.

Dual-band Moxon antenna

A dual-band Moxon can be implemented in several ways: two nested Moxon rectangles with separate feedlines, a coupled/open-sleeve arrangement with one feedpoint, switchable elements, or a carefully optimized shared structure.

A common-feed design depends on intentional parasitic coupling and cannot be derived by overlaying two independent single-band rectangles. Model both bands simultaneously and verify S11, feedpoint Z, gain, front-to-back ratio, and element currents on each band.

2m/70cm dual-band Moxon

The 2m/70cm combination is popular because the frequency ratio is close to 3:1 and both antennas are physically small. It is also easy to underestimate interaction: the 2m elements can be electrically active at 70cm harmonics, while the 70cm feed structure, spacers, and coax can disturb the 2m field.

For a simple portable satellite or terrestrial antenna, two separate Moxons mounted with controlled spacing and separate feeds may be more predictable than a shared-feed hybrid.

Multiband Moxon antenna

Multiband Moxons have been built with nested elements, open-sleeve coupling, separate feed circuits, switched conductors, and Moxon/Yagi combinations. Each method introduces additional resonances and mutual coupling.

A “multiband Moxon antenna calculator” therefore needs to define a specific topology; there is no meaningful universal form where the user enters several frequencies and receives independent A–E values that can safely be assembled together.

Satellite use

Moxon satellite antenna: 2m, 70cm, and crossed-element options

A Moxon satellite antenna is attractive when broad coverage and moderate gain are more useful than a narrow, high-gain beam. A single 2m Moxon or 70cm Moxon can serve as a simple manually aimed or fixed antenna for suitable amateur-satellite passes.

The broad main lobe reduces pointing sensitivity, while the rear rejection can help reduce unwanted terrestrial signals.

Polarization is the larger challenge. Many satellite links experience changing polarization because the spacecraft orientation and propagation path vary. Two identical Moxon rectangles can be mounted at right angles and fed with equal current magnitudes 90 degrees apart to create a turnstile-style field with two orthogonal components.

When two 50-ohm antennas are combined in parallel, the junction is about 25 ohms, so a quarter-wave matching section in the mid-30-ohm range can transform the system back toward 50 ohms. Accurate electrical line lengths, including coax velocity factor, are required.

For 2m/70cm satellite work, calculate each single-band Moxon first, then model the complete physical assembly: crossed elements, separation, support structure, feedlines, phase lines, and matching sections.

Calculation method

Moxon antenna formula and calculation method

Wavelength from design frequency

Every Moxon calculation begins with wavelength. In free space, wavelength is λ = c / f, where c is the speed of light and f is frequency. For convenient amateur-radio units, λ in meters is approximately 299.792458 divided by frequency in MHz.

A 14.2 MHz signal therefore has a wavelength a little over 21 meters, while 146 MHz is just over 2 meters. The antenna dimensions are fractions of wavelength, but they are not fixed fractions for every build because conductor diameter changes end effect and coupling. The calculator must therefore use both design frequency and physical element diameter, not frequency alone.

How A–E dimensions are derived

The classic MoxGen-style method treats the conductor diameter as a fraction of wavelength, d/λ, and applies empirical corrections developed from NEC-optimized Moxon models.

In practical terms, electrically thicker elements require a slightly shorter side-to-side dimension and a larger end gap to maintain the intended feed-point impedance and reflector coupling. This is why a 1/2-inch aluminum 6m Moxon should not be built by simply scaling a thin-wire HF drawing.

The output geometry uses five familiar dimensions. A is the overall width. B is the driven-element tail. C is the open gap between the tail tips. D is the reflector tail. E is the total depth, so E = B + C + D.

The driven-element conductor length is A + 2B and the reflector conductor length is A + 2D. Those relationships are geometric; the values of A, B, C, and D themselves come from the chosen design model. The model is an empirical fit to optimized antenna behavior, not a fundamental closed-form law of electromagnetics.

Why different Moxon calculators can give different results

Two Moxon antenna calculators may disagree even when both are reasonable. One may assume thin wire and use fixed wavelength multipliers; another may include conductor-diameter corrections. One may optimize for a near-50-ohm feedpoint, while another targets a different feed-point Z or a slightly different balance between F/B ratio and resonance.

Different programs can also use different physical definitions for dimensions— centerline-to-centerline versus outside-edge measurements—or round intermediate values differently.

At VHF/UHF, the user’s “wire diameter” may not describe the real RF geometry if the antenna uses strap, PCB traces, thick insulation, corner fittings, or a coax launch that becomes part of the radiator. For serious builds, compare the calculated dimensions with an NEC model and sweep the model over frequency.

Simulation

Modeling a Moxon antenna in EZNEC, 4NEC2, and MMANA-GAL

A calculator answers “what dimensions should I start with?” Antenna modeling answers “what will this particular physical version probably do?” That second question becomes increasingly important when the build uses thick tubing, a metal boom, nearby mast hardware, multiple bands, crossed satellite elements, a PCB, or a mounting height where real-ground reflections dominate the elevation pattern.

Exporting a Moxon model or coordinates

The useful bridge between the Moxon generator and modeling software is a set of wire coordinates based on A–E. Historical MoxGen tools could create model files for EZNEC/NEC workflows; a modern web calculator can use the same concept by converting the generated geometry into a coordinate set.

The model should preserve conductor radius, driven-element center gap/feed source, reflector continuity, tail direction, and the exact C gaps. Keep the first model in free space to verify the antenna itself, then add real ground, height, mast, and nearby conductors as separate steps.

What to check in the model

Run a frequency sweep that extends beyond the intended operating band. Plot feed-point resistance and reactance, 50-ohm VSWR or S11, and a Smith chart if the software provides one.

Then inspect forward gain, 180-degree F/B ratio, worst-case rear quadrant, -3 dB beamwidth, azimuth pattern, elevation pattern, take-off angle, and radiation efficiency. Display antenna currents to confirm that the reflector carries the expected parasitic current and that additional elements in a multiband or 3-element design are behaving as intended.

Finally, test small changes to B, C, D, conductor diameter, and feedline/choke geometry to estimate construction sensitivity. NEC optimization is most useful when it confirms a physically buildable tolerance range.

FAQ

Moxon antenna FAQ

What is a Moxon antenna?

A Moxon antenna is a compact 2-element parasitic beam made from a driven element and reflector with their ends folded toward each other. The coupled tips create two open gaps that help shape the reflector current. The result is a broad forward lobe, useful gain, and unusually strong rejection to the rear in a structure narrower than a conventional full-width 2-element Yagi.

How do I calculate Moxon antenna dimensions?

Choose the design frequency and the actual diameter of the wire, rod, or tubing. The calculator converts those inputs into A–E dimensions for the classic 2-element Moxon rectangle. Frequency sets the wavelength; conductor diameter affects end effect and the required gap. Use the output as a construction starting point, then verify the finished antenna with an analyzer.

How much gain does a Moxon antenna have?

A well-optimized classic 2-element Moxon is typically in the same gain class as a 2-element Yagi, around 6 dBi in free-space models near the design frequency. Installed peak gain depends on height and real-ground reflections. If substantially more forward gain is required, a longer Yagi with additional directors is usually the more appropriate design.

What is the feed-point impedance of a Moxon antenna?

It is not one universal number, because Moxon geometry can be optimized for different impedances. The most common amateur design targets roughly 50 ohms so it can be fed directly with 50-ohm coax. Actual resistance and reactance vary with frequency, conductor diameter, construction, height, nearby objects, and common-mode current on the feedline.

How do I tune a Moxon antenna?

Measure the antenna near its intended installation, save a baseline sweep, and change only one dimension at a time. Make equal changes on both sides. The driven tail B is useful for fine reactance adjustment, reflector tail D influences feedpoint resistance, and the end gap C strongly affects coupling and the rear null. Re-sweep after every small change.

Does a Moxon antenna need a balun?

A Moxon designed near 50 ohms normally does not need an impedance-transforming balun, but a 1:1 current choke is strongly recommended because the balanced driven element is being fed with unbalanced coax. Suppressing common-mode current helps keep the feedline from changing the impedance and filling in the rear null.

What is the most critical Moxon dimension?

The end gap C is one of the most sensitive dimensions because it controls coupling between the folded tips and strongly influences the frequency and depth of the rear null. It is not the only important dimension: A, B, and D also affect impedance and resonance. Keep both gaps equal and avoid conductive spacer material across them.

Is a Moxon better than a Yagi?

Neither is universally better. Compared with a conventional 2-element Yagi, a Moxon is more compact side-to-side, has a broader forward beam, and can provide much stronger rear rejection with similar gain. A 3- or more-element Yagi can provide more forward gain and a narrower beam.

Is a Moxon better than a dipole?

A Moxon is better when you want directional coverage and rear rejection. A dipole is better when you want the simplest possible antenna and broad bidirectional coverage. The Moxon adds a reflector and support structure, but provides several decibels of forward directivity and can reduce signals arriving from behind the antenna.

Can I mount a Moxon vertically?

Yes. Rotating the whole rectangle by 90 degrees produces vertical polarization and can be useful for FM, repeaters, and other vertically polarized services. The forward direction still runs from the reflector toward the driven element.

Can a Moxon antenna be dual-band or multiband?

Yes, but a multiband Moxon is not created reliably by stacking independent A–E results. Nested elements, open-sleeve coupling, separate feeds, switched conductors, and other techniques all create mutual coupling. Model the complete structure on every band and check feedpoint Z, currents, gain, F/B ratio, and pattern before final construction.

Can I build a Moxon from wire instead of aluminum?

Yes. Wire Moxons are especially practical on HF, while aluminum rod or tubing is convenient at 10m, 6m, 2m, and UHF. What matters to the calculator is the conductor diameter used by the design. Do not copy dimensions from a thick-tubing antenna to thin wire without recalculating.

What is a 3-element Moxon antenna?

The classic Moxon has only two elements. A “3-element Moxon” usually adds a director to a Moxon-style driven-element/reflector pair or uses another hybrid geometry. The added element changes mutual coupling, gain, beamwidth, and feedpoint impedance, so it needs its own model or validated design. The standard A–E calculator on this page does not calculate a universal 3-element version.

Can I use a Moxon antenna for satellites?

Yes. Single Moxons can work as broad-beam 2m or 70cm satellite antennas, and two identical rectangles can be crossed and phased 90 degrees apart for a turnstile-style field. Crossed systems require careful phase-line and impedance matching. At 70cm, compact feedline and accurate construction become especially important.

How high should a Moxon antenna be mounted?

There is no single correct height. On HF, height strongly changes take-off angle and the elevation pattern through ground reflection. On VHF/UHF, clear line of sight and local clutter often matter more, but nearby structures can still detune the antenna. Tune and model the Moxon near the height and environment where it will actually be used.