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Antenna Utilities

Antenna Builder

An interactive 3D antenna design and pattern modelling environment. It provides parametric templates for thirteen antenna families, with real time analytical electromagnetic modelling, 2D and 3D pattern visualisation, frequency sweeps with a Smith chart, matching network synthesis, and coaxial feed line analysis.

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The Templates tab with the antenna families and the Beginner and Expert mode toggle.
The Templates tab with the antenna families and the Beginner and Expert mode toggle.
Per family frequency presets for the 2 metre, 70 centimetre, WiFi, GPS, and HF bands.
Per family frequency presets for the 2 metre, 70 centimetre, WiFi, GPS, and HF bands.
The Parameters tab with the per family geometric controls and the target impedance.
The Parameters tab with the per family geometric controls and the target impedance.
The WebGL viewport with orbit, pan, zoom, wireframe, axes, and ground plane controls.
The WebGL viewport with orbit, pan, zoom, wireframe, axes, and ground plane controls.
The analytical result block with gain, directivity, impedance, VSWR, return loss, and bandwidth.
The analytical result block with gain, directivity, impedance, VSWR, return loss, and bandwidth.
The 2D polar pattern with an optional 3D pattern surface overlay in the viewport.
The 2D polar pattern with an optional 3D pattern surface overlay in the viewport.
Real ground correction, conductor material and gauge analysis, and Yagi vertical stacking.
Real ground correction, conductor material and gauge analysis, and Yagi vertical stacking.
The VSWR, S11, impedance, and Smith chart sweep with a hover readout across frequency.
The VSWR, S11, impedance, and Smith chart sweep with a hover readout across frequency.
Matching network synthesis and coaxial feed line analysis with component values and a Smith path.
Matching network synthesis and coaxial feed line analysis with component values and a Smith path.
A parameter sweep that plots a chosen metric against a geometric variable to find the optimum.
A parameter sweep that plots a chosen metric against a geometric variable to find the optimum.
Export options, and the Simulate tab showing the cloud full wave backend as coming soon.
Export options, and the Simulate tab showing the cloud full wave backend as coming soon.

Overview

Antenna design sits in an awkward gap between handbook calculation and full wave simulation. Handbook formulas from Balanis, Stutzman, and Kraus produce a usable first cut for the common antenna families in seconds, but they miss the second order effects that decide whether a design works in practice. Full wave simulation tools such as CST, HFSS, and Ansys give a definitive answer, but they require licensed software, model preparation, mesh tuning, and compute time that does not fit the early sizing loop. As a result, engineers either over engineer with full wave for problems that do not need it, or under engineer with hand calculations for problems that do.

The noIM3 Antenna Builder occupies that gap on purpose. Thirteen parametric antenna templates cover the great majority of practical RF antenna design work, namely the centre fed dipole, the folded dipole, the quarter wave monopole over a ground plane, the ground plane antenna with sloping radials, the Yagi Uda array, the vertical collinear array, the log periodic dipole array, the corner reflector, the TM10 microstrip patch, the base station sector panel, the axial mode helical with right hand circular polarisation, the magnetic loop, and the wideband discone. Each template provides sensible defaults for common operating frequencies, such as the 2 metre and 70 centimetre amateur bands, WiFi at 2.4 and 5 GHz, GPS L1, and the HF bands, and exposes every geometric parameter for full manual control. Beginner mode hides the advanced controls, while Expert mode exposes everything.

Real time analytical models compute gain, directivity, radiation resistance, input impedance, VSWR, return loss, efficiency, half power beamwidth, and 2 to 1 VSWR bandwidth as you change the geometry. Radiation patterns render on a 2D polar canvas for the E plane and the H plane at once, with a linear or a dB scale and a 40 dB dynamic range, and an optional 3D pattern surface overlays directly on the geometry in the WebGL viewport so the spatial behaviour is visible rather than abstract. Beyond the core results, the tool synthesises L, Pi, and T matching networks with real component values, models the effect of a coaxial feed line, corrects the pattern for real ground, and analyses the conductor material and gauge. The analytical model is first order and is intended for preliminary design and sizing. A cloud full wave simulation backend that runs Method of Moments, FDTD, and FEM is coming soon, and until then you should verify any production design in a full wave tool before fabrication.

Capabilities

Thirteen parametric antenna templates

The tool covers the centre fed dipole, the folded dipole, the quarter wave monopole over a ground plane, the ground plane antenna with sloping radials, the Yagi Uda array, the vertical collinear array, the log periodic dipole array, the corner reflector, the TM10 microstrip patch, the base station sector panel, the axial mode helical with right hand circular polarisation, the magnetic loop, and the wideband discone. Each template carries sensible defaults for common operating frequencies and allows full manual override of every geometric parameter.

Interactive 3D WebGL viewport

A viewport powered by Three.js provides orbit, pan, and zoom. You can toggle the wireframe view, the coordinate axes, and the ground plane grid. The camera frames the antenna automatically on every geometry rebuild. An overlay shows the physical size, the electrical length, and the resonant frequency at a glance, so geometry changes are visually intuitive rather than blind to the model.

Real time analytical electromagnetic modelling

Validated handbook models drive instant results in the browser. Radiation resistance comes from numerical integration of the far field pattern function. Yagi gain uses the Viezbicke empirical charts. Patch resonant length uses the Hammerstad and Jensen end effect extension. Helical gain uses the Kraus axial mode formula. The log periodic array uses the Carrel relationships, and the sector panel uses the 3GPP and ITU-R F.1336 reference pattern. All results update in real time as the parameters change.

2D polar pattern visualisation

The E plane, the H plane, or both are rendered at once on a 2D canvas. You can toggle between a linear amplitude scale and a logarithmic dB scale with a 40 dB dynamic range. Half power beamwidth markers and the front to back ratio are reported for directional antennas. The pattern view updates in real time alongside the analytical results.

3D pattern surface overlay

An optional 3D radiation pattern surface overlays on the antenna geometry inside the WebGL viewport. It helps you understand the spatial behaviour of the radiated power, identify side lobes that a single 2D cut can miss, and produce intuitive visuals for design reviews and engineering reports.

Impedance, VSWR, and bandwidth

Input impedance is returned as R plus jX. VSWR and return loss are computed against a configurable reference impedance, with a default of 50 ohm. The 2 to 1 VSWR bandwidth is surfaced directly so the matching requirement is visible rather than implied. The Smith chart shows the impedance locus with constant resistance and constant reactance circles and a 2 to 1 VSWR circle for the configured impedance.

Matching network synthesis

The tool synthesises L, Pi, and T matching networks that transform the antenna impedance to the system impedance. It returns real inductor and capacitor values, a Q figure, a Smith chart path, and a schematic, with both low pass and high pass arrangements where they exist. This supports feed point matching and bandwidth assessment before you size the matching components.

Coaxial feed line analysis

The feed line section transforms the antenna impedance through a chosen length of coaxial cable, from a built in cable catalogue or a custom cable, using a lossy transmission line model. It reports the impedance, the VSWR, and the S11 at the transmitter, together with the matched cable loss and the electrical length, so the match seen at the radio is clear rather than implied.

Real ground and conductor analysis

The ground and radial system section corrects the pattern and the gain for real ground. For a vertical antenna it reports the ground resistance, the ground efficiency, the radial system, and the corrected gain, and for a horizontal antenna it reports the height, the pattern efficiency, and the take off angle. The conductor analysis section reports the conductor loss and the radiation efficiency for the chosen conductor material and wire gauge, so the realised gain reflects the real conductor rather than an ideal one.

Yagi array factor and vertical stacking

Yagi designs add an array factor overlay that isolates the effect of the element spacing and the driven length from the empirical gain charts. A vertical stack option pairs the Yagi with a second identical Yagi at a configurable spacing and reports the stacking gain, the optimal spacing, and the stacked elevation pattern, which gives an immediate read of the gain improvement for a typical stack.

Parameter sweep optimisation

Sweep one geometric variable across a range and plot a chosen metric, such as gain, VSWR, or front to back ratio, against that variable. You set the variable, the minimum, the maximum, and the number of steps, and the chart shows the value that gives the best performance. This turns a series of manual edits into a single optimisation view.

Export and CAD integration

Export the antenna geometry as a Wavefront OBJ for import into CST, HFSS, Ansys, or any CAD tool. Export the analytical results breakdown as CSV. Export the analytical impedance sweep as a one port Touchstone S1P file. A two port Touchstone S2P export will follow with the cloud full wave backend.

Cloud full wave simulation (coming soon)

A cloud full wave simulation backend is in development. When it is available, it will run Method of Moments for wire and surface structures, FDTD for volumetric and layered designs, and FEM for complex geometries, and it will return S parameters, near and far field data, and current distribution results, along with goal based optimisation. Until then, the analytical model provides the results for preliminary design and sizing.

Beginner and Expert modes

Beginner mode hides the advanced controls and presents a simplified parameter set, so a new user reaches a usable design quickly. Expert mode exposes every geometric parameter, along with the matching and feed line sections, for fine tuning and for unusual designs that fall outside the template defaults.

Standards & methodology

  • IEEE 145 standard definitions of terms for antennas
  • Balanis Antenna Theory analysis and design textbook formulations
  • Stutzman and Thiele Antenna Theory and Design textbook formulations
  • Kraus Antennas reference for axial mode helical analysis
  • Hammerstad and Jensen microstrip end effect extension formulae
  • Viezbicke NBS Yagi Uda empirical design charts
  • Carrel log periodic dipole array design relationships
  • 3GPP and ITU-R F.1336 reference radiation pattern for the sector panel

When to use this tool

  • Rapid antenna prototype dimensioning before fabrication or full wave simulation
  • VSWR and impedance analysis for matching network design
  • Matching network synthesis with real component values for L, Pi, and T topologies
  • Coaxial feed line analysis to see the impedance and VSWR a radio actually sees
  • Yagi array design for amateur radio and point to point links
  • Microstrip patch design for PCB integrated wireless modules
  • GPS and GNSS helical sizing for satellite receiver terminals
  • HF magnetic loop design for portable and mobile operation
  • Collinear, ground plane, and discone sizing for VHF and UHF base and monitoring stations
  • Antenna pre compliance checks against gain and directivity specifications
  • Teaching RF engineering with visual 3D patterns and impedance concepts
  • Producing antenna design documentation for ACMA licence applications

Is this the right tool for you?

Reach for the Antenna Builder in any of the following situations.

  • You are dimensioning an antenna prototype before fabrication and want a fast, validated first cut from analytical models rather than launching a full simulation campaign.
  • You are designing a Yagi Uda array for amateur radio on the HF, VHF, or UHF bands and want to see how the element lengths and spacings drive the gain, the beamwidth, and the front to back ratio in real time.
  • You are designing a microstrip patch for a PCB integrated wireless module and need the TM10 resonant length and the impedance with the substrate effects applied correctly.
  • You are sizing an axial mode helical for a GPS, GNSS, or amateur satellite ground station and need accurate gain and circular polarisation handling.
  • You are designing an HF magnetic loop for portable or mobile operation and need the radiation resistance, the efficiency, and the bandwidth at the operating frequency.
  • You are designing a matching network for a complex impedance antenna and need the R plus jX, the VSWR, and the 2 to 1 bandwidth, along with real L, Pi, and T component values, before you size the components.
  • You are checking how a length of coaxial cable shifts the match seen at the radio and need the impedance, the VSWR, and the cable loss at the transmitter.
  • You are evaluating two or three candidate geometries against a gain or VSWR specification and want a rapid parametric comparison rather than building each one in CAD.
  • You are about to commit a design to full wave simulation and want a pre submission geometry and analytical sanity check to avoid wasting compute time on a flawed starting point.
  • You are responsible for an antenna pre compliance check against a customer or regulator specification and need engineering grade gain, directivity, and pattern documentation.
  • You are validating an inherited antenna design against the current expected performance and need an analytical baseline before deciding whether to redesign.
  • You are producing antenna design documentation for an ACMA radiocommunications licence application and need exportable geometry and pattern evidence.
  • You are training new RF engineers in antenna fundamentals and want a teaching tool that exposes the geometry and the radiation pattern visually rather than as equations.
  • You are exporting antenna geometry to CST, HFSS, or Ansys for further analysis and need a clean Wavefront OBJ that imports without remeshing.
  • You are sanity checking a vendor proposed antenna design against the underlying analytical physics and want an independent calculation against the Balanis, Stutzman, and Kraus formulations.
  • You are designing for an unusual frequency or geometry that is not in the templates and need Expert mode access to every geometric parameter.

Frequently asked questions

Which antenna types are supported?

Thirteen parametric templates are supported, namely the centre fed dipole, the folded dipole, the quarter wave monopole over a ground plane, the ground plane antenna with sloping radials, the Yagi Uda array, the vertical collinear array, the log periodic dipole array, the corner reflector, the TM10 microstrip patch, the base station sector panel, the axial mode helical with right hand circular polarisation, the magnetic loop, and the wideband discone. Together these cover the great majority of practical RF antenna design work. For dish reflector analysis, see the noIM3 Parabolic Antenna Calculator.

What analytical models drive the real time results?

The results come from validated handbook formulations. Radiation resistance is computed by numerical integration of the far field pattern function. Dipole input reactance uses the thin wire approximation. Yagi gain uses the Viezbicke NBS empirical charts. Patch resonant length uses the Hammerstad and Jensen end effect extension. Helical gain uses the Kraus axial mode formula. The log periodic array uses the Carrel relationships, and the sector panel uses the 3GPP and ITU-R F.1336 reference pattern. The references include Balanis Antenna Theory and Stutzman and Thiele Antenna Theory and Design.

Can I synthesise a matching network?

Yes. The tool synthesises L, Pi, and T matching networks that transform the antenna impedance to the system impedance. It returns real inductor and capacitor values, a Q figure, a Smith chart path, and a schematic, with both low pass and high pass arrangements where they exist. You can also model a coaxial feed line to see the impedance, the VSWR, and the cable loss at the transmitter.

When will cloud full wave simulation be available?

A cloud full wave simulation backend is in development and is shown as coming soon in the tool. When it is available, it will run Method of Moments for wire and surface structures, FDTD for volumetric and layered designs, and FEM for complex geometries, and it will return S parameters, near and far field data, and current distribution results, along with goal based optimisation and a two port Touchstone S2P export. Until then, the analytical model provides the results for preliminary design and sizing.

Can I export geometry to CST, HFSS, or Ansys?

Yes. Wavefront OBJ export covers the antenna geometry in a format that every major CAD and electromagnetic simulation tool imports. This is useful when a noIM3 Antenna Builder design becomes the starting point for a more detailed simulation campaign in a vendor specific environment. You can also export the calculation breakdown as CSV and the analytical impedance sweep as a one port Touchstone S1P file.

How is this different from the Antenna Selector and the Parabolic Antenna Calculator?

The Antenna Selector is the right tool for shortlisting antenna archetypes against application requirements such as frequency, gain, polarisation, and application. The Parabolic Antenna Calculator handles dish reflector gain, beamwidth, and aperture analysis once a dish has been chosen. The Antenna Builder is the full design environment for building a specific antenna and modelling its pattern, impedance, and bandwidth. Use the selector for shortlisting, the parabolic calculator for dish detail, and the builder for full antenna design.

Is the analytical accuracy good enough for fabrication?

For first cut dimensioning of common antenna families at common frequencies, the analytical accuracy from the Balanis, Stutzman, and Kraus formulations is typically within a few per cent on gain and within a few hundred ohms on input impedance, which is appropriate for sizing decisions. Expect roughly plus or minus 1 dB on gain and plus or minus 10 to 20 per cent on impedance and bandwidth within the stated validity range of each antenna. For final fabrication, especially for patch antennas, electrically small designs, or any design near a metallic enclosure, verify the design in a full wave tool before fabricating, so that the second order effects the analytical model cannot represent are caught.