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Guides
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- Beyond Analytical Formulas: Accurate Coil Inductance Calculation with AN-SOF
- Complete Workflow: Modeling, Feeding, and Tuning a 20m Band Dipole Antenna
- DIY Helix High Gain Directional Antenna: From Simulation to 3D Printing
- Evaluating EMF Compliance - Part 1: A Guide to Far-Field RF Exposure Assessments
- Design Guidelines for Skeleton Slot Antennas: A Simulation-Driven Approach
- Simplified Modeling for Microstrip Antennas on Ungrounded Dielectric Substrates: Accuracy Meets Simplicity
- Fast Modeling of a Monopole Supported by a Broadcast Tower
- Linking Log-Periodic Antenna Elements Using Transmission Lines
- Wave Matching Coefficient: Defining the Practical Near-Far Field Boundary
- AN-SOF Mastery: Adding Elevated Radials Quickly
- Enhancing Antenna Design: Project Merging in AN-SOF
- On the Modeling of Radio Masts
- The Equivalent Circuit of a Balun
- AN-SOF Antenna Simulation Best Practices: Checking and Correcting Model Errors
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- AN-SOF 9: Taking Antenna Design Further with New Feeder and Tuner Calculators
- AN-SOF Antenna Simulation Software - Version 8.90 Release Notes
- AN-SOF 8.70: Enhancing Your Antenna Design Journey
- Introducing AN-SOF 8.50: Enhanced Antenna Design & Simulation Software
- Get Ready for the Next Level of Antenna Design: AN-SOF 8.50 is Coming Soon!
- Explore the Cutting-Edge World of AN-SOF Antenna Simulation Software!
- Upgrade to AN-SOF 8.20 - Unleash Your Potential
- AN-SOF 8: Elevating Antenna Simulation to the Next Level
- New Release: AN-SOF 7.90
- AN-SOF 7.80 is ready!
- New AN-SOF User Guide
- New Release: AN-SOF 7.50
- AN-SOF 7.20 is ready!
- New Release :: AN-SOF 7.10 ::
- AN-SOF 7.0 is Here!
- New Release :: AN-SOF 6.40 ::
- New Release :: AN-SOF 6.20 ::
- Show All Articles (2) Collapse Articles
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Models
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- Download Examples
- Modeling a Center-Fed Cylindrical Antenna with AN-SOF
- Yagi-Uda Array
- Monopole Over Real Ground
- Helix Antenna in Axial Mode
- Modeling a Circular Loop Antenna in AN-SOF: A Step-by-Step Guide
- A Transmission Line
- An RLC Circuit
- Explore 5 Antenna Models with Less Than 50 Segments in AN-SOF Trial Version
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- Modeling a Super J-Pole: A Look Inside a 5-Element Collinear Antenna
- Simulating the Ingenious Multiband Omnidirectional Dipole Antenna Design
- The Loop on Ground (LoG): A Compact Receiving Antenna with Directional Capabilities
- Precision Simulations with AN-SOF for Magnetic Loop Antennas
- Advantages of AN-SOF for Simulating 433 MHz Spring Helical Antennas for ISM & LoRa Applications
- Radio Mast Above Wire Screen
- Square Loop Antenna
- Receiving Loop Antenna
- Monopole Above Earth Ground
- Top-Loaded Short Monopole
- Half-Wave Dipole
- Folded Dipole
- Dipole Antenna
- The 5-in-1 J-Pole Antenna Solution for Multiband Communications
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- The Lazy-H Antenna: A 10-Meter Band Design Guide
- Extended Double Zepp (EDZ): A Phased Array Solution for Directional Antenna Applications
- Transmission Line Feeding for Antennas: The Four-Square Array
- Log-Periodic Christmas Tree
- Enhancing VHF Performance: The Dual Reflector Moxon Antenna for 145 MHz
- Building a Compact High-Performance UHF Array with AN-SOF: A 4-Element Biquad Design
- Building a Beam: Modeling a 5-Element 2m Band Quad Array
- Broadside Dipole Array
- Log-Periodic Dipole Array
- Broadband Directional Antenna
- A Closer Look at the HF Skeleton Slot Antenna
- The 17m Band 2-Element Delta Loop Beam: A Compact, High-Gain Antenna for DX Enthusiasts
- Enhancing Satellite Links: The Moxon-Yagi Dual Band VHF/UHF Antenna
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Validation
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- Simple Dual Band Vertical Dipole for the 2m and 70cm Bands
- Linear Antenna Theory: Historical Approximations and Numerical Validation
- Validating Panel RBS Antenna with Dipole Radiators against IEC 62232
- Directivity of V Antennas
- Enhanced Methodology for Monopoles Above Radial Wire Ground Screens
- Dipole Gain and Radiation Resistance
- Convergence of the Dipole Input Impedance
- Impedance of Cylindrical Antennas
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Helix Antenna in Axial Mode
The helix is a good example where we need curved segments to describe the geometry of the antenna. When the length of the helix is of the order of or greater than the wavelength, it can work in the so-called “axial mode”. To do this, we need to add a ground plane as a reflector.
Step 1 | Setup
Go to the Setup tabsheet and set an operating frequency of 100 MHz in the Frequency panel. Then, go to Environment panel > Ground Plane box, select Perfect, and set the ground plane position at Z = 0 (xy-plane), Fig. 1. Make sure the Discrete Sources option is selected in the Excitation panel.
![](https://antennasimulator.com/wp-content/uploads/2022/10/Fig15-16a.png)
![](https://antennasimulator.com/wp-content/uploads/2022/10/Fig15-16b.png)
Step 2 | Draw
Go to the Workspace tab, right click on the screen, and select Helix from the displayed pop-up menu >. The Draw dialog box for the Helix will be shown, Fig. 2. The helix will start above the ground plane, at the point (0,0,0.3) m, and run along the Z axis. We will then add a vertical wire that will connect the helix to the ground plane and where we will place the source.
The recommended helix dimensions for the axial mode can be obtained from any antenna book. Here we will set the helix radius, pitch (spacing between turns), and number of turns shown in Fig. 2. In the Attributes tab, we will leave the recommended number of segments of 103. The wire cross-section will be circular with 3 mm in radius
![](https://antennasimulator.com/wp-content/uploads/2022/10/Fig15-17a.png)
![](https://antennasimulator.com/wp-content/uploads/2022/10/Fig15-17b.png)
After drawing the helix, right click on the helix and choose the Start Point to GND command from the pop-up menu. The Draw dialog box for a Line will be displayed, where the coordinates of the ends of the wire are already set to connect the helix to the ground plane, Fig. 3. Set up 2 segments and a radius of 3 mm for this vertical wire. Finally, right click on the vertical wire, choose the Source/Load command, and connect a voltage source to the segment that is closest to the ground plane. Refer to Adding Sources > to add the source.
![](https://antennasimulator.com/wp-content/uploads/2022/10/Fig15-18a.png)
![](https://antennasimulator.com/wp-content/uploads/2022/10/Fig15-18b.png)
Step 3 | Run
Click on the Run Currents and Far-Field (F11) button on the toolbar. After the calculations are complete, click on the Far-Field 3D Plot button on the toolbar to display the radiation pattern, Fig. 4(a). The main lobe is on the axis of the helix, hence the name “axial mode”.
Because the helix is right-handed, the radiated field is circularly polarized, and the right-handed component predominates. Go to the AN-3D Pattern Plot menu and choose E-right or E-left to see the difference between both components, Figs. 4(b) and 4(c). To make the comparison between the color scales meaningful, go to Edit > Preferences in AN-3D Pattern and set the maximum of E-left to the same value as the maximum of E-right.
To draw a left-handed helix, specify a negative number of turns. Repeat the calculations and compare the E-right and E-left components.
![](https://antennasimulator.com/wp-content/uploads/2022/10/Fig15-19a.png)
![](https://antennasimulator.com/wp-content/uploads/2022/10/Fig15-19b.png)
![](https://antennasimulator.com/wp-content/uploads/2022/10/Fig15-19c.png)