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    Modeling Helix Antennas in Axial Radiation Mode Using AN-SOF

    Created OnOctober 24, 2022
    Updated OnMay 26, 2025
    By:Tony Golden

    Perfect for Beginners: Quick Guide to Helix Antenna Simulation
    Master axial-mode helix design in AN-SOF with this easy step-by-step tutorial. Learn ground plane setup, helix creation, and radiation pattern analysis. Start modeling professional antennas today!

    Helix Antenna in Axial Mode

    The helix antenna demonstrates the importance of curved segments for accurate geometry representation. When the helix length approaches or exceeds the operating wavelength, it operates in axial mode – characterized by endfire radiation along its axis. This requires a ground plane reflector for proper operation.

    Step 1: Setup

    1. Frequency Setup:
    2. Ground Plane Configuration:
    3. Excitation:
    Fig. 1(a): Setting the operating frequency for the helix antenna.
    Fig. 1(b): Setting the ground plane for the helix antenna.

    Step 2: Drawing the Structure

    1. Helix Creation:
      • Right-click on the workspace > Select Helix from pop-up menu
      • Draw Helix dialog appears (Fig. 2)
      • Start point: (0, 0, 0.3) m (above ground plane)
      • Orientation: Z-axis
    2. Axial Mode Dimensions:
      • Set parameters per antenna textbooks:
        • Radius
        • Pitch (turn spacing)
        • Number of turns (shown in Fig. 2)
      • Attributes tab:
        • Segments: 103 (recommended)
        • Cross-section: Circular, radius = 3 mm
    3. Ground Connection:
      • Right-click helix > Start Point to GND
      • Draw Line dialog auto-populates connection points (Fig. 3)
      • Set:
        • Segments: 2
        • Radius: 3 mm
    4. Source Placement:
    Fig. 2(a): Specifying the helix dimensions.
    Fig. 2(b): Specifying the helix segmentation and cross-section.
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    Fig. 3(a): Specifying the vertical wire that connects the helix to the ground plane.
    Fig. 3(b): Specifying the segments and cross-section for the vertical wire.

    Step 3: Simulation & Analysis

    1. Run Simulation:
      • Click Run Currents and Far-Field (F10)
      • View 3D radiation pattern via Far-Field 3D Plot button (Fig. 4a)
      • Observe main lobe along helix axis (axial mode characteristic)
    2. Polarization Analysis:
      • In AN-3D Pattern Plot:
        • Compare E-right vs. E-left components (Figs. 4b, 4c)
      • For accurate comparison:
        • Set matching scale maxima (Edit > Preferences)
    3. Left-Handed Variant:
      • Create by specifying negative turn count
      • Re-run simulation and compare polarization components
    Fig. 4(a): Normalized radiation pattern of the helix.
    Fig. 4(b): Right-handed circularly polarized component of the far-field.
    Fig. 4(c): Left-handed circularly polarized component of the far-field.

    Key Features Demonstrated

    • Curved segment modeling for helical structures
    • Axial mode radiation characteristics
    • Circular polarization analysis
    • Ground plane integration
    • Parametric comparison (right vs. left-handed)

    The complete simulation showcases AN-SOF’s capability to model complex antenna behavior with precise geometrical control.

    About the Author

    Tony Golden

    ANTENNA SIMULATION ENGINEER & PHYSICS PH.D. With over 25 years of experience in Computational Electromagnetics, I’m a dedicated researcher specializing in antenna modeling and design. As the founder of Golden Engineering LLC, I develop intuitive yet powerful simulation tools to help RF engineers optimize designs, educators demonstrate concepts, and hobbyists bring antenna projects to life.

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