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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 9.50 Release: Streamlining Polarization, Geometry, and EMF Calculations
- 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 (3) 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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Enhancing VHF Performance: The Dual Reflector Moxon Antenna for 145 MHz
The Moxon antenna, or Moxon rectangle, represents a straightforward yet mechanically robust wire antenna meticulously crafted for VHF bands. It owes its name to the renowned radio amateur operator Les Moxon (call sign G6XN). This antenna comprises two folded dipole elements, one of which acts as the driven element, while the other serves as the reflector element. An adjustable gap is deliberately left between these folded dipoles, permitting fine-tuning of the antenna to minimize the VSWR (Voltage Standing Wave Ratio). Consequently, this antenna can be mechanically tuned, negating the necessity for an impedance matching network.
In our article titled “Enhancing Satellite Links: The Moxon-Yagi Dual Band VHF/UHF Antenna,” we introduce a dual-band design optimized for satellite communications. This design amalgamates a 5-element Yagi-Uda array with the Moxon configuration, leveraging the Moxon portion as the excitation point, while the Yagi section is electromagnetically induced for feeding.
In this article, we introduce a modified version of the Moxon antenna featuring two reflector elements, as depicted in the accompanying figure. These reflectors are oriented at an angle of 76° relative to each other. This particular configuration delivers a notable reduction in the beamwidth within the plane of the driven element (the vertical plane denoted as y-z in the figure), resulting in a corresponding increase in gain.
To optimize the performance of this antenna, the gaps have been meticulously adjusted to achieve an input impedance of 47 Ohms precisely at the resonance frequency of 145 MHz, eliminating the need for an external matching network. The key characteristics and outcomes of this antenna design are summarized below:
- Resonance Frequency: 145 MHz
- Input Impedance: 47 Ohms (self-resonant)
- Bandwidth: 7% (VSWR < 2)
- Peak Gain: 6.3 dBi
- Front-to-Back Ratio: 19 dB
- Beamwidth: 130° Horizontal / 80° Vertical
- Polarization: Vertical
As depicted in the figure below, we present the antenna model as simulated using the AN-SOF Antenna Simulator. The three-dimensional radiation pattern is illustrative, showcasing a peak gain of 6.3 dBi. Additionally, the VSWR curve is provided, and it is evident that the resonant frequency of 145 MHz corresponds to the dip in this curve.
Further insight is offered by the polar diagrams at the bottom of the figure, representing the horizontal (on the left) and vertical (on the right) slices of the 3D radiation pattern. These diagrams distinctly show that the vertical pattern is narrower in comparison to the horizontal pattern.
For amateur radio enthusiasts and practitioners, this antenna design serves as an excellent choice when there is a demand for a VHF-frequency directive antenna that is easy to construct, mechanically robust, self-resonant, and delivers outstanding performance.