📡 9M2PJU Basic Antenna Calculator

A modern, responsive web application for calculating dimensions and properties of common amateur radio antennas.

Live view: https://antenna.hamradio.my

🌟 Features

• Multiple Antenna Types: Calculate dimensions for vertical, dipole, yagi, and quad antennas
• Real-time Calculations: Instant results as you change frequency
• Professional Design: Modern, responsive interface that works on all devices
• Accurate Physics: Based on electromagnetic theory and practical antenna design
• Educational: Learn about antenna properties and characteristics

🚀 Getting Started

Prerequisites

• A modern web browser (Chrome, Firefox, Safari, Edge)
• No additional software installation required

Running the Application

1. Download all files to a directory
2. Open index.html in your web browser
3. Enter your desired frequency in MHz
4. Select an antenna type to view calculations

📊 Supported Antenna Types

1. Vertical Antenna

• Height: Quarter-wavelength calculation
• Ground Plane: Optimal ground plane dimensions
• Impedance: 36.8 Ω (typical for ground plane verticals)
• Gain: 2.15 dBi

2. Dipole Antenna

• Total Length: Half-wavelength calculation
• Each Side: Individual element lengths
• Impedance: 73 Ω (free space)
• Gain: 2.15 dBi

3. Yagi Antenna

• Driven Element: Resonant length
• Reflector: 5% longer than driven element
• Director: 5% shorter than driven element
• Boom Length: Optimal spacing between elements
• Gain: 7-10 dBi (varies with design)

4. Quad Antenna

• Loop Perimeter: Approximately 1 wavelength
• Side Length: Square loop dimensions
• Impedance: 100-140 Ω
• Gain: 3-4 dBi

🔬 Technical Details

Calculations Include

• Velocity Factor: 0.95 (typical for wire antennas)
• Speed of Light: 299,792,458 m/s
• Wavelength Calculations: λ = c/f
• Practical Adjustments: Real-world construction considerations

Physics Principles

• Resonance: Antennas are designed to resonate at specific frequencies
• Impedance Matching: Optimal feed point impedance for transmission
• Gain Patterns: Directional characteristics and efficiency
• Ground Effects: Impact of ground plane and height above ground

📱 Responsive Design

The application is fully responsive and works on:

• Desktop computers
• Tablets
• Mobile phones
• All modern web browsers

🛠️ File Structure

9M2PJU-basic-antenna-calculator/
├── index.html          # Main HTML file
├── styles.css          # CSS styling and responsive design
├── script.js           # JavaScript calculations and interactivity
└── README.md           # This documentation file

🎯 Usage Examples

Example 1: 20m Band Dipole

• Frequency: 14.074 MHz
• Result: Each side approximately 5.07 meters
• Total length: 10.14 meters

Example 2: 2m Band Vertical

• Frequency: 146.52 MHz
• Result: Height approximately 0.49 meters
• Ground plane: 0.46 meters

Example 3: 70cm Band Yagi

• Frequency: 432.1 MHz
• Result: Driven element approximately 0.66 meters
• Boom length: 0.14 meters

⚠️ Important Notes

Theoretical vs. Practical

• Dimensions are theoretical and may require fine-tuning
• Local conditions (height, ground conductivity, nearby objects) affect performance
• Construction materials and techniques impact final results

Safety Considerations

• Check local regulations before erecting antennas
• Consider height restrictions and building codes
• Ensure structural integrity of antenna supports
• Follow electrical safety guidelines

Fine-tuning Required

• SWR measurements help optimize antenna performance
• Field strength measurements verify calculations
• Adjustment range typically ±2-5% of calculated values

🔧 Customization

The application can be easily customized:

• Modify velocity factors for different materials
• Add new antenna types
• Adjust calculation algorithms
• Customize the user interface

📚 Educational Value

This calculator helps amateur radio operators:

• Understand antenna theory and electromagnetic principles
• Plan antenna projects with accurate dimensions
• Learn about different antenna types and their characteristics
• Compare antenna performance across frequency ranges

🤝 Contributing

Feel free to contribute improvements:

• Report bugs or issues
• Suggest new features
• Submit code improvements
• Enhance documentation

📄 License

This project is open source and available under the MIT License.

🆘 Support

For questions or support:

• Check the calculations against established references
• Consult amateur radio literature
• Verify results with experienced operators
• Test in real-world conditions

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Happy Building! 🚀

Remember: The best antenna is the one you can actually build and use effectively.