Five Eighths Wave Antenna Length Calculator

This calculator helps you determine the optimal length for a five-eighths wave antenna based on frequency and operating mode.

Input Parameters

Calculation Results

Antenna Length Results

Please enter the frequency and select parameters, then click Calculate.

Calculation Formula

Antenna Length = (5/8) × λeff

Where:
λeff = Effective wavelength = c / (f × 1.8)
c = Speed of light (299,792,458 m/s)
f = Frequency in MHz

Five Eighths Wave Antenna Calculator Usage Guide

Learn how to use the Five Eighths Wave Antenna Length calculator and understand its applications.

How to Use This Calculator

  1. Enter the operating frequency of your radio system in MHz (e.g., 144.0 for 144 MHz).
  2. Select the operating mode (Monopole, Dipole, or Inverted-L) based on your antenna setup.
  3. Choose the ground type that best represents your operating environment.
  4. Click the "Calculate" button to compute the optimal antenna length.
  5. The results will show the effective wavelength and the recommended antenna length in both meters and feet.

Understanding Five Eighths Wave Antennas

A five-eighths wave antenna is a type of resonant antenna that is approximately 5/8 of the wavelength of the operating frequency. Unlike quarter-wave vertical antennas that are 1/4 wavelength, five-eighths wave antennas are slightly longer, which makes them more efficient for certain applications.

Applications

  • Ham radio operations (particularly for 2m, 70cm bands)
  • Mobile communications
  • Portable and emergency communications
  • Amateur radio contesting

Advantages

  • Improved efficiency compared to quarter-wave antennas
  • Better radiation pattern for some applications
  • More omnidirectional radiation pattern
  • Can be mounted on vehicles with improved performance

Note: For optimal performance, it's recommended to construct and tune your antenna according to these calculations. The actual performance may vary based on construction techniques and operating environment.