Enter the frequency (MHz) into the Calculator. The calculator will evaluate the Antenna Trap. 

Antenna Trap Formula

L = 31.8 / f


  • L is the Antenna Trap ((inductance))
  • f is the frequency (MHz)

To calculate the Antenna Trap, divide 31.8 by the frequency.

How to Calculate Antenna Trap?

The following steps outline how to calculate the Antenna Trap.

  1. First, determine the frequency (MHz). 
  2. Next, gather the formula from above = L = 31.8 / f.
  3. Finally, calculate the Antenna Trap.
  4. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

frequency (MHz) = 500


What is an Antenna Trap?

An Antenna Trap is a parallel LC (inductor and capacitor) circuit that acts as a resonator at a particular frequency. It’s commonly used in antennas to isolate parts of the antenna at certain frequencies, effectively allowing the antenna to operate efficiently on multiple bands.

Why is the frequency in MHz for calculating the Antenna Trap?

Frequency is measured in MHz (Megahertz) in this context because antenna operations are typically within the radio frequency (RF) spectrum, which ranges from 3 kHz to 300 GHz. MHz is a practical unit for these calculations, offering a balance between precision and ease of use.

How can I improve the efficiency of my antenna?

Improving antenna efficiency can involve several strategies, including optimizing the antenna design for your specific application, ensuring the antenna is correctly tuned to the desired frequency, reducing losses by using quality materials, and minimizing obstructions in the antenna’s near field.

Can the Antenna Trap formula be used for any type of antenna?

The Antenna Trap formula, as given, is a basic calculation that applies broadly to resonant LC circuits within antennas. However, the specific design and requirements of different types of antennas (e.g., dipole, Yagi, loop) may necessitate additional considerations or adjustments to the formula for optimal performance.