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Antenna Matching Calculations

You can use 1/4 wave length matching stub to match you transmission line to your load. Some antennas are designed with a different impedance than 50 ohms. Using a 1/4 wave length matching stub you can transform the transmitter coax into another impedance. An example is a full wave length loop is usually 100 ohms.

Below is a form to calculate 1/4 wavelength matching sections. It uses some common values of coax that amateur radio operators can usually purchase from their supplier.

Below is a form for calculating Matching Section using coax.

The Top section you will enter the transmitter coax impedance, the antenna impedance, and it will calculate the impedance of the 1/4 wave length matching stub.

The Middle section you enter the frequency of your system, select the type of coax, and it will calculate the length of coax needed for 1/4 wave length matching stub.

The Bottom section you enter the transmitter coax impedance, select the type of matching stub (different types of coax & number in parallel), and it will calculate the end impedance of the matching stub.

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