Gamma matching is the most commonly used matching device used for a planar dipole in the Yagi-Uda antenna. The input impedance of such a dipole is typically less than 50 ohms and may have a reactance. Gamma matching allows you to match such a dipole with a 50-ohm coaxial feeder. This calculation based on approximate method, described in book “C. A. Balanis, Antenna Theory: Analysis and Design, 3rd ed”. This method is suitable for resonant antennas with relative small reactance. You can get by this calculator only rough estimate, which can be used as a starting point for further optimization by the electromagnetic simulator. Since the methodology for calculating the Gamma matching and the T-matching are the same, the calculation of the T-matching has also added.
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Limitations and features of antenna calculations
We have made a comparative analysis of this calculator results in the ANSYS HFSS simulator. As can be seen from the resulting table, the output data of the calculator can only be used as an approximation. Simulation results based on default data from this calculator are highlighted in blue. As you can see, the impedance value is different from the optimal one. The value close to the optimal one is highlighted in red. We can come to the conclusion that when using this calculator in practice, you should make a reserve for both the length of the matching rod and the maximum capacitance of the capacitor and then make the final tuning using a vector analyzer.
Related links:
- C. A. Balanis, Antenna Theory: Analysis and Design (3rd ed.), John Wiley & Sons, Inc., pp. 531-538;
- Beam Matching - L. B. Cebik, W4RNL (SK);
- Omega and Gama Matching - Tom Rauch, W8JI;
- Are gamma matches as bad as all that - Owen Duffy, VK2OMD ex VK1OD;
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