Inset Fed Microstrip Patch Antenna Calculator -

In the world of radio frequency, everything is about harmony. Elena’s feedline had a characteristic impedance of , but the edge of her patch antenna was pushing over

A rectangular patch antenna typically has an input impedance ranging from 100 to 300 Ohms at its radiating edge (the edge where the feed line connects). Standard RF transmission lines, however, usually have a characteristic impedance of 50 Ohms. Connecting a 50-Ohm line directly to a 200-Ohm patch edge would result in a massive impedance mismatch, causing significant signal reflection (high VSWR) and rendering the antenna inefficient.

“Inset feed isn’t magic — it’s just moving inward until the edge’s high impedance drops to 50 ohms. This calculator does that without frying another prototype.”

y0 = (L / math.pi) * math.acos(math.sqrt(target_Z / Rin0))

Enter the —a elegant, single-layer solution that shifts the feed point inward from the edge to achieve perfect matching. But manually calculating the inset feed position involves complex equations, fringing fields, and iterative solving.

This demonstrates that a well-calibrated calculator gets you >95% of the way to a working design.

If you prefer not to rely on online tools, you can create a simple yet effective calculator yourself.