Antenna Calculator — Inset Fed Microstrip Patch

It was 11:47 PM. Dr. Priya Varma stared at the Smith chart on her laptop, the complex impedance plot spiraling like a taunting seashell.

She already had the patch dimensions: length ( L ), width ( W ), on a humble FR4 substrate. But theory gave her a 200-ohm input impedance at the patch’s radiating edge — useless for her 50-ohm system. She needed to move the feed point inward along the width, where impedance drops to 50 ohms.

That’s where the “inset feed calculator” entered — not as a fancy app, but as a haunting set of equations. inset fed microstrip patch antenna calculator

Most online calculators just solve this iteratively — and that’s the “good story” of how a simple trigonometric insight saves your antenna from becoming a dummy load.

Three days later, the etched board sat on the VNA. She pressed the SMA connector gently against the inset feed point. The display flickered… then locked. It was 11:47 PM

Priya knew the formula by heart, but manual errors had already melted two prototypes. The first: return loss of -4 dB (basically a heater). The second: resonant at 2.7 GHz (hello, satellite interference).

She laughed — a tired, relieved laugh. The calculator hadn’t lied. The cosine-squared impedance taper worked. She already had the patch dimensions: length (

Her mission: design a compact 2.45 GHz patch antenna for a wildlife tracking collar. It had to be tiny, efficient, and cheap. No room for bulky coaxial probes or intricate matching networks. Only one option remained: the .