Inset Fed Patch Antenna Calculator -

[ W = \frac3e82(2.45e9)\sqrt\frac4.4+12 \approx 37.3 \text mm ]

If ( R_\textin(0) ) is not known from the exact formula, use the approximation: [ R_\textin(0) \approx 90\frac\varepsilon_r^2\varepsilon_r - 1\left(\fracLW\right)^2 \quad (\textfor thin substrates) ] Given: ( f_r = 2.45 \text GHz ) ( \varepsilon_r = 4.4 ) (FR4) ( h = 1.6 \text mm ) ( Z_0 = 50\ \Omega ) inset fed patch antenna calculator

To match the feed line impedance ( Z_0 ) (e.g., 50 Ω): [ Z_0 = R_\textin(0) \cos^2\left(\frac\piLy_0\right) ] [ y_0 = \fracL\pi \cos^-1\sqrt\fracZ_0R_\textin(0) ] [ W = \frac3e82(2

[ \varepsilon_\textreff = \frac4.4+12 + \frac4.4-12\left(1+12\frac1.637.3\right)^-0.5 \approx 4.18 ] The inset fed (or recessed microstrip line feed)

[ \Delta L = 0.412 \times 1.6 \frac(4.18+0.3)(37.3/1.6+0.264)(4.18-0.258)(37.3/1.6+0.8) \approx 0.74 \text mm ]

1. Introduction A rectangular microstrip patch antenna is one of the most common planar antennas. Feeding it directly with a microstrip line creates an impedance mismatch because the patch edge has high impedance (typically 150–300 Ω), while the feed line is usually 50 Ω. The inset fed (or recessed microstrip line feed) technique solves this by placing the feed point inside the patch, where the input resistance drops to 50 Ω at a specific inset depth.