# Step 2: Effective dielectric constant ereff = ((er + 1) / 2) + ((er - 1) / 2) * (1 / math.sqrt(1 + 12 * h / W))
This feature is designed for educational tools, RF simulation prep, or as a module in a larger antenna design suite. 1. Overview This feature calculates the required inset feed point distance for a rectangular microstrip patch antenna to achieve a specific input impedance match (typically 50Ω). It also computes key antenna parameters: resonant frequency, patch dimensions, and effective dielectric constant.
# Step 3: Delta L num = (ereff + 0.3) * (W / h + 0.264) den = (ereff - 0.258) * (W / h + 0.8) delta_L = h * 0.412 * (num / den) patch antenna inset feed calculator
Suggested feed line width for 50Ω: 3.05 mm | (f_r) (GHz) | h (mm) | εr | Expected (y_0) (approx) | |---------------|--------|----|----------------------------| | 2.45 | 1.6 | 4.4 | 9.1–9.5 mm (FR4) | | 5.8 | 0.8 | 2.2 | 4.8–5.2 mm (5880) | | 1.9 | 1.0 | 3.55 | 15.0–16.0 mm (Rogers 4003C) |
# Step 1: Width W W = (c / (2 * f)) * math.sqrt(2 / (er + 1)) # Step 2: Effective dielectric constant ereff =
# Convert back to mm return "patch_width_mm": W * 1000, "patch_length_mm": L * 1000, "effective_epsilon_r": round(ereff, 4), "edge_resistance_ohms": round(Rin0, 2), "inset_distance_from_edge_mm": round(y0 * 1000, 3), "input_impedance_at_inset_ohms": round(Rin0 * (math.cos(math.pi * y0 / L)**2), 2)
--- Results --- Patch width (W) : 37.26 mm Patch length (L) : 28.96 mm Effective εr : 4.125 Edge input resistance : 215.8 Ω Inset distance (y0) : 9.32 mm from edge Impedance at inset : 49.98 Ω It also computes key antenna parameters: resonant frequency,
# Step 6: Inset distance y0 if Z0 < Rin0: arg = Z0 / Rin0 if arg > 1: arg = 1 y0 = (L / math.pi) * math.acos(math.sqrt(arg)) else: y0 = 0.0 # Already matched at edge (Z0 >= Rin0)
# Step 5: Edge resistance approximation (cavity model) Rin0 = 90 * (er**2 / (er - 1)) * (L / W)
# Step 4: Effective length -> Physical length L Leff = c / (2 * f * math.sqrt(ereff)) L = Leff - 2 * delta_L
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