Microstrip Patch Antenna Calculator
Rectangular patch W and L from frequency and substrate (Balanis transmission-line model) — FR-4 and Rogers presets included.
The length L sets resonance (≈ half a guided wavelength); width W mainly sets bandwidth and impedance. Edge impedance is 200–300 Ω: feed via an inset (~L/3 deep notch) or a quarter-wave transformer to reach 50 Ω. FR-4's lossy tanδ (~0.02) halves the gain vs Rogers above ~3 GHz — fine for 2.4 GHz hobby boards, poor at 5.8 GHz.
Patch Antenna Calculator computes rectangular microstrip patch dimensions for a target frequency and substrate — free, instant and private in your browser. Students and IoT designers making WiFi/BLE/GPS antennas on plain PCB use it to skip the datasheet algebra: type your numbers, read the answer with the substituted formula shown step by step, and share an exact permalink of the calculation.
About Microstrip Patch Antenna Calculator
Patch Antenna Calculator computes rectangular microstrip patch dimensions for a target frequency and substrate using the standard engineering relation: W = c/(2f)·√(2/(εr+1)); L = c/(2f√εeff) − 2ΔL (Balanis transmission-line model). Worked live: a 2.45 GHz patch on 1.6 mm FR-4 comes out ~37 × 28 mm with a ground plane ~10 mm larger all round. The result recalculates on every keystroke, the worked-example panel shows your numbers substituted into the formula, and the Copy permalink button encodes the inputs in the URL so a colleague opens exactly your calculation. Everything runs client-side — nothing you type leaves your device.
How to use Microstrip Patch Antenna Calculator
- 1Enter your values — the tool starts with realistic defaults for this exact use case, so the worked example is meaningful immediately.
- 2Read the live result and the worked-example panel, which substitutes your numbers into the formula step by step.
- 3Adjust any input to compare scenarios, then use Copy result or Copy permalink to share the calculation.
Why use Microstrip Patch Antenna Calculator?
- ✓Implements the real formula — W = c/(2f)·√(2/(εr+1)) — with the substitution shown, not a black box
- ✓Built for students and IoT designers making WiFi/BLE/GPS antennas on plain PCB
- ✓Copy result and permalink buttons — share the exact calculation in a README, forum answer or design review
- ✓100% free, no sign-up, runs entirely in your browser (works offline once loaded)
Frequently asked questions
How do you calculate patch antenna?+
Rectangular microstrip patch dimensions for a target frequency and substrate follows W = c/(2f)·√(2/(εr+1)); L = c/(2f√εeff) − 2ΔL (Balanis transmission-line model). For example, a 2.45 GHz patch on 1.6 mm FR-4 comes out ~37 × 28 mm with a ground plane ~10 mm larger all round. The calculator applies the same relation and shows the substituted arithmetic so you can verify every step.
Why is my FR-4 patch antenna so inefficient?+
FR-4's loss tangent (~0.02) burns signal as dielectric heat — fine at 2.4 GHz for short-range, increasingly lossy above ~3 GHz where Rogers-class laminates earn their price. Gain loss of 2–3 dB versus a proper substrate is typical at 5.8 GHz.
How do I feed the patch — the edge is 200+ Ω?+
Two standard tricks: an inset feed (notch the microstrip ~L/3 into the patch, where impedance falls toward 50 Ω) or a quarter-wave transformer line of √(50·Z(edge)) impedance. Probe (coax) feeding from below picks its radius the same way.
Is the Patch Antenna Calculator free and private?+
Yes — completely free with no sign-up or usage limits, and it runs entirely in your browser: the values you enter are never uploaded or stored on a server.
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