Calculators / Patch Antenna

Microstrip Patch Antenna
Calculator

Calculate the patch width, patch length, effective dielectric constant, and resonant frequency of a rectangular microstrip patch antenna using the Bahl & Trivedi transmission-line model.

▶ Start Calculating 📖 Theory

Frequency Tuning 2.40 GHz

0.5 GHz10 GHz

Radiating Patch Dielectric Substrate Ground Plane

⚙ Patch Antenna Engine

Resonant Frequency (fr)

Design frequency for the patch resonance

Substrate Thickness (h)

Common: 0.8, 1.6, 3.2 mm (FR4)

Relative Permittivity (εr)

FR4 ≈ 4.4, Rogers RO4003C ≈ 3.55, PTFE ≈ 2.1

Loss Tangent (tan δ)

FR4 ≈ 0.02, RO4003C ≈ 0.0027, PTFE ≈ 0.0002

Quick Substrate Presets

Advanced Parameters

Conductor Thickness (t)

Typical copper: 35 µm (1 oz), 70 µm (2 oz)

Feed Type

Edge feed: simple, Zin ≈ 200–300 Ω at edge

Inset Feed Depth (y₀)

0 = edge. Inset reduces input impedance to 50 Ω

Target Impedance (Ω)

Sets inset-feed depth for impedance match

Calculated Results

Patch Width (W) —mm

Patch Length (L)—

Eff. Length (L_eff)—

Wavelength (λ)—

λ/2 in substrate—

Eff. Permittivity (εreff)—

Length Extension (ΔL)—

Radiation Resistance (Rr)—

Quality Factor (Q)—

Bandwidth (BW)—

Gain (approx.)—

Input Impedance (Zin)—

Enter values above to calculate.

📖 Design Theory

A rectangular microstrip patch is a conducting patch on a grounded dielectric substrate. It resonates when its length L ≈ λg/2 in the substrate medium.

Step 1 — Patch Width

W = c / (2fr √((εr+1)/2))

Step 2 — Effective εr

εreff = (εr+1)/2 + (εr-1)/2 · (1+12h/W)^-½

Step 3 — Patch Length

L = c/(2fr√εreff) − 2ΔL

ΔL = fringe extension (Hammerstad formula)

The substrate thickness h and εr set the wavelength compression. Thicker/lower-εr substrates give wider bandwidth but larger patch size.

📡 Substrate & Field Visualiser

Live Simulation | ◉ Cross-Section & Radiation Pattern

Substrate View Display Mode

εr Tuning 4.4

1.012.0

h/λ ratio 0.02

Field Lines

Cross-Section

Top View (Patch)

ℹ

Design Insights

Enter frequency and substrate parameters to see live design insights and trade-offs.

Common Applications

📶

WiFi & Bluetooth

2.4 / 5 GHz patch antennas on PCBs for IoT devices, routers and wearables.

🛰️

GPS / GNSS

1.575 GHz (L1) circularly polarised patches widely used in navigation systems.

📡

Radar & 5G mmWave

Patch arrays at 24–77 GHz in automotive radar and 5G base-station tiles.

🚀

Aerospace & Defence

Low-profile conformal patch arrays on aircraft fuselages and missiles.

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Microstrip Patch Antenna Calculator