What is the formula for microstrip patch antenna dimensions?

For a rectangular microstrip patch antenna: Patch Width W = c / (2*f * sqrt((εr+1)/2)), where c is speed of light, f is resonant frequency, and εr is substrate dielectric constant. The patch length L = Leff − 2ΔL, where Leff = c / (2*f*sqrt(εreff)) and ΔL accounts for fringing effects. The effective dielectric constant εreff = (εr+1)/2 + (εr-1)/2 * (1 + 12*h/W)^(-0.5).

How does substrate thickness affect patch antenna performance?

Increasing the substrate height (h) widens the bandwidth and reduces surface wave losses, but also increases fringing fields and shifts the effective resonant length. Thicker substrates (h/λ > 0.05) can excite spurious modes. For optimal performance, substrate height is typically kept between 0.003λ and 0.05λ, where λ is the free-space wavelength at the resonant frequency.

What dielectric constant substrates are used for patch antennas?

Common substrates include Rogers RT/duroid 5880 (εr ≈ 2.2) for low-loss microwave applications, FR4 (εr ≈ 4.4) for low-cost PCB designs, Rogers RO4003 (εr ≈ 3.55), and PTFE-based laminates. Low-dielectric substrates yield larger antennas with higher bandwidth, while high-dielectric substrates allow miniaturisation at the cost of reduced bandwidth and efficiency.

How do I use this bulk microstrip patch antenna calculator?

For a single calculation, enter the resonant frequency (GHz), substrate dielectric constant, substrate height (mm), and conductor thickness. Click Calculate to get patch width, effective length, physical length, effective dielectric constant, and estimated directivity. For bulk mode, upload a CSV/TXT file with format: Freq_GHz,Er,H_mm,T_mm (one row per antenna). Download or copy all results as CSV.

Microstrip Patch Antenna Calculator

Q: What is a microstrip patch antenna?

A microstrip patch antenna (also called a patch antenna) is a flat, low-profile antenna fabricated by etching a metallic patch on a grounded dielectric substrate. Common shapes include rectangular and circular patches. They are widely used in GPS, Wi-Fi, 5G, satellite communications, and radar systems due to their compact size, low cost, and ease of integration with printed circuit boards.

Features

Advanced Microstrip Patch Antenna Design Tool

Everything RF and PCB antenna engineers need — from substrate parameter entry to full dimensional synthesis and far-field estimation, single or bulk batch.

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Patch Width & Length

Compute physical patch width (W) and effective/physical length (L) based on resonant frequency and substrate dielectric properties using Pozar's transmission-line model.

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Effective Dielectric Constant

Calculate εreff accounting for fringing fields at patch edges, conductor thickness correction (ΔL), and substrate height-to-width ratio.

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Bulk Processing

Upload TXT/CSV with hundreds of antenna specifications and get complete dimensional data, frequency estimates, and quality checks in one pass.

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Live Real-time Preview

Patch dimensions and resonant frequency preview update instantly as you type — no submit needed for quick sanity checks.

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Far-field Directivity

Estimate broadside directivity (dBi) and radiation efficiency category for your patch design based on substrate loss tangent and aspect ratio.

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Export CSV / Copy

Copy all results to clipboard or download as a formatted CSV file for documentation, simulation setup, and manufacturing specifications.

How It Works

Four Steps to Patch Antenna Design

1

Enter Resonant Frequency

Input the desired resonant frequency in GHz. The live preview instantly estimates patch width and length as you type.

2

Set Substrate Parameters

Choose a substrate preset or manually enter the dielectric constant (εr), substrate height, conductor thickness, and loss tangent for your PCB material.

3

Review Live Dimensions

See patch width (W), physical length (L), effective dielectric constant (εreff), fringing extension (ΔL), and estimated directivity update in real time.

4

Export & Simulate

Download or copy your results as CSV. Use the dimensions as starting points in your EM simulator (HFSS, CST, FEKO) for final tuning before fabrication.

Microstrip Patch Antenna Calculator: Complete Design Guide

A microstrip patch antenna is one of the most widely deployed antenna types in modern wireless systems, combining a flat metallic radiating patch with a printed-circuit-board dielectric substrate and a solid ground plane. Used extensively in GPS receivers (1.575 GHz), Wi-Fi access points (2.4 GHz / 5.8 GHz), 5G mmWave modules, vehicle radars (77 GHz), and satellite terminals, patch antennas owe their popularity to low cost, conformal mounting, and straightforward integration with active RF circuits.

Key Formulas Used in This Calculator

The transmission-line model (Pozar, 1984) remains the industry-standard analytical approach for rectangular patch antenna synthesis. The patch width is determined by W = c / (2f · √((εr+1)/2)), which sets the dominant TM010 mode. The effective dielectric constant is εreff = (εr+1)/2 + (εr−1)/2 · (1+12h/W)^−0.5, accounting for field fringing at the open edges. The fringing correction length is ΔL = 0.412h · (εreff+0.3)(W/h+0.264) / ((εreff−0.258)(W/h+0.8)). The physical patch length then becomes L = c/(2f·√εreff) − 2ΔL.

Design Examples

For a 2.4 GHz patch on FR4 (εr = 4.4, h = 1.6 mm, t = 0.035 mm): W ≈ 38.0 mm, εreff ≈ 4.09, L ≈ 29.4 mm. For a 5.8 GHz patch on Rogers RT5880 (εr = 2.2, h = 0.787 mm): W ≈ 20.3 mm, εreff ≈ 1.97, L ≈ 16.6 mm. These values serve as excellent starting points for full-wave EM simulation and prototype tuning.

Substrate Selection Tips

Low-permittivity substrates (εr 2–3) provide wider bandwidth (typically 2–5%) and lower surface-wave losses but result in larger physical dimensions. High-permittivity substrates (εr 8–12) allow miniaturisation suitable for handset integration but reduce bandwidth and radiation efficiency. For most microwave applications, Rogers RO4003 (εr = 3.55, tan δ = 0.0027) offers an excellent balance of loss, dimensional stability, and cost.

FAQ

Frequently Asked Questions

What is a microstrip patch antenna?

A microstrip patch antenna is a flat metallic patch etched on a grounded dielectric substrate. It radiates primarily from the two open-end fringing fields (E-plane edges) and is used in GPS, Wi-Fi, 5G, radar, and satellite communication systems.

What is the formula for patch antenna width?

W = c / (2f · √((εr+1)/2)), where c is the speed of light (3×10⁸ m/s), f is the resonant frequency in Hz, and εr is the substrate relative permittivity.

How does substrate dielectric constant affect patch size?

A higher dielectric constant (εr) reduces the effective wavelength inside the substrate, making the patch physically smaller. However, higher εr also reduces bandwidth and can increase surface wave excitation, lowering radiation efficiency.

What is the typical bandwidth of a patch antenna?

A single-layer rectangular patch antenna typically achieves 2–5% fractional bandwidth (at −10 dB return loss). Bandwidth can be increased to 10–30% using stacked patches, slots, or thick low-permittivity substrates.

How do I use the bulk file upload feature?

Prepare a TXT or CSV file with one antenna per line in the format: Freq_GHz, Er, H_mm, T_mm, TanD. Only the first three columns are mandatory. Upload the file or paste the data into the text area, then click Process Bulk to compute all entries at once.

Bulk Microstrip Patch Antenna
Calculator