High Gain PCB Antenna Design: Techniques, Array Layouts & Dimension Guide

When a standard PCB antenna’s 2-3 dBi gain isn’t enough, you need a high gain PCB antenna design. I’ve worked on projects where every extra dB of antenna gain meant the difference between a working product and one that couldn’t maintain a reliable link. The good news is that achieving 8, 10, or even 15+ dBi from a PCB-based antenna is entirely possible—if you understand the techniques and tradeoffs involved.

This guide covers everything you need to design a high gain PCB antenna for your application. I’ll explain the techniques that actually increase gain (and by how much), provide practical array layouts with dimensions, and help you select the right substrate material. Whether you need 6 dBi for a WiFi access point or 15 dBi for a point-to-point link, these design approaches will get you there.

Understanding PCB Antenna Gain Fundamentals

Before diving into techniques, let’s clarify what “gain” actually means and how it relates to antenna size and bandwidth.

Gain vs Directivity vs Efficiency

Gain equals directivity multiplied by efficiency. A highly directional antenna with poor efficiency won’t achieve high gain. Both factors matter.

Typical Gain by PCB Antenna Type

The Gain-Bandwidth-Size Tradeoff

Higher gain always comes at a cost. Understanding these tradeoffs helps you make informed design decisions.

Techniques to Increase PCB Antenna Gain

Here are the proven methods to boost gain in high gain PCB antenna designs, ranked by effectiveness.

Gain Improvement Techniques Summary

Technique 1: Antenna Arrays

Arraying multiple antenna elements is the most effective way to increase gain. The theoretical gain increase follows a simple rule.

The practical gain is typically 0.5-2 dB below theoretical due to feed network losses, mutual coupling, and element efficiency.

Technique 2: Stacked Patch Antennas

Adding a second patch above the driven patch improves both gain and bandwidth.

Technique 3: Parasitic Elements

Adding non-driven elements near the main antenna can increase gain by shaping the radiation pattern.

Technique 4: Low-Loss Substrate Materials

Substrate loss directly reduces antenna efficiency and gain. Switching from FR4 to low-loss materials provides measurable improvement.

Technique 5: Ground Plane Optimization

For patch antennas, ground plane size affects both resonant frequency and gain.

High Gain PCB Antenna Array Design

Array design is the primary method for achieving 10+ dBi gain from a high gain PCB antenna. Let me walk through the practical aspects.

Array Element Spacing

Element spacing critically affects both gain and pattern shape. The general rule is half-wavelength (λ/2) spacing.

Element Spacing by Frequency

Feed Network Topologies

The feed network distributes power to array elements with proper phase and amplitude.

Corporate Feed Design

Corporate feeds use power dividers to split signal equally to all elements.

2×2 Array Layout Example

A 2×2 patch array is a practical design achieving 11-13 dBi gain.

4×4 Array Layout Example

For maximum gain, a 4×4 array can achieve 15-17 dBi.

High Gain PCB Antenna Dimensions by Frequency

These tables provide starting dimensions for high gain PCB antenna designs at common frequencies.

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433 MHz High Gain Dimensions

868/915 MHz High Gain Dimensions

2.4 GHz High Gain Dimensions

5.8 GHz High Gain Dimensions

PCB Yagi-Uda Antenna Design

The Yagi-Uda is an excellent high gain PCB antenna option when an end-fire pattern is acceptable.

Yagi Element Dimensions

Yagi Gain vs Number of Elements

PCB Yagi Implementation Tips

Substrate Selection for High Gain PCB Antennas

Material selection significantly impacts high gain PCB antenna performance. Here’s a practical comparison.

Substrate Comparison for Antenna Performance

When to Use Low-Loss Substrates

Efficiency Comparison at 2.4 GHz

Common Mistakes That Kill High Gain Antenna Performance

Mistake 1: Insufficient Ground Plane

Problem: Ground plane barely extends beyond patch edges. Effect: Gain reduced 2-3 dB, pattern distorted, impedance shifted. Solution: Extend ground plane minimum λ/4 beyond patch edges.

Mistake 2: Wrong Element Spacing in Arrays

Problem: Using substrate wavelength instead of free-space wavelength for spacing. Effect: Elements too close, mutual coupling, reduced gain. Solution: Calculate spacing using free-space wavelength (c/f), not substrate wavelength.

Mistake 3: Feed Network Losses Ignored

Problem: Designing array without accounting for power divider and transmission line losses. Effect: Actual gain 2-3 dB below expected. Solution: Budget 0.5-1.5 dB loss for feed network, use wider traces, minimize length.

Mistake 4: FR4 at High Frequencies

Problem: Using FR4 above 3 GHz without accounting for increased loss. Effect: Efficiency drops below 60%, gain significantly reduced. Solution: Switch to Rogers or PTFE substrate for frequencies above 3 GHz.

Mistake 5: Phase Errors in Arrays

Problem: Unequal feed line lengths causing phase mismatch between elements. Effect: Beam squinting, reduced gain, pattern distortion. Solution: Ensure all feed paths have equal electrical length, account for bends.

High Gain PCB Antenna Design Resources

Simulation and Design Tools

PCB Substrate Suppliers

Reference Designs and Application Notes

Impedance Calculators

Frequently Asked Questions

What is the maximum gain achievable from a PCB antenna?

Practical high gain PCB antenna designs can achieve 20-22 dBi with 8×8 element arrays at frequencies like 5.8 GHz. At lower frequencies, the physical size becomes the limiting factor—a 20 dBi antenna at 433 MHz would require a PCB over 1 meter square. The theoretical limit depends on the aperture size: gain ≈ 4πA/λ², where A is the physical area. For a 200×200 mm PCB at 2.4 GHz, the maximum theoretical gain is approximately 23-24 dBi. Real-world designs achieve 80-90% of this theoretical maximum due to efficiency losses, feed network losses, and edge effects. For most applications, 15-18 dBi represents a practical upper limit before the PCB size becomes unwieldy.

Can I achieve high gain with FR4 substrate?

Yes, but with limitations. FR4’s loss tangent (0.02) reduces efficiency by 10-20% compared to low-loss materials like Rogers. At 2.4 GHz, you can reasonably achieve 12-14 dBi with FR4 using a 4×4 patch array. Above 5 GHz, FR4 losses become more significant, and you’ll lose 2-3 dB compared to low-loss substrates. For prototyping and cost-sensitive applications below 3 GHz, FR4 is acceptable if you budget for the efficiency loss. For production designs requiring maximum performance, especially above 3 GHz, invest in Rogers RO4003C or similar low-loss materials. The cost premium is typically 3-5× for the substrate, but the performance improvement justifies it for gain-critical applications.

How much gain does each additional array element add?

Doubling the number of elements theoretically adds 3 dB of gain. A 2×2 array (4 elements) should provide +6 dB over a single element, and a 4×4 array (16 elements) should provide +12 dB. In practice, you’ll achieve 80-90% of this due to feed network losses and mutual coupling. So a realistic expectation is: 2 elements = +2.5 dB, 4 elements = +5 dB, 8 elements = +7.5 dB, 16 elements = +10 dB. The feed network becomes increasingly critical as array size grows—poorly designed networks can waste 1-2 dB of the potential gain increase. Use wider transmission lines (lower loss), minimize feed path length, and consider substrate-integrated waveguide (SIW) for very large arrays.

What is the best element spacing for a PCB antenna array?

Use half-wavelength (λ/2) spacing measured in free-space wavelength, not substrate wavelength. This is the most common mistake in array design. At 2.4 GHz, λ/2 is 62.5 mm—use this value regardless of substrate dielectric constant. The substrate wavelength only affects the individual patch dimensions, not the array spacing. Spacing less than 0.4λ causes excessive mutual coupling, reducing gain and increasing pattern distortion. Spacing greater than 0.7λ creates grating lobes that reduce gain in the main beam direction. For most applications, 0.5λ to 0.6λ provides the best balance of gain, beamwidth, and sidelobe performance. If space is constrained, 0.45λ is the absolute minimum for acceptable performance.

How does beamwidth change with increasing gain?

Higher gain means narrower beamwidth—there’s no escaping this fundamental relationship. Approximate beamwidths: 6 dBi = 70-90°, 10 dBi = 40-50°, 15 dBi = 20-30°, 20 dBi = 10-15°. This has significant implications for your application. A high-gain antenna for a point-to-point link (narrow beam acceptable) differs from one for a base station covering a sector (wider beam needed). For mobile devices or situations where orientation varies, high gain can actually hurt performance because the narrow beam may not point at the target. Consider your use case carefully—sometimes two separate 10 dBi antennas covering different sectors outperform a single 15 dBi antenna with a narrow beam pointing the wrong direction.

Conclusion

Designing a high gain PCB antenna requires balancing multiple factors: antenna type selection, array configuration, substrate material, and feed network optimization. The techniques outlined in this guide can take you from a basic 2-3 dBi monopole to a sophisticated 15+ dBi array—the approach depends on your specific requirements for gain, size, cost, and radiation pattern.

Start by determining your minimum gain requirement based on link budget analysis. If you need 10+ dBi, you’re looking at array designs. For 6-9 dBi, single-element patches, stacked patches, or Yagi antennas are practical options. Pay careful attention to element spacing (use free-space wavelength), feed network design, and substrate selection—these details separate working designs from disappointing ones.

For critical applications, invest in electromagnetic simulation during the design phase. Tools like HFSS, CST, or even free options like openEMS can predict performance before fabrication. Validate with measurements using a VNA and antenna range or anechoic chamber. The effort invested in proper design and verification pays dividends in achieving your gain targets reliably and consistently across production units.