Designing Antennas on PCB: A Beginner to Advance Guide

In today’s world of widespread wireless connectivity, the demand for small, affordable, and reliable antennas is higher than ever. Antennas act as real-world implementations of electromagnetic wave principles. They enable the sending and receiving of signals for a variety of wireless uses. While there is a lot of theoretical and experimental research in this area, only a few designs become widely used in actual products.

Among the different options, Printed Circuit Board (PCB) antennas have become a practical choice for modern devices. By embedding the antenna directly onto the circuit board, the designers can minimize system size or cut costs, and remove the need for external antenna modules. This integration makes PCB antennas particularly suitable for compact electronics like Wi-Fi systems or IoT devices and BLE modules, and wearables. In this guide, we'll look at the basics of PCB antennas, the different types, what to consider when designing them, best practices, and a bit about advanced topics that can help you improve your antenna design skills.

Understanding PCB Antennas

A PCB antenna is a metal trace formed on the circuit board, designed to transmit and capture electromagnetic signals. It is designed to resonate at a specific frequency or range of frequencies. This design lets the device communicate wirelessly.

Key advantages of PCB antennas:

• Low cost (no extra manufacturing beyond PCB etching)
• Compact size and integration
• High reliability (no moving or detachable parts)
• Customizable for application needs

They are also sensitive to PCB layout, ground plane design, and component placement, which makes careful engineering essential.

Types of PCB Antennas

1) Antenna inverted-F (IFA)

It is one of the most popular types of compact devices. And features a bent shape to reduce space. This works well for single-band applications. It found applications in Bluetooth, Wi-Fi, and cellular devices. It is compact and easy to match but has very narrow bandwidth.

Red Colour: Top Layer  and Blue Colour: Bottom Layer

NOTE: Don't place any copper on the bottom side of the PCB in the white area shown in the above image.

2) Meandered Antenna

A longer conductive path folded into a smaller physical area. It is used when PCB space is limited, but electrical length needs to be maintained.

3) Monopole and Dipole Antennas

• Monopole: One conductor up against a ground plane.
• Dipole: The two conductors are pointing in opposing directions.

The ground plane is the primary distinction between these two antennas. They are simple to tune and design. But has a larger footprint compared to meandered shapes.

4) Loop Antennas

• Conductive loop structures that radiate magnetic fields.
• Excellent for NFC and RFID.

Symbol of Loop Antenna:

Pros: High efficiency for short-range.

Cons: Not ideal for longer distances.

3.5 Patch Antennas

• Flat metal patch over a ground plane, separated by a dielectric.
• Often used for GPS.

Pros: Directional radiation, compact.
Cons: Narrow bandwidth.

Quick Comparison Table:

4. Basics of PCB Antenna Design

Before you design a PCB antenna then you need to understand the main factors that affect performance.

1. Resonant Frequency

The antenna should resonate at or near the desired operating frequency. This is determined by the electrical length, which is influenced by:

• Trace length
• PCB dielectric constant (εr)
• Antenna geometry

2. Impedance Matching

The majority of RF circuits are built to operate with a characteristic impedance of 50 Ω. A mismatch can cause signal reflection, reducing efficiency. Impedance matching can be achieved using:

• Matching networks (capacitors, inductors)
• Adjusting trace dimensions
• Fine-tuning ground plane

3. Ground Plane

The efficiency of a PCB antenna largely depends on the dimensions and geometry of its ground plane.

• Too small: reduced efficiency
• Too large: frequency shift
• Should be free of cuts or vias directly under the antenna region

4. Substrate Material

FR-4 is widely used. For frequencies above 3 GHz, low-loss substrates such as Rogers are preferred to minimize signal attenuation. This is because they have stable dielectric properties.

5. Trace Width & Shape

Trace width affects impedance and current distribution. To determine the ideal geometry we use calculators or simulation programs like ADS or CST.

6. Easy Steps for Beginning PCB Antenna Design

Step 1: Assess Your Requirements

• Operating frequency
• Bandwidth
• Available space
• Adherence to the law is needed

Step 2: Choose the kind of antenna that

Select the geometry that best meets your application and spatial requirements.

Step 3: Select the PCB Substance

FR-4 is commonly used for standard applications, while Rogers or comparable substrates are chosen for high-frequency designs.

Step 4: Initial Layout

Draw the antenna shape according to the calculated length for your frequency.

Step 5: Include the Ground Plane and Feed

Maintain a clear space surrounding the antenna and abide by the RF design guidelines for feed lines

Step 6: Make a simulation

Validate performance using an EM simulator.

Step 7:Test and Prototype

Measure and adjust as needed using a Vector Network Analyzer VNA.

Design Example: 2.4 GHz PCB Antenna Design

Suppose we want an Internet of Things device to have a Bluetooth antenna.

1) Establish the Frequency

• The target frequency is 2.4 GHz in the Wi-Fi band and Bluetooth.
• About 31 mm or a quarter wavelength (λ/4) is needed.
• In which wavelength  λ = c/f = 3×108/2.4×109 = 125 mm

2) Choose Antenna Type

For PCB, commonly used are:

• Antenna inverted-F (IFA)
• Meandered monopole
• Printed dipole

Here, we’ll go with Inverted-F because it’s compact, widely used in BLE/Wi-Fi, and easier to match.

3) Calculate Initial Dimensions

• Length ≈ λ/4 = 31 mm, but slightly shorter because of PCB dielectric (FR4 has εr = 4.2).
• Effective length = 15–20 mm, depending on layout.
• Trace width: 1–2 mm for mechanical strength.

4) Design in PCB Tool

• Place the antenna trace at the edge of the PCB (so it radiates freely).
• Keep a 50 Ω feed line from the RF IC/connector to the antenna pad. (Use microstrip or coplanar waveguide calculator to define exact width, e.g., ~1.2 mm on 1.6 mm FR4).
• Add a matching network (usually 2–3 pads with 0 Ω resistor initially, then tune later using L/C values).

5) Ground & Clearance

• Keep a ground plane beneath the feed line, but no ground under the antenna element (leave clearance area).
• Maintain at least 5–10 mm clearance around the antenna area for better efficiency.

6) Tuning

• Use a Vector Network Analyzer VNA to measure the PCB prototype.
• Make minor adjustments to the antenna length, trim the copper, or tune with appropriate parts, capacitors, and inductors.

Once you’ve finished your antenna layout, upload your Gerber files to JLCPCB and get an instant online quote in minutes. This allows you to quickly test and refine your antenna performance with real hardware.

PCB Antenna Design Best Practices

1. Keep Antenna Area Clear: Avoid placing components, traces, or copper pour under/near the antenna.

2. Mind the Feed Line: Use controlled impedance traces for RF feed lines (usually 50 Ω).

3. Optimize Ground Plane: Use a dedicated ground pour beneath RF circuits but not under antenna radiating areas.

4. Tuning and Prototyping: Include test pads or tuning components to adjust the antenna in real conditions.

5. Isolation from Noise Sources: The antenna should be placed at a distance from high-speed digital lines and switching regulators to avoid interference.

6. Simulation Before Fabrication: Use an electromagnetic simulation tool to confirm your design before proceeding with manufacturing.

Complex Ideas (A Quick Look)

• MIMO Antenna Design – Multiple antennas for parallel data streams in Wi-Fi 6 and 5G is known as MIMO antenna design.
• Beamforming – Beamforming is the process of directing signals by varying their amplitude and phase.
• Multi-Band Antennas – A single antenna structure that operates across several frequency bands is known as a multi-band antenna.
• Antenna Diversity – Using several antennas to increase dependability in multipath environments is known as antenna diversity.

These call for a more in-depth understanding of S-parameters, RF simulation, and sophisticated PCB stack-up design.

Conclusion:

PCB antennas play a vital role in modern wireless devices, enabling compact, reliable, and cost-effective communication solutions. It takes careful layout, testing, and an understanding of RF principles to design them. Whether you’re a beginner learning about monopoles and IFAs or exploring advanced concepts like beamforming, mastering PCB antenna design opens the door to a wide range of wireless innovations.

FAQs:

1. What factors should be considered when designing a PCB antenna?

Key factors include:

• Operating frequency and target bandwidth
• Antenna type (e.g., monopole, dipole, patch, inverted-F)
• PCB material and dielectric constant (Dk)
• Ground plane size and shape
• Impedance matching and feed line design
• Clearance area to minimize interference These factors directly affect antenna performance, efficiency, and signal strength.

2. What are the most common types of PCB antennas?

Common PCB antenna types include:

• Monopole antennas – simple and compact
• Dipole antennas – good radiation pattern and balance
• Patch antennas – widely used in GPS, Wi-Fi, and IoT devices
• Inverted-F antennas (IFA/PIFA) – space-efficient and versatile
• Meander line antennas – ideal for space-constrained designs

The choice depends on application, size constraints, and target frequency.

3. How do PCB material properties affect antenna performance?

PCB materials determine the dielectric constant (Dk), loss tangent, and thickness, which influence signal propagation and efficiency.

• FR4 is cost-effective but less consistent at high frequencies.
• Rogers or PTFE-based laminates provide superior performance for RF and high-frequency applications. Using the right material helps reduce signal loss and improve overall antenna efficiency.

4. How can you ensure proper impedance matching for a PCB antenna?

Proper impedance matching minimizes signal reflection and maximizes power transfer. Techniques include:

• Adjusting the feed line width and length
• Adding matching components like capacitors or inductors
• Using tuning stubs or baluns
• Simulating and testing using RF design tools A well-matched antenna typically has a return loss (S11) below -10 dB at the operating frequency.

5. Can JLCPCB manufacture PCBs for RF and antenna applications?

Yes. JLCPCB offers high-quality PCB manufacturing for RF and antenna designs, including advanced materials like Rogers for high-frequency performance. With precise fabrication tolerances, controlled impedance capabilities, and rapid prototyping services, JLCPCB supports designers from concept to production.