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What is a PCB Antenna? All You Need to Know

A PCB antenna sits on the PCB itself and requires no external parts. As a result, it offers cost and space savings, among other benefits. Read more about it in this comprehensive guide and learn why it makes an excellent choice for RF communication systems. Among the topics we will be discussing are.

  • What is it, and how does it work?
  • Common applications
  • Its different types
  • And the steps on how to design one

What is a PCB Antenna?

It’s a type of antenna placed on a printed circuit board. It uses traces as its conductive elements. In other words, it forms part of the circuit board compared to being externally connected.

When used with an RF circuit, it helps turn radio waves into small pulses of an electric current. It can also function as a transmitter and perform an opposite purpose.

Fabricating it directly on the board offers several benefits, including lower cost and easy integration. It finds helpful uses in electronic devices with wireless communication for various frequency bands, including cellular, Wi-Fi, and Bluetooth.

How PCB Antenna Works

A PCB-printed antenna helps transmit or receive high-frequency electromagnetic waves. It works with a high-frequency circuit to convert the energy of RF waves into electric signals and vice versa. Here’s its operation in more detail:

Transmitting: The RF circuit sends a varying electric charge to the antenna. The charge generates an electromagnet wave that radiates into space, carrying the transmitted signal.

Reception: the electromagnet field induces a charge in the antenna, generating a fluctuating current and voltage. The RF circuit decodes it to separate or extract the transmitted signal.

The wave radiation varies based on its design. It’s typically directional, semi-directional, or omnidirectional. Here is what that means.

  • A directional type only has one direction
  • The semi-directional type has a defined angle of signal propagation
  • On the other hand, the omnidirectional type can send signals in all directions.
5G PCB antenna
5G PCB antenna
Resource: https://www.microwavejournal.com

PCB Antenna Applications

Applications where integrating an antenna on a printed circuit board is necessary – and a benefit – include those listed below.

  • Wireless Communication Systems: examples include the 3G and 4G PCB antennae for long-range cellular communication and Wi-Fi or Bluetooth types for short-range communication.
  • Automotive Systems: vehicle GPS systems and other wireless applications like keyless entry use it to send and receive signals.
  • RFID: the radio waves of various RF identification and tracking systems and devices use compact antennas fabricated on printed circuit boards.
  • Medical Devices: an array of medical monitoring devices, including wearable types, rely on it to send and receive communication waves

Advantages of PCB Antenna

An internal PCB antenna is a popular option when manufacturing wireless electronic systems and devices. The integration offers these advantages.

  • Cost: you need no additional materials or parts to produce this since it uses circuit board traces and circuits. That brings down the cost of making your wireless communication device.
  • Size: they occupy minimal space, making them an excellent option for compact, handheld devices like mobile phones or wearable monitoring gadgets.
  • Manufacturability: it requires fewer materials to place on a circuit board, making it a preferred option for many wireless systems.

Circuit board antennas have a few disadvantages. Their compactness can limit their bandwidth and reduce their efficiency. They’re also more prone to environmental interference.

PCB antenna types and designs
PCB antenna types and designs
Resource: https://www.researchgate.net

Types of PCB Antenna

You can distinguish the various types of PCB antennas by their design features or structures. In light of that, we have these different designs.

PCB Monopole Antenna

It only has one conducting element: a single and straight section of the trace. These types are simple to fabricate, compact, and inexpensive to create and place on a circuit board. They offer 360-degree coverage.

PCB Dipole Antenna

Unlike the monopole type, it has two conductive elements of equal lengths. It offers a bidirectional radiation pattern, making it a narrow-band version.

PCB Patch Antenna

It looks like a patch on the circuit board and can be of various shapes, including rectangular, square, and round. Despite being relatively large, it offers several benefits, such as high gain.

PCB Loop Antenna

It uses conductors that form a loop shape, with receiver and transmitter terminals connected to either end. This design has a lower efficiency than most other types but is one of the simplest to design or use.

PCB Helical Antenna

It uses a helix-shaped conducting element. The spiraling conductor offers several benefits, one of them being space savings. The design also makes it a directional type with a high gain but narrow bandwidth.

PCB Slot Antenna

The conductive material (trace) is slotted. This design creates a resonator that radiates electromagnetic energy when supplied with an RF signal. The same happens when RF waves hit it.

PCB Yagi antenna

The Yagi uses a driven element, such as a dipole receiver between a signal reflector and one or more signal directors. It has a high gain but takes up more space than most other PCB antenna types.

Planar Inverted F Antenna

As its name suggests, it looks like an upside-down F on the circuit board. It’s an omnidirectional with high efficiency and reduced footprint benefits. It’s popular in mobile or handheld devices like smartphones and tablets.

Meander Line Antenna

The conductive element folds back and forth, creating a meandering structure that considerably shortens the overall length. Although more compact, it presents a challenge in the radiation pattern and several other properties.

Designing a PCB GSM antenna
Designing a PCB GSM antenna
Resource: https://forum.arduino.cc

How to Design a PCB Antenna

PCB antenna design involves these main steps:

  • Specifying its type
  • Calculating the size
  • Determining the electrical requirements,
  • Creating the schematics and layout
  • And, finally, running simulations.

Antenna Type and Board Material

Determine the desired design or structure. There are many choices. They range from monopole to dipole structures and more. Your choice will depend on the desired radiation pattern and bandwidth or frequency and size constraints.

Determine the board material. Your options include FR4 and metals and depend on the following factors: required electrical characteristics, mechanical property requirements, and cost.

Antenna Size

This step requires a few calculations to determine the following specifications: antenna height, width, and length. Here, we assume the circuit board material (substrate) is FR4.

To calculate the substrate height, use this formula where C stands for light velocity in m/s, and Σr the dielectric constant of the substrate.

For the trace width, here’s the formula to use. Again, Σr is the material dielectric constant.

Finally, use this formula to determine the trace length. Here, Σff represents effective permittivity, and ΔL the physical length.

The formula below gives you the microstrip width-to-depth ratio. In the formula, “W” means the trace width, while “A” means the effective area.

Electrical Requirements

Your RF circuit will operate within various constraints depending on its end-use application or environment. Start by specifying the following: the operating frequency and radiation pattern, polarization, impedance, etc.

Schematics and Layout

Create its schematics using a design program. This part also involves creating the physical layout. With the components laid out and the interconnections made, you can run it to predict its operation.

Design Simulation

Once all requirements are in place and the design read, run it using a simulation program. Simulations help you pick errors in the design before prototyping or final production. You can use various simulation programs, including ANSYS, CST studio, and HFSS.

4G PCB antenna design
4G PCB antenna design
Resource: https://www.youtube.com/watch?v=m0B-63Q-R_8

PCB Design Considerations

Designing a PCB requires careful consideration of various parameters, or it may not operate efficiently. To optimize it for signal transmission or reception, consider these factors.

Position

You can typically place it anywhere on the board. It depends on the application. However, corners make the most ideal positions. It has up to five transmission and reception directions when placed in a corner, making it more effective.

Size and Weight

Printed circuit board antennas are lightweight and small. Depending on the board’s end use, ensure yours doesn’t exceed acceptable limits for size and weight, especially if you’re designing it for a portable or wearable device.

Ground Plane

Size the ground plane correctly. Make it sufficiently large. An improperly placed ground affects the radiation pattern, leading to inefficiency of the entire RF circuit.

Component Clearance

Keep components away. They cause interference and affect signal transmission or reception. These include electronic devices and mounting screws, and other metallic parts.

Transmission Line

The transmission line is the conductive path that carries the RF signal to the receiving circuit. Make it straight to avoid signal degradation.

Chip antenna vs. PCB antenna
Chip antenna vs. PCB antenna
Resource: https://www.youtube.com/watch?v=ZVo2RkBS14o

PCB Antenna vs. Chip Antenna

A circuit board antenna is printed on the board using conductive traces. A chip type involves placing a dielectric material between two conductive pieces. In addition to the structural and design differences, other features that set the two apart include the following.

A printed type takes up more space than a chip type but costs less. It also produces stronger signals and supports a higher bandwidth. However, it’s more prone to environmental factors, such as interference.

The chip type is more compact and easy to modify. Environmental factors also affect it less. On the downside, it costs more and has a long signal strength and limited frequency range.

Conclusion

The PCB antenna is one of the most popular types today. It’s easy to implement, customizable, and available in many design options. Many wireless communication device circuit boards use it, from mobile phone boards to GPS and other IoT systems.

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