Have you previously attempted to monitor your wireless activity? By enabling devices to be able to connect to standardized matching networks, Bluetooth PCB antenna design has spread the Bluetooth electronics worldwide. For example, I am using wireless headphones to stream music through my phone.
Later, I’ll get into my car then use the hands-free system to answer calls. When I arrive home, I can communicate with my house assistants so they can inform me about the weather, schedule a time for supper, take off the shoes, and provide me with a massage. Ah, I see now that I said it too soon.
Applications for Bluetooth-enabled devices are numerous and include healthcare, entertainment, IoT, entertainment, as well as virtual reality. Creative designers seems to have a variety of applications where PCB bluetooth antenna is very useful
What is a PCB Bluetooth Antenna?
For sharing data across small distances, Bluetooth can be described as a unique wireless communication technique or technology. 2.4GHz devices can utilize the PCB bluetooth antenna. RP-SMA, U.FL, as well as SMA connectors are used in sizes ranging from tiny to the sub-miniature connections.
Depending on whatever connection is used, different types and sizes of cables are utilized. The majority of Bluetooth antennas remain omnidirectional, however 2.4GHz directional antennas are also available. Through-hole, wall, surface, and pole mounting options are all available.
Antenna compatibility varies amongst Bluetooth devices. Checking connection compatibility as well as frequency rating is done to match the appropriate antenna to the appropriate device. Depending on the brand of antenna, gain and range might vary. Whenever the antenna and device have different connections, connector adapters may additionally be employed.
Important Elements to Consider While Defining The PCB Bluetooth Antenna Needs
First and foremost, is the product wearable?
Antenna selection and design are particularly difficult for the wearable devices. For the majority of Bluetooth wearables, omnidirectional coverage seems to be a fiction. Every antenna radiation which reaches a mammal’s (or human’s) body at 2.4GHz would be taken in by our bodies. Another Bluetooth gadget on the body’s other side won’t be able to receive it.
While a good number of product developers would claim that a wearable requires omnidirectional coverage, the truth is that whenever a gadget is close to the body, it loses all of its energy towards the body regardless.
The real use case should also be taken into account. If the product is put on within the ear, whatever radiation it emits inside the body would not be effective for any signal transmission.
A broad view field can be helpful since cellphones can function even when not actively held close close to the body. Nevertheless, when the smartphone is held close to the head, any energy that would have been radiated through the body for the signal purposes becomes lost. Because of this, extending the antenna farther from the hand or head enhances its communication capabilities with neighboring devices. Because of this, extending any antenna farther from the head or hand enhances its communication capabilities with neighboring devices. T hat BluFlux range extending smartphone case patent is based on the idea.
Compared to an earphone inside the ear or a telephone held close to the head, as well as the smart watch worn on a wrist has very little adjacent human tissue. There will be a distinct design constraints for each use case and device.
The fundamental idea is that the Bluetooth antenna cannot emit through close human tissue.
Would your product be mounted or enclosed in metal?
Solid metal inside the route of transmission would completely block the E-M waves from your antenna. If the product is completely contained in metal, you must install your antenna externally and it must radiate outward from its enclosure rather than into it. This limits your options to the types of directional antenna such as a PIFA (planar-inverted-f-antenna) or patch .
If the metal coverage of your enclosure is just partial, proper antenna placement remains essential, and depending upon that precise geometry, it could still be necessary for the antenna to be an external one.
A smart meter installed on a metal or sheet metal wall won’t be able to transmit radiation via sheet metals, thus it will additionally require the directional antenna to provide the greatest field of vision.
What’s the bluetooth range?
Your target range of the product is the next query. Avoid using a bluetooth chip antenna that is smaller than 20mm if you need a stable Bluetooth connection across distances that are higher than what Bluetooth was intended for (50m to 100m).
As previously learned above, the dielectrics (as well as highly permeable materials) have been put into micro antennas to enable their operation in electrically small regimes.
PCB Real Estate – Does your antenna, RF components, as well as ground plane fit inside a 40 mm by 40 mm space on your Circuit board?
The efficiency, installation impedance match, as well as patterns of the antenna will be impacted by this minimum Circuit board area requirement. The PCB is needed as “counterpoise” when employing the Bluetooth chip antenna, almost always. The PCB and the actual chip structure are both components of an antenna.
What are the Requirements for the Clearance Area and Circuit Board Ground Plane?
To create an efficient 12 wave antenna, the quarter wavelength antenna has to be paired with a long enough ground plane. Moreover, the omnidirectional antenna needs space to transmit without being interfered by a ground plane
Also, you’ll really have to reserve some room for coordinating parts that will adjust the operating band of the antenna so that it coincides with ISM bands for your specific PCB layout as well as supporting parts.
Because these PCB design components are essential for such antenna to function properly for Bluetooth, the majority of manufacturers of chip antenna would give layout recommendations that take them into consideration.
Any layout principles worth employing should at the very least adhere to the rule of quarter wave, which states that such ground plane must be at least one quarter wavelength length in the direction of polarization.
This seems to be 31 mm for Bluetooth, although longer is usually preferable (for instance, Johanson’s layout requirements recommend 40 mm for its 2.4GHz antennas‘ ground plane lengths). This required orientation and position of an antenna with regard to this ground plane are determined by an antenna’s directivity.
You require an omnidirectional or directional antenna depending on the materials around you and the purpose. The use case as well as materials of your product will affect the amount of directivity you require from the antenna, as explained below.
We would like a ground plane that’s about least 31 mm in length and ideally the same width for such IFA antenna or omnidirectional monopole fed against by the narrow edge of the PCB.
Choosing the Appropriate Type of Bluetooth Antenna for Your Circuit Board Design
You must acquire the ability to reason like the RF designer even if you’ve got no prior knowledge in the field.
Narrowly defining the functional specifications of your product serves as the initial step in selecting a suitable Bluetooth antenna to work with your PCB. Consider the following inquiries
- Is the product wearable or flexible?
- What form factor restrictions have you?
- Is the product packed in packaged or mounted in metal?
- What antenna gain and communication range are necessary?
You will be a bit closer to selecting the ideal Bluetooth antenna to suit your device after you’ve more precisely defined your needs according to your responses to such questions.
A chip antenna or microstrip is preferred if the product gets wearable because it most likely has limited space. Metal plate antennas could be the ideal option in achieving better antenna gain whenever long-range communication is your most crucial need.
You may choose the optimum antenna for the device by optimizing the functional design needs within the aforementioned framework.
Antennas using Ceramic Chips
Pre-packaged ceramic chip antennas have a relatively compact form factor but a low efficiency and gain. They might not be the ideal choice for applications including location-tracking or ranging because of their limited bandwidth and high cost. Such chips are ideal for stiff wearable technology, which frequently uses low-range applications.
Several chip antennas were produced by a variety of manufacturers. It allows designers a lot of leeway when choosing the appropriate gain, bandwidth, as well as form factor to aid the devices that are bluetooth-enabled.
Antennas made of metal plate
Large quantities of power may be handled by the metal plate antenna, which have good efficiency, low bandwidth, as well as linear gain.
In applications that need small form factors, they might not have been the best option due to their high cost and large footprint. These antennas may be made as a inverted-F, monopole, or dipole antenna and work with linear polarized radiation.
These antennas, as their name suggests, are made from metal plates with a particular pattern etched into it. This PCB also isn’t directly attached with the metal plate antennas. Instead, the antenna is located above the circuit board with the right-angle bracket which connects it to other components. Power planes, g rounding planes, as well as other components should not be present in the area underneath the antenna.
Microstrip Antennas
You could choose to mount the microstrip antenna on the PCB if the form factor cannot support the plate antenna when costs become a major consideration. These antennas outperform chip antennas with respect to the linear efficiency and gain. These may be printed onto the Circuit board, making them easier to fabricate and having a better bandwidth than the plate antenna.
While designing the microstrip antenna, precise configuration is necessary. Little variations in the microstrip’s size can alter the antenna’s resonant frequency, which lowers linear efficiency and gain at 2.4 GHz with greater resonance shifts. The range of communication will also be reduced as a result of this. Your product’s maker has to comply with the antenna’s tight tolerances.
PCB Bluetooth Antenna Design Options and Varieties
PCB Bluetooth antenna designs using an inverted F antenna
When utilizing dielectric materials having high value of dielectric constant, the inverted-F antenna’s body can be sheet-like or linear, and the bluetooth antenna’s size can also be decreased. The inverted F antenna, among the most popular in the practical applications, has a cheap design cost however raises the certain volume when used as the on-board antenna.
Typically, the antenna gets mounted on the PCB’s top layer. Its floor is often situated close to the antenna on the upper layer. The antenna should not, however, be positioned near the antenna. This area ought to be clear.
PCB Bluetooth antenna design with curved-flow
It is more challenging to estimate the meandering antenna’s length. The topological geometric space as well as deposited area dictates its length, which is typically somewhat longer compared to the quarter wavelength. This meander antenna frequently comes in a PCB package, or an integrated antenna. This antenna, similar to that inverted F type, is often mounted on the PCB’s top layer. Its ground is often positioned on the upper layer, close to the antenna.
Relevant PCB Bluetooth Antenna Design Considerations
- The antenna’s signal (frequency more than 400 MHz) becomes readily attenuated, thus the distance present between this antenna as well as the neighboring ground would be at least thrice its line width.
- This characteristic impedance of strip and microstrip lines depends on the slab’s thickness, line width, the vias, as well as the dielectric constant.
- This parasitic inductance produced by the through hole will significantly attenuate high-frequency signals. As a result, avoid having a through in the RF lines.
Conclusion
To cohabit with the complete zoo of devices which use its 2.4 GHz ISM bands, such as various WLAN technologies as well as microwave ovens, Bluetooth devices hops between the frequency channels. Although Bluetooth Low Energy offers less channels (40) compared to the normal Bluetooth (79), there is no difference from the antenna’s standpoint because the entire frequency range is used.
