Flexible printed circuit boards usually work with the wireless antenna designs. It does this effectively, so as to supersede the antenna with respect to the traditional PCB, and then offer free dimension of the integration of the wireless system and antenna to the designer.
What are the Materials Used for the FPC Antenna?
Since the FPC antenna’s adhesives are usually affixed to other substances, the adhesive’s secondary adhesiveness would experience a reduction. Also, if the copper cloth corners are bent, you can attach them to the shell’s surface with a less curved radius.
Furthermore, due to stress from bending, it can easily experience warping. This is why when separating the FPC antenna from the adhesive paper, don’t bend at the two ends of your antenna. In addition, you should not touch the adhesives present on the two antenna ends using your fingers. This is because these ends are known to receive the highest bending stress. Ensure that the adhesives on both ends are kept clean and prevent creases on copper cloth regions at both ends.
Usually, FPC antennas are thin, and are just 0.15 mm. Also, they feature a strip that is peelable, as well as an adhesive section. All these can be fitted into smaller electronic devices and in different configurations. Also, they are usually supplied with a connector and a cable. These are used for fixing them into the bottom housing or cover of the electronic product of the manufacturer. FPC antennas are usually lightweight, below 1 gram.
What are the Features of the Flexible PCB Antennas?
The FPC Antennas are low profile, flexible, and very economical and reliable antennas, which are widely utilized in wireless industries. This antenna is made of polyimide flex PCB that has a patterned and conductive material (usually copper) for the best antenna topology.
You can use it in developing different antenna types. These include dipoles, monopoles, as well as the printed F antenna. These antennas have coaxial cables which help in connecting to the needed circuit.
Main features of the FPC Antenna
You can bend the FPC antennas to ensure their embedding into small devices like the IoT module whereby the space in the circuit board is at premium and you cannot place the surface mount antennas.
Furthermore, you can place the FPC antennas horizontally, vertically, and co-planar to the parent PCB without affecting the performance. These antennas perform in a consistent manner when on curves, when flat, or when vent to some degree. This is why they are appropriate for devices whereby the SMD antenna won’t fit into the parent PCB with the needed ground place.
Also, you can customize the FPC antenna’s cable length, which makes connection to modules very easy. Traditionally, a PCB’s size and its accessible ground planes usually affect the SMD antenna’s performance. However, this isn’t applicable to the FPC antenna, because the flexible circuits has been customized for that antenna placed on it. What this ensures is higher performance levels, space saving, as well as fewer steps in integration.
The flexible printed circuit provides a similar performance whenever it is compared to the external omni directional antennas such as omni directional radiation patterns as well as high efficiency levels. However, it needs less ground space to be able to achieve these performance levels. Therefore, these antennas usually optimize the circuit board for them to function.
With respect to cost, the FPC antennas are less expensive than the externally mounted types. You can achieve high performance levels without having to deploy external antennas. You can fabricate the FPC antenna making use of standard techniques of PCB manufacturing. This makes them repeatable antennas and very reliable.
The Advantages of FPC Antenna has no Ground
SMD chip antenna and the FPC antenna have different working principles. SMD antennas utilize the ground plane (already installed) for radiating and its principle for working is reciprocating. Also, dipole antennas make use of two radiators, and each radiator’s length is associated to the frequency’s wavelength that is utilized by that antenna. Also, embedded antennas feature heat sinks within its mass range, and they utilize areas on the printed circuit board as its counterpoint, which is also its ground plane.
For the SMD antennas, the ground plane’s length is related to the antenna’s wavelength. You have to provide the right ground plane into the design to ensure the antenna will be able to operate with great efficiency.
At this stage, FPC antennas act differently because they don’t require ground planes to offer radiation. This is why they allow designers to arrange the circuit’s components freely into the design.
However, this coaxial cable now forms part of an antenna. During the design of the cable extender of the antenna, you should take care to ensure that this component of the antenna is taken away from the remaining components which might create interference and noise.
Placing Your FPC Antennas
Because ground planes aren’t a consideration for FPC antenna design, the parent PCB size isn’t a factor such as chip or SMD antennas. Moreover, placing FPC antennas must follow some important rules, since the majority of antennas are usually sensitive to their environment.
This antenna radiates in six different spatial directions. These are right, left, back, front, down, and up. Ideally, in 3 to 5 of the directions, you shouldn’t have any obstacles. This allows the antenna to function effectively. Also, for the other directions having obstacles on its radiation oath, a minimum gap still has to exist, which would be specified in the antenna datasheet of the manufacturer.
Furthermore, the device’s plastic casing won’t behave as an obstacle. This can only happen if the casing’s material is painted in a metallic way or is glass filled. The metal components and objects near the FPC antenna like PCBs and data lines are usually the culprits blocking the signal.
Requirements of the FPC Antenna Direction
The device’s shape determines the appropriate orientation of a FPC antenna in relation to the circuit board. The antenna’s position relative to the circuit board would depend on the ground wire’s proximity.
No matter the chosen solution, the distance is now an important design dimension. This would be indicated in the datasheet of the manufacturer.
In addition, the antenna’s I-PEX connector cables connect it into the design. Also, the design of this characteristic impedance of the transmission line inside the product should be 50 ohms and has to be kept very short. All the other components of a radiofrequency system like power amplifiers and transceivers must be designed to have a 50 ohm impedance value.
To build the layout of your transmission line, we advise that you utilize a commercial radio frequency design package. You must take into account the dielectric constant, copper thickness, and PCB thickness. This program would calculate the transmission line’s required width as well as the proper spacing between an antenna feeder and the ground planes on the two sides to be able to maintain a system impedance of 50 ohms.
FPC Antenna vs PCB Antenna: What’s the Difference?
Traditionally, a PCB’s size along the ground plane will have a direct influence on the SMD antenna’s performance. This isn’t applicable to the FPC antennas, as flexible circuit boards are customized for whatever antennas are placed on them. This permits high performance levels, space saving, as well as lesser integration steps.
The FPC antennas provide similar performance whenever it is compared to the external omni directional antennas such as omnidirectional radiation patterns, as well as high efficiency levels. However, it needs a smaller ground space in order to achieve these performance levels. Therefore,. These antennas help in optimizing the circuit boards to deliver their functions.
In addition, FPC antennas are less expensive than the PCB antennas (the externally mounted ones). You can achieve high performance levels without having to deploy external antennas. You can fabricate the FPC antenna making use of standard techniques of PCB manufacturing.
This makes them repeatable antennas and very reliable. Also, the FPC antenna’s adhesive backing ensures the easy mounting of the FPC antenna family in custom and unique enclosures, coupled with enabling an enclosure that is environmentally sealed and protection from accidental damage to the antenna or tampering.
Furthermore, FPC antennas perform well in different applications. These include cellular IoT, wideband cellular sub-6 5G, 4G, 3G, and 2G, 5G New Radio, etc.
Will FPC Antenna Suit Your Design Appropriately?
For the small printed circuit boards, the SMD antennas might be the obvious choice. However, FPC antennas are very useful in applications having insufficient space.
The off-the-shelf flexible printed circuit antennas aren’t recommended for smallest devices. However, many applications exist whereby FPC antennas function effectively. They are very useful alternatives for the designs whereby the ground plane’s space and length are limited.
Conclusion
In summary, the FPC Antennas are low profile, flexible, and very economical and reliable antennas, which are widely utilized in wireless industries. You can bend the FPC antennas to ensure their embedding into small devices like the IoT module. Furthermore, you can place the FPC antennas horizontally, vertically, and co-planar to the parent PCB without affecting the performance.
