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How to optimize RF performance for 5G connected devices

Everyone understands that 5G will bring with it a huge uplift in speed and capacity as well as device density per cell to support massive IoT. 5G is fundamentally changing the way we communicate, delivering improved latency and throughput. These benefits, plus network slicing, are just a few ways in which 5G will transform life for businesses and consumers. Central to 5G’s delivery will be antenna technology, and as such, the entire RF front end design layout. This is highly complex and 5G IoT deployments are reliant on optimized antenna and RF performance so 5G can deliver on its promises.

Quectel, which was the first company to bring 5G IoT modules to market, also offers a comprehensive range of antennas for 5G. Customers can buy both the module and the antenna from Quectel at the same time, thereby ensuring smooth integration of antenna and module. This is particularly valuable in the 5G environment where modules such as the Quectel RM500Q, offer 4×4 MIMO ports and multiple antennas are required to utilize all ports, demonstrating the complexity of the typical 5G antenna scheme.

The different types of antenna and the technological and design options available can have huge impacts on performance. Antenna types include laser direct structuring (LDS) and liquid crystal polymer (LCP) antennas, tuneable antennas and devices that are co-designed to accommodate multiple antennas, offer decoupling for high isolation and can support MIMO or beamforming.

Key design challenges include the antenna position, and the following are important considerations that must be clearly defined at the start of the project:

  • The housing material (metal or plastic)
  • The proximity of metal components such as batteries, connectors and shield cans
  • Noisy components that cause interference
  • The location of the module within the device
  • The printed circuit board (PCB) size, position and orientation,
  • The device instal position
  • Other antennas sharing the selected frequency

All the above influence ultimate antenna performance and therefore should be considered when selecting an antenna for a specific deployment. 5G involves multiple antennas so it is very important to assess how each will interact. If an off-the-shelf antenna is selected, consider how the antenna was designed and seek to replicate the conditions it was designed for.

Customisation is therefore often selected as a better approach for handling the complexities of some 5G deployments than off-the-shelf products. Typically, customized antenna technologies include laser direct structuring, which is the prevailing antenna manufacturing technology on the market and offers high design flexibility with surface mount technology (SMT) component integration possible. Advantages here include a short design cycle, potentially with just a seven-day turnaround after design, but this can be more expensive than flexible printed circuit (FPC) or sheet metal technology and double curved surface designs are not possible.

FPC is another traditional antenna manufacturing technology. It is cost effective and can be integrated with spring contacts for ease of assembly. However, FPC offers limited layout complexity, with a cost between sheet metal and LDS.

Finally, sheet metal is the most flexible 3D antenna manufacturing technology with antenna volume and RF performance improvements possible. The technology offers lower assembly cost and higher yield, but the tooling cost is greater than for FPC or LDS.

Antenna selection criteria depends on the ultimate use case by broadly speaking, the choice is divided into four key areas:

1. External antenna with cable

This offers great performance with the lowest risk and the antenna is sited far from the electronics. In addition, the antenna implementation is known and tested.

2. Terminal antenna

This is ideal for a low signal area such as a basement and offers known performance, with low risk.

3. Embedded Flex/PCB, SMD Antenna

This is a higher risk, lowest cost option that demands extensive experience to ensure good performance. The surface mount design (SMD) type of antenna is ideal for high volume deployments.

4. Custom antenna

This offers the most flexibility for addressing mechanical constraints and performance. The antenna is molded to fit the product and can be fitted where a standard antenna would not normally have fitted.

5G mmWave is another challenge from an antenna point of view. Typically referring to radio frequencies from around 30GHz to 300GHz, 5G mmWave offers ultra-wideband support, beamforming and a short wavelength. Careful design of the antenna is essential and Quectel provides a mmWave antenna service that addresses antenna placement, antenna radome material and mechanical design analysis, installation tolerance evaluation, thermal evaluation, calibration and software development, antenna RF path design and over-the-air testing.

These and other methods to take advantage of Quectel’s comprehensive antenna portfolio and design capabilities were detailed in a recent Quectel Masterclass in which Quectel’s Carol Zhao, Colin Newman and Stephan Sherlock detailed the challenges involved in 5G antenna optimization, how Quectel can help the design process and how newer technologies such as 5G mmWave are presenting additional complexities.

The Masterclass, titled: Optimizing Antenna and RF Performance for 5G Connected Devices, can be listened to here.