What Does the Future of 5G Mobile Phone Antenna Design Look Like?

With the limited rollout of 5G technology beginning over the last year, 5G has finally arrived for some users, even if most mobile phones are not yet ready to use this new network. In fact, 5G networks are predicted to grow to cover 40% of the world by 2024.

Antennas for 5G mobile devices have been demonstrated in these new 5G networks, and new mobile phones are being introduced to reliably work as a part of the new 5G networks by using MIMO (Multiple-Input-Multiple-Output) antenna arrays.  Mobile phones are relatively small devices which have limited space available inside of their cases for packaging these new 5G Antennas incorporating MIMO technology. The 5G Antenna designs are more complex to design and fabricate than those used for earlier 3G and 4G systems, so antenna engineers are under pressure to respond to these new design challenges.

Here is an overview of what you need to know about 5G Antenna design for mobile phones.

Getting to Know Traditional Antenna Designs

Traditional monopole or dipole wire antennas have been in use for more than 100 years. If you are going to build a HAM radio, you may still use one if you are operating at 30 MHz

Because of the exposure to the elements these traditional antennas faced, they were later fabricated from metal tubing to provide mechanical strength and to not collapse in wind, rain, ice, and snow storms. Metal tubing was also adopted for AM, FM, and TV antennas because of the higher power levels used by these broadcast systems.

The first 1G mobile phones used monopole antennas that were outside of the mobile phone case, so these antennas were susceptible to being broken or damaged by users even though they were built from small diameter metal tubes. This antenna breakage problem persisted through the 2G release, but 3G Antennas solved this problem by being packaged inside of mobile phone cases. This also introduced a new level of complexity for the design of mobile phones with Wi-Fi and Bluetooth antennas and circuits also being added to every mobile device.

The increasing number of antennas inside of a mobile phone case led to the development of mobile phone planar antennas that were designed as a part of the PCBs to optimize the performance of each system. Although this took up space on the PCBs of mobile phones, it was a necessity until antennas evolved to being fabricated  as surface mounted chips, which are more commonly recognized as integrated circuits (ICs) today.

Now, IC antennas are the most common type of antenna that you will find in mobile phones. 3G, 4G, and 5G antennas are all fabricated as surface mounted chips (ICs).

Sub 6 GHz Antenna Design

Antenna designers must design mobile phone antennas that are optimized for each communication system (3G, 4G, 5G, both Wi-Fi bands, Bluetooth, and GPS) used by that mobile phone, and every communication system but 5G operates at frequencies less than 6 GHz.  Lower frequency antennas can be large, and all these antennas must fit into the space available inside a mobile phone case. Mobile phones must optimize the space required for every component used to minimize the size of the phone.  MIMO, or Multiple-Input-Multiple-Output antenna systems, are an important aspect of the new 5G mobile phone architecture that must be carefully integrated into the mobile phone to optimize the high data transfer capabilities of 5G networks for each user.

Therefore, housing a seven or more antennas inside a mobile phone case is challenging for any designer. Each antenna must be efficiently connected to its associated circuitry that is also located inside the phone, so everything must be properly connected to work as a highly reliable communication system, and each communication system must not interfere with the operation of surrounding circuits used by other communication systems. This is a monumental task for the successful design and deployment of every mobile phone, which will be increasingly difficult for 5G mobile phones.

5G Millimeter-Wave Antennas

The increased demand for faster mobile data transfer rates requires more bandwidth for receiving and transmitting data, so this bandwidth is only available if mobile phones operate at higher frequencies, which are commonly referred to as the Millimeter-Wave spectrumMillimeter-Wave antennas for 5G systems are required to use the MIMO technology that is necessary for the successful deployment of this system for users.  This is a new type of antenna for mobile devices, and it is a critical technology that is required for the successful use of 5G networks.

5G Antennas operate at frequencies greater than 28 GHz, and these antennas are fabricated for mobile phones using chip-integrated phased array technology, which permits the 5G Antenna to be hidden from sight since it is built using a semiconductor fabrication process so the antenna is inside of an IC package.  These 5G MIMO phased array antennas are designed to support multiple beams, which are necessary to provide users with the higher data rates available for transmission and reception of data within 5G systems.  These phased array antenna uses multiple beams to simultaneously talk to one or more 5G base stations.

However, atmospheric losses for data sent at Millimeter-Wave frequencies is higher than the losses experienced by the lower frequencies used for 4G systems, so 5G systems must be built using more base stations.  This means that 5G systems will not be built using the massive cell phone towers that are used today for 3G and 4G systems but will be built using small base stations placed onto the sides of buildings in metropolitan environments.  An individual using a 5G mobile phone on the street or sidewalk will be able to exchange data from one or more 5G base stations that are within eyesight of the individual holding the mobile phone.  The Millimeter-Wave phase array antenna contained within the mobile phone makes this possible, which enables data to be transferred at significantly higher speeds.  This concept permits 5G technology to load webpages in a fraction of a second, and to also watch movies on a mobile phone while walking down the street, which is not typically possible with 4G systems today.

Performance is Important, But So is Safety

When anyone is designing and manufacturing devices such as mobile phones that are commonly stored in pockets and are also pressed into contact with an individual’s head during a phone conversation, then the mobile phone must be safe for the person using it. A poor mobile phone design would not only be dysfunctional, but also unsafe for the individual using the device. These safety concerns for individuals using mobile phones was previously addressed since anyone using a mobile phone is being exposed to the RF radiation emitted by one or more of the antennas contained within that phone, so the safety concerns for mobile phone users has been widely studied.

Safety standards for 3G and 4G mobile phones used today are defined for frequencies below 6 GHz in terms of the Specific Absorption Rate (SAR) standards, which must be met for every mobile phone used today in the US, and elsewhere in the world.  The important thing to realize is that SAR standards have also been defined for the Millimeter-Wave frequencies used for 5G systems, and there are not any known health risks associated with human exposure to mobile phone radiation at these frequencies.  Hence, 5G systems do not currently pose any adverse health risks for users.

Mobile Phone 5G Antenna Design

5G Antennas are being bundled into phones that already contain 3G, 4G, both Wi-Fi bands, Bluetooth, and GPS antennas, so a large engineering effort is required to ensure that all of these communication systems work properly when needed, and not interfere with one another if multiple antennas for different communication systems are used simultaneously.  Expert antenna and communication systems engineering expertise is required to successfully design and deliver 5G mobile phones to customers.

For more information on how to design and fit a Millimeter-Wave 5G antenna design into your products, contact us today.