FAQ: Everything You Need to Know about 5G mmWave and Sub-6 Antennas

Sub-6 GHz spectrum is being re-farmed worldwide from sunsetting 2G and 3G networks. These frequencies are ideal for wide-area coverage, as they travel farther and through more obstacles than mmWave.

Experts from Telit, Taoglas and Qualcomm Technologies, Inc. have answered the top questions about 5G, mmWave and sub-6 GHz. Discover what you need to know about regulatory issues, use cases, isolation techniques and more.

Jeff Clemow

 VP Strategic and Channel Sales, Telit

Safi Khan 

Regional Product Marketing Director, Telit

Jeff Shamblin

Lead Engineer – Millimeter Wave Projects, Taoglas

Anand Venkataraman

Director of Product Management, Qualcomm Technologies, Inc.

1. Can you provide recommendations for 5G device antennas that support mmWave for mobility use cases?

Safi Khan, Telit: The mmWave antenna for mobility would be the low-power (LP) version from Qualcomm Technologies (QTM525 LP mmWave antenna). There are no other options.

2. What are the 5G use cases for sub-6 GHz and mmWave, and how are these frequencies planned for one location?

Jeff Clemow, Telit: Sub-6 and LP mmWave will support mobility while high-power (HP) mmWave supports static use cases. Sub-6 improves uplink over LTE, so for the next step up from 4G LTE High Category (Cat), 5G sub-6 is the right choice. For high bandwidth, mmWave will be the best option.

3. What are the regulatory issues, such as with C-Band used by satellites?

Safi Khan, Telit: Major mobile operators spent billions of dollars to acquire C-Band spectrum. The FCC has mandated that they pay spectrum clearance fees. These fees also cost a few billion dollars to pay the incumbent satellite operators to clear the spectrum.

4. 5G mmWave is a more complicated design that will translate to production and deployment. What is the easiest way to plan production?

Jeff Clemow, Telit: mmWave is different from LTE and 5G sub-6 due to the mmWave antenna being an active antenna design. For North America, the FCC requires end-device certification at the system level. This requirement complicates existing certification plans and production.

The 5G module and antenna design must be calibrated for the end device, which is a new step in manufacturing end products. You will have to add code during production for the antenna. There is no option for an easier path.

The best mitigator of the challenge is having a trusted partner, which is how we position ourselves with our customers.

5. For the 600 MHz band, will a 60 mm board be an adequate length for an antenna to work for the end user and pass compliance in most countries?

Jeff Shamblin, Taoglas: A 60 mm board is too short to meet the efficiency requirements needed to pass certification at the 600 MHz band. An 80 mm board or longer is recommended to meet the minimum antenna efficiency requirements when coupled to a small PCB’s ground layer.

6. Have you deployed any antenna or equipment in the higher mmWave (i.e., 32 GHz)?

Anand Venkataraman, Qualcomm Technologies: Our modem-RF systems are designed for global band support, including mmWave, sub-6 and legacy LTE bands. For mmWave, our modem-RF solutions support n258 (24.25-27.5 GHz) for North America, Europe and Australia, in addition to the following bands:

• n257 (26.5-29.5 GHz)
• n260 (37-40 GHz)
• n261 (27.5-28.35 GHz)

We’re at the forefront of supporting the newest 5G bands expected to commercialize, such as 41 GHz band n259 and new sub-6 bands like n53 and n70. We have a superior modem-to-antenna solution for challenging low-frequency LTE bands such as B71 (600 MHz).

7. What are barriers to rolling out mmWave? What applications will deploy mmWave (aside from mobile phones)?

Jeff Clemow, Telit: The primary barrier of mmWave will be that it requires a line-of-sight view of the tower. The beamforming requirements will make designs more complicated. Any use case that requires high bandwidth, especially on the uplink, will opt for mmWave.

Other barriers are mobile network operator (MNO) deployment timelines and support with backhaul to maximize network performance.

8. With mmWave 5G small cells, will we need external antennas for end-user devices?

Safi Khan, Telit: It would depend on the design of the end-user devices. The antennas need to be under a radome, so they can be internal antennas as long as they can “see” the signal from the small cell.

9. When can we expect mmWave CPE chipsets for SA architecture?

Jeff Clemow, Telit: The 3GPP Release (Rel) 16 chipsets will be coming out with the first iteration software by the end of the year. Modules will be another six to nine months before they’re available in mass production volumes.

10. Will the Snapdragon^® X65 support stand-alone (SA) mode for mmWave-only operation?

Anand Venkataraman, Qualcomm Technologies: The Snapdragon X65 is the world’s first 10 Gigabit 5G and the first 3GPP Rel 16 modem-RF system. It enables acceleration of 5G expansion while enhancing coverage, power efficiency and performance for users.

mmWave has been deployed by major operators in the U.S. and Japan, and more than 150 worldwide have invested in it. Its features are driving 5G mmWave rollouts and 5G SA network development.

Snapdragon X65 supports:

• Extended mmWave capabilities for global expansion
• 200 MHz carrier bandwidth in mmWave spectrum and SA mode
• mmWave spectrum aggregation up to 1 GHz
• 300 MHz sub-6 spectrum (FDD and TDD)

11. What are the isolation techniques used for cellular and GNSS antenna integration?

Jeff Shamblin, Taoglas: When integrating cellular and GNSS antennas into a product, we use the following to increase isolation between the antennas:

• Spatial diversity (i.e., maximize separation distance)
• Polarization diversity
• Pattern diversity

There are techniques in which slots or other apertures can be etched or integrated into the PCB. The antennas use a ground plane to increase isolation by altering the current flow on the PCB ground layer.

12. Do you have to simulate the whole board in full-wave simulation software to access shielding and noise immunity, or is using some general rule OK?

Jeff Shamblin, Taoglas: It will be more accurate to simulate all PCB layers to get a precise measure of shielding effectiveness and noise immunity. When we only want to characterize antenna performance (e.g., return loss and radiation patterns), we can consider the PCB ground layer(s) to measure antenna performance accurately.

One of the differences between these two scenarios is the frequency bandwidth under consideration. Noise immunity can involve much wider frequency bandwidths when compared to the frequency response of an antenna under consideration.

13. How does the placement of an antenna affect performance?

Jeff Shamblin, Taoglas: Antenna placement is vital when designing antennas in a small form factor device. The antenna uses the host ground layer (PCB of the radio board) as a ground plane from which to operate.

For most IoT devices, such as smartphones and laptops, the ground layer is only one-quarter wavelength to a wavelength at sub-6 GHz frequency bands. This scenario results in a small or resonant ground plane in which antenna impedance and efficiency are affected by location on the PCB.

Good antenna placement at the start of a project will result in higher antenna gain and broader frequency bandwidth.

14. What is the best distribution method for 5G signals in the 24-40 GHz band in indoor venues that will provide high reliability and low cost?

Anand Venkataraman, Qualcomm Technologies: 5G NR mmWave’s multi-gigabit speed and ultralow latency can elevate user experiences. This technology provides an unlimited capacity for devices, including:

• Smartphones
• Tablets
• Extended reality (XR) headsets
• Always-connected laptops

Qualcomm Technologies has been working with indoor venue owners and operators to better understand 5G NR mmWave indoor performance.

• Indoor Enterprises 
  Enterprises can fulfill their vision of a mobile office future using 5G NR mmWave private networks. These networks bring improved security and user experiences that are not achievable with today’s connectivity solutions.
• Dense Venues 
  Concert halls, convention centers and stadiums are plagued with wireless connectivity issues. As the venues have many visitors during events, multiple users will simultaneously access the wireless network.The primary challenge is for the wireless network to have enough capacity to sustain good performance. Densification of Wi-Fi and LTE networks is helpful but restricted by bandwidth availability. Venue network data demands can be satisfied with 5G NR mmWave.
• Transportation Hubs 
  Other venues that can benefit from mmWave are transportation hubs, such as airports and train stations. For an airport concourse about 160,000 square feet in size, comprehensive coverage and a median throughput of around 4.2 Gbps could be achieved using approximately 10 5G NR mmWave small cells.

Snapdragon is a product of Qualcomm Technologies, Inc. and/or its subsidiaries.