High Accuracy GNSS Antennas
GPS utilization in the commercial world has evolved from a simple L1 GPS requirement to L1/L2, L1/Glonass, L1/Glonass/Beidou/Galileo, and the upcoming inclusion of the L5 GPS band into the mix. From an antenna design and performance perspective, it is always easier to achieve optimal performance when the bandwidth required is reduced. The addition of Glonass, Beidou, Galileo, and L2 and L5 bands push antenna companies to continually improve antenna performance while expanding the serviceable bandwidth.
Taoglas offers a wide range of GNSS antennas to allow for customers to pick an antenna form factor and frequency band count that is optimized for the application. External GNSS antennas intended for outdoor, stationary use can be designed to have the classic low axial ratio characteristics along with wide beamwidth hemispheric coverage to improve the probability of satellite acquisition. As more GNSS bands are required these antenna parameters need to be optimized over the wider bandwidth.
GNSS For Autonomous Driving
A good fit for autonomous driving applications in the automotive industry is the Taoglas GPDF.47.8.A.02 stacked patch GNSS antenna for L1/L2/GPS/Galileo applications where superior axial ratio in a low profile design is needed for low profile integration requirements. When absolute best performance is needed and a larger antenna can be accommodated the Taoglas QHA.01.A.0159111 Quad Helix antenna provides lowest axial ratio performance across a wide beamwidth to allow for satellite reception for the most demanding RTK applications. This antenna is ideal for some up and coming use cases such as autonomous lawnmowers and industrial robotics.
On the other hand, for mobile applications where the orientation of the device and GNSS antenna varies and the device may be used indoor, broader beamwidth radiation pattern performance works well, allowing the antenna to pick direct as well as a large number of reflected signals from multiple directions. This broad beamwidth attribute can be designed into a smaller internal GNSS antennas, making the antenna easier to integrate inside of the consumer device.
Active GNSS Antennas
When an external GNSS antenna is used where there is a long cable run between the antenna and GNSS receiver, an active GNSS antenna can be selected wherein an LNA is included to overcome cable losses and preserve the noise figure. Where cable losses are not a consideration the LNA can be removed and a passive antenna can do the job. An example of a GNSS antenna optimized for a specific use case is the Taoglas Bolt A.90 GPS antenna, which works well for an outdoor application where surge protection is needed. This antenna can be integrated into small cells or base stations where high transmit power levels are present. The A.90 has an LNA to accommodate long cable runs and a surge protection circuit for demanding outdoor applications.
A broad line of GNSS antennas of varying size and gain is required to optimize for the various GNSS satellite functions based on Physics dictating that an antenna needs to increase in volume to accommodate a larger bandwidth. To stay optimized as more frequency bands are added and the required frequency response decreases (as L2 and L5 do in comparison to L1) the dimensions of the antenna will need to increase. By providing a wide range of antenna sizes in our GNSS line-up, Taoglas offers our customers the ability to make trade-offs in size and performance, a trade-off that often needs to be made as the size of consumer devices continue to shrink.
So as you can see from this discussion a broad line of GNSS antennas, external, internal, active (amplified), and passive will provide customers with the antennas needed for optimization across an ever-expanding set of use cases. In the GNSS world, “one size definitely does not fit all”.
Author, Jeff Shamblin, VP Engineering for Taoglas