Integration is more than just connecting a GNSS antenna to a device so it can receive signals. Done right, the integration process optimizes the antenna’s capabilities and, in turn, helps ensure that the device provides the performance and reliability that end users expect.
There are five types of GNSS antennas: chip, flexible PCB, patch, dipole, and helical Antennas. Each has its own set of unique integration considerations.
But other choices apply across the board, starting with whether to use an active or passive antenna for patch, dipole, or helical.
Pro tip: Regardless of antenna type, make these kinds of GNSS decisions early in the device design process. If they’re done after the form factor, PCB layout, and other attributes have been finalized, then the options can be limited and expensive. For example, now, an active (or even custom) antenna might be the only way to achieve the performance targets. In contrast, a lower-cost, off-the-shelf passive antenna would have met those requirements if the initial design had accommodated its needs, such as PCB size and placement.
Passive antennas have no integrated electronics and thus require no power. This simplicity reduces their cost and streamlines integration in embedded systems.
Active antennas use a Low-Noise Amplifier (LNA) to boost signal gain and filtering to remove out-of-band signal interference and noise, such as spurious emissions from the device’s power supply. The additional cost of these front-end electronics is often justifiable for mission-critical applications, use cases that require centimeter-level accuracy, or devices that will spend much of their time with obstructed sky views due to foliage or urban concrete canyons.
The device’s PCB also serves as the ground plane for a patch antenna. The PCB should be at least 70 x 70 mm in order to optimize the antenna’s performance. The PCB also should be designed in a way that frees up the ideal location for the antenna.
This is another example of why the GNSS antenna needs to be considered early in the device design stage. If it’s an afterthought, then it will have to make do with whatever spot hasn’t been earmarked for other components. That often results in suboptimal GNSS performance, leading to expensive, time-consuming changes such as a PCB redesign, antenna fine-tuning, or both.
The ground plane is also an essential factor for dipole and helical antennas. For example, in vehicular applications, the metal roof acts as the ground plane and helps improve performance. However, metallic window tinting could attenuate the GNSS signals if the antenna is mounted inside at the top of the windshield. Since the window tinting attenuates the signals, active antennas provide more gain to compensate for the attenuation.
The cable length is another critical consideration. One rule of thumb is that the greater the distance between the antenna and the device, the more likely it is that an active GNSS antenna will be necessary to overcome cable attenuation.
Vehicular applications highlight another benefit of active antennas. Whether it’s a passenger, commercial, or first responder vehicle, it almost certainly will have a 4G/5G cellular antenna. The proximity to the GNSS antenna can lead to interference that undermines GNSS performance. Active GNSS antennas have bandpass filters to mitigate interference from cellular and any other transmitting antennas, such as Specialized Mobile Radio (SMR), that operate close to the GNSS bands.
Finally, another tip that applies to every type of antenna is to take full advantage of its integration guide. This provides valuable guidance on PCB positioning, copper clearance, ground plane size, and impedance matching.
Taoglas offers Engineers a suite of user-friendly digital tools designed to streamline, simplify, and customize antenna design and integration. These tools help engineers quickly develop their prototypes. The toolset includes the Taoglas Antenna Integrator, Antenna Builder, and Cable Builder.
The latest addition to the suite, the Taoglas Antenna Integrator, allows users to preview their embedded antennas, including the performance of multiple-input multiple-output (MIMO) antenna systems, during the concept phase of a project. This feature accelerates time to market and helps prevent potential issues with component placement inside the product. Discover more by clicking the button below.
When to Call in the Experts
Once the antenna is integrated, the final step often is tuning. This process requires specialist expertise and tools such a GNSS constellation simulator and anechoic chamber, which is why even highly experienced systems designers call in the experts. One example is the Taoglas CSA.20 Passive Antenna Testing, Matching, and Fine-Tuning service, which achieves the optimal resonant frequencies by implementing a lumped element electrical matching network or through small physical modifications to the antenna itself.
Another example is the Taoglas GSA.40 testing service, an approximately three-week process covering aspects such as system level testing, and testing the device in a static, open-sky scenario. Taoglas’ Engineering team collaborates with the client’s design team to determine if the test results meet the product’s performance requirements.
If not, Taoglas sales and engineering can make recommendations to improve the antenna performance. Clients also can use the Taoglas GSA.30 GPS Acquisition & Tracking Sensitivity Testing service, which include a GPS constellation simulator and anechoic chamber to measure Acquisition & Tracking sensitivity of the GNSS system (receiver and Antenna) and ensure there is no in-band interference affecting the GNSS system performance. This two-week testing process includes steps such as measuring the antenna passively on a VNA to determine the return loss, which will confirm whether the antenna has been correctly integrated into the product.
For more integration tips and services, speak to Taoglas’ Engineering team by clicking on the button below.
