Characterize axial ratio of a GPS antenna in seconds

GPS antenna design challenges

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GPS is almost a common feature in many portable consumer electronics. GPS antennas are embedded into devices that already have other antennas like Bluetooth, WiFi, GSM, CDMA or even FM. Printed antennas are widely preferred option for small form factor devices like smart phones, tablets, etc. where limited real estate is one of the concerns. Circularly polarized single feed microstrip patch antennas are widely employed in stand-alone GPS receivers like radar and GPS.

Mechanical design, interference with other antennas and loading effect are some of the factors that will have an impact on antenna gain and antenna pattern of the GPS antenna. Other antennas or components of the portable consumer electronics like PCB components, plastic, metal, battery, etc. may also cause some level of interference and isolation. 

Another challenge in embedding a GPS antenna to a device is the orientation of the GPS antenna to achieve the maximum field strength. The orientation depends on the device e.g. if the device is going to be mounted on a car dash, GPS antenna’s orientation can be portrait however on a smart phone GPS antenna’s orientation may be trickier because smart phone can be held vertically or horizontally in the hand.

With time-to-market pressure and limited budget it is hard to design and test your GPS antenna throughout the whole development phase.

RFxpert is the only compact bench-top scanner that characterizes GPS antennas in your own lab environment in real-time.

Thanks to the principle of reciprocity in antenna theory, testing a GPS antenna in transmit mode will provide the necessary results to evaluate its performance in receive mode. With CP Analysis option, RFxpert calculates Right-Hand Circular Polarization (RHCP), Left-Hand Circular Polarization (LHCP) and graphs Axial Ratio (AR) patterns of a transmitting GPS antenna in sub-second.

The loading effect of other antennas used on a device or even placing the device on different surfaces will have an impact on the GPS antenna performance. With RFxpert, you can monitor layout changes and optimize the position of the GPS antenna in real-time.

Users’ hand or head will detune the GPS antenna. You can use RFX2 with OTA Phantom Fixture to minimize the loading effects of hand and head confirm that the GPS antenna meets the axial ratio requirements.

You can evaluate patch antennas with high permittivity sintered material substrates or low-cost microstrip substrates or different bill of materials for ground plane of GPS antenna like aluminum, brass, stainless steel, ceramic etc. to produce a circular polarization with low axial ratio on your lab-bench in seconds.

You can perform tests on prototypes early on GPS antenna design stages to evaluate the wideband performance reliability of the GPS antenna and to confirm that the GPS antenna is suitable for multi-band GNSS applications.

You can check the amplitude pattern uniformity of the GPS antenna at different angles. RFxpert presents test results in four hemispherical views (Combined, RHCP, LHCP, and Axial Ratio), four Bisection views (Combined, RHCP, LHCP, and Axial Ratio), and two Bisection Cut views combining the Combined, RHCP and LHCP patterns.

With RFxpert you can evaluate GPS antennas as you prototype in your own lab environment in real-time. RFxpert is the only compact bench-top scanner that gives you the ability to accelerate your development cycle and reduce your time to market. To learn more about how to design and characterize GPS antennas better click the "Demo Video" button at the bottom of the page.