With the 5G network approaching, we’re already starting to see its effects on the various industries and professions that will interact with this innovative brand of next-generation connectivity. One of the technologies being influenced by the future unveiling of 5G are chipsets, which are becoming more highly integrated with on-board power amplifiers, antennas, and frequencies increasing to mm wave range. As a result of these accommodations to the 5G network, it’s made conducted RF power measurements physically impractical or even impossible to perform. New MIMO devices offer minimal access to test points that help make measurements and physical connections for conducted testing possible, instead of requiring over-the-air or radiated testing.
To address the lack of physical connectivity, engineers of companies like Noisecom are developing over-the-air testing techniques to quantify and analyze devices inside RF chambers, which allow devices to be remotely activated and endure a multitude of tests involving transmit and receive antennas inside the chamber. The antennas are normally connected to several signal sources to stimulate device and measuring instruments like spectrum analyzers, vector network analyzers, or power meters that capture and measure responses. For reliable and repeatable measurements inside any of these chambers, these factors and the test system as a whole need to be calibrated and quantified.
The ideal device for this method of calibration processing are noise sources, since they provide a known source with calibrated data points capable of being used to determine cable and air path loss, antenna efficiency, and the chamber’s total response. Once the system is calibrated and quantified, those same noise sources (with known characteristics) can be utilized as reference sources for the device under test to receive signals.
Noise sources for over-the-air testing applications additionally serve as a cost-efficient option for expensive microwave and mm wave signal generators. Noisecom provided a demonstration of this process at this week’s IMS 2018 show in Philadelphia, PA. Their calibrated noise sources cover a complete range of microwave and mm wave frequencies necessary for 5G device trials in over-the-air chamber tests. During the process of over-the-air testing, a calibrated noise source outside the chamber connects to a transmit antenna inside the chamber, while receive antennas (also inside the chamber) also connect to an instrument outside the chamber.
The noise source can have one or two known ENR values with calibration data for the bandwidth in question. There are some distinct benefits of utilizing two ENR levels like the ability to determine Y factor noise figures of the device under dest for radiated measurements. It’s worth noting the chamber could be equipped with a precision positioner capable of manipulating the device being tested, so the receive antenna can be exposed to the calibrated output of the noise source.