Wireless Coexistence in Medical Devices
With the rapid increase of electronic devices in medical care it is critical that devices do not needlessly radiate interfering signals. Intentional radiation should be low power and carefully controlled. An array of functions in the medical industry rely on wireless technology such as remote patient monitoring, transferring important patient data from a medical device to a separate platform, bedside drug delivery systems and pacemaker devices. Interfering with any of these links could have devastating consequences. Because of this, designers of systems with wireless links must be cognizant of the operating environment in this setting.
The need for interference management among wireless devices has been established, but how is it being addressed? The FDA has regulated a number of standards that manufacturers must consider when evaluating wireless coexistence. Additionally, all wireless devices must meet FCC part 15 requirements at a minimum. Proper circuit design to minimize spurious signals and maximize efficiency of the desired signals is important for this.
A vector network analyzer (VNA) measures the signal reflected back to the instrument port relative to the signal transmitted into the device under test. VNAs are a critical tool for evaluating RF circuit performance and the filters required to reject signals which might otherwise be radiated and interfere with other systems. VNAs might be used to characterize the antenna systems for wireless medical devices to evaluate gain and radiation pattern in order to verify Effective Radiated Power (ERP) and ensure that interference to other devices is minimized.