Low Mass Antenna Boosts RFID Device Performance

Components of the HYDRA system include an RFID reader (aka an RFID transceiver or interrogator), RF cables, antennas, and one or more Intelligent Multiplexer Modules (IMMs). The IMM is the core building block of the HYDRA system. In one of its basic embodiments, the IMM comprises an RF directional coupler, RF switch, RFID chip, micro-controller, and power generation and management hardware. In this basic implementation, a single RF port from the RFID reader is attached to the IMM and transfers power thereto. Internally within the IMM, the RF directional coupler diverts a small amount of RF power to rectification and power management circuitry for conversion to DC power that drives the RFID chip, microcontroller, and RF switch. The RFID chip enables communication with the RFID reader and allows the reader to administer changes to the microcontroller‘s embedded software. The microcontroller controls the RF switch, which passes power along to one or more output channels. Connections to the output channels can include antennas, additional IMMs, or other sensors. The HYDRA system may include numerous alternate embodiments to enhance and customize the basic functionality. In one embodiment, the microcontroller is replaced with a simple timer. In another embodiment, the switch has multiple output ports to connect to a distributed chain of HYDRA system or local antennas. Also, the entirety of RF power exiting a HYDRA module can be rectified and used to power a local sensor node, which could be implemented via WiFi or Bluetooth Low Energy (BLE). Features of the HYDRA system include the ability to cover both open regions and enclosures, the ability to switch RF power to an unused load for assisting in the resolution of tag antenna ambiguities, and the ability to accept plug-and-play add-ons such that the reader’s software can use the system without requiring any embedded modifications. The HYDRA system is technology readiness level (TRL) 7 (system prototype demonstrated in an operational environment) and is now available for patent licensing. Please note that NASA does not manufacture products itself for commercial sale.

Current RFID readers, such as the EPC Global Class 1 Gen 2, are limited by narrow bandwidth restrictions, maximum transmit power, and a limited number of RF ports, which results in relatively coarse ranging resolution and accuracy, limited techniques for localization, and limited antenna functionality. Some of the currently available solutions, such as using larger antennas or adding switched multiplexers, often result in unacceptable cost, volume, aesthetics and mass penalties. The Agile RFID Antenna System integrates a frequency multiplexer into the RFID reader antenna system to provide greater antenna functionality without requiring additional reader RF ports, resulting in improvements in reader-tag communications read accuracy, read range, and localization. The Agile RFID Antenna System is at a TRL 8 (Technology has been proven to work in its final form and under expected conditions) and has been used on the International Space Station to support logistics management and it is now available for your company to license and develop into a commercial product. Please note that NASA does not manufacture products itself for commercial sale.

NASA's patch antenna technology exhibits higher operational bandwidth (on the order of 20%) than typical patch antennas (less than 10%) and can operate across integer-multiple frequency bands (e.g. S/X, C/X, S/C). Testing of the antenna design has demonstrated &#62 6dB of gain on both S and X bands (boresight), with an axial ratio of &#60 6dB and voltage standing wave ratio (VSWR) &#60 3:1 throughout the entire near-Earth network (NEN) operating bands (22.4GHz and 88.4GHz) with hemispherical coverage. The patch size is on the order of 10 x 10 cm and with associated electronics, is about 1 cm in height.

The RFID Tag with Long Range and Wide Coverage Capabilities technology allows a RFID tag to direct a RFID reader beam signal back in the direction of arrival. This technology requires no added power to provide telemetry for long range readers by using multiple beams instead of one narrow beam signal. Each of the predetermined number of beams is typically associated with a unique identification number to derive bearing information. This innovation is suited for IC-based RFID tags as well as Surface Acoustics Wave (SAW) tags, which are useful for extreme environments. The technology improves the ability to obtain telemetry (quantity, location, or sensor information) without GPS over a distant range. When the tag reports its identification, it also provides angular information to the source, which makes this technology useful for navigation and mapping applications. Because the technology provides an estimated angle between the signal antenna and the surface of each tag, the technology is able to triangulate the position of a mobile item identified with a RFID tag. The same innovation can be integrated to a RFID reader in order to enhance its range and distribute power to passive tags. The innovation has commercial applications in construction, oil and gas, seaport/harbor management, Internet of Things (IoT) and many more industries.

This novel technology builds upon a previously (NASA-developed) store-and-forward overlay architecture using COTS RFID protocols for BAP devices. It enables the range-extension and priority forwarding of critical sensor-collected data, even when an RFID interrogator is not in range. With this method, an RFID sensor maintains data queues of varying priority, maintaining at least one high priority queue. When high priority data is collected, the RFID sensor activates a BAP mode that enhances the effective range of the RFID link to the interrogator. After high priority queues are cleared, BAP mode is deactivated to preserve onboard battery life and passive RFID operations resume for proximity-based data delivery. This technology may deliver the most value in applications where long battery lifetime and remote sensing/data collection are essential and when regularly scheduled data transfer may not be available or possible if the target is out of the normal coverage area. The RFID sensor tags described here can operate in a low to no power mode and collect data until a trigger or threshold value is measured. At this time, the critical data can be transmitted from outside passive RFID coverage areas to the nearest interrogator. Although this technology was developed to enhance the effective range of CO2 sensors worn by astronauts aboard the International Space Station, it could find additional applications in food, pharmaceutical, and other industries whose perishable and/or fragile goods rely on a stable climate throughout the transport and storage lifecycle.