Radio Relays Improve Wireless Products
- Sunday, 01 November 2009
Originating Technology/NASA Contribution
In order to transmit communications through Earth’s atmosphere, satellites and space vehicles need radio equipment that can operate at higher frequencies than on Earth. These higher frequencies, until recently, have demanded mechanical switches in radio relays. Unfortunately, the mechanical switches had some problems with frequency routing, which inspired NASA to seek more rugged, reliable solutions.
NASA began to design new, lightweight, microelectromechanical systems, or MEMS. MEMS are extremely small devices (a fraction of a millimeter long) with moving parts, already used in sensors for airbag accelerometers and video game controllers, as well as radio electronics for cell phones, digital mirror displays, and hand-held radios. Switching to MEMS relays for actuators (and not just sensors) from older mechanical switches offered the Agency improved performance in higher frequencies. A California company helped NASA create new MEMS relays that offer some new benefits as well.
After developing a radio frequency (RF) MEMS relay under U.S. Department of Defense contracts, Signal Hill, California-based XCOM Wireless Inc. continued its research with a Phase II Small Business Innovation Research (SBIR) contract in 2003 through NASA’s Jet Propulsion Laboratory (JPL). In order to improve satellite communication systems, XCOM produced wireless RF MEMS relays and tunable capacitors that use metal-to-metal contact—moving microscopic metal beams into contact with special electrodes—operating much like a light switch small enough to fit on the cross section of a human hair. They have the high speed of solid-state switches, but with mechanical contacts that outperform semiconductor technology. Also, by introducing a MEMS relay with electrostatic—and not electromechanical—actuation, XCOM was able to produce a MEMS relay that consumed less power and was easier to manufacture than earlier relays.
These MEMS relays are used for signal tuning, routing, and phase-shifting circuitry, thus enabling wireless systems to adapt to changing operating conditions, radar or communications waveforms, and other mission needs. For its work with NASA, XCOM Wireless concentrated on frequencies in the range of 70 GHz–100 GHz, while most commercial radio frequencies use the range from 0.1 GHz–6 GHz. Despite the difference in bandwidth, XCOM’s president, Dr. Daniel Hyman, says that the NASA technology is a “fundamental switching device” now incorporated into all of XCOM’s products.
After designing these improved devices, XCOM entered into a partnership with MEMS manufacturer, Innovative Micro Technology Inc. (IMT), based in Santa Barbara, California. With its NASA-derived design improvements and IMT’s manufacturing abilities, XCOM automated its relay manufacturing and testing, and reduced costs to one-tenth the previous amount. This, Hyman says, gave the new relays potential to be “a mainstream product with thousands of solid industrial customers in a stable and growing market.”