This Small Business Technology Transfer (STTR) Phase I project will develop micromachined antenna tuning module products for cell phone and portable computing applications. The proposed technology can reduce the mismatch between the device's RF frontend and its operating environment (user's head, user's hand, metallic objects, etc.). Compared to competing approaches, the proposed technology can provide antenna tunability and reduced size, while reducing system costs and power consumption. The research will focus on the integration of the varactor technology with a low-loss RF design. Follow-on work could develop the entire prototype module. A proof-of-concept experiment demonstrated that a micromachined varactor was able maintain optimal matching while antenna output impedance was varied over a range. Anticipated technical results include demonstrating a product with a tuning range that will sufficiently cover probably antenna impedance mismatch conditions.
The broad impact/commercial impact of this project includes addressing several key problems currently in the wireless sector: power consumption, bandwidth and signal reception. The ability to tune the antenna can deliver substantial benefits. For the radio transmitter, minimized mismatch reduces wasted reflected power. Battery power savings is critical, and additional features are requiring more and more power. For the radio receiver, minimized mismatch improves signal reception. For cell phones, this would directly result in improved call quality and reduced dropped calls. For data, improved reception will increase bandwidth without increasing transmitter power. With more than 1 billion cell phones manufactured a year, the commercial impact for the proposed micromachined antenna tuning module is enormous.
In the NSF STTR Phase I project, the Laserlith team sought to develop micromachined antenna tuning module (ATM) products for cell phone and portable computing applications. By tuning the antenna, performance can be improved while reducing power consumption (30% to 40%). Compared to competing approaches, MEMS technology can provide tunability and reduced size, while decreasing system costs and power consumption. The Laserlith team successfully met Phase I project objectives. The project began on two fronts: development of the antenna tuning module (ATM) and development of the corresponding MEMS varactor. The MEMS varactor is based on varactor elements originally demonstrated for higher frequency aerospace applications. The focus of the Phase I work was to increase the capacitance of the varactor to meet the requirements of the lower frequency wireless applications. The ATM development required programming a tuning algorithm for the microprocessor based system and creating test printed circuit boards (PCBs) to test and refine the code. A MEMS varactor tuning element was developed for the antenna tuning module with a capacitance range beyond the original goal of 5 pF. This could potentially cover most anticipated handset tuning applications. Based on interest from several power amplifier suppliers and handset manufacturers, the team also evaluated the use of its tuning technology for broadband power amplifier applications. Testing has demonstrated high power added efficiency for next generation waveforms over very wide frequency ranges while meeting linearity requirements.
