N131-080 TITLE: Frequency Agile Millimeter Wave (MMW) Signal Generator

TECHNOLOGY AREAS: Sensors, Electronics

OBJECTIVE: Develop innovative technology and techniques to enable a frequency-agile MMW signal generator tunable for high performance military and commercial applications from 30 GHz to 120 GHz and with a path to extend the range to 300 GHz.

DESCRIPTION: The short wavelengths associated with MMW frequencies enable high baseband throughput and very high antenna gain with relatively small antennas. This enables high speed, high directivity portable links and sensors for applications ranging from covert short to mid-range communications to high resolution imaging, scanning and targeting. Future portable/mobile military MMW equipment may have to become multifunctional and be able to utilize frequency bands in an agile, flexible manner. This can be important in many military systems where frequency agility provides significant system performance advantages due possibly to growing network congestion, or more likely to enable agile switching between applications optimized in diverse frequency bands.

For example, the large range of atmospheric attenuation over the millimeter wave bands allows a user to flip between higher attenuation short range covert applications, or lower attenuation longer range applications like rapid deployment of high speed access links. Also, more widespread application of cognitive radio techniques has frequency agility as a prerequisite. Beyond communications, rapidly tunable low phase noise MMW oscillators and signal generators have active/passive sensor front-end utility in dynamic, re-configurable wideband signal generation and reception. This forward-looking electronics hardware effort develops techniques for small footprint portable MMW transceivers that will enable broad and continuous tunability over the frequency range of 30 - 120 GHz with a path to extend the range to 300 GHz. In addition to wide frequency tunability, successful electronic and/or photonic approaches shall support low phase noise and fast tuning capabilities and produce moderate output power at reasonable efficiency.

For the purpose of this SBIR topic, frequency-agile MMW communications should be highlighted and used to focus on the signal generator design, development, and demonstration. Terrestrial transmission distances targeted for the low attenuation bands should be 1 - 5 km with a path to achieving 10 km and beyond. Accordingly, the net MMW transmit power should be >+10 dBm with a path to >+30 dBm, where antenna gains of approximately 50 dBi are assumed to be available, and data rates up to 10 Gbps are targeted. A prototype of this tunable MMW signal generator will be built and demonstrated.

State of the Art: Existing commercial MMW implementations use small form factor, mid-power MMW generators based on solid-state IMPATT and/or GUNN diodes in high precision resonant cavities, and more recently high quality radio frequency (RF) Monolithic Microwave Integrated Circuits (MMIC) based on Si, SiGe, GaAs, InP and GaN. While high carrier frequency operation and reasonable output power of these devices are possible, they typically operate in a narrow band mode and have not demonstrated the wide tunability required for this SBIR topic. These limitations are not primarily due to the devices themselves, but due to the complex high gain/high power electrical amplifier circuitry and frequency generation circuitry that is required for these purposes which imposes severe limits on broadband operation. For this reason, current MMW signal generation devices are typically centered in well used bands like 60 GHz, 72 GHz and 94 GHz. The next planned bands include 120 GHz and 220 GHz. If broadband tuning is required, the only solutions available today involve combing multiple sources optimized for specific frequencies.

PHASE I: Define and develop a design for a widely tunable 30-120 GHz signal generator that can be used as a source for high quality tunable MMW signals. This phase will specify the signal generator requirements and specifications based on available high gain antenna structures and highlighted MMW wireless communications application.

PHASE II: Implement the detailed design of the key components of the tunable MMW signal generator specified in Phase I. A concept demonstration using a low phase noise, single frequency prototype of this signal generator will be built to demonstrate 30-120 GHz tunability at targeted power levels. A path to 300 GHz frequency operation shall be developed.

PHASE III: A low size, weight, and power (SWAP) frequency agile signal generator prototype will be developed, tested, and evaluated with a baseline 10 Gbps modulation signal applied for demonstration purposes. A total output of power in excess of +20 dBm in the sidebands over the entire range of 30-120 GHz will be demonstrated. Single frequency source tunability to 300 GHz will be demonstrated.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The commercial sector is very interested in high-capacity short to mid-range wireless communications for voice, video, and data services. For increased capacity and less network congestion, these wireless applications continue to migrate to higher operating frequencies as affordable electronics technology becomes available. This technology will add to the toolkit of electronics transceiver hardware suitable to cover the full MMW spectral region of interest to commercial wireless system designers.

REFERENCES:
1. Bains, A.S. 1993. "An Overview of Millimeter Wave Communications for Military Applications." Defense Science Journal: Vol 43, No l, pp. 27-36. http://publications.drdo.gov.in/gsdl/collect/defences/index/assoc/HASH01bf/cf0da7db.dir/doc.pdf.

2. Nagatsuma, T., Hirata A., Harada, M., Ishii, H., Machida, K., Minota, T., Ito, H., Kosugi, T., Shibata, T. 2004. "Millimeter-Wave Photonic Integrated Circuit Technologies for High-Speed Wireless Communications Applications." ISSCC:

3. Chong, Chia-Chin, Hamaguchi, Kyoshi, Smulders, Peter F.M., Yong, Su-Khiong. 2007. "Millimeter-Wave Wireless Communication Systems: Theory and Applications." EURASIP Journal on Wireless Communications and Networking: no. 72831. http://downloads.hindawi.com/journals/specialissues/598767.pdf

KEYWORDS: Millimeter Wave; Communication Links; Wireless Communications; Tunable Sources; Oscillators; Signal Generation

** TOPIC AUTHOR (TPOC) **

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