N101-075 TITLE: Electric Field Tunable Multi-Ferroic Phase Shifters for Phased-Array Applications

TECHNOLOGY AREAS: Materials/Processes, Sensors, Electronics

ACQUISITION PROGRAM: IMS (Integrated Warfare Systems - Radar component) TBD

OBJECTIVE: Develop and demonstrate high power electric field tunable multi-ferroic material based phase shifters for X-band phased array applications.

DESCRIPTION: Modern active electronically scanned phased array radars provide outstanding capability but are unfortunately expensive. To a large degree, this results from the need for power and low noise amplifiers at each antenna element. A promising alternative architecture shares the amplifiers among many elements and thus requires a phase shifter at each element. This choice imposes challenging power handling and insertion loss requirements on the phase shifter. Historically, ferrites are the materials of choice for tunable reciprocal and non-reciprocal microwave devices where tuning is realized by varying a bias magnetic field, H, because they exhibit very low losses. But magnetic field tuning is slow, and requires large current. In addition, such devices cannot be easily miniaturized or integrated with semiconductor processing technologies which will result in lower cost.

Multi-ferroic materials provide a tantalizing alternative combining the tunability of ferrite materials with voltage control and miniature size. The possibility of electric field tuning in devices based on multi-ferroic materials arises from coupling of a ferroic material to piezo-electric material. Recent demonstration of voltage tuning of a composite multi-ferroic ferrite-piezoelectric resonators is significant in this regard. When bilayers of yttrium iron garnet (YIG)-lead zirconate titanate (PZT) and YIG/lead magnesium niobate�lead titanate (PMN-PT) bilayers are subjected to an electric field, mechanical deformation in the piezoelectric produces a frequency shift in the magnetic response of the ferrite. Such electrical tuning is rapid, requires minimal power, and has the potential to be integrated in a hybrid manner with other circuits.

It can be expected that device improvements that build on existing experiments will lead to a laboratory demonstration of a multi-ferroic phase shifter exhibiting reasonable power handling and low insertion loss, in a compact, easily hybridized form. The goal of this program is to utilize multi-ferroic devices in S-Band (2-4 GHz) C-band (4-8 GHz) or X-Band (8-12 GHZ) phase shifter networks. Successful proposals will support a digital phase shifter element demonstration capable of handling output power levels of > 1W peak, > 0.2W average, switching delay of < 1 microsecond, phase resolution > 4-bits, and < 2 dB insertion loss across a complete band.

PHASE I: Demonstrate, using test results of the performance of suitable multi-ferroic devices, that the phase shifter along with its required dc magnetic field bias having the specifications listed in the description above may be successfully fabricated in a multi-ferroic based planar technology.

PHASE II: Fabricate, test, and deliver two multi-ferroic phase shifters in a conventional connectorized microwave fixture, with integrated planar dc magnetic bias, meeting the specifications of Phase I, along with a compatible control interface suitable for laboratory demonstration.

PHASE III: Target industrial partners for technology transition with potential integration into one or more Navy systems.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The proposed technology is expected to result in a high level of interest in these circuits for current and future generation phased-array radar systems.

REFERENCES:
1. J. Teti, and F. Darreff, "MEMS 2-bit Phase-Shifter Failure Mode and Reliability Considerations for Large X-Band Arrays," IEEE Trans. Microwave Theory and Tech., Vol. 52, No. 2, pp. 693-701, 2004.

2. W. J. Kim, W. Chang, S. B. Qadri, H. D. Wu, J. M. Pond, S. W. Kirchoefer, H. S. Newman, D. B. Chrisey, J. S. Horwitz, "Electrically and magnetically tunable device using (Ba, Sr) TiO3/Y3Fe5O12 multilayer," Appl. Phys. A 71, pp.7-10 (2000).

3. G. Srinivasan and Y. K. Fetisov, "Ferrite-piezoelectric layered structures: Microwave magnetoelectric effects and electric field tunable devices," Ferroelectrics 342, 65 (2006).

4. Ce-Wen Nan, M. I. Bichurin, S. Dong, D. Viehland, and G. Srinivasan, "Multiferroic magnetoelectric composites: Historical perspective, status and future directions," J. Appl. Phys. 103, 031101 (2008).

KEYWORDS: Multi-ferroic, ferrite, piezoelectric, phase shifters, phased-array radar

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