Contains research objectives and reports on five research projects.Joint Services Electronics Program (Contract DAAG29-83-K-0003)National Institutes of Health (Grant 1 P01 CA3 1303-01

Bhattacharjee, Tushar

Borgeaud, Maurice

Hegi, Larry

Kyhl, Robert L.

Morgenthaler, Frederic R.

Rappaport, Carey M.

Vlannes, Nickolas P.

Zeskind, Dale A.

DSpace@MIT

Microwave and Quantum Magnetics27. Microwave and Quantum MagneticsAcademic and Research StaffProf. F.R. Morgenthaler, Prof. R.L. Kyhl30, Dr. T. Bhattacharjee, D.A. ZeskindGraduate StudentsM. Borgeaud, L. Hegi, C.M. Rappaport, N.P. ViannesObjectiveOur objective is to develop an understanding of electromagnetic, magnetostatic, andmagnetoelastic wave phenomena and to employ them to create novel device concepts useful formicrowave signal-processing applications.27.1 New Techniques to Guide and Control MagnetostaticWavesJoint Services Electronics Program (Contract DAAG29-83-K-0003)Frederic R. Morgenthaler, Dale A. Zeskind, Larry HegiProfessor Morgenthaler presented a paper on "Magnetoelastic Versus Magnetostatic Waves forMicrowave Signal Processing" at the Fourth International Conference on Ferrites (ICF-4) hldOctober 31 - November 2, 1984 in San Francisco; the abstract follows:Comparisons are made between microwave signal processors that employ magnetoelastic bulkwaves propagating in nonuniform bias fields and those using magnetostatic waves in thin filmwaveguides with either uniform or nonuniform bias. Special attention is paid to frequencydispersion and available bandwidths as well as dynamic range and physical size.The magnetoelastic delay-lines considered are a new type of YIG single-crystal bulk-wavedevice that employs transducers buried in small laser-drilled channels. The synthesizedfrequency dispersion is controlled by special nonlinear magnetic-field profiles. Increased timedelays over "single-ended" operation have been shown to be possible and no wave reflectionsfrom optically-polished crystal surfaces are required.For magnetostatic waves, gradients in either the field magnitude, direction or both can beemployed to affect wave dispersion. Computer simulation has revealed that a great deal ofcontrol over the mode energy distributions can be exercised by the proper choice of gradients.For example, a forward-volume wave can be forced to have field-displacement characteristicsOEmeritusRLE P.R. No. 127197Microwave and Quantum Magneticsthat are very strongly nonreciprocal. Such modes may be useful for thin film isolators and/orcirculators.27.2 Optical and Inductive Probing of MagnetostaticResonancesJoint Services Electronics Program (Contract DAAG29-83-K-0003)Frederic R. Morgenthaler, Nickolas P. Vlannes, Robert L. KyhlOptical and induction probing have been used to examine the characteristics of magnetostaticwaves in thin films of yttrium iron garnet. The experiments were based on the development of twonew probes. These probes have increased spatial resolution and greater versatility than previousdesigns.The optical probe used infrared laser light with a wavelength of 1.15 tfm, and the magneto-opticeffects of YIG to examine magnetostatic forward volume waves (MSFVW). The principle YIGsample used was 47.4 1im thick, double-sided, one-inch disk of LPE-YIG on (111) GGG.Launching and receiving antennas were deposited on the surface of the YIG for propagating anddetecting MSFVW. Initial experiments were done with light illuminating almost the completemicrowave MSFVW-beam path. The unfocused light experiments were done to establish theexistence of MSFVW modulation of optical signals, and then to examine the characteristics ofMSFVW when input power, microwave frequency, and applied d.c. magnetic field were changed.The light was then focused for localized probing of MSFVW to explore the evolution of thetransverse profile of an MSFVW, and to investigate the effects of changes in microwave frequencyand input microwave power. Output power from the MSFVW delay-line was monitored, andnonlinear phenomena were observed.A magnetic induction probe for studying MSW has been developed that has several novelfeatures and has been used to measure amplitudes and dispersion relations of magnetostaticsurface waves (MSSW) and magnetostatic backward volume waves (MSBVW). The probe isbased on two types of metal loops and have been demonstrated to be accurate tools in modelingmagnetostatic waves in LPE-YIG. Improvements in the probes are possible, and the presentpreliminary results are illustrative rather than exhaustive. Further experimental research of MSWwith these new tools is desirable and much remains to be done.The doctoral thesis of Nickolas P. Vlannes titled "Optical and Induction Probing ofMagnetostatic Waves in Thin Films of Yttrium Iron Garnet" was completed in May 1984; theabstract follows:Two new probes for examining microwave (1-4 GFIz) magnetostatic waves propagating inRLE P.R. No. 127 198Microwave and Quantum Magneticsyttrium iron garnet (YIG) thin films have been developed. One probe uses the magneto-opticeffects of YIG to examine the RF-magnetization of magnetostatic forward volume waves(MSFVW). By employing magnetic induction, the second probe senses the microwave magneticfield, which fringes from the surface of YIG thin films, to characterize magnetostatic surfacewaves (MSSW) and backward volume waves (MSBVW).The optical probe system uses focused and unfocused light from a 45 mW, 1.15 / m He-Ne laserto examine linear and nonlinear MSFVW properties. Focused light experiments for localizedprobing had an effective spatial resolution of 100 pim. The nonlinear MSFVW effects arecharacterized by a MSFVW power saturation, and then a decline as input power to the MSFVWwas increased. Unfocused light experiments indicated that as input power to MSFVW increased,modulation of light increased. However, localized probing of nonlinear effects showed that oversmall regions, a monotonic increase in light modulation with increasing input power does notalways occur. Localized probing of linear MSFVW examined the evolution of a MSFVW profile asit propagated from its launching antenna.The induction probe is designed for studies of amplitude profiles, dispersion relations, andphase propagation direction. Sensing elements were either 25.4 [m gold wire wrapped around aplastic support, or aluminum rectangular loops photolithographically fabricated on glass. Thegold wire method yielded a highest resolution of 120 [m. The aluminum loops achieved asmallest size of 45 [m. Investigations of MSSW in a uniform bias field found that the wave"focused", in that as the MSSW propagated, the peak value of the amplitude increased while thewidth of the wave decreased until a maximum profile amplitude occurred, after which the MSSWincreased in profile width and the amplitude decreased. Direct measure of the wavelengths ofMSSW and MSBVW gave the dispersion relations, and confirmed the backward nature ofMSBVW.Figures 27-1a, 27-1b, and 27-2 give details of the photolithographically derived induction probeand its relation to the liquid phase epitaxy (LPE) magnetic film of Yttrium Iron Garnet (YIG).Figures 27-3 and 27-4 give optical circuit schematics for both the unfocused and focused lightexperiments.27.3 Magnetoelastic Waves and DevicesJoint Services Electronics Program (Contract DAAG29-83-K-0003)Frederic R. Morgenthaler, Maurice BorgeaudThe evolution of the microwave magnetoelastic delay line, originally proposed by Schl6mannand Eschbach,' and Strauss 2 some twenty years ago, has in recent years been aided by the fieldsynthesis procedure of Morgenthaler 3 that was applied by Platzker and Morgenthaler4 and laterRLE P.R. No. 127199CB -HolderI Cable-Gold Bonding-- WiresrobeRG-402conductor.750"Figure 27-1: a) Photolithographic Probe Tip in Holder:ViewPerspectiveb) Photolithographic Probe Tip in Holder: Cross-SectionView (B-B' axis perpendicular to page)4.5 pm.51 nmiANTENNAFigure 27-2: Probe Tip on LPE-YIGRLE P.R. No. 127Microwave and Quantum Magnetics200Microwave and Quantum MagneticsFigure 27-3: Optical Circuit Schematic - Unfocused Light Experiment1.15 pmMa inLaser.6328 ImLaserMirror250mm 250mn 38.ImFL FL FL^ ^LCircularApertureChopper Beam SteererFigure 27-4: Optical Circuit Schematic - Focused Light Experimentsby Itano 5 and Wadsworth. 6 In all of this prior work the fine wire elements that constituted thetransducer were external to the YIG single crystal generally pressed against a highly polished flatsurface that also acted as a reflector for elastic waves. This constraint has now been removed byforming tiny laser-drilled channels within the crystal.The S.M. thesis of Maurice Borgeaud titled "An Improved Two-Port Magnetoelastic Delay Line"and completed in January 1984, was based on this concept and has demonstrated its feasibility.RLE P.R. No. 127201Microwave and Quantum MagneticsThe abstract follows:A new form of linearly dispersive microwave delay line is described, in which the transducersare mounted directly inside a magnetically saturated rod of Yttrium Iron Garnet (YIG), thanks toholes laser drill through the rod. The delay line operates by utilizing the magnetoelasticinteraction between spin waves and elastic waves where the focusing and defocusing conditionsare governed by a nonlinear axial magnetic field profile.Principle features include physical separation between the input and output signals, longerdelay than in the traditional "one edge" delay line because the waves spend a longer time in theelastic domain, no acoustic reflection at the ends of the rod and good coupling between theantennas and the material.Measurements made on the designed delay line are reported. Results agree with theoreticalpredictions. In the preliminary experimental configuration, it has been possible to delay a 10nanosecond pulse of 1200 nanoseconds over the range 3.2-3.4 GHz with an insertion loss of31 dB.References1. E. Schlomann, in Advances in Quantum Electronics, (Columbia University Press, New York1961) p. 437.2. W. Strauss, "Elastic and Magnetoelastic Waves in Yttrium Iron Garnet," Proc. IEEE 53, 10,1485-1495, October 1965.3. F.R. Morgenthaler, "The Synthesis of Cylindrically Symmetric Static Magnetic Fields in aLocally Saturated Ferromagnet," AlP Conference Proceedings, Magnetism and MagneticMaterials-1i 974, No. 24, 20th Annual Conference, San Francisco, California.4. F.R. Morgenthaler and A. Platzker, "Magnetic Field Synthesis Procedures for Magnetostaticand Magnetoelastic Devices," Proceedings of the 1978 International Symposium onCircuits and Systems, New York, May 1978, pp. 574-578.5. L.M. Itano, "Microwave Delay Line with Thin Film Antennas," S.M. Thesis, Department ofElectrical Engineering and Computer Science, M.I.T., August 1981; Microwave andQuantum Magnetics Group Technical Report No. 43.6. A.K. Wadsworth, "Improvements in the Design of Microwave Magnetoelastic Delay Lines," S.M.Thesis, Department of Electrical Engineering and computer Science, M.I.T., January1982; Microwave and Quantum Magnetics Group Technical Report No. 46.27.4 Microwave HyperthermiaFrederic R. Morgenthaler, Tushar Bhattacharjee, Carey M. RappaportOur understanding of both physics and physiology is challenged in trying to optimizetechniques for heat production and for the thermometry associated with Hyperthermia modalitiesused in connection with cancer therapy.RLE P.R. No. 127 202Microwave and Quantum MagneticsFundamental considerations are based on designing proper microwave applicators which mustbe able to handle the microwave power required to raise the temperature of the tumor. They mustalso minimize the amounts of microwave power being delivered to the healthy tissue or beingradiated into free space.27.5 Synthesis of Microwave ApplicatorsNational Institutes of Health (Grant 1 P01 CA3 1303-01)Frederic R. Morgenthaler, Carey M. RappaportNoninvasive microwave hyperthermia has recently been shown to be an effective cancertreatment modality. Since this treatment is external to the body and utilizes heat, rather thanionizing radiation or toxic chemicals, it is less traumatic to healthy tissue.120I-zg 100-1oo(nzz 80L 60- MUSCLEU 40Ll- 200100 1000 10000FREQUENCY (MHz), io8E0E 6>-!-4--2 - MUSCLES0 0FAT0 0100 1000 10000FREQUENCY (MHz)Figure 27-5: Electrical Characteristics of Low and High Water ContentBiological Tissue as Function of FrequencyUsing published measured values of the electrical and thermal properties of tissue (see Fig.27-5), and by carefully modelling the geometry of specific biological structures, an attempt will bemade to deposit power in assumed tumor locations well below the skin surface withoutexcessively heating intervening tissue. Despite the exponential attenuation of microwaveradiation propagating through lossy muscle tissue, certain source distributions can focus powerRLE P.R. No. 127203Microwave and Quantum Magneticsa) 1.o042 .0.0-.75 -.50 25 O .25 .50 .75z/Lb)1.0 . . .9.8 -4 A.2 5 . ::: .C9.-.75 -.50 -.25 0.0 .25 .50 .75z/LFigure 27-6: Power Contour Patterns for Symmetric Finite LengthCylinder at .915 GHz (e ' = 50, e" = 31). a) R = 4.1cm, L= 10 c, b) R = 4.6 cm, L = 100 cm.into a small volume 6 to 9 cm within the tissue. This large depth of penetration makes tumors inthe head, arm, leg, and breast, candidates for microwave hyperthermia treatment. Computergenerated power density contours (such as that shown in Fig. 27-6) are very helpful.The doctoral research of Carey Rappaport will address the problem of determining the idealsource distribution for tumors arbitrarily located in layered tissue volumes modelled as planarslabs, circular cylinders, and spherical sections. Emphasis will be placed on high resolutionfocusing at depths of several wavelengths. The effectiveness of optimum microwave focusingcompared to other modalities, specifically focused ultrasound, will be examined, also, using acombination of complimentary modalities for specific cases will be considered.Using the derived theoretical optimum as a basis, various existing and proposed applicators willbe evaluated. Determination of those characteristics which yield the desired effects will help indesigning an applicator which most nearly approximates the ideal distribution. Specialconsideration will be given to designs which provide monitoring of the radiated powerdistribution.The adjustable trough-guide applicator described in the last report is currently undergoingevaluation.RLE P.R. No. 127 204Microwave and Quantum MagneticsPublicationsBorgeaud, M. and F.R. Morgenthaler, "An Improved Two-Port Magneto-elastic Delay Line,"Trans. Magn.. March 1985, to be published.Morgenthaler, F.R., "Magnetoelastic Versus Magnetostatic Waves for Microwave SignalProcessing," in Proceedings of the fourth International Conference on Ferrites (ICF4),October 31-November 2, 1984, (American Ceramics Society Advances in Ceramicsseries), to be published.Vlannes, N.P. and F.R. Morgenthaler, "Examination of Magnetostatic Waves by New Optical andInduction Process," Proceedings of the Magnetism and Magnetic Materials Conference1984, J. Appl. Phys., 15 April 1985 tentatively scheduled publication date.Morgenthaler, F.R., C. Rappaport, and T. Bhattacharjee, "Applicator Synthesis for Microwave andRF Hyperthermia," Poster paper presented at the Fourth International Symposium onHyperthermic Oncology, Aarhus, Denmark, July 2-6, 1984.Morgenthaler, F.R., "Control of Magnetostatic Waves in Thin Films by Means of SpatiallyNonuniform Bias Fields," IEEE Trans. Circuits Syst., special issue on MagnetostaticWaves and Applications for Signal Processing, March/April 1985, to be published.ThesesBorgeaud, Maurice, "An Improved Two Port Magnetostatic Delay Line," S.M. Thesis, Departmentof Electrical Engineering and Computer Science, M.I.T., January 1984.Vlannes. Nickolas P., "Optical Induction Probing of Magnetostatic Waves in Thin Films of YttriumIron Garnet," Ph.D. Ihesis, Department of Electrical Engineering and Computer Science,M.I.T., May 1984.RLE P.R. No. 127205RLE P.R. No. 127 206

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