Recent advances in microwave amplifiers have increased efficiencies and power levels at frequencies from 0.3--150 GHz. These improvements have occurred in both solid-state and vacuum-tube systems. Of special note is the very high power device where power levels of 1 GW are routinely generated. This paper will review the latest results of these RandD efforts. 3 refs., 4 figs

Reid, D.W.

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LA-UR -88-1070“TLE RECF~ ADVANCES IN HIGH-POWER MICROWAVEAMP1.IFIERSLA-uR--88-107ODE88 007820AuTHOqs) D. W. Reid6UBM~TEDTO 1988 IEEE NTT-S International Microwave Symposium,New York, NY, Nay 25-27, 1988..llIIk II, IXIrl *IIS pqmf~~l(,,,,,.,lllllrnl Nt’1ltlr’1 1111I)IM’l,AIMitR,, ,,11,1,tiUIIIIIIIw,]rk \Pmuwd II} ,In JX,,. \ III lhr Irntfr’d ~I:IICSI“IIItrIl SI,IIC. tIIISrr IInWIII 11111Irrb ;tpcntt thrrrr)l, mII .Int ad IhclfLoaminlos &MYngMiT/i&5i$ERECENT ADVANCES IN HIGH-POWER MICROWAVE AMPLIFIIIRS*Don W. Reid,AT.DO,H81110S A18moB National Laboratory, LAMAlamo% NM $7646ABSTRACTLatent ●dvances in microwwe a.mpliflere haveixxreaaed effkiencias and power levels d frequenciesfrom 0.9 to 160 (3Hz. These improvements have oc-CUITd in both eolid-state and vacuum-tuba ayetema.Of special note is the very high power device wherepower levels of 1 GW are routinely generated. Thispaper will mviow the Meat maulta of theM R&Defforte.hlTRODUCTIONRecent milhry requiremeata for high-powermicmwave nm@iflem have driven the developmentof theee eyatema to new levels of outpu: power andTciency ● fhqvendea horn0,9to160 GIIz. Tbeeaner remarkabig improvamente havo ~ insolid.state and tuba ~ ampliffere,SigMkant progreaahaa bean made la the powerr capability ofaothtete ampliflere and in iboir●l Cy,b the ‘iaatfewyam, (Ma haa begun tompio . silicon u c baaic wafer mmterial hecauaa of iainereaaad electron mobillty thatgivesit t4ecapa-bility u operate●t highar fhquendes. Below 9 G13s,etlicon bipolar or field-o~ect txanalator WET) con.figurations are the devh of choke fnrrfpower ampli-fication, Above S OHSand aapedally above 10 CIWan F’ETeonflgurathm built with CaAe h the devka ofchoice,Eelow 10 GKa, not much hoe happened in theway of pwer ou!put fkomtubaampiiflere, MoJtofthe impmvamenthas hen ●chieved h the am of●ffleiency, Klystrons with 60% beam offlcioncy ●mnow common.pke. Ithas been shown thet this●f!lciency can be improved ta ●bout 76% wing adepreeaml collector. ‘ho new devices hate been—introduceci in the paat two yeara, the Klystrode andthe laaertron. Great strides have been made in thesuper power area where vacuum-tube devices are nowcapable of generating 1 (3Wof rfpower ●t abort puhelengths,SOLID-STATEAMPLIFIERSThe SDIO roquimxnente formegawatta of rfpower at UHF frequencies have xuulted in eolid.etatiapedflc weight (g/W) improvarnanta u showninFig. 1, Theea data are for n oompleteamplifier in-cluding driver atagee, output combiner, and powerconditioning. Thaae improvamonte occur becaueeaiagle device output power ievels hsve improved from150 peak W per single-ended device to over 700 peakW. At the same time, ●flkien-dee have improvedfkom●bout 60% to ovar 70%, Considerable km abc ~t60% b over 70%. Considerable ●dva.nceain amplifSerpackaging technology have ●laocontributed subatan-tJally ta the amplifier weight rwhwtion./:[ “:’”’9\:~O.@‘I\. . ‘\0.4 - ‘.. . .. \ -..-.. . . . . . . . ,.~. 1,SpocMkwdght Improvomonts for eolld-mWmampllftort‘Work spormtmedOySurvivability, bthality, ●nd KQyTechnolqiea (SLKT) of ttm Strategic Defense InithtiveOffIce (8DIO).A very recent advance in the state of the art atUHF frequencies is the static induction tranaistnr(SIT).l A SIT in both double-ended and eingle-endedeon&urations is shown in Fig. 2. The single-endeddevice has delivered 280 W of cw power with 7.o ctBofgain and 79%effkiency.?ig. * 3tatkInductionTmndetmm OodgwauomAe the flequeney inawea9a, the output power ofthe bipolar tranaietor decraaam according to thecurve ehown in Fig, & Tho aaareh for●did-etate rfdevice at 10 OHSand dove hae led to the uee of (h&ae ●tranehor material in place of the conventionalsilicon. Although the field ie new, solid-etateN.—..-. —-“---”-t----H”---r,Il_—....———..——w la Me tonPREO (MMY)~, 8. BipolarWmddoroutput power v. f’rqumncyamplifiers are being built from 3 to 30 GHz. TheGa4s transistors are typically built in the FETconfiguration and produce a few watts per device at10 (3Hz to of the order of O.5W at 30 GHz.VACUUM-TUBE AMPLIFIERSAlthough the Klystrode, en old idea fkomthe1930s, has now been developed, it haa only recentlybeeII introduced for tdeviaion eervice at 60 kW CW,2The Klyatmde depends on a grided cathode for itaoperation. The grid i-driven with rfpower at the●ppropriate frequency. This has the effect ofbundiing the beam ae it leaves the cathode. A etingdc voltage is applied between the grid and the amxleor bcdy of the tube to supply energy ta the prebunched●lectron beam. The beam then tmuaite ●etutdardklyawon output cavity where ite dc energy iaextrtwted u rfpow~r.The uaa of ● grid to prebunch the beam makesthe Klyatmde much smaller tJ2ana conventionalklyetron Itsimilar frequencies. It alao typically haaomr 70%beam ●ff3deney. A pmgmn ispraaentlybein(! conducted at EIMAC to develop ● tube capableof 5W)-kWpuk power ●t 42S MHa and 70%beameffidmmy. ‘I%etube and magnet will weigh lees than110 lb. h artiet’e oonapt of what the tube will looklike iBehown in Fig. 4.-K kOH VOLTAGIjh COW4CTION /Fig.4. Mht’swloq)t orb600kw KIy?’(m.+Auotber vacuum-tuba device that Men on ‘heeoneapt o<a pmbunched or emiuion gatad beam ia thelaaertIon, This device waa patanted by b AlamoeNatiot,al Laborebv in 1982s and has recently betmworke~ion ●t eeverd Iaboremriea internationally, Itoperetoe in exactly the came faehion nathe Klyahdeexcept that a laser pulsed at the desired freauencycaus& e photoemis&e cathode to emit. Tl& -generates a prebunched beam that paaees throughthe dc field and into the output cavity. Computerdmuhtione chow thattholaeertron hae tbecapability of ●chieving greater than 80%beamef!ldeney●tUHF fhquondoo.M! LUME’I’ERWAVE AMPLJPIC/.TIONhehttvdy high powers are dedred ●tmillimeter wave fhqueaciee, one wually turns tos traveling-wave tube (’ITWI’)or ●croaeed-fieldamplifier (CFA) for am~li-fkation of the microwave~wer. For example, TWA’X am ●vailable in sw powmlevele of40 W at 20 GHx and 100 W ●t 80 Glla. ACFA is available at 94 GHx and hae ● peek outputpower of 9 kW. Wfidenciaa raage km 20% ●t20 GIHato 18% ●t 80 CMIXfor TW7k and SO%ef-ild$ncy ●t 84 GHx for a mflection-unpli!katlonmodeCFA.Oneoftbe moreuddng dovelopmena in rfamplifier technology overthepact few yearn hex beenthe gyrotron. The device hen been built anboth anemplifSer end an an oadlhtnr. Originally developedfor w en● plasma-heating rfaxnplifier in the fbaionenergy program, it is now eeen M n potential foreeveral high-fhquancy ●pplicedone, @rotrone havebeen built ●t 28 GHz to deliver 840 kW ofcw power ●t50%buam eff$dency. At 80 G* the output powu is200-kW cw ●t about 40%efffdency. One of the tmlyrunarkable achievemante is ●t 340 G= whamoutput powera of 100-kW cw and 9C0-kW puk havebeen rneaaumd ●t effSdendeeof about 25%. An R&DP~ h Pi-ntJY beingimplemented●t Verian toddevo 1-MWpeak power d 140 GHx.VEI?Y HI(3HPOWER VACUUM TUBESThu pouibllity of ueiag mkmwevee u ●battlefield weapon hne eparked a great deal oflz4tereetla very high power rfoedllatom ●t generallyabort pulaa lengths, Powers arQtypically of thegigawett level and pulse lengths em between Sf and100 ns; although one device, the large orbit gyrotron,has the capability of running CW.No prominentdevices in this arena are the relativistic magnetronand the virtual cathode mcillator or Vircator. Todate, tha higheet power mlativietic magnetron has●chieved 1 (3W●t an efflcioncy of ●bout 10% ●t S (3Hzwith ● pulee length of 60 ns. The Vircator hen●chieved greater than 40 t3W●t an ●ffkiency of 5%.Pulee lengths are 100 ta 150 no and the devicesoperate over very wide frequency rengee of theorder of 1 b 40 GHz. The large orbitgyro-n hendelivered 1 (JW●t ●bout 40% effidency and chowsevidence ofoperating from 2 to SS GHx. This willprove to ba an excitingfield with many meaaummentand field breakdown challongm to ha solved,ACKNOWIJDGMENT8ThfIauthor wlahee to acknowledge theudetuma of Dr. ~OWUd hay and Mr. MiktCwone of Varian Hates, Mr. Bruce Welpoleof Ray’tkm, and Dr. Robert Hoebarling of LoeAlamoe National Laboratory for supplyhtg the latestinformation on etate-of-the-mt devica1.2.9.BXBLIOQRAPHYI. Bencuya, A. L Cogan, S. J, Butler, and R. J,Rognn, ‘%adc InductJonThnaietore Optimizedfor Migh.Voltage Operation and HighMicmwwe Power Outpu&”= Trum Elec.hV, Xi (7), lS21-1927, July 1986.M, 11.Scbrader and D, H, Prei@ “Compact HighEfficiency LightWeight 200-600 MHz HighPowor RfSouroe,” Pmt. 1985 ParticleAccelerator Conf., Vaneouvu, BC, Ceneda,1985 ~EE ‘hens, Nucl, 8d, 8%2761, May 19.16,1985,M. ‘1’,Wileon and P, J, Tallerico, “LightModulated Switchee and Radio FrequencyEmlttere,” U.S. Patent 4S1S072, January 26,198:!,

Recent advances in high-power microwave amplifiers

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Recent advances in high-power microwave amplifiers

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