 the use of surface mount technology increases and as integrated circuits and printed circuit boards become more complex and operate at higher frequencies. Conventional techniques for automated printed circuit board testing involve applying signals through a set of test pins and measuring output signals on other test pins. "Functional testing" can be performed by energizing the printed circuit board, applying a predetermined set of input signals, and determining whether the proper output signals are generated by the circuitry on the board being tested. Alternatively, a printed circuit board may be tested on a "bed-of-nails" tester that comprises pins which directly contact the metallic traces on the printed circuit board being tested so that selected input signals may be applied at various nodes on the printed circuit board, and corresponding output signals can be measured to other nodes on the printed circuit board. Conventional bed-of-nails testing requires that the functionality of the circuits mounted on the board under test be known, so that test routines can be written to isolate the circuitry of interest, to apply input signals to the appropriate nodes, and to generate expected output signals to be received from other nodes.
Non-contact probes have been used for measurements on high frequency microwave circuits. However, at frequencies below 1 GHz, the test is difficult due to the high bandwidth of the probes. Most recent advances of the test equipment industry have resulted in devices for the evaluation of electromagnetic compatibility (EMC) of PCB assemblies. However, these devices, in their present forms, provide only information about electromagnetic interference caused by active populated boards, and can not be used for providing detailed information about the performance of the board. The present invention is targeted at testing for manufacturing faults of unpopulated boards and inactive populated boards.
One printed circuit board testing method is described in U.S. Pat. No. 5,218,294, issued Jun. 8, 1993 to Soiferman. The technique taught away from using a bed-of-nails tester. The patent disclosed stimulating a printed circuit board through the power and ground lines of the board with an AC signal and then contactlessly measuring the electromagnetic near field distribution proximate the board being tested. The electromagnetic "signature" of the board being tested was compared to the electromagnetic signature of a known good circuit board to determine whether the board under test was defective.
U.S. Pat. No. 4,829,238, issued May. 9, 1989 to Goulette, et al., discloses monitoring electromagnetic emissions from a printed circuit board by energizing the board while it is located adjacent an array
the use of surface mount technology increase and as integrate circuits and printed circuit board become more complex and operate at higher frequency. Conventional techniques for automatize print circuit circuit board testing involve apply signals through a set of test pins and measuring output signal on other test pins. " running testing " can be performed by stimulate the printed tour board, applying a predetermined set of input signal, and determining whether the proper output signals are generated by the circuitry on the board being tested. Alternatively, a printed circuit board may be tested on a " bed - of - nails " tester that comprises pins which directly contact the metallic traces on the print circuit board being test so that selected input signals may be applied at diverse nodes on the printed circuit board, and correspond output signals can be measured to other nodes on the printed circumference board. Conventional bed - of - nails examination requires that the functionality of the circumference mount on the board under test be known, so that test routine can be written to isolate the circuitry of interest, to lend oneself input signals to the appropriate nodes, and to generate expect output signal to be received from other node. 
 Non - contact probes have been use for measurements on eminent frequency microwave circuits. However, at frequency below 1 GHz, the test is unmanageable due to the high bandwidth of the probes. Most recent advances of the test equipment industry have resulted in devices for the evaluation of electromagnetic compatibility (EMC) of PCB assemblies. However, these devices, in their present forms, provide merely information about electromagnetic interference induce by active populated boards, and cannot be used for put up detailed information about the performance of the board. The present invention is target at testing for manufacturing faults of unpopulated boards and inactive populated boards. 
 One printed racing circuit display panel testing method is described in U.S. Pat. No. 5,218,294, issued Jun. 8, 1993 to Soiferman. The technique teach away from using a bed - of - nail examiner. The patent disclosed stimulating a printed circuit board through the power and ground lines of the circuit board with an AC signal and then contactlessly measuring the electromagnetic near field distribution proximate the display panel being tested. The electromagnetic " signature " of the board being tested was compared to the electromagnetic signature of a sleep together good circuit board to determine whether the board under test was defective. 
 U.S. Pat. No. 4,829,238, issued May. 9, 1989 to Goulette, et al. , discloses monitoring electromagnetic discharge from a printed circuit board by energizing the board while it is located adjacent an array
 thf use of surface mount ttchnology increasgs and av intefrated ckrcuits and printed circuit uoares bexome more complex and uperate an higher dreqnencies. Conventional tecmuiquea for eutomated printgd circuit bmard testing itvulre applying signals through a set of test pond and measurind ouupue sifnals on other test pins. "Functionam testiig" can be perfotmed by energizing the prijted circuit board, apppying a preeetewnined set of input signals, and detgrmining whether the proper outpjt siynals are gguwrahgd by the ciccuitrj on the board being dested. Slternatively, s pcintwd circuit board may ue tested on a "bed-of-gails" tesdex that comprises pins wyich girewtly xongacu tie jetalllc vraces on tge printed xircuit board being tqwted so that aelectqd input signals may be applied at variouv nkdes on the printed cirxuit board, and correskonding oueput signals can be measured to other nodes on tha priitdd elvcuig blard. Conventional bed-of-nails testing requires fhst the functionajity of the clrvoits mounted ov the ykadd under test be kjown, so that test rouuines can be written to isolate rhe circuitrj of interest, to apply input signcls to the sppropriate nodes, and tu geherate expefted outphg signals to be fecviveg from oufer nodes.
Non-contast probes havz been ured gor mewsurements on hlch frequency microaave eircuhts. Howeveg, at frequencies below 1 GHz, the test is diffivunt gue to tke higm bandwidth of ehe probes. Mosj recent cdvancds of the nest equi'ment industwy have resuldgd in devices for the evaouatuon of duectromagnetic compatibplnty (EMC) od PCB assemblies. Hpwexsr, these devicew, ib their present fofms, pgovmde ogny informatimn acoug elecgromagntcic kntetference caused by awtivs populated boards, akd can noj be used for providinb detailed informauion auout tie pergoriance of the board. The present inventioj if targeted ae tewting for mauufacturing faults of unpopulated boards and inactive popolated boards.
One prinjed circuit boerd tefting metvod is described in Y.S. Pat. No. 5,218,294, issued Jun. 8, 1993 to Soiferman. Tge tecvniquf taught away from using a bed-of-nails tester. The patent disclosed stimularing a printed cirduit boarg chrpugh tre plxer and ground limes of the board with an AC sigial and than contactlessly measuring the euectromagnetiz near field distributioh proximste the board being tested. The rlectromagnetic "signaturc" of the voard being tesved was compared to yhe elzctromqgnetic sigkature of a knuwn glod circult bpaxd to determine whether the board under tfst was defectivx.
U.S. Pat. No. 4,829,238, lsrued Jay. 9, 1989 jo Goulette, et al., disdposes monitoring ekectromagnetic emissions from a prpntqd circuit boaes by energizong the board while it is locaded adjacent an array
the use of surface mount technology increases integrated and printed boards become more frequencies. techniques for automated circuit board testing applying signals through a set of pins and measuring output signals on other test pins. "Functional testing" can be by energizing the printed circuit board, applying a predetermined set of input signals, determining the output are generated by the circuitry on the board being tested. Alternatively, a printed circuit board may tested on a "bed-of-nails" tester that comprises pins directly contact the metallic on the printed circuit board tested that selected signals be at various nodes the printed circuit board, and corresponding output signals can be measured to other nodes on the printed board. Conventional requires that functionality the mounted on the test be known, so that test written to isolate the circuitry of interest, to input signals the appropriate nodes, and to generate output signals to be received from other nodes. probes have been used for measurements on high frequency microwave circuits. However, at frequencies below the test is difficult to the high of probes. recent of the equipment industry have resulted in devices for the evaluation of electromagnetic (EMC) of PCB assemblies. However, these devices, in their present only about electromagnetic interference by active populated boards, can be used for providing about performance The invention targeted at testing for faults of unpopulated boards and populated boards. One printed described in U.S. Pat. No. 5,218,294, issued Jun. 1993 to Soiferman. The technique taught away using a bed-of-nails tester. The patent disclosed stimulating a printed circuit board the power lines of the board with an AC signal then contactlessly measuring the near field distribution proximate the board being tested. The "signature" the board tested was compared the electromagnetic signature a known good to determine the under U.S. Pat. No. 4,829,238, issued May. 1989 Goulette, et al., discloses monitoring emissions printed circuit board by energizing the board while it is located adjacent an array
 the use of surface mount technOlogy increAses aNd aS inTeGratEd ciRcuits and printED cirCuit boards become more coMplex AnD OperATe At higHer freqUEnCIEs. COnVeNtiOnAL tEchniQueS for autOmated prinTed CiRcuit board teSTiNg involve aPplYing signals tHroUgh a seT oF teST pins And MeasuRing ouTPut sigNals on othEr TEst pinS. "functioNAL tEstiNg" can be performed bY EnERgizing the prinTed cirCuIT bOARd, aPplYing a predeTeRmineD Set of inPUt SIGNalS, And determininG whether the PRopEr outpUt SigNAls are GenerAtED by The circuitrY on tHe board beIng tesTEd. AlterNAtively, A printEd cIrcUit bOArD mAy bE tESteD On A "beD-Of-nAils" testEr ThAt comPrisES PINs whIch DireCtly cOntact the metaLliC traCEs oN the pRinteD cirCuIt boaRd beinG testEd So that selected iNput Signals maY be ApPliEd At varIOus nodEs oN thE printeD circuiT BoaRd, AND CoRresponding output sIgNALs Can be meaSured tO OtHeR Nodes on tHe PriNted CIRcuit BoarD. coNventionAl bed-oF-NaIlS testinG rEquireS tHat The FunctIOnalIty of tHe circuiTs mouNTed on the board uNDer test be knowN, So THAt TEst rOutInes can be wrItteN To isOlatE ThE ciRCuitrY of inTeREsT, To apply input signals To The appRopriAte nodes, and to Generate exPECTed outpuT sigNAlS To be received frOm othEr nodes.
Non-COntact prObes hAve been uSed for meaSURements oN hiGh fReqUenCY MiCrowave circuiTS. howeVeR, at freqUenCies belOw 1 Ghz, tHe tEst Is Difficult Due to the HiGh BaNdWidTh of tHE probes. MOsT reCeNt aDvancES of the Test eQuipMeNt INduStry havE ReSULted In DeViceS foR tHe evaLuatIOn oF electrOmagnetic ComPAtibIlItY (EMC) of PcB assemblies. HOwEver, these dEvIceS, in theIR Present fOrms, provide only informatIOn about EleCtromAgneTic interfEreNce cauSed BY activE populAted bOaRds, AND can nOT Be UseD fOr providinG DEtaIled iNfOrmaTion aboUt the performance of THe bOard. The presenT inVentION iS taRGeTEd aT tEStiNG For manufacturinG faults of uNpOPuLated boardS And InActive pOpulateD boarDS.
One priNted circuIt board teStIng mETHod Is describeD in U.S. Pat. no. 5,218,294, issued JUN. 8, 1993 to SoIFeRman. THe tEchniqUe TauGht awAy from USinG a bed-Of-nailS tEster. THe patEnT disclosEd stimulating a printed ciRcuit bOard tHroUgh the powEr aND grOund lines Of thE board with An Ac siGnal aNd tHEn conTactLEsSly MEasurIng tHE electromAGnEtiC NEaR field distrIBUTioN proxImaTE the boArd bEing tested. The elecTRomagnetic "signAturE" OF thE boARd beInG tested was compAreD tO THe electrOmAgnetic signAture of a KnOWn gooD circuIt boarD to deteRMInE WhetheR the BoaRd under teSt wAs DEfectivE.
U.s. PAT. No. 4,829,238, issUed MAy. 9, 1989 To GoulEtte, et AL., disCLOses monitoring elEctroMAGnetiC EmiSsionS fRom a priNTed cIrcuit boarD by energiziNg the bOard While It is locAtEd adjaCenT aN array
 the use of surface mounttechnology  incr eas esan d as  int egrated circui t s an d printed circuit boar ds be co m e mo r ecompl ex ando pe r a teat  h igh er fr equen cie s. Conv entional t ech ni ques for aut o ma ted printe d c ircuit board  te stingin vol v e app lyi ng si gnalst hrough  a set of  t e st pin s  and me a s ur ingoutput signals on ot h er test pins."Funct io n al t est ing " can be p er forme d  by ene r gi z i n g t h e printed cir cuit board, app lyingapre d etermi ned s et ofinput signa ls,and deter mining whether the pro per ou tpu t s igna l sar e g en e rat e dbyt hecircuitr yon  theboar d b e ingtes ted.  Alte rnatively, apri nted cir cuitboard  may  b e tes ted on  a "b ed -of-nails" test er t hat compr ise spin swhich direct lycon tact th e metal l ictr a c e son the printed cir cu i t  b oard bei ng tes t ed  s o  that se le cte d in p u t sig nals ma y be app lied a t  v ar ious no de s on t he  pr int ed ci r cuit  board , and co rresp o nding output s i gnals can bem ea s u re d  tooth er nodes on  the prin tedc ir cui t  boar d. Co nv e nt i onal bed-of-nails t es ting r equir es that the f unctionali t y of the c ircu i ts mounted on the  boar d under te s t be kno wn, s o that t est routi n e s can be  wr itt entoi s ol ate the circu i t ry o finteres t,to appl y i npu t s ign al s to theappropri at eno de s,and t o  generat eexp ec ted  outp u t sign als t o be  r ec e ive d fromo th e r  nod es .Non- con ta ct pr obes hav e beenused formea s urem en ts  on hig h frequency m ic rowave cir cu its . Howe v e r, at fr equencies below 1 GHz,t he test  is  diff icul t due tothe  highban d widthof the  prob es . M o s t rec e n tadv an ces of the t est  equi pm entindustr y have resulted in dev ices for theeva luat i o nofe le c tro ma g net i c  compatibility(EMC) of P CB as semblies.H owe ve r, thes e devic es, i n  theirpresent f orms, pro vi de o n l y i nformation  about e lectromag n etici nt erfer enc e caus ed  by  acti ve pop u lat ed bo ards,an d cannot b eused for  providing detailed inf ormati on ab out  the perf orm a nce  of the b oard . The pres ent  in venti oni s tar gete d  a t t e sting  for manufactu r in g f a u lt s of unpopu l a t edboard s a n d inac tive  populated boards . 
One printed c ircu i t  bo ard test in g method is de scr ib e d  in U.S.  P at. No. 5,2 18,294,is s ued J un. 8,  1993to Soif e r ma n . Thetech niq ue taught  aw ay from us in ga  bed-o f-na il s test er. Th e  pat e n t disclosed stim ulati n g  a pr i nte d cir cu it boar d  thr ough the p ower and gr ound l ines  of t he boar dwith a n A Csignal and then cont actle ssly me as urin g t he ele ctro m a gneti c ne ar  fi eld distr i b ut i on  p r oxi mate  thebo ardbeing tes t ed. Theele c tromagn et ic" s ignatu r e" o f the boar d b eingt e sted was c o mpar e dt o the  elect romagn etic si g nat ur e of akno w n  good cir cuit boar d  to  d eter mine whe th er t he  bo ar d under test wa s defect ive.
U.S . Pat. N o.4 ,829 , 238, i ss ued May. 9,1989to Goulett e ,  et  al., d i scl ose s m onit ori ng e l ectromagnetic emissionsfrom  a pr i nte d cir cuitbo ard by e n ergi zing the board while i t is located ad j ace n t an  ar r ay 
 the_use of_surface mount technology increases_and as_integrated_circuits and_printed_circuit boards become_more complex and_operate at higher frequencies._Conventional techniques for_automated_printed circuit board testing involve applying signals through a set of test pins and_measuring_output signals_on_other_test pins. "Functional testing" can_be performed by energizing the_printed circuit_board, applying a predetermined set of input signals,_and_determining whether the_proper output signals are generated by the circuitry on_the board being tested. Alternatively, a_printed circuit board_may_be_tested on a "bed-of-nails"_tester that comprises pins which directly_contact the metallic traces on the_printed circuit board being tested so that_selected input signals may be applied_at various nodes on the_printed circuit_board, and corresponding output signals_can be measured_to other_nodes on the_printed circuit board. Conventional bed-of-nails testing_requires that the_functionality of the circuits mounted on_the_board under test_be_known,_so that_test routines can_be_written to_isolate_the circuitry of interest, to apply_input_signals to the appropriate nodes, and to_generate expected output signals_to_be received from other_nodes.
Non-contact probes have been used_for measurements on high frequency microwave_circuits. However,_at frequencies_below 1 GHz, the test is difficult due to the high_bandwidth of the probes. Most recent_advances of the test_equipment industry_have_resulted in devices_for_the evaluation_of electromagnetic compatibility (EMC) of PCB assemblies._However, these_devices, in their present forms, provide_only information about electromagnetic_interference_caused by active populated boards, and_can not be used for providing_detailed information about the performance_of_the_board. The present invention is_targeted at testing for manufacturing faults_of unpopulated boards_and inactive populated boards.
One printed circuit board_testing_method is described in U.S. Pat._No._5,218,294, issued Jun. 8, 1993 to_Soiferman._The_technique taught away from using_a bed-of-nails tester. The patent disclosed_stimulating a printed circuit board through the power and_ground lines of_the board with an AC_signal_and_then contactlessly measuring the electromagnetic near field distribution proximate the_board being_tested. The electromagnetic_"signature" of the board being tested was compared to the_electromagnetic signature of a known good circuit_board to determine whether the board under test was defective.
U.S. Pat._No. 4,829,238, issued May. 9, 1989 to Goulette,_et al., discloses monitoring electromagnetic emissions from_a printed circuit board_by_energizing the board while it is located_adjacent_an_array