Broadband Electromagnetic Emission from PZT Ferroelectric Ceramics after Shock Loading

It was experimentally registered pulsed electromagnetic (EM) radiation in frequency range higher than television one using wideband horns with coaxial and waveguide outputs. The EM radiation was received during shock loading of lead zirconate titanate (PZT) ceramics cylinders in conventional piezoelectric ignition mechanisms. Digital oscilloscope allows registering whole series of EM pulses and each pulse from the series transmitted from horn antenna of (1-18) GHz operating band frequencies. There is (1-4) ps delay between the shock and the first pulse of the series. Duration of the series is about (3-4) [mu]s. The PZT cylinders were cleaved along their axes and the surfaces formed in the process were investigated by scanning electron microscope. It was concluded that from electrical point of view PZT ceramics contain interacting subsystems. It was found that EM radiation spectrum of pulse detected by waveguide detector heads has harmonics reaching 80 GHz. Presence of harmonics higher than 20 GHz indicates on radiation due to deceleration of electrons emitted during the switching. The EM pulses in the series appear randomly and have different amplitudes which partly confirmed thesis on independent switching dynamics of small volumes governed by a local electric field.Original Abstract: Tesiami impulsinio elektromagnetinio (EM) spinduliavimo registravimo eksperimentai aukstesniame nei televizijos bangu ruoze, naudojant placiajuoscius ruporus su bendraasiais ir bangolaidiniais isejimais. EM spinduliavimas, atsirandantis po svino cirkonato titanato (SCT) segnetoelektriniu keraminiu cilindru, esanciu piezoelektriniuose uzdegimo mechanizmuose, smuginio apkrovimo, buvo priimamas ruporais. Skaitmeninis oscilografas leido uzregistruoti visq EM impulsu serija, kurios trukme apie 4 [mu]s ir kurioje galima stebeti kiekviena jos impulsa, kai signalas buvo siunciamas is ruporo, turincio 1 GHz - 18 GHz darbo dazniu juosta. Buvo aptikta, kad po smugio pirmas serijos impulsas veluoja 1 [mu]s-4 [mu]s, o spinduliavimo, detektuoto bangolaidinemis galvutemis, spektras turi harmonikas iki 80 GHz. SCT cilindrai buvo perskeliami isilgai cilindro asies ir skelimo pavirsiai buvo nagrinejami skenuojanciuoju elektroniniu mikroskopu. Buvo padaryta isvada, kad SCT keramika turi elektriskai saveikaujancias posistemes. Aukstesniu negu 20 GHz harmoniku buvimas rodo, kad toks spinduliavimas atsiranda del perjungimo metu emituotu elektronu stabdymo procesu. EM impulsai serijose pasirodo ch