A uniplanar balun that transforms unbalanced coplanar waveguide (CPW) to balanced coplanar strip line (CPS) is characterised through simulation and measurement. By illustrating the effect of many of the critical design parameters, the operation of this balun is discussed and a set of design criteria is defined. The parameter study discusses the size and shape of the radial open, the type and length of the CPW taper and the thickness and type of the bond wires. Newly developed etched bond wires are implemented to provide better manufacturing repeatability and reliability. A complete balun testing procedure is developed and described, consisting of three separate tests. The balun is tested in the normal back-to-back configuration, as a terminated single balun, and the magnitude and phase imbalance is also determined by using a three-port test circuit connected to the balun. The advantages of implementing this full test procedure, and thus fully characterising the balun under test, are emphasised throughout. Results obtained by using this procedure show that the basic balun works well over the full operating band, except for the phase imbalance, which is usable but not optimal. A simple technique to correct the phase imbalance of the balun is introduced, and validated through measurements of the balun connected to the three-port test circuit. As a final validation the balun is connected as feed for an etched dipole antenna for which good impedance matching and pattern results are shown. AFRIKAANS : ’n Enkelvlak balon (BALans-na-ONbalans) wat van ongebalanseerde enkelvlak golfgeleier (CPW) na gebalanseerde enkelvlak strooklyn (CPS) transformeer, word gekarakteriseer deur simulasie en metings. Deur die effek van baie van die kritiese ontwerpsparameters te demonstreer, word die werking van die balon bespreek en ’n stel ontwerpskriteria opgestel. Die parameter studie bespreek die radiale ope struktuur se vorm en grote, die tipe en lengte van die CPW transformator and die dikte en tipe van die konneksie drade. Nuut ontwikkelde geëtste konneksie drade word geïmplementeer om beter vervaardigingsherhaalbaarheid en betroubaarheid te verseker. ’n Volledige balon toetsprosedure word ontwikkel en beskryf en bestaan uit drie aparte toetse. Die balon word getoets in die normale rug-aan-rug konfigurasie, as ’n enkel getermineerde balon en die grote asook fase van die wanbalans word bepaal deur die gebruik van ’n drie-poort toetsbaan wat aan die balon gekoppel word. Die voordele verbonde daaraan om hierdie volledige toetsprosedure toe te pas, en daardeur die balon volledig te karakteriseer, word deurlopend beklemtoon. Die resultate wat hierdie prosedure oplewer wys dat die basiese balon goed werk oor die volledige frekwensieband, behalwe vir die fase-wanbalans parameter, wat bruikbaar, maar nie ideaal is nie. ’n Eenvoudige tegniek om die fase-wanbalans van die balon te korrigeer word bekend gestel en getoets deur die drie-poort toetsbaan weer te gebruik. As ’n finale validasie word die balon aan ’n geëtste dipool gekoppel word, waarvan goeie impedansie aanpassings en patrone gewys word. Copyright / Dissertation (MEng)--University of Pretoria, 2010. / Electrical, Electronic and Computer Engineering / unrestricted

Made available in DSpace on 2016-01-26T12:51:45Z (GMT). No. of bitstreams: 1 carlosdemarchi_tese.pdf: 849020 bytes, checksum: f72fc171abbb042bef869d955b6fd632 (MD5) Previous issue date: 2004-09-10 / Objective: Balloon atrial septostomy (BAS) is a life-saving palliative procedure for some congenital heart defects and typically performed in the cardiac catheterization laboratory. The aim of this study was to evaluate BAS under echocardiographic guidance. Method: From August 1997 through January 2004, 31 children with congenital heart defects with indication of ASB were submitted to the procedure under exclusive echocardiographic guidance. Success was admitted the obtaining of atrial septal defect (ASD) with size of four millimeters (mm) or greater and torn septal tissue flapping freely. Results: Male infants predominated (83.9%). Median age was 5 days (1 - 150) and median weight was 3300g (1800 - 7500). Transposition of the Great Arteries was present in 80.6%, Tricuspid Atresia in 12.9%, Total Anomalous Pulmonary Venous Return in 3.2% and Pulmonary Atresia with intact ventricular septum in 3.2%. The procedure was successful in all cases. ASD size increased from 1.8 ± 0.8 mm to 5.8 ± 1.3 mm (P<0.0001) and arterial oxygen saturation increased from 64.5 ± 18.9% to 85.1 ± 9.2% (P<0.0001). As complications occured three balloon ruptures, one tear of right femoral vein, one case of supraventricular tachycardia and one case of atrial flutter. Conclusion: BAS under echocardiographic guidance is a safe and effective method. It can be performed at the bedside, identifies the catheter location avoiding serious complications and evaluates the immediate result of the procedure. / Atnosseptostomia com balão (ASB) é procedimento de grande valor no tratamento de cardiopatias congênitas e monitorado tradicionalmente por radioscopia. O objetivo do presente estudo foi avaliar a ASB monitorada pela ecocardiografia. Casuística e Método: Entre agosto de 1997 e janeiro de 2004, 31 crianças foram submetidas à ASB sob monitoração ecocardiográfica exclusiva. Admitiu-se sucesso a obtenção de comunicação interatrial (CIA) com diâmetro igual ou maior que quatro milímetros (mm) e com ampla mobilidade das suas margens. Dados coletados: diâmetro da CIA e saturação arterial de oxigênio (SAT) iniciais e finais e número de trações do cateter balão. Resultados: Sexo masculino predominou (83,9%). A idade mediana foi de 5 dias (1-150) e o peso teve mediana de 3300g (1800-7500). Transposição das Grandes Artérias ocorreu em 80,6%, Atresia Tricúspide em 12,9%, Drenagem Anômala Total de Veias Pulmonares em 3,2% e Atresia Pulmonar com septo Integro em 3,2%. Sucesso foi obtido em todos os casos. O tamanho da CIA aumentou de 1,8 0,8 mm para 5,8 1,3 mm (p <0,0001) e a SAT aumentou de 64,5 18,9 % para 85,1 9,2 % (p < 0,0001). Complicações ocorridas: três rupturas de balão, uma lesão de veia femoral direita, uma taquicardia supraventricular e um flutter atnal. Conclusões: ASB monitorada pela ecocardiografia é método seguro e eficaz. Possibilita a realização do procedimento à beira do leito evitando o transporte da criança, identifica o posicionamento do cateter reduzindo complicações graves e avalia o resultado imediato do procedimento.