Center-tap push-pull transformer with toroidal core helically wound with a single coaxial cable creates a high frequency wideband transformer. This transformer has a high-turn ratio, a high coupling coefficient, and a flat broadband response

De Parry, T.

English

NASA Technical Reports Server

	December 1966
	
Brief 66-10600 
	
..
	
AEC-NASA TECH BRIEF 
AEC-NASA Tech Briefs describe innovations resulting from the research and development program 
of the U.S. AEC or from AEC-NASA interagency efforts. They are issued to encourage commercial 
application. Tech Briefs are published by NASA and may be purchased, at 15 cents each, from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
High Frequency Wide-Band Transformer Uses Coax to

Achieve High Turn Ratio and Flat Response 
The problem: 
To design a high frequency wide-band transformer 
with a high turn ratio, a high coupling coefficient, and 
a flat broadband response. It is difficult to obtain ef-
ficient coupling in standard high frequency trans-
formers with turn ratios above 2:1. Also, flat broad-
band frequency response is not readily available in 
transformers with very high turn ratios.
The solution: 
A toroidal core is spirally wound with a single 
coaxial cable. The inner conductor of the coaxial 
cable functions as the primary winding and the outer 
coax shielding is segmented to form the secondary 
winding. 
How it's done: 
A center-tap push-pull transformer configuration 
is shown which consists of a helical winding of coaxial 
(continued overleaf) 
This document was prepared under the sponsorship of the Atomic liability resulting from the use of the information contained in this 
Energy Commission and/or the National Aeronautics and Space document, or warrants that the use of any information, apparatus, 
Administration. Neither the United States Government nor any per- method, or process disclosed in this document may not infringe pri-
son acting on behalf of the United States Government assumes any vately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19660000598 2020-03-11T17:45:11+00:00Z
cable on a ring of ferrite core material. The ferrite 
inner conductor, with input terminals I and 2, cor-
responds to the primary winding. The outer shielding, 
with output terminals 3 and 4, corresponds to the 
secondary winding. 
The cable is initially wound on the core at a 1:1 
ratio. The method used to obtain a 4:1 stepdown ratio 
is illustrated. For each half of the transformer I and II 
there are effectively four primary windings magneti-
cally coupled to one secondary winding. The effect of 
reducing the number of turns in the secondary is 
accomplished by sectionally discontinuing the outer 
shielding and rewiring the resulting sections into 
four parallel networks. Thus, the secondary is elec-
trically equivalent to a single turn of a conductor 
about a magnetic core wound with four primary turns. 
Notes: 
I. Specific performance. data of this design indicate 
that the coupling coefficient between primary and 
secondary approaches 1. Stray inductance loss is 
lowered by this configuration. The amount of 
coupling and/or stray inductance loss may be 
varied as a function of the diameters of the two 
conductors.
2. Empirical study of the frequency response of this 
transformer indicates a completely flat response 
from 100 Kc to 10 Mc. 
3. The networks in parallel need not be single turn as 
illustrated, but may be any number as required to 
meet specific requirements. 
4. Inquiries concerning this innovation may be di-
rected to:
Office of Industrial Cooperation 
Argonne National Laboratory 
9700 South Cass Avenue 
Argonne, Illinois 60439 
Reference: B66-10600
Source: T.De Parry 
Particle Accelerator Division 
(ARG- 107) 
Patent status: 
Inquiries about obtaining, rights for commercial 
use of this innovation may be made to: 
Mr. George H. Lee, Chief 
Chicago Patent Group 
U.S. Atomic Energy Commission 
Chicago Operations Office 
9800 South Cass Avenue 
Argonne, Illinois 60439 
Brief 66-10600	 Category 01


High frequency wide-band transformer uses coax to achieve high turn ratio and flat response

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