US3443248A - Strip hybrid power divider - Google Patents

Description

May 6, 1969 D. c. BRODERICK STRIP HYBRID POWER DIVIDER Filed Nov 16, 1966 FIG. 2

David C. Broderick,

INVENTOR.

FIG 3 United States Patent M US. Cl. 333-11 2 Claims ABSTRACT OF THE DISCLOSURE A radio frequency power divider device for providing equal phase and amplitude division of radio frequency power consistent with isolation between output terminals.

The invention finds application in many existing and proposed multi-element antenna systems having electronic beam steering. Operation is intended to be in the VHF.- U.H.F. range, although, it could easily be extended to microwave. Also, it must be small in size and inexpensive to produce since large quantities will be necessary for multiple power division. In the past, division of radio frequency power has been accomplished through the use of simple Ts and Ys built in coaxial lines, wave guides, strip transmission lines, etc. Also, the use of hybrid junctions, hybrid rings, and directional couplers have provided means for dividing power. These methods, though functioning well in many applications, fall short when applied as described above. The PS and Ys have no provision for isolation; hence, they cannot be used. At

V.H.F. and U.H.F., hybrid junctions such as the magic tee are inapplicable because of the tremendous sizes they assume. Hybrid rings must be discounted because they are quite large and expensive to produce. Directional couplers likewise become very expensive and unwieldly to use in large quantities.

The present invention fulfills all of the functional requirements for anticipated applications and assumes small physical dimensions and low cost per unit. It is readily adaptable to cascading so as to provide multiple division of radio frequency power. Its functional operation is identical to most hybrid configurations, so it is not unique in this respect. The hybrid form is somewhat unusual in that two of the hybrid arms are physically, although not operationally, removed. Also, the packaging of the remaining two arms in a common transmission line is different, though not entirely unique. The features, which it is felt are entirely original, are the containment of the whole structure in a strip transmission line environment and the simplicity of construction.

It is, accordingly, a primary object of the present invention to provide a strip hybrid power divider of relatively small size, low cost, and ease of construction.

Another object of the present invention is the packaging of a parallel plate two arm hybrid configuration in a strip line environment.

Other objects and advantages of the invention will become apparent to those skilled in the art from a consideration of the following detailed description taken in conjunction with the accompanying drawings wherein:

FIGURE 1 is a longitudinal sectional view showing details of a preferred embodiment of a strip hybrid power divider according to the invention;

FIGURE 2 is a schematic diagram illustrating the electrical configuration of the structure of FIGURE 1; and

FIGURE 3 is a schematic diagram illustrating a possible alternative layout of a co-planar electrical configuration of the structure of FIGURE 1.

Referringmore particularly to FIGURE 1, a pair of outer conductor ground plane members 10 and 12 are 3,443,248 Patented May 6, 1969 shown mounted in parallel spaced relationship fixed or attached together in any well-known manner. As illustrated, input connecter 11 and the two output connectors 21 and 31 are located at opposite ends of the strip transmission line. Input connector 11 and output connectors 21 and 31 are of the type N series of coaxial connectors, having center conductors 6, 26, and 36, respectively, and surrounding body portions.

The radio frequency input signal is applied to cente conductor 6 of input connector 11. Center conductor 6 is connected to a brass interconnection conductor and parallel arm shorting bar 40, which is further shorted to two inner conductors, namely, upper inner strip line conductor 20 and lower inner strip line conductor 22. These four members are of electrically conductive material and may be conveniently secured together by a conductive means, such as solder. A centrally positioned dielectric 30 separates upper inner strip line conductor 20- and lower inner strip line conductor 22 equally from outer conductor ground plane members 10 and 12. The output signals present at output connectors 21 and 31 are equiphase because the signal paths from the inputare completely symmetrical. The inventive hybrid is similar in construction to known hybrids except that two of the hybrid arms are removed and two strip line conductors are added on the upper and lower portion of a centrally positioned dielectric. The addition of the strip two line conductor allow the instant hybrid to operate as if the removed hybrid arms were present. Outer conductor ground plane members 10 and 12 are several times wider than the upper and lower inner strip line conductors 20 and 22, as taught on page 775 of the book entitled, Encyclopedic Dictionary of Electronics and Nuclear Engineering, by Robert I. Sarbacher and printed by Prentice-Hall, Inc., Englewood, N.J., in the original printing in 1959, and having Library of Congress Catalog Card Number 59- 11990.

As will be evident to those skilled in the art, energy in the brass interconnecting conductor and parallel arm shorting bar 40 will be propagated in the upper and lower dielectrics 32 and 34 by means of the strip transmission line configuration of the components. Similarly, radio frequency energy Within the strip hybrid power divider will be propogated by such strip transmission. line configuration to both center conductors 26 and 36 of output connectors 21 and 31 with equal phases and maximum amplitudes, provided there is a precise quarter wave length spacing between the junction of the brass interconnecting conductor and parallel arm shorting bar with the upper and lower inner strip line conductors and the two output center conductors 26 and 36.

FIGURE 2 shows the various characteristic impedances which are of interest. /2R0 represents the impedance of each line connecting input terminal 9 to output terminals 19 and 29. The parallel combination of these two impedances is Ro/ /2. This is the equivalent charac teristic impedance of the composite structure. The characteristic impedance of the two physically removed arms 39 is shown by 2R0 in the configuration.

FIGURE 3 simply shows a possible alternative embodiment wherein the parallel arms for the strip hybrid power divider are in a co-planar arrangement.

While modifications and changes may be made in the constructional details and features of this invention without departing from the spirit or scope thereof, it is to be understood that I desire to be limited only in the scope of the appended claims.

I claim:

1. A hybrid power divider in a strip transmission line environment comprising: an input connector and first and second isolated output connectors, said input connector and said first and second isolated output connectors each having a center conductor and a surrounding body portion; said transmission line having an upper and a lower inner strip line conductor disposed between upper and lower outer conductor ground plane member; a body of solid dielectric material separating said upper and lower inner strip line conductors for at least one quarter wave length, said upper and lower inner strip lines being positioned in a straight line; an interconnecting conductor and parallel arm shorting bar, said interconnecting conductor and parallel arm shorting bar being electrically connected between said center conductor of said input connector and a junction of said upper and lower inner strip line conductors, said center conductor of said first isolated output connector electrically connected to said upper inner strip line conductor at one quarter wave length from said junction, said center conductor of said second isolated output connector electrically connected to said lower inner strip line conductor at one quarter wave length from said junction, said surrounding body portion of said input connector being fixedly attached to both of said upper and lower outer conductor ground plane members, said surrounding body .4 portion of said first isolated output connector being fixedly attached to said upper outer conductor ground plane member and said surrounding body portion of said second isolated output connector being fixedly attached to said lower outer conductor ground plane member, the arrangement forming an electrically conductive strip transmission line system for dividing radio frequency power.

2. A hybrid power divider in a strip transmission line environment as set forth in claim 1 wherein said input and output connectors are type N coaxial connectors.

References Cited UNITED STATES PATENTS 3,089,103 5/1963 Oliner 333-9 3,091,743 5/1963 Wilkinson 333-11 XR 3,164,791 1/1965 Dent 333-41 HERMAN K. SAALBACH, Primary Examiner.

M. NUSSBAUM, Assistant Examiner.

US. Cl. X.R.

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