GB2165707A - Microwave power divider/combiner circuits - Google Patents

Abstract

A microwave stripline circuit for dividing microwave signal power any number of ways for amplification employs a divider (16) including a folded line (32) to present a pair of amplifiers (47) with signals 180 DEG out of phase. A combiner (17) on the other side of the amplifiers has a folded line (37). The divider input (14) and the combiner output (15) are each arranged between a pair of lines (43, 44), (50, 51) connected to respective amplifiers, at a distance of one-quarter wavelength from one line and an effective distance of three- quarters wavelength from the other line due to the folding. All lines are arranged in a rectangular array. <IMAGE>

Description

SPECIFICATION Microwave circuits This invention relates to microwave circuits, specifically microwave stripline circuits and more particularly to a power divider-combiner for such circuits.

A Planar N-way Combiner/Divider for Microwave circuits is disclosed in U.S. Patent No. 4,463,326 issued July 31, 1984.

According to the invention in its broadest aspect there is provided a microwave stripline circuit comprising a conductive member providing a ground plane, a layer of insulation having one side bonded to the conductive member, a plurality of power amplifiers having inputs and outputs, an input power divider connected to the amplifier inputs, an output power combiner connected from the amplifier outputs, an input conductor connected to the divider, an output conductor connected from the combiner, the divider having first and second parallel transverse conductors spaced apart one-quarter wavelength, the first and second conductors having first and second pairs of adjacent ends connected by third and fourth parallel longitudinal conductors normal to the first and second conductors, the input conductor being connected to the first conductor normal thereto one-quarter wavelength from the fourth conductor, the balance of the first conductor being a folded line of an elec tricai length equal to three-quarters of a wavelength but of a linear length equal to onequarter wavelength, the combiner having fifth and sixth transverse conductors parallel to the first and second conductors and spaced onequarter wavelength apart, seventh and eighth longitudinal conductors in line with the third and fourth conductors, respectively, and connecting pairs of adjacent ends of the fifth and sixth conductors in positions normal thereto, one amplifier being connected from the third conductor to the seventh conductor, another amplifier being connected from the fourth conductor to the eight conductor, the output conductor being connected to the sixth conductor normal thereto one-quarter wavelength from the sixth conductor, the balance of the sixth conductor being a folded line of an electrical length equal to three-quarters wavelength but of a linear length equal to one-quarter wavelength, all of the conductors being bonded to the other side of the layer of insulation.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a top plan view of a known divider; Figure 2 is a longitudinal sectional view of the divider taken on the line 2-2 shown in Fig. 1; Figure 3 is a top plan view of a dividercombiner constructed in accordance with an embodiment of the present invention; Figure 4 is a longitudinal sectional view of the divider-combiner taken on the line 4-4 shown in Fig. 3; and Figure 5 is a diagrammatic view of the divider-combiner shown in Fig. 4.

A conventional power divider 10 is shown in Fig. 1 bonded to a layer of insulation 11 (Fig. 2), which in turn, is bonded to a conductor 13. Conductor 13 provides a ground plane for a microstrip (i.e. microwave stripline) circuit for operation at S band. Operation of a circuit according to the present invention shown in Figs. 3-5 occurs, for example, between 2.9 and 3.1 GHz.

In Fig. 3, input and output conductors are provided at 14 and 15, respectively. Conductors 14 and 15 are connected to and from a divider 16 and a combiner 17, respectively.

Resistive terminations 18 are connected midway along portions 19-23 of divider 16 and resistive terminations 24 are connected midway along portions 25-29 of combiner 17.

Divider 16 and combiner 17 may be constructed with the proportions shown in Fig. 4.

Portions 30-34 of divider 16 correspond to portions 39-35 of combiner 17.

Electrical connectors 40 connect portions 41-46 of divider 16 to a set of amplifiers 47, the outputs of amplifiers 47 are connected to portions 48-53 of combiner 17 by connectors 54.

As shown in Fig. 4, divider 16 is bonded to an insulator block 55 which, in turn, is bonded to a conductive plate 56 providing a ground plane.

Respective pairs of radio frequency (RF) amplifiers 47 are fixed to each of a plurality of insulator blocks 57 (not completely shown in Fig. 4). Th amplifiers 47 are shown only diagrammatically and only in Fig. 3. Insulator blocks 57 are bonded to plate 56 as shown in Fig. 4.

Divider 16 and combiner 17 are shown diagrammatically in Fig. 5. Note that all portions 14, 15, 30-34, 41-46, 19-23, 25-29, 48-53, 35-39, and 15 are parallel either to a vertical line or to a horizontal line except for portions 32 and 37. All portions of 32 and 37 also lie on lines parallel to a vertical line or a horizontal line. "Portion 32" refers to the shortest conductive distance (electrical length) connecting the left ends of portions 43 and 44. "Portion 37" refers to the shortest conductive distance connecting the right ends of portions 50 and 51.

The dimensions shown in terms of wavelength A in Fig. 5 are both the electrical lengths and linear lengths indicated except for the 3 A/4 dimensions. The 3 A/4 dimensions are the electrical length only of the upper folded line of portion 32 above conductor 14, and the electrical length only of the lower folded line of portion 37 below conductor 15.

The two folded lines of portions 32 and 37 may take a variety of forms different from those shown.

The folded lines in the divider 16 and in the combiner 17 should be on opposite sides of the vertical locations of conductors 14 and 15. However, the present invention may provide an n-way divider-combiner where N is either a positive odd integer iarger than 2 or a positive even integer equal to or larger than 2.

For example, if n=2, only conductors 14, 32, 43, 21, 44, 27, 50, 51, 37 and 15 are employed.

If n=3, all of the n=2 conductors are employed with 31, 42, 20, 38, 52 and 28.

An alternative n=3 includes the n=2 conductors plus 33, 44, 22, 26, 49 and 36.

The divider-combiner shown in Fig. 4 is a 6way divider-combiner. A 4-way divider-combiner may be made simply by omitting (from the 6-way) 30, 41, 19, 25, 48, 35, 34, 46, 23, 29, 53 and 39.

Amplifiers 47 and the materials of insulators 55 and 57 are entirely conventional. The same is true of the conductive material of conductor 56 and the bonding material.

The connectors 40 and 54 are conventional.

The same is true of resistive terminations 18 and 24.

The following portions (including conductors 14 and 15) of the divider-combiner in Fig. 3 are made of a conventional conductive material: 30-34, 41-46, 19-23, 25-29, 48-53 and 35-39.

The power supplied to combiner 17 in Fig.

3 via one connector 54 is equal to that supplied by each of the others. The combining efficiency is about 95 percent. All the power is ultimately delivered via conductor 1 5.

It will be noted that, in the prior art, n-way divider-combiners were unknown except where n=2P and p is a positive integer. Thus, n=3, n=5, n=6 or n=7, for example, were not possible in the prior art.

The folded lines in portions 32 and 37 place the signals at the right ends of conductors 43 and 44 180 degrees out of phase with respect to each other. This keeps the amplifiers connected thereat from interacting.

The prior art type divider-combiner of Fig. 1 is undesirable for at least two reasons, namely, that it requires more space and that it is more lossy.

Claims (4)

1. A microwave stripline circuit comprising a conductive member providing a ground plane, a layer of insulation having one side bonded to the conductive member, a plurality of power amplifiers having inputs and outputs, an input power divider connected to the amplifier inputs, an output power combiner connected from the amplifier outputs, an input conductor connected to the divider, an output conductor connected from the combiner, the divider having first and second parallel transverse conductors spaced apart one-quarter wavelength, the first and second conductors having first and second pairs of adjacent ends connected by third and fourth parallel longitudinal conductors normal to the first and second conductors, the input conductor being connected to the first conductor normal thereto one-quarter wavelength from the fourth conductor, the balance of the first conductor being a folded line of an electrical length equal to three-quarters of a wavelength but of a linear length equal to one-quarter wavelength, the combiner having fifth and sixth transverse conductors parallel to the first and second conductors and spaced one-quarter wavelength apart, seventh and eighth longitudinal conductors in line with the third and fourth conductors, respectively, and connecting pairs of adjacent ends of the fifth and sixth conductors in positions normal thereto, one amplifier being connected from the third conductor to the seventh conductor, another amplifier being connected from the fourth conductor to the eight conductor, the output conductor being connected to the sixth conductor normal thereto one-quarter wavelength from the sixth conductor, the balance of the sixth conductor being a folded line of an electrical length equal to three-quarters wavelength but of a linear length equal to one-quarter wavelength all of the conductors being bonded to the other side of the layer of insulation.

2. A microwave stripline circuit as claimed in claim 1, wherein the first and second conductors have half-wave first extensions at least at one end thereof, and at least a ninth longitudinal conductor connecting the ends of the extensions to the input of a third-way power amplifier, the fifth and sixth conductors having half-wave second extensions in directions opposite to those connected to the first and second conductors, and a tenth longitudinal conductor connecting the adjacent ends of the second extensions to the output from the third-way power amplifier.

3. A microwave stripline circuit as claimed in claim 2, wherein a resistive termination is connected midway along the second and fifth conductors and the extensions thereof.

4. A microwave stripline circuit substantially as described with reference to Figs. 3 to 5 of the accompanying drawings.