JPH0388402A - Wireless frequency dividing net - Google Patents

Abstract

PURPOSE: To improve a bandwidth at a low loss by providing a dimension and a formation that the radio frequency signal input of a common input node is equally divided at the entire branch output port. CONSTITUTION: A frequency network is composed of sixteen same branches 1a to 1p extending between a 1st common node 2 and a 2nd common node 3, and each branch 1 is formed by three coaxial cables having the same length and connected by a 1st branch node 4 and a 2nd branch node 5. In using, sixteen same radio frequency signals are supplied to branch input ports 7a to 7p, and a signal appeared in the output port 8 is to be the sum of input signals. Then, it has the dimension and formation that the radio frequency signal of the specified frequency input of the 1st common node 2 connected to the common input port is equally divided at the entire branch output port. Thus, the bandwidth is extended at a low loss.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a radio frequency network that can be used to split a radio frequency signal or to combine a plurality of radio frequency signals.

[Conventional technology]

Applications of frequency couplers are particularly in transmitters, for example television transmitters. Traditionally, television transmitters have used a talistron in the radio frequency stage to amplify the signal sent to the antenna.

Klystrons can generally successfully and reliably perform this work, but they require complex cooling systems, typically use circulating water, and therefore require regular maintenance. There is. Additionally, if the klystron fails, the transmitter will no longer work.

[Problem to be solved by the invention]

For these reasons, there is a movement to replace klystrons with arrays of solid-state radio frequency amplifiers operating in parallel. In the case of arrays or parallel solid state amplifiers, it is necessary to combine the in-phase output signals so that the failure of any individual amplifier does not invalidate the entire output.

[Means to solve the problem]

The present invention relates to a radio frequency network consisting of a first common node connected to a common input or output port, a second common node, and at least three branches therebetween, each branch connected to a balanced load. A first branch node connected to a first branch node and a second branch node connected to a branch output or input port at a distance therefrom. In the above frequency network, the radio station/wave number signal of a specific frequency input of the common input port is divided equally among all the branch output ports, and multiple identical radio frequency signals of the specific frequency given in the same phase to all branch input ports are output as a common output. They are sized and configured to appear coupled at a port.

It is desirable that all the distances between the nodes be equal to 1/4 of the working wavelength of the input values. However, for many applications, narrow bandwidth frequencies are unsatisfactory. This is because it is known that the impedance value of the branch portion between each of the second common node and the first branch node has some influence on the bandwidth of the frequency network. The bandwidth can be increased by selecting appropriate impedances for these parts. It is desirable that its impedance be low relative to other parts of the frequency network.

To increase the bandwidth, install a 1/4 wavelength converter between the first common node and the common input/output port, and make the length of the additional line 1/4 of the wavelength at the center of the bandwidth. This can be done by:

It is also advisable to improve the bandwidth by connecting to the first common node a shorting stub having a length, for example, equal to a quarter wavelength. As an example, this structure allows for an input VSWR of less than 1.021
A 20W coupler with a bandwidth of ~109 MIIz can be realized.

When using a radio frequency network as a splinter, when each output load fails, the input matching degrades, but all other inputs remain at the same amplitude and phase. This degradation in input performance can be eliminated, for example, by a circulator.

When using a radio frequency network as a combiner, when each input fails, the output power will drop somewhat below this input value, depending on the number of inputs that have already failed.

Most of the excess verso appears in loads adjacent to the failed input, while the remainder is evenly distributed around other loads.

The radio frequency network of the present invention can be constructed by coaxial cables, multiwire cables, waveguides, or even LC circuits, thereby providing a 90° phase shift.

In order to make it easier to physically realize the above-mentioned frequency network, it is convenient to make the quarter wavelength line an odd multiple of the quarter wavelength. However, increasing the length has the disadvantage of narrowing the working bandwidth.

〔Example〕

Referring to FIG. 1, the frequency network consists of 1G identical branches 1a-1p extending between a first common node 2 and a second common node 3. Each branch 1 is composed of three equal length coaxial cables connected at a first branch node 4 and a second branch node 5. A balanced load 6 is connected to the first branch node 4, while
The branch input port door is connected to the second branch node 5. The length between the nodes is in each case one quarter of the wavelength at the center of the working bandwidth of the frequency network, so that a phase shift of 90' is imparted in each part of the frequency network for that wavelength. The first common node 2 is connected to the output port 8 .

In use, 16 identical radio frequency signals are applied to branch input port door a-7p. The signal appearing at output port 8 is essentially the sum of the input signals.

Now, referring to Figure 2, the bandwidth of the frequency network is the first
It can be increased by connecting a quarter wavelength converter 9 between the first common node 2 and the output capo 18 of the frequency network shown in the figure. The above configuration can be further improved by connecting a shorted quarter-wave stub 10 to the first common node 2. Bandwidth can also be improved by adjusting the impedance of the lines extending between the second common node 3 and the first branch nodes 4a-4p. The effects of these modifications are illustrated in Figure 3.4.5.

FIG. 3 shows insertion loss and input VSWR versus frequency for the frequency network shown in FIG. 1. In each branch,
The impedance of the line from the second common node 3 to the first branch node 4 is 280 ohms, and the impedance of the line between the two branch nodes 4.5 is 50 ohms.
ohms, and the impedance of the third line is 12.5 ohms.

It can be seen that the loss and VSWR increase rapidly as the distance from the center frequency of 670M1lz increases.

FIG. 4 shows the effect of the circuit according to FIG. However, in that case there is no shorting stub. Within each branch 1, the second common node 3 to the first common node 2
Impedances of 5 ohm, 50 ohm, and 100 ohm are set respectively.

The quarter wavelength converter has an impedance of 25 ohms. It will be seen that the bandwidth with very little loss is much larger, spanning the range of about 470-960 Mllz, and that the VSWR in this range is also considerably reduced.

FIG. 5 shows the effect of adding a shorting stub with an impedance of 49 ohms. The impedance of the line in each branch extending from the second common node to the first branch node increases to 50 ohms, all other impedances remaining the same. Loss is 470-8'60
VSW increases only slightly with respect to MHz bandwidth.
It can be seen that R is further significantly reduced.

The frequency network described with reference to the figures is constructed symmetrically with respect to impedance, but by changing the ratio of the impedance in one branch to any impedance in the remaining branches, the power in that branch is It was found that it changes for each power. This is useful for use in sprinters when it is desired to distribute the output power unevenly.

Although the radio frequency network of the present invention has been described with respect to a television transmitter, it can be used with many other types of transmitters and where multiple radio frequencies are combined together or generated from a single identical signal. It is something.

[Brief explanation of drawings]

FIG. 1 is a diagram of a 1'6-way coupler according to an example of the present invention, FIG. 2 is a diagram of a modification of the coupler shown in FIG. 1, and 3.4.5
The figures are graphs of insertion loss and VSWR with respect to frequency for the frequency network shown in FIG. 1, the frequency network without stubs in FIG. 2, and the frequency network with stubs in FIG. 2, respectively. 2...First common node, 3...Second common node, 1a to 1p...Branch,
4...First branch node, 5...
Second branch node 3 7...branch port, 9...quarter wavelength converter, 10'...stub, drawing engraving (no change in content) Figure 2 JP-A-88402 (5) Figure 3 Procedural amendment (method) % formula % 2. Name of the invention Radio frequency division network 3. Person making the amendment Name of applicant related to the case 7゛Marconi Co., Ltd. 4. Agent 5, date of amendment order: July 31, 2016, Ime 1: ``River υJl''

Claims (15)

[Claims] 1. a first common node connected to a common input port, a second common node, and at least three identical branches therebetween, each branch connected to a first branch node to which a balanced load is connected; a second branch node spaced apart from and connected to the branch output ports, the size and configuration of which is such that the radio frequency signal input at said second common node is divided equally among said branch output ports; Split net. 2. The impedance of the branch portion between each of the second common node and the first branch node is such that substantially the entire radio frequency signal having any one of the frequency input ranges at the common input port is output from the branch output. 2. The radio frequency division network of claim 1, wherein the radio frequency division network is divided evenly among the ports. 3. The impedance of each branch portion between the second common node and the first branch node is considerably lower than the impedance of the branch portion between the first and second branch nodes, and 3. The radio frequency division network of claim 2, wherein the impedance is lower than the impedance of the branch portion between. 4. 3. The radio frequency network of claim 2 comprising a shorting stub connected to said first common node. 5. 5. The radio frequency division network of claim 4, wherein the length of the stub is equal to the length of any branch between the first common node and the second branch node. 6. 3. The radio frequency of claim 2, further comprising a quarter wavelength converter connected between said first common node and a common input port, the length of said converter being one quarter of the center wavelength of said range. Split net. 7. 3. The radio frequency division network of claim 2, wherein each portion of each branch has a length equal to one quarter of the center wavelength of said range. 8. consisting of a first common node connected to a common output port, a second common node, and at least three identical branches therebetween, each branch being connected to a first branch node to which a balanced load is connected. and a second branch node connected to a branch input port spaced apart therefrom, the dimensions and configuration of which is such that a plurality of identical radio frequency signals applied in phase across said branch input ports are connected to said first branch input port. A radio frequency coupling network configured to appear coupled to a common node. 9. The impedance of the branch portion between the second common node and each of the first branch nodes is such that a plurality of identical radio frequencies, all in one of the frequency ranges, are all applied to the entire branch input port in the same phase. 10. The radio frequency coupling network of claim 9 which appears coupled to a substantially common output port. 10. The impedance of each branch portion between the second common node and the first branch node is
and the second branch node, the impedance of the branch portion between the second branch node and the first branch node is substantially lower than the impedance of the branch portion between the second branch node and the first
10. The radio frequency coupling network of claim 9, wherein the impedance is lower than the impedance of the branch portion between the common nodes. 11. 10. The radio frequency coupling network of claim 9 comprising a shorting stub connected to said first common node. 12. 12. The radio frequency coupling network of claim 11, wherein the length of the stub is equal to any portion of the branch between the first common node and the second branch node. 13. 10. The radio frequency of claim 9, comprising a quarter-wavelength converter connected between said first common node and a common input port, the length of said converter being one-fourth of the center frequency of said range. network. 14. 10. The radio frequency coupling network of claim 9, wherein each portion of each branch has a length equal to one quarter of the center frequency of the range. 15. an amplification stage comprising a video modulated radio frequency signal input, signal splitting means for splitting said signal into a plurality of equal signals, and a plurality of solid state amplifiers operating in parallel, each of said equal signals being connected to said solid state amplifier. and the output of each of the amplifiers is connected to a plurality of input ports and a combining network, which connects a plurality of input ports and a video modulating signal to which the audio modulating signal is combined. a common output port connected to a signal mixing stage for mixing, and the coupling network has a first common node connected to the common output port, a second common node, and the first and second common nodes. a plurality of identical branches between common nodes, each of which is connected to a first branch node to which a balance load is connected;
a second connected to each of the above input ports separated therefrom;
a branch node, wherein the dimensions and configuration of said coupling network are such that said output appears coupled at said output port from a solid state amplifier.