JPH0846528A - Power combiner circuit - Google Patents

Abstract

PURPOSE:To obtain the power combiner circuit in which which frequencies are easily matched by inserting an inductive impedance to a feeding point of an antenna to cancel a capacitive impedance by other tuner. CONSTITUTION:Plural radio equipments 3a-3d sending a radio wave with a different frequency are connected to a common antenna 1 via tuners 2a-2d and a coaxial line 5 in the power combiner circuit 4. Then a reactance circuit is inserted between a feeding point 10 of the antenna 1 and a connecting point of a coaxial line 5 by connecting coils 6, 8 and a capacitor 7. Thus, a delay current flowing to other tuners is partly cancelled by using the delay current flowing to the coil 6 and part of a lead current flowing to the other tuners is partly cancelled by supplying the delay current to a series circuit comprising the capacitor 7, the coil 8, a coaxial cable 9 and the antenna 1 to improve the overall VSWR (voltage standing wave ratio).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power combining circuit for combining power from a plurality of tuners and outputting the combined power to one common antenna in an antenna common matching device.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing the structure of a conventional combining circuit of this type, where 1 is an antenna, 1a, 1b, 1c,
1d is a coaxial line, 2a, 2b, 2c and 2d are tuners, 3a, 3b, 3c and 3d are radios, 4 is a power combining circuit, and 5 and 9 are coaxial lines.
Reference numeral 9 is a type of coaxial cable that is a coaxial line. In this specification, the antenna feeding point is the coaxial cable 9
It means the starting point 10 of.

FIG. 3 shows a tuner 2 (2a, 2b, 2c, 2).
When d is not specified, it is represented by 2. In the connection diagram showing the internal configuration of the wireless device 3 as well), L1 and L2 are fixed coils, and C
1, C2, C3 and C4 are variable capacitors. Normally, L1 and L2 are loosely coupled to each other, and L1
And C2, L2, and C3 are adjusted to substantially parallel tuning with respect to the used frequency, respectively, and the ratio of the currents I1 and I2 flowing through the capacitors C2 and C3 is approximately I1 / I2 = C2 / C3.
And the voltages E1 and E2 at both ends are approximately E1 / E
2 = C3 / C2.

Therefore, the magnitude of impedance can be adjusted by adjusting C2 / C3. Also, C
The phase angle of the impedance can be adjusted by adjusting 1, C4. The impedance of the feeding point 10 of the antenna 1 is phase-rotated between the coaxial lines 5 and 1a, and the tuner 2
Assuming that the impedance at the output point of a is r + jx, the output impedance of the tuner 2a is a conjugate of the impedance r-jx.
If so, it means that the tuning by the tuner 2a is completed.

Therefore, the ideal characteristic of the tuner 2 is that it can perfectly match the impedance of the antenna feed point with respect to self-transmitted waves, and exhibit infinite impedance with respect to other frequencies. Is desirable. As described above, by adjusting the capacitances of C1 to C4, it is possible to match in a considerably wide frequency range, but the impedance to other frequencies becomes relatively low, so that a large number of radios 3 are connected to the common antenna 1. There is a problem that matching is difficult due to the influence of the other tuner 2 when the power is combined with.

[0006]

Since the conventional power combiner circuit is constructed as described above, when combining powers from a large number of tuners, VSWR is caused by the influence of impedances from other tuners. There is a problem that a frequency at which the (voltage standing wave rate) is significantly lowered is generated and matching cannot be performed at that frequency.

FIG. 4 is an explanatory diagram showing the influence of parallel connection of other tuners on the standing wave rate. The frequencies used are represented by the numbers shown in column 41, and the numbers 1, 2, 3, and 4 are used. Assume the antenna feedpoint impedance for each frequency as in column 42. In these values shown in the column 42, the value of VSWR for the characteristic impedance of 50Ω is 4 in all cases. Since the output impedance of the radio device 3 is adjusted to be approximately 50 ohms at the output frequency, the antenna feed point impedance in each tuner is shown in the column 42.
It is easy to match the range of.

The equivalent impedance (column 43) when two sets of tuners are connected in parallel is the impedance of another tuner as seen from the coaxial line side, -j500Ω, the rotation of the coaxial line until reaching that position. When the angle is calculated as 2π (0.033), the value becomes the value shown in the column 431, and the VSWR for the coaxial line having the characteristic impedance of 50Ω is the column 432.
It becomes as shown in. It is well known that the rotation angle is 2πl / λ, where l is the length of the coaxial line and λ is the wavelength in the line.

When the column 42 does not include an imaginary part (pure resistive impedance), VSWR of the column 432 does not decrease so much, and when the lagging impedance (inductive impedance) does not exist, another tuner is used. The VSWR is improved from 4 to 3 due to the capacitive load due to V. With respect to the phase-advancing impedance (capacitive impedance), the phase angle of the impedance is further advanced due to the capacitive load due to another tuner, and VSWR is lowered. I know that With this level of VSWR, matching is possible with each tuner.

Similarly, in the case of FIG. 2 in which four sets of tuners are connected in parallel, a frequency at which VSWR deteriorates to 8.7 occurs as shown in the column 44. There is a possibility that it will be out of the matching range due to 2.

An object of the present invention is to provide a power combining circuit which can be matched by the tuner 2 even in such a case.

[0012]

In the power combining circuit according to the present invention, each of a plurality of radios transmitting radio waves of different frequencies is connected to a common antenna via a tuner and a coaxial line. In the connected power combiner circuit,
A reactance circuit is inserted between the feeding point of the antenna and the connection point of the coaxial line, and the equivalent impedance of the antenna seen from the output point of any of the plurality of radios transmitting the different frequencies. Is also provided with a means for adjusting so as to change in the delay direction (direction in which the capacitive phase angle decreases, that is, direction in which the inductive phase angle increases).

The reactance circuit is inserted between a coil connected between a connection point of the antenna and the coaxial circuit and a ground potential, and between the connection point and a supply point of the antenna. And a series circuit of a capacitor and a capacitor.

Further, in the reactance circuit, the coaxial line is connected to the transmission frequency of a radio device that transmits a frequency at which the impedance at the feeding point of the antenna is capacitive among the plurality of radio devices that transmit different radio waves. It is characterized in that it operates so as to cancel out a part of the capacitive impedance exhibited by the tuners connected in parallel via.

[0015]

In the power combiner circuit of the present invention, an inductive impedance is inserted at the feeding point of the antenna to cancel the capacitive impedance of another tuner.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention.
The same reference numerals as in FIG. Further, 6 and 8 are coils, and 7 is a capacitor. A phase-advancing current flowing to another tuner is partially canceled by a phase-delaying current flowing in the coil 6, and a phase-delaying current flows in the series circuit of the capacitor 7, the coil 8, the coaxial cable 9 and the antenna 1. , It is possible to cancel a part of the phase-advancing current flowing to the other tuner, and improve the overall VSWR.

That is, the results shown in columns 45 and 46 are obtained by appropriately selecting the values of the coils 6, 8 and the capacitor 7 for the conventional circuits of columns 43 and 44. In addition,
It goes without saying that the values of the coils 6 and 8 and the capacitor 7 in the above embodiment are selected for the case of four sets connected in parallel.

[0018]

As described above, according to the present invention, a power combining circuit for connecting a large number of tuners to a common antenna,
This has the effect of canceling the capacitive load exhibited by other tuners and obtaining a power combining circuit that can be easily matched at any frequency.

[Brief description of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional circuit.

FIG. 3 is a connection diagram showing a configuration of a tuner.

FIG. 4 is an explanatory diagram showing the influence of another tuner on the standing wave rate.

[Explanation of symbols]

 1 Antenna 2 Tuner 3 Radio 4 Power combiner circuit 5 Coaxial line 6 Coil 7 Capacitor 8 Coil 9 Coaxial cable 10 Antenna feeding point

Claims (3)

[Claims] 1. A power combining circuit in which each radio of a plurality of radios transmitting radio waves of different frequencies is connected to a common antenna via a tuner and a coaxial line, and a feeding point of the antenna is provided. And a reactance circuit is inserted between the connection point between the coaxial line and the coaxial line, and the phase angle of the equivalent impedance when the antenna is viewed from the output point of any one of the plurality of radios transmitting the different frequencies, A power combining circuit comprising: a means for adjusting so as to change in a delay direction (a direction in which a capacitive phase angle decreases, that is, a direction in which an inductive phase angle increases). 2. The reactance circuit is inserted between a coil connected between a connecting point of the antenna and the coaxial circuit and a ground potential, and between the connecting point and a feeding point of the antenna. The power combiner circuit according to claim 1, wherein the power combiner circuit is configured by a series circuit including a coil and a capacitor. 3. The reactance circuit uses the coaxial line for the transmission frequency of a radio device that transmits a frequency at which a feeding point impedance of an antenna is capacitive among a plurality of radio devices that transmit different radio waves. 3. The power combiner circuit according to claim 2, wherein the power combiner circuit operates so as to cancel out a part of the capacitive impedance exhibited by the tuners connected in parallel via the circuit.