JPH06303009A - Multicoupler - Google Patents

Abstract

PURPOSE:To provide a multicoupler in which miniaturization and low-cost are facilitated. CONSTITUTION:In the antenna multicoupler having a sender side filter and a receiver side filter, in which one terminal of the sender side filter and one terminal of the receiver side filter are connected to a common antenna terminal 8, the sender side filter is interposed between a band elimination filter 2 and the antenna terminal 8 and includes a low pass filter 4 acting as a phase shift circuit and the receiver side filter includes a band pass filter 6, the band pass filter 6 is formed by plural dielectric coaxial resonators 18a-18d connecting to a coupling line 16 via coupling capacitors, and at least the dielectric coaxial resonator 18a at the side of a common terminal among the dielectric coaxial resonator is connected to the coupling line 16 via a capacitor 20a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a duplexer, and more particularly to a duplexer used as an antenna duplexer or a duplexer for sharing one antenna for transmission and reception, for example.

[0002]

2. Description of the Related Art FIG. 3 is a circuit diagram showing a conventional antenna duplexer.

In FIG. 3, 22 is a three-stage band elimination filter, 24 is a low-pass filter which is a π-type phase shift circuit, and these constitute a transmitting side filter. Reference numeral 26 denotes a three-stage band pass filter, which constitutes a receiving side filter. The band elimination filter side terminal of the transmission side filter is connected to the output end of the transmitter, and the low pass filter side terminal of the transmission side filter is connected to the antenna terminal 28. On the other hand, one terminal of the reception side filter is connected to the input terminal of the receiver, and the other terminal is connected to the antenna terminal 28 via a cable 30. The cable 30 is, for example, a microstrip line or a semi-rigid cable.

In such a duplexer, it is necessary to use a bandpass filter 26 as a filter on the receiving side in order to obtain a predetermined frequency characteristic. However, in the bandpass filter 26 in which a dielectric coaxial resonator is coupled with a capacitor. , The input impedance becomes a low impedance of several tens of Ω on the low frequency side of the pass band, and becomes a high impedance of several thousand Ω on the high frequency side. In this case, since the pass characteristic of the band elimination filter 22 of the transmission side filter changes greatly, the input impedance seen from the transmission side is increased by using the cable 30.

However, using a component having a large mounting area such as the cable 30 has been an obstacle to downsizing and cost reduction of the duplexer.

Therefore, an object of the present invention is to provide a duplexer which can be easily reduced in size and cost.

[0007]

According to the present invention, in order to achieve the above object, a transmission side filter and a reception side filter are provided, and one end of the transmission side filter and one end of the reception side filter are both common terminals. And a low-pass filter interposed between the band-elimination filter and the common terminal and functioning as a phase shift circuit, and the reception-side filter is connected to the band-pass filter. In a duplexer that includes a pass filter,
The band-pass filter couples each of a plurality of dielectric coaxial resonators to a coupling line, and a coupling capacitor is interposed between coupling points, and at least a common terminal side of the dielectric coaxial resonators has a dielectric coaxial resonance. Is connected to the coupling line via a capacitor,
A shared device is provided.

[0008]

Since at least the dielectric coaxial resonator on the common terminal side of the plurality of dielectric coaxial resonators of the bandpass filter that constitutes the reception side filter is connected to the coupling line via the capacitor, the transmission side sees it. The input impedance of the low-pass side of the bandpass filter becomes large and becomes small at the wide-range side. Therefore, the pass characteristic of the band elimination filter that constitutes the transmitting filter is not affected by the receiving filter. In addition, since the capacitor used in the coupling line is used in the reception side filter, it contributes to downsizing and simplifies the assembly, thus enabling further cost reduction.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of a duplexer according to the present invention. This embodiment is applied to an antenna duplexer.

In FIG. 1, 2 is a three-stage band elimination filter, 4 is a low-pass filter which is a π-type phase shift circuit, and these constitute a transmission side filter. 6
Is a four-stage band pass filter, which constitutes a receiving side filter. The band elimination filter side terminal of the transmission side filter is connected to the output end of the transmitter, and the low pass filter side terminal of the transmission side filter is connected to the antenna terminal (common terminal) 8. on the other hand,
One terminal of the receiving filter is connected to the input terminal of the receiver, and the other terminal is connected to the antenna terminal 28.

Band elimination filter 2 of the transmitting filter
In, the dielectric coaxial resonators 12a, 12b, 12c are respectively coupled to the coupling line 10 via capacitors, and the coupling inductor is interposed between the coupling points. Further, in the band pass filter 6 of the receiving side filter, the dielectric coaxial resonators 18a, 18b, 18c, 18d are respectively coupled to the coupling line 16, between the coupling points, between the connection terminal with the receiver and the antenna. A coupling capacitor is interposed between the terminal 8 and the terminal 8. In the present embodiment, the dielectric coaxial resonator 18a on the antenna terminal side of the dielectric coaxial resonator of the reception side filter is connected to the coupling line 16 via the capacitor 20a, and further the dielectric coaxial resonance. Bowl 1
8c is connected to the coupling line 16 via the capacitor 20b.

In the antenna duplexer of this embodiment, the band elimination filter 2 cuts the noise component in the reception band of the transmission signal output from the transmitter so that the noise component does not sneak into the receiver. To Then, the low-pass filter 4 functions as a phase shift circuit that cuts the harmonic components of the transmission signal and shifts the phase of the input impedance of the reception side filter of the transmission side filter as seen from the reception side to be a high impedance. . On the other hand, the band pass filter 6
Cuts unnecessary frequency band components from the received signal and inputs it to the receiver.

Generally, in a shared machine, the input impedance of the reception band of the transmission side filter as seen from the reception side and the reception as seen from the transmission side are seen so as not to affect the pass band characteristics of the transmission side and the reception side. Ideally, both input impedances in the transmission band of the side filter are infinite.

In the present embodiment, the input impedance of the reception band of the transmission side filter viewed from the reception side is infinite due to the low pass filter 4. On the other hand, since the dielectric coaxial resonator 18a is connected to the coupling line 16 via the capacitor 20a, the pass band filter 6 increases the input impedance of the transmission band of the reception side filter as seen from the transmission side. . For this reason, it is possible to reduce the size and cost of the duplexer without using a component such as a cable that hinders downsizing and cost reduction as in the past. Further, in the present embodiment, by using the capacitor used in the coupling line 16, the assembly is simplified and the cost can be further reduced. In addition, since the input impedance of the filter on the transmitting side and the input impedance of the filter on the receiving side have high impedances in the other band, a duplexer with the desired characteristics can be obtained simply by adjusting and connecting each filter individually, and adjustment is easy. Is.

FIG. 2 is a diagram showing an example of frequency characteristics of the transmission side filter and the reception side filter of the antenna duplexer of this embodiment. In FIG. 2, A shows the frequency characteristic of the transmitting filter, and B shows the frequency characteristic of the receiving filter.
In this embodiment, since the dielectric coaxial resonator on the common terminal side is connected to the coupling line via the capacitor, the attenuation pole is formed near the pass frequency band in the frequency characteristic of the receiving filter. , The characteristics at the end of the pass band have been improved to be extremely sharp. Further, because of this, it is possible to realize desired filter characteristics with a smaller size.

The duplexer of the present invention may be an integrated type in which all the filters are housed in one case or a separate type in which the filters on the transmitting side and the receiving side are housed in separate cases.

Although the above embodiments have been described with respect to the antenna duplexer, the present invention is also applied to a duplexer such as a duplexer, a diplexer, or a duplexer, which generally divides or combines a high frequency signal. be able to.

[0019]

As described above, according to the present invention, good frequency characteristics can be obtained, downsizing and cost reduction of a duplexer can be achieved, and assembling is easy and adjustment is easy.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a duplexer according to the present invention.

FIG. 2 is a diagram showing an example of frequency characteristics of a transmission-side filter and a reception-side filter of the duplexer of FIG.

FIG. 3 is a circuit diagram showing a conventional antenna duplexer.

[Explanation of symbols]

 2 band elimination filter 4 low-pass filter 6 band-pass filter 8 antenna terminal 10, 16 coupling line 12a-12c, 18a-18d dielectric coaxial resonator

Claims (1)

[Claims] 1. A transmission-side filter and a reception-side filter, wherein one end of the transmission-side filter and one end of the reception-side filter are both connected to a common terminal, and the transmission-side filter includes a band elimination filter and the band elimination filter. In a duplexer configured to include a low-pass filter interposed between the common terminal and functioning as a phase shift circuit, wherein the reception-side filter includes a band-pass filter, a plurality of the band-pass filters are provided. Each of the dielectric coaxial resonators is coupled to a coupling line, and a coupling capacitor is interposed between the coupling points, and at least the dielectric coaxial resonator on the common terminal side of the dielectric coaxial resonators is connected via the capacitors. A duplexer connected to the coupling line.