JPS6036660B2 - antenna sharing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an antenna duplexer mainly used in a radio section of a mobile communication device.

More specifically, the present invention relates to an antenna duplexer in which the transmitting side and the receiving side are each constructed using bandpass filters.

When a mobile radio device or the like performs simultaneous transmission and reception calls, it is complicated and expensive to install separate antennas for transmission and reception, so one antenna is usually used in common.

In this case, an antenna duplexer is used that uses a common antenna and has the function of separating a transmitted signal and a received signal. Since these are basically two-wave branching filters, various types of wave splitters are used for the transmission frequency and reception frequency, such as Takagi pass type, low pass type, band rejection type, and band pass type. It is composed of a combination of shapes, etc.

However, in this type of duplexer, the transmitting side and receiving side reactor wavers are combined using a coaxial cable or the like and taken out as an antenna terminal. This will be explained below using the drawings. FIG. 1 shows a conventional antenna duplexer, in which a transmitter filter 5 and a receiver filter 6 are connected by cables 3 and 4, respectively, and are connected to an antenna 1 via an antenna line 2.

At this time, the operation is as follows: First, the receiving antenna 1 passes through the cables 2 and 4, enters the receiving side filter 6, and then enters the amplifier 8.
The received signal is amplified and converted into an IF signal below, but the explanation is omitted hereafter. At this time, the received signal frequency is set at the connection point 10, and the length of the cable 3 is set so that the input impedance to the transmitting side is high impedance (open), so that the received signal does not wrap around. Similarly, the transmitted signal passes through the final power multiplier 7, the transmitting filter 5, and is fed to the antenna via the cable 3. In this case, at the connection point 10, the length of the cable 4 is set so that the receiving signal side has an infinite impedance with respect to the transmitting signal frequency. If the impedance at the respective terminals 9 and 11 of the transmitting filter 5 and the receiving filter 6 is very low (short circuit), their cables 3 and 4 will be approximately Synthesis point 10 using one with a length of a quarter wavelength
This is achieved by performing impedance conversion so that they have high impedance when viewed from the front. However, in the configuration shown in FIG. 1, it is necessary to set the cable 4 to a certain length as described above, which increases the size of the entire device.

Also, during manufacturing, the cable 4 must be connected to the transmitting side filter 5, the receiving side filter 6, and furthermore to the antenna line 2, which not only requires a lot of man-hours but also requires a work space for the connection. As a result, the device becomes larger. Frequency adjustment is also difficult. In view of the above-mentioned drawbacks, the present invention provides an antenna duplexer that is smaller, more suitable for mass production, and furthermore, frequency adjustment is easier.

An embodiment of the invention will be described below with reference to the drawings.

FIG. 2 is a diagram showing the basic configuration of the present invention.

The operating principle is the same as the conventional example. The antenna 21 is connected to a terminal 30' of an antenna duplexer 27 via a cable 22. The antenna duplexer 27 connects a transmitting filter 23 and a receiving filter 24 connected via a transmitting side multiplier 25.
The received signal is multiplied by a multiplier 26 and then converted into an IF signal, which is omitted hereafter. The present invention is designed to open impedance to the receiving frequency band when looking at the transmitting side from the connection point 30 from the antenna terminal, and at the same time open impedance to the transmitting frequency band when looking at the receiving side. The impedance conversion circuit section 31 (for example, 1/4 skin long line) is configured on one board, the transmitting section filter 23 and the receiving filter 24 are integrated, and the antenna terminal is connected from the terminal 30. It was designed to be taken out.

Such a configuration capacitively couples the input/output and interstage coupling of the transmitting and receiving band filters, and forms them on a single printed circuit board (Samurai Application No. 53-109003 filed by the same applicant). This can be realized by incorporating the impedance conversion circuit section into this printed slope.

Special exposure 1986-10 in which inter-stage coupling was performed by capacitive coupling
An example of the bandpass filter according to the invention of No. 9003 is shown in the third example.
It is shown in the figure and briefly explained. In this example, the resonators are basically coupled by capacitive coupling, and the coupling method is as follows:
An interelectrode capacitance configured on the printed circuit board 500 is used. This example is an example of a three-stage configuration. Electrode 403 in FIG.
Capacitive coupling is performed between 407, 407, 408, 408, 409, 409, and 410. Resonators 47-49
Shielding plates 42 and 43 are provided between them to prevent them from being spatially coupled. The tuning screw 44 is a part of a capacitive structure for configuring a resonant circuit together with a resonator, and specifically, it is configured using a screw or the like so that the tuning frequency can be mechanically varied. A printed circuit board 500, in which these resonant circuit parts are arranged in a case and metal patterns 404 to 409, 403, and 410 are formed on both surfaces thereof, is configured to support one end of each resonator. In addition, in Figure 3, 4
5 and 46 are input/output terminals, and 601 to 603 are fixing screws. Now, FIGS. 4A and 4B are examples of the impedance conversion circuit section which is the gist of the present application.

A is a case in which folded lines 55 and 56 are used on a printed circuit board, and a strip line using a printed circuit board is substituted for the normally used coaxial cable. Since the transmission and reception filters are capacitively coupled, the line length of this return line is normally close to g/2. Figure 4B
1 is an example in which the conversion circuit section is constituted by a band-stop reactor, and is a circuit in which inductors and external capacitors as shown at 57 and 58 are provided on a printed board 54. Figure 4C
shows its equivalent circuit. The center frequency of the filter 59 may be selected approximately at the center of the reception band, and the center frequency of the filter 60 may be selected approximately at the transmission band.

In fact, it is desirable to use a variable capacitance type external capacitor. By the way, in a filter configuration where the transmitting frequency band and the receiving frequency band are separated by tens of MHz or more, and the input impedance of the transmitting and receiving filters is designed to be open in the receiving band and the transmitting band, respectively, an impedance conversion circuit is required. Since the line lengths of the lines 55 and 56 in Fig. 4 that constitute the section can be set to 0, they can be constructed by direct connection, and as shown in Fig. 4D, the lines occupy less area on the board, resulting in a smaller size. . A more specific embodiment of the present invention will be described below.

In this example, an example will be described in which three stages of resonators are used as a transmitting filter and five stages are used as a receiving filter. As shown in FIG. 5, the resonator constituting the bandpass wave generator has an outer conductor 31 fixed to a fixing weight 38, and a center conductor section composed of a center conductor 32 and a cylinder 33. The center conductor 32 is the outer conductor 3
1, one end thereof is fixed with a screw 39, and the cylinder 33 is fixed at the other end to the center conductor 32 and at the same time to the coupling substrate 34 of the resonator. Each resonator is coupled by a capacitor (not shown) configured on this coupling substrate 34, and a tuning screw 35 sets the resonance frequency. In the case of this embodiment, as described above, the impedance conversion circuit connecting the transmitting section filter and the receiving section filter may be a straight line, and this straight line is connected together with the transmitting section filter on the printed circuit board, that is, the coupling board 34. It is configured so that the antenna terminal is taken out from the straight line.

The terminal 36 is the transmitting side, and the terminal 37 is the receiving side. In this case, the resonators are arranged in nine stages in series, and are directly connected by the printed circuit board 34, and the antenna terminal is taken out directly from the terminal 41.

Terminal 40 is a tangential connector to the antenna feed line. In this method, resonators of the same size are used, and a cylindrical resonator is fixed in an integrated housing, and a special distance or space is required for connecting the transmitting and receiving filters. Therefore, it has excellent features such as being able to be made compact in the longitudinal direction of a plurality of resonators arranged in a row, and also being economical because adjustment of the inter-stage coupling can be eliminated. Furthermore, by partially short-circuiting the lines 55 and 56 shown in FIG. 4 as necessary, frequency adjustment can be easily performed.
As described above, the present invention forms an impedance conversion circuit section using a strip line on a substrate on which an input/output section forming at least a part of a band-moderated overheat wave filter or an inter-coupling section is formed. This allows miniaturization and mass production, and furthermore, frequency adjustment is easy, and its industrial value is great.

[Brief explanation of the drawing]

FIG. 1 is an electrical wiring diagram of a conventional antenna duplexer, and FIG. 2 is a block diagram showing the principle configuration of the antenna duplexer of the present invention.
FIG. 3 is a sectional view showing an example of the configuration of a capacitively coupled bandpass filter, FIGS. 4A to D are views showing an example of the configuration of a switching circuit, and FIG. 5A is an antenna in an embodiment of the present invention. Figure B is a front view showing a specific configuration of the shared device, and Figure B is a bottom view thereof. 21"...Antenna, 22""Cable, 23...
・Transmission filter number, 24... Reception filter number,
25... Transmitting side amplifier, 26... Receiving side amplifier, 31... Impedance conversion circuit section. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. A bandpass filter whose input/output or interstage coupling part is formed on a printed circuit board by a conductor pattern, an antenna electrically connected to the printed circuit board for transmitting and receiving, and a strip line on the printed circuit board. What is claimed is: 1. An antenna duplexer comprising: an impedance conversion circuit section formed by the above, and a transmission circuit and a reception circuit that perform transmission and reception via the antenna, the front impedance conversion section, and the bandpass filter.