Structure of a duplexer for radio equipment

Abstract: A structure of a duplexer for duplex radio equipment has a transmission circuit board loaded with a transmitter section and a transmit filter for filtering a high frequency signal fed from the transmitter section. A reception circuit board physically independent of the transmission circuit board is loaded with a receive filter for filtering a received high frequency signal and a receiver section for receiving the high frequency signal from the receive filter. A connection circuit board mechanically connects the transmission circuit board and reception circuit board and is loaded with a matching circuit for matching the phase of the high frequency signal to be inputted to the receive filter and the phase of the high frequency signal outputted by the transmit filter. Connectors electrically interconnect the transmit filter and receive filter to the matching circuit.

Description: BACKGROUND OF THE INVENTION The present invention relates to a duplexer for duplex radio equipment and, more particularly, to a segmentalized duplexer for duplex radio equipment. A duplexer is one of major component parts of radio equipment and selectively serves a transmitting function and a receiving function. The transmitting function is implemented by a transmitter section, a transmit filter, and a matching circuit to which a transmit signal is applied from the transmitter section via the transmit filter. The transmit signal is fed from the matching circuit to an antenna to be radiated as a transmit signal wave. The receiving function is implemented by a receive filter, a receiver section, and the matching circuit which feeds a received wave coming in through the antenna to the receiver section via the receive filter. It has been customary to mount all the circuit sections of the duplexer including the transmitter section, receiver section, transmit and receive filters and matching circuit on a single printed circuit board. Such a configuration has the following problems. (1) Freedom available in mounting the various parts and elements is severely limited. This is especially problematic when it comes to portable radio equipment which need extremely dense arrangements. (2) It is difficult to examine the characteristics of the transmitter section only or those of the receiver section only. This impedes maintenance which is needed in the event of the failure of the equipment (3) The specifications of the transmit filter or those of the receive filter are usually changed by redesigning the matching circuit. The matching circuit, therefore, cannot be redesigned unless the whole printed circuit is redesigned. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a structure of a duplexer for radio equipment which promotes efficient mounting and facilitates maintenance and design changes. A structure of a duplexer for duplex radio equipment has a transmission circuit board loaded with a transmitter section and a transmit filter for filtering a high frequency signal fed from the transmitter section. A reception circuit board physically independent of the transmission circuit board is loaded with a receive filter for filtering a received high frequency signal and a receiver section for receiving the high frequency signal from the receive filter. A connection circuit board mechanically connects the transmission circuit board and reception circuit board and is loaded with a matching circuit coupled to the transmit and receive filters and an antenna for matching the impedance thereof. Connectors electrically interconnect the transmit filter and receive filter to the matching circuit. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken with the accompanying drawings in which: Fig. 1 is a perspective view of a duplexer embodying the present invention; and Fig. 2 is a block diagram schematically showing electric circuitry of the duplexer shown in Fig. 1. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to Fig. 1 of the drawings, a duplexer for radio equipment embodying the present invention is shown and generally designated by the reference numeral 10. As shown, the duplexer 10 is generally made up of a transmission circuit board 12, a reception circuit board 14, and a connection circuit board 16 which are physically independent of one another. The connection circuit board 16 connects the transmission and reception circuit boards 12 and 14 generally in a U configuration. The transmission circuit board 12 has a transmitter section 18 and a transmit filter 20 and outputs a high frequency signal to be transmitted. The transmit filter 20 filters out noise from the the output signal of the transmitter section 18 so as to pass only the predetermined high frequency signal. The reception circuit board 14 has a receiver section 22 and a receive filter 24. The receiver section 22 receives a high frequency signal from a remote station, not shown, while the receive filter 24 passes only the predetermined high frequency signal to the receiver section 22 by removing noise from the received signal. The reception circuit board 14 has substantially the same dimensions as the transmission circuit board 12. The transmission and reception circuit boards 12 and 14 are arranged back-to-back and in parallel to each other. As shown in Fig. 2, the connection circuit board 16 has a matching circuit 26 which is interconnected to an antenna 30 via an antenna terminal 28. The matching circuit 26 is constituted by a transmit matching section 32 and a receive matching section 34. The transmit matching section 32 matches the output impedance of transmit filter 20 and the impedance of antenna 30 and receive side (14) as viewed from the antenna terminal 28. In other words, a combination of the transmit filter 20 and transmit matching section 32 serves to pass the transmit high frequency signal from the transmit section 18 and to block the other signals. As shown in Fig. 1, the transmit matching section 32 is implemented as a line of copper foil extending out from the antenna terminal 28. The transmit matching section 32 has the same impedance as the transmit filter 20. The receive matching section 34 matches the input impedance of receive filter 24 and transmit side (12) as viewed from the antenna terminal 28. In other words, a combination of the receive filter 24 and receive matching section 34 serves to pass the receive high frequency signal from the antenna 30 and block the other signals. The receive matching section 34, like the transmit matching section 32, is implemented as a line of copper foil extending out from the antenna terminal 28 and has the same impedance as the receive filter 24. The connection circuit board 16 is affixed at its back to the adjoining ends of the parallel transmission and reception circuit boards 12 and 14, thereby supporting the two boards 12 and 14 generally in a U configuration. Connectors 36 and 38 adapted for high frequency electrically interconnect respectively the transmission circuit board 12 and the reception circuit board 14 to the connection circuit board 16. Specifically, the connector 36 sets up electrical connection of the output side of the transmit filter 20 to the transmit end 40 of the transmit matching section 32, while the connector 38 sets up electrical connection of the input side of the receive filter 24 to the receive end 42 of the receive matching section 34. In operation, to transmit a signal to a remote station, the transmitter section 18 of the transmission circuit board 12 produces a predetermined high frequency signal. The high frequency signal is routed through the transmit filter 20, connector 36 and transmit end 40 to the transmit matching section 32. The output of the matching section 32 is fed to the antenna 30 via the antenna terminal 28 and thereby radiated as a high frequency signal wave. A high frequency signal wave from a remote station comes in through the antenna 30 and is applied to the receive matching circuit 34 via the antenna terminal 28. The output of the receive matching circuit 34 is routed through the receive end 42 and connector 38 to the receive filter 24. The filtered signal from the receive filter 24 is fed to the receiver section 22. Of course, the generally U-shaped configuration of the assembly of the three physically separate circuit boards, 12, 14 and 16 shown and described is only illustrative and may be suitably changed or modified by taking account of the positions of the connectors 36 and 38 as well as other conditions. In summary, it will be seen that the present invention provides a duplexer having various unprecedented advantages, as enumerated below. (1) Various components of a duplexer such as a transmitter section, receiver section, transmit filter, receive filter and matching circuit are mounted with improved efficiency. This is especially desirable for those radio equipment which need extremely dense arrangements, e. g. portable radio equipment. (2) Since transmission, reception and connection circuit boards are physically independent of each other, the characteristics of the transmitter section and those of the receiver section can be examined independently of each other. This will facilitate maintenance when an error occurs in the equipment. (3) The transmitter section, receiver section and matching circuit can be designed independently of one another and, therefore, the designing time is reduced. Various modifications will become possible for those skilled in the art after receiving the teachings of the present disclosure without departing from the scope thereof.

Claims: A duplexer for radio equipment, comprising: a transmission circuit board loaded with a transmitter section and a transmit filter for filtering a high frequency signal fed from said transmitter section; a reception circuit board physically independent of said transmission circuit board and loaded with a receive filter for filtering a received high frequency signal and a receiver section for receiving said high frequency signal from said receive filter; and a connection circuit board mechanically connecting said transmission circuit board and said reception circuit board to each other and loaded with a matching circuit coupled to said transmit and receive filters and an antenna for matching the impedance thereof. A duplexer as claimed in claim 1, further comprising connector means for electrically interconnecting said transmit filter and said receive filter to said matching circuit. A duplexer as claimed in claim 1, wherein said reception circuit board and said transmission circuit board have the same shape. A duplexer as claimed in claim 1, wherein said matching circuit comprises a transmit matching section and a receive matching section each being connected to an antenna terminal, said transmit matching section and said receive matching section each comprising a line of copper foil provided on said connection circuit board. A duplexer as claimed in claim 1, wherein said transmission circuit board, said reception circuit board and said connection circuit board are assembled generally in a U configuration as viewed from a side. A duplexer comprising: transmitter means for generating a transmit high frequency signal; receive means for receiving a receive high frequency signal; antenna means for radiating said transmit high frequency signal and picking up said receive high frequency signal; matching means coupled to said transmitter, receiver and antenna means for matching the impedance thereof; transmit board means for loading said transmitter means thereon; receive board means for loading said receiver means thereon; and connect board means for loading said matching means thereon and mechanically connecting said transmit and receive board means. A duplexer as claimed in claim 6, wherein said connect board means comprises means for mechanically connecting said transmit and receive board means generally in a U shape as viewed from a side. A method of assembling a duplexer for duplex radio equipment, comprising the following steps of: loading a transmit filter on a transmit board; loading a receive filter on a receive board; loading a matching circuit on a connect board; electrically coupling said matching circuit to said transmit and receive filters and to an antenna, said matching circuit matching the impedance of said transmit and receive filters and said antenna; and mechanically connecting said transmit and receive boards to said connect board. A method as claimed in claim 8, wherein said connecting step comprises the step of mechanically connecting said transmit and receive boards to said connect board generally in a U shape as viewed from a side. A method as claimed in claim 8, further comprising the steps of: loading on said transmit board a transmit section coupled to said transmit filter; and loading on said receive board a receive section coupled to said receive filter.

Inventors: UEDA HIDEKI, UEDA, HIDEKI
Applicants: NIPPON ELECTRIC CO, NEC CORPORATION
Application year: 1990
Main classification: H04B1
IPC codes: H04B1, B60R1, H05K1