JPH0648202U - Dielectric filter and duplexer composed of this filter - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To realize a filter and a duplexer consisting of this filter that can significantly improve cost and productivity. [Structure] Through holes 2 ₁ , 2 ₂ formed in a dielectric block 1
Cylindrical resonator element in the 2 _{n 4 1, 4} 2 TE having a to 4 _n
An input / output coupling capacitance circuit formed as follows is coupled to the first-stage and last-stage resonant elements 4 ₁ and 4 _n of the M mode dielectric resonator type bandpass filter. This input / output coupling capacitance circuit is fixed to the bases of the conductors 6 ₁ and 6 _{n in} which the bases are inserted into the open ends of the first-stage and last-stage resonance elements, and the first-stage and last-stage resonance elements. It is formed of supports 7 ₁ and 7 _n made of a solid dielectric fixed to the open end.
Of the input and output coupling capacitance circuits that combine the two band pass filters described above and make the center frequencies in the pass band of both filters different, and that are coupled to the first-stage and last-stage resonant elements of both filters. , One of the input / output coupling capacitance circuits is connected to a common input / output terminal to form a duplexer.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 INDUSTRIAL APPLICABILITY The present invention provides a dielectric filter suitable for a constituent element of a base station in wireless communication, especially a mobile wireless communication device such as a car phone or a mobile phone, and an antenna duplexer formed by using the filter. The present invention also relates to a dielectric filter suitable as a constituent element of a terminal in the mobile radio communication device.

[0002]

[Prior art]

FIG. 13 is a cross-sectional view showing an example of a bandpass filter formed by using a conventional TEM dielectric resonance element. 1 is a common dielectric block, 2 ₁ to 2 ₃ are through holes, and 4 ₁ to 4 ₃ through hole 2 ₁ to the resonance element made of 2 ₃ thin metal layer deposited on the inner peripheral surface of, the 11 ₁ and 11 ₃ in the input-output coupling elements, the conductor projections provided on the upper surface of the disk-shaped conductor, the disk-shaped conductor portion is fixed by soldering to the respective upper end portions of the resonant element 4 ₁ and 4 _3. Reference numerals 12 ₁ and 12 ₃ denote input / output coupling capacitive elements, in which thin metal layers are provided on both surfaces of the dielectric substrate, and the protruding portions of the input / output coupling elements 11 ₁ and 11 ₃ are provided on the thin metal layer provided on one surface of the dielectric substrate. Connect by soldering and attach the lead terminals 13 ₁ and 13 ₃ to the thin metal layer provided on the other surface of the dielectric substrate by soldering, and connect the lead terminals 13 ₁ and 13 ₃ to the input / output terminals (not shown). No)) is connected by soldering.

[0003] Figure 14 is a sectional view showing an example of a band-stop filtering device formed by using a conventional TEM dielectric resonance element, 1 ₁ to 1 ₃ solid dielectric, 2 ₁ to 2 ₃ through Holes, 4 ₁ to 4 ₃ are resonance elements, 11 ₁ and 11 ₃ are input / output coupling elements, 11 ₂ is a branch coupling element, and these have the same configuration as the input / output coupling elements 11 ₁ and 11 ₃ shown in FIG. Is. 9 is a dielectric base plate, a thin metal layer 14 ₁ and 14 ₃ forming the capacitive element at both ends of the surface are deposited, together with depositing a thin metal layer 15 which forms a coupling line to the middle-section, thin metal both end portions of the layer 15 connected to the thin metal layer 14 ₁ and 14 _3, each length from both ends of the thin metal layer 15 to the middle of the branch point, an electrical length of the guide wavelength is formed on the _^1/4 is there. With dielectric thin metal layer 14 ₁ and 14 ₃ by attaching thin metal layer deposited on the surface to the back surface end portions of the substrate 9 to form output binding capacity element, a ground on the back surface center portion of the dielectric substrate 9 A microstrip line is formed with a thin metal layer 15 provided with a conductor and attached to the surface. The thin metal layers 14 ₁ and 14 ₃ provided on the surface of the dielectric substrate 9 are connected to the conductor protrusions of the input / output coupling elements 11 ₁ and 11 ₃ , and the input / output coupling capacitors provided at both ends of the back surface of the dielectric substrate 9 are connected. Ru thin metal layer for forming connected to the input and output terminals via the lead terminals 13 ₁ and 13 ₃ (not shown) tare.

[0004]

[Problems to be solved by the device]

The conventional filters shown in FIGS. 13 and 14 each have a large number of components forming an input / output coupling circuit, and the connection points between the input / output coupling elements 11 ₁ and 11 ₃ and the resonant elements 4 ₁ and 4 ₃ , Input / output coupling elements 11 ₁ and 11 ₃ and input / output coupling capacitance element connection points, input / output coupling capacitance element and extraction terminals 13 ₁ and 13 ₃ connection points, and extraction terminals 13 ₁ and 13 ₃ and input / output Since many connection points, such as the connection points with terminals, are connected by soldering, there is the disadvantage of poor productivity and high cost. The connection between the input / output coupling elements 11 ₁ and 11 ₃ and the resonant elements 4 ₁ and 4 ₃ may be performed by interposing an elastic conductor between them, instead of soldering, but the number of soldering points is reduced. Although this can be done, it results in an increased number of parts.

[0005]

[Means for Solving the Problems]

 The present invention is a TEM mode dielectric resonator type bandpass filter having a cylindrical resonant element provided in a through hole formed in a common dielectric block. The input / output coupling capacitance circuit to be coupled is connected to the conductor with the base inserted at each open end of the first-stage and last-stage resonant elements, and is fixed to the base of each conductor, and each open-end of the first-stage and last-stage resonant elements is connected. A dielectric filter formed by a support made of a solid dielectric fixed to the side is realized, and a TEM mode having a cylindrical resonant element provided in a through hole formed in the solid dielectric is realized. In a dielectric resonator type band elimination filter, a capacitive coupling circuit that couples the coupling line between each resonant element and each resonant element, a conductor with a base inserted at the open end of each resonant element, and each conductor Solid dielectric fixed to the base of the and fixed to the open end of each resonant element By implementing a dielectric wave filter formed by comprising a support Ri, it is intended to Nozoko conventional drawbacks.

[0006]

【Example】

1 (a) is a sectional view showing an embodiment of the present invention [a sectional view taken along the line BB of FIG. 1 (b)], and FIG. 1 (b) is a sectional view taken along the line AA of FIG. 1 (a). 1 is a common dielectric block, 2 ₁ to 2 _n are through holes formed at appropriate intervals in the longitudinal direction of the common dielectric block 1, and 3 ₁ to 3 _n are through holes 2 ₁ to 2 _n . A counterbore provided at the upper end, 4 ₁ to 4 _n are thin metal layers attached to the inner peripheral surfaces of the through holes 2 ₁ to 2 _n , or a resonance element composed of a cylindrical conductor fitted in each through hole. , 5 is a thin metal layer, are except the inner peripheral surface of the 3 _n adhere to a common entire outer surface of the dielectric block 1 to the counter bore 3 _1. The lower ends of the resonant elements 4 ₁ to 4 _n are electrically connected to the thin metal layer 5, and the upper ends of the resonant elements 4 ₁ to 4 _n are thinned by the inner peripheral surface of the counterbore holes 3 ₁ to 3 _n. since the cut off layer 5 electrically resonant element 4 ₁ to the lower end short-circuit ends of the 4 _n, so that the respective upper end is disposed combline type is an open end. 6 ₁ conductor forming one of the input (or output) terminal, 7 ₁ in support of the base of the conductor ₆₁ consists of a suitable solid dielectric, secured by a suitable adhesive to the base of the conductor 6 ₁ , a cylindrical portion of the support member ₇₁ is inserted into the open end of the resonant element 4 _1, suitable between the inner bottom face upper edge to the flange portion and the counterbore 3 ₁ which has been projecting cylindrical portion It is fixed with an adhesive. Omitting the flange portion of the support member ₇₁ of the support ₇₁ is formed into a simple cylindrical shape, it may be fixed with a suitable adhesive to the open end of the resonant element 4 _1. 8 ₁ is a conductor forming the other input (or output) terminal, are the base fixed by soldering to the appropriate location of the thin metal layer 5. 6 _n is a conductor that forms one of the output (or input) terminals, 7 _n is a support, and 8 _n is a conductor that forms the other of the output (or input) terminals. These are conductor 6 ₁ and support 7 ₁ and a conductor ₈₁ the same structure.

As described above, a TEM mode dielectric resonator element in which a thin metal layer is attached to the inner peripheral surface of the through hole formed in the solid dielectric or a cylindrical conductor is inserted into the through hole. in the electromagnetic field distribution only outside of the resonant elements, cages inwardly considered based on traditional absence of an electromagnetic field, therefore, is as shown in FIG. 13 prior art, on the resonant element 4 ₁ An input / output coupling element 11 ₁ is connected to an end portion, and an input / output coupling capacitive element 12 ₁ is interposed between the lead terminal 13 ₁ and the input / output coupling element 11 ₁ to form an input / output circuit. . However, as a result of repeated experiments on various prototypes by the present inventor, it was confirmed that the electromagnetic field also exists inside the resonant element. This is considered to be due to the generation of leakage potential (current) inside the resonant element due to the continuity of the potential. The present invention has been made based on the above-mentioned newly discovered facts, and the opposing axial length between the resonant element 4 ₁ and the base of the conductor 6 ₁ and the opposing axial length between the resonant element 4 _n and the base of the conductor 6 _n are respectively set. With proper selection, it is possible to form required input / output coupling capacitances between the resonance element 4 ₁ and the base of the conductor 6 ₁ and between the resonance element 4 _n and the base of the conductor 6 _n .

FIG. 2 is an equivalent circuit diagram of the dielectric filter of the present invention shown in FIG. 1, where R ₁ to R _n are resonant circuits, T ₁ and T _n are input / output terminals, and M is a magnetic field coupling coefficient. The capacitances of the first-stage and last-stage resonance circuits R ₁ and R _n are the combined capacitance of the resonance circuit forming capacitance and the input / output coupling capacitance. FIG. 3 is a diagram showing an example of the transmission characteristics of the dielectric filter of the present invention shown in FIG. 1, where the horizontal axis is frequency and the vertical axis is attenuation.

In the embodiment shown in FIG. 1, since there is no fine adjustment element for the resonance frequency, it is necessary to make the resonance length of each resonance element match the required resonance length as much as possible. It is easy to match the resonance length of each resonance element with a desired value by adjusting the spots by a counter boring process. The dielectric filter of the present invention shown in FIG. 1 may be housed in a shield case, and a conventionally known appropriate resonance frequency fine adjustment element may be attached to the upper wall of the shield case. FIG. 1 shows an example in which the counterbore holes 3 ₁ to 3 _n are provided at the upper ends of the through holes 2 ₁ to 2 _n , but it is common that the counterbore holes 3 ₁ to 3 _n are not provided. Through holes are drilled from the upper surface to the lower surface of the dielectric block 1, resonance elements are provided in each through hole, and thin metal layers are attached to both side surfaces, both end surfaces and the lower surface of the common dielectric block 1. Without depositing a thin metal layer on the upper surface of the common dielectric block 1, the ground surface of the common dielectric block 1 is kept exposed, and the bases 7 ₁ and 6 _n of the bases of the conductors 6 ₁ and 6 _n are The present invention can be implemented by fixing the 7 _n flange to the upper surface of the common dielectric block 1. When the supports 7 ₁ and 7 _n are formed in a simple columnar shape having no flange, as described with reference to FIG. 1, a suitable adhesive is applied to each open end of the resonant elements 4 ₁ and 4 _n. Stick with.

An example of the actual dimensions of the dielectric filter of the present invention shown in FIG. 1 is as follows. The center frequency of the pass band is 900 MHz, the dielectric constant of the common dielectric block 1 is 94, and the order is 3. The common dielectric block 1 has a length of about 20 mm, a height of about 10 mm, and a width of about 4 mm. When forming relatively large the merits dielectric wave filter is formed of a coaxial contact plugs instead of forming the input and output terminals in the conductor 6 ₁ and 8 ₁ and 6 _n and 8 _n, commonly the outer conductor Is fixed to the upper surface of the dielectric block with an adhesive or screw and connected to a thin metal layer attached to the outer surface of the common dielectric block, and the lower end of the inner conductor is connected to the first and last resonance elements. It is inserted inside and formed so as to oppose the resonant element over the axial length as appropriate.

[0011] The above has described the case of forming the merits dielectric wave filter to comb-line type, a counter bore 3 ₁ provided in the upper portion of the through hole 2 ₁ shown in FIG. 1, the through-holes 2 ₂ forming the interdigital by the corresponding zag liana provided alternately provided in the lower end portion of the through hole 2 _2, the counterbore of the through hole adjacent to the upper and lower ends of the through hole You can When the counterbore is not provided, a thin metal layer is provided on the upper and lower surfaces of the common dielectric block around the short-circuited end of the resonant element, and this thin metal layer is used as a common dielectric. By connecting to the thin metal layers attached to both sides of the block and exposing the background of the common dielectric block without providing a thin metal layer around the open end of the resonant element, the interdigital type Can be formed.

FIG. 4 is a cross-sectional view showing an essential part of an example in which the present invention is applied to a band elimination filter. 1 ₁ to 1 ₃ are solid dielectrics, 2 ₁ to 2 ₃ are through holes, 4 ₁ Through 4 ₃ are resonance elements composed of thin metal layers attached to the inner peripheral surfaces of the through holes 2 ₁ through 2 ₃ or cylindrical conductors fitted in the through holes, 6 ₁ through 6 ₃ are conductors, and 7 ₁ 1 to 7 ₃ are supports, and the configurations of the combinations of 6 ₁ and 7 ₁ , 6 ₂ and 7 ₂ and 6 ₃ and 7 ₃ are the same as the configuration of the combination of the conductor 6 ₁ and the support 7 ₁ in FIG. . Reference numeral 9 is a dielectric substrate, and 10 is a thin metal layer, which forms a coupled line consisting of a microstrip line together with a ground conductor provided on the back surface of the dielectric substrate 9 although not shown. The branch lines provided at one end portion of the thin metal layer 10 to the conductor _61, a branch line which is provided at the other end to the conductor 6 _3, while the connecting branch lines provided in the middle portion in the conductor 6 _2, each the length between the branch point, is formed on the _^1/4 of the guide wavelength in electrical length. Although not shown, the solid dielectric 1 ₁ to 1 ₃ in common sheet - Rudoke - housed in the scan, and connect the input and output terminals at both ends of the coupling line formed of the thin metal layer 10, commonly optionally Attach the resonance frequency fine adjustment element to the shield case. Although the case where the order is 3 is illustrated in FIG. 4, the present invention can be implemented by appropriately increasing or decreasing the order.

FIG. 5 is an equivalent circuit diagram of the dielectric filter of the present invention shown in FIG. 4, in which R ₁ to R ₃ are resonance circuits, T ₁ and T ₃ are input / output terminals, and L ₁ and L ₂ are in coupled line capacity that put the resonance circuit R ₁ to R ₃ is a combined capacitance of the coupling capacitance and the capacitance forming a resonant circuit, the conductor 6 ₁ to 6 ₃ and the resonant element 4 ₁ to 4 _3. FIG. 6 is a diagram showing an example of transmission characteristics of the dielectric filter of the present invention shown in FIG. 4, in which the horizontal axis and the vertical axis are the same as in FIG.

Next, a duplexer formed using the dielectric filter of the present invention will be described. For example, eight through-holes are drilled in a common dielectric block, and the resonance element provided in each through-hole is a combline type, and the first, the fourth, the fifth, and the eighth are counted from either end. A coupling element similar to the coupling element consisting of the conductor 6 ₁ and the support 7 ₁ shown in FIG. 1 is provided at each open end of each resonant element, and the coupling element is provided at the fourth and fifth resonant elements. Each conductor of the element is connected to a common input / output terminal, and the center frequency f ₁ in the pass band of the band pass filter composed of the first to fourth resonant elements and the fifth to eighth The duplexer can be configured by appropriately differentiating the center frequency f ₂ in the pass band of the band pass filter configured by the resonance elements up to.

FIG. 7 is an equivalent circuit diagram of the duplexer configured in this way. T ₁ and T ₈ are input (or output) terminals, T ₄₅ is a common output (or input) terminal, and By connecting a common antenna to the terminal T ₄₅ and connecting a transmitter or a receiver to the terminals T ₁ and T ₈ , respectively, it acts as an antenna duplexer. FIG. 8 is a diagram showing an example of the transmission characteristic, and the horizontal axis and the vertical axis are the same as those in FIG. In the above, the case where two combline type bandpass filters are combined to form a duplexer has been explained. Either of both bandpass filters should be composed of interdigital bandpass filters. One may be a combline type and the other may be an interdigital type bandpass filter, and in any case, the invention can be implemented by appropriately increasing or decreasing the order of each bandpass filter. Also, instead of forming the dielectric blocks of the two bandpass filters with the common dielectric block of the two bandpass filters, the dielectric blocks of each bandpass filter are formed separately. Of course, it is okay.

The dielectric filter of the present invention shown in FIG. 4, that is, two band stop filters are combined and the center frequency f ₃ in the stop band of one band stop filter and the other band stop filter are combined. the center frequency f ₄ in the stopband of vessels with varying appropriately, among our Keru input and output terminals on one of the band-stop filtering device, either one of the terminals, the length of _^1/4 of the guide wavelength in electrical length connected to a common terminal via a line, out of the input and output terminals of the other band-stop filtering device, either one of the terminals, via a _^1/4 of the length of the line guide wavelength in electrical length It is possible to configure a duplexer by connecting the same to a common terminal. FIG. 9 is an equivalent circuit diagram of the duplexer thus configured, where T ₃ and T ₄ are output (or input) terminals, and T ₃₄ is a common input (or output) terminal. Of the signals applied to the common terminal T ₃₄ , the frequency f ₃ component is transmitted to the terminal T ₃ without being transmitted to the terminal T ₄ , and the frequency f ₄ component is not transmitted to the terminal T ₃ Transmitted to ₄ . FIG. 10 is a diagram showing an example of the transmission characteristics of this duplexer, and the horizontal and vertical axes are the same as those in FIG.

FIG. 11 is an equivalent circuit diagram of a duplexer configured by combining the band-pass filter of the present invention shown in FIG. 1 and the band-stop filter of the present invention shown in FIG. 4, which is a band-pass filter BPF. The center frequency in the pass band of the band stop filter BEF and the center frequency in the stop band of the band stop filter BEF are selected to be equal, and the resonance circuit at the first stage (or the final stage) of the band stop filter BEF is electrically long and a common terminal T _C via the line length of _^1/4, the resonant circuit of the final stage of the band-stop filtering unit BEF (or first stage) to the terminal T _E, the first-stage band-pass wave filter BPF (or The resonance circuit at the final stage is connected to the common terminal T _C , and the resonance circuit at the final stage (or the first stage) of the bandpass filter BPF is connected to the terminal T _P. Of the signal applied to the common terminal T _C , the center frequency component in the pass band or stop band of both filters is not transmitted to the terminal T _E on the side of the band stop filter B EF, but passes through the band pass filter. is transmitted to the terminal T _P of filter BPF side, the frequency components other than the center frequency in the pass band or stop band of the two wave filter is Ku band such be transmitted to the terminal T _P of the band-pass wave filter BPF side Transmitted to the terminal T _E on the blocking filter B EF side. FIG. 12 is a diagram showing an example of the transmission characteristics of this duplexer, and the horizontal and vertical axes are the same as those in FIG.

[0018]

[Effect of device]

 The input / output coupling circuits provided in the first-stage and final-stage resonant circuits of the proposed bandpass filter and the capacitive coupling circuit between each resonant circuit and the coupled line in the proposed band-stop filter have both a smaller number of parts than conventional products. Moreover, the number of soldering points is small, and therefore, the cost and productivity can be significantly improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an equivalent circuit diagram of the dielectric filter of the present invention.

FIG. 3 is a diagram showing an example of transmission characteristics of the dielectric filter of the present invention.

FIG. 4 is a sectional view showing an essential part of another embodiment of the present invention.

FIG. 5 is an equivalent circuit diagram of the dielectric filter of the present invention.

FIG. 6 is a diagram showing an example of transmission characteristics of the dielectric filter of the present invention.

FIG. 7 is an equivalent circuit diagram of a duplexer configured by using the dielectric filter of the present invention.

FIG. 8 is a diagram showing an example of transmission characteristics of a duplexer configured by using the dielectric filter of the present invention.

FIG. 9 is an equivalent circuit diagram of a duplexer configured by using the dielectric filter of the present invention.

FIG. 10 is a diagram showing an example of transmission characteristics of a duplexer configured using the dielectric filter of the present invention.

FIG. 11 is an equivalent circuit diagram of a duplexer configured by using the dielectric filter of the present invention.

FIG. 12 is a diagram showing an example of transmission characteristics of a duplexer configured using the dielectric filter of the present invention.

FIG. 13 is a cross-sectional view showing an example of a conventional bandpass filter.

FIG. 14 is a cross-sectional view showing an example of a conventional band elimination filter.

[Explanation of symbols]

1 common dielectric block 2 ₁ to 2 _n through hole 3 ₁ to 3 _n counterbore hole 4 ₁ to 4 _n resonant element 5 thin metal layer 6 ₁ and 6 _n conductor 7 ₁ and 7 _n support 8 ₁ and 8 _n Conductor 1 ₁ to 1 ₃ Solid dielectric 6 ₂ and 6 ₃ Conductor 7 ₂ and 7 ₃ Support 9 Dielectric substrate 10 Metal thin layer 11 ₁ and 11 ₃ Input / output coupling element 11 ₂ Branch coupling element 12 ₁ and 12 ₃ Input Output coupling capacitance element 13 ₁ and 13 ₃ Lead-out terminal 14 ₁ and 14 ₃ Thin metal layer 15 Thin metal layer

Claims (6)

[Scope of utility model registration request] 1. A TEM mode dielectric resonator type bandpass filter having a cylindrical resonant element provided in a through hole formed in a common dielectric block, wherein a resonant element at a first stage and a final stage are provided. Each of the input and output coupling capacitance circuits to be coupled is a conductor having a base portion inserted into each open end portion of the first-stage and last-stage resonant elements, and each conductor of the first-stage and last-stage resonant elements fixed to the base portion of each conductor. A dielectric filter formed by a support made of a solid dielectric fixed to the open end side. 2. The dielectric filter according to claim 1, wherein the conductor forming the input / output coupling capacitance circuit is an inner conductor of a coaxial plug, and the outer conductor of the coaxial plug is fixed to a required position. vessel. 3. A TEM mode dielectric resonator type band stop filter provided with a cylindrical resonant element provided in a through hole formed in a solid dielectric, wherein a coupling line between the resonant elements and each resonant element are provided. A conductor having a base portion inserted into the open end portion of each of the resonant elements, and a solid dielectric fixed to the base portion of each conductor and fixed to the open end side of each of the resonant elements. And a support made of a dielectric filter. 4. A TEM mode dielectric resonator type bandpass filter having a cylindrical resonant element provided in a through hole formed in a common dielectric block, the two TEM mode dielectric resonator type bandpass filters being provided. TEM mode
The center frequencies of the passbands of the dielectric resonator type bandpass filter are made different so that the first and last resonant elements of the two TEM mode dielectric resonator type bandpass filters are used. Each of the input and output coupling capacitance circuits to be coupled is a conductor having a base portion inserted into each open end portion of the first-stage and last-stage resonant elements, and each conductor of the first-stage and last-stage resonant elements fixed to the base portion of each conductor. And a support made of a solid dielectric fixed to the open end side of the two TEM mode dielectric resonator type band pass filters. A duplexer comprising an input / output coupling capacitance circuit connected to a common terminal. 5. A TEM mode dielectric resonator type band stop filter provided with a cylindrical resonant element provided in a through hole formed in a solid dielectric body, the two TEM mode being provided. A capacitive coupling circuit for coupling the resonant element and the coupling line between the resonant elements in the dielectric resonator type band stop filter, a conductor having a base inserted at the open end of each resonant element, and And a support made of a solid dielectric fixed to the base of each conductor and fixed to the open end side of each resonance element.
The center frequencies in the respective stop bands of the TEM mode dielectric resonator type band stop filters are made different, and the coupled lines in the two TEM mode dielectric resonator type band stop filters are each one of one end, through a _^1/4 of the length of the line of the guide wavelength is connected to the common terminal in electric length, the two TEM mode of - de dielectric resonator band-stop filter A duplexer in which each other end of each coupled line in the wave filter is connected to each independent terminal. 6. A TEM mode dielectric resonator type bandpass filter having a cylindrical resonance element provided in a through hole formed in a common dielectric block, and a through hole formed in a solid dielectric. And a TEM mode dielectric resonator type band stop filter having a cylindrical resonant element provided therein, the first and last stages of the TEM mode dielectric resonator type bandpass filter. A conductor having an input / output coupling capacitance circuit coupled to each resonance element with a base inserted at each open end of the first-stage and last-stage resonance elements, and fixed to the base of each conductor, the first-stage and last-stage resonances A support made of a solid dielectric fixed to each open end of the element, and a coupling line between each resonance element and each resonance element in the TEM mode dielectric resonator type band stop filter. A capacitive coupling circuit that couples the bases to the open ends of the resonant elements. And the conductor, together with the fixed to the base of each conductor to form the by the solid dielectric than made support fixed to the open end side of the resonator element, the TEM
The center frequency in the pass band of the mode dielectric resonator type band pass filter and the center frequency in the stop band of the TEM mode dielectric resonator type band stop filter are selected to be equal, and the TEM mode is selected. Any one of the coupling lines in the TEM mode dielectric resonator type band stop filter by connecting the input / output coupling capacitance circuit of either one of the de dielectric resonator type band pass filter to a common terminal. the one end portion, _^1/4 of the guide wavelength in electrical length
Connected to the common terminal via a line having a length of
A duplexer characterized in that the other end of the coupling line in the EM mode dielectric resonator type band stop filter is connected to an independent terminal.