JP2000068704A - Dielectric filter, antenna multicoupler and communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size and the cost and to make the characteristic excellent. SOLUTION: An antenna multicoupler is constituted by arranging the circuit elements of dielectric resonators 1 to 5, pin diodes D1 to D6, capacitors C1...C23, inductors L1...L21 and resistors R1 and R2 on a base substrate 21. Then, a DC circuit pattern 23 from a DC circuit part to the pin diodes D1 to D6 is respectively formed extending from the short circuit end face side of the respective resonator 1 to 5 to its opening end face side and the DC circuit pattern 23 to the pin diode D2 to D6 is provided at a part in a gap between the adjacent dielectric resonators. The circuit elements R1, R2, C22, C23, L2, L3, L6, L7 and L8 for a DC circuit are arranged on the short circuit end face side or close to the short circuit end face side of the respective resonators 1 to 5 and the circuit element of a high frequency circuit is arranged on the opening end face side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter, an antenna duplexer, and a communication device used in, for example, a microwave band.

[0002]

2. Description of the Related Art Hitherto, a variable frequency dielectric filter has been known in which a variable impedance element such as a PIN diode or a variable capacitance diode is connected to a dielectric resonator, and the voltage is controlled to change the resonance frequency. ing. When an antenna duplexer is configured using such a dielectric filter, for example, a structure as shown in FIG. 8 has conventionally been employed.

This antenna duplexer is an antenna duplexer having the same circuit configuration as the antenna duplexer according to the present invention shown in FIG. 4, and has a λ / 4 type dielectric coaxial resonance on the transmission filter side on a base substrate 11. Units 1 and 2, λ on the reception filter side
/ 4 type dielectric coaxial resonators 3 to 5, PIN diodes D1 to D6 as variable impedance elements, capacitors C1... C23 for coupling and DC circuits, inductor L
1 ··· L21 and resistors R1 and R2 are arranged.

The base substrate 11 has a transmitting terminal T on its surface.
A circuit pattern for connecting the above components including x, the receiving terminal Rx, the control terminals CONT1, CONT2, and the ground electrode 12 is formed. The resonators 1 to 5 are arranged in parallel so that their open end faces are in the same direction and their axes are parallel to each other. The circuit elements are arranged on the open end faces of the resonators. It is connected by attaching.

[0005]

However, in the above conventional antenna duplexer, all the circuit elements are arranged on the open end side of the resonator, and a DC control signal for controlling the voltage of the variable impedance element is provided. And a high-frequency circuit that is a high-frequency signal path, and has the following problems.

There are many restrictions on wiring of circuit patterns and arrangement of circuit elements, and it is difficult to reduce the size.

The wiring of the circuit pattern becomes complicated, and the high-frequency circuit pattern and the DC circuit pattern (hatched portion in FIG. 8) are arranged close to each other, and the circuit elements (L2, L3, L6, L
8) Since a high-frequency signal pattern may pass underneath,
High frequency signals are skipped or unnecessary capacitance is generated, and characteristics are deteriorated.

Therefore, an object of the present invention is to provide a high-frequency circuit section and a DC circuit section which can be arranged separately,
It is an object of the present invention to provide a small, inexpensive dielectric filter, antenna duplexer, and communication device having good characteristics.

[0009]

In order to achieve the above object, a dielectric filter according to a first aspect of the present invention has a plurality of dielectric resonators and is electrically connected to at least one of the dielectric resonators. A base on which a voltage controllable impedance variable element, a circuit element for coupling each dielectric resonator or a voltage control of the impedance variable element, and a circuit pattern for mounting each of the components and connecting each of the components are formed. And a part of a circuit pattern of a DC circuit unit for applying a DC voltage to the variable impedance element is arranged between adjacent dielectric resonators.

A dielectric filter according to a second aspect of the present invention is the dielectric filter according to the first aspect, wherein the dielectric resonator is a cylindrical member having a substantially quadrangular cross-section having a chamfer or a concave portion provided in at least one corner. Yes, the corner portion provided with the chamfer or the concave portion is disposed in close contact with the base substrate and the adjacent dielectric resonator, and a part of the circuit pattern of the DC circuit portion is disposed in the gap formed by the chamfer or the concave portion. It is characterized by having done.

According to a third aspect of the present invention, in the dielectric filter according to the first aspect, the dielectric resonator has a cylindrical shape, and adjacent dielectric resonators are closely arranged.
A part of the circuit pattern of the DC circuit portion is disposed in a gap formed between adjacent dielectric resonators.

The antenna duplexer according to claim 4 is electrically connected to at least one of a dielectric resonator for a transmission filter, a dielectric resonator for a reception filter, and a dielectric resonator for each filter. A variable voltage-controllable impedance variable element, a circuit element for coupling each dielectric resonator or a voltage control of the variable impedance element, and a circuit pattern for mounting the respective components and connecting the respective components. A part of a circuit pattern of a DC circuit unit for applying a DC voltage to the variable impedance element is disposed between adjacent dielectric resonators.

According to a fifth aspect of the present invention, there is provided an antenna duplexer according to the fourth aspect, wherein the dielectric resonator has a cylindrical shape having a substantially quadrangular cross section having a chamfer or a concave portion provided in at least one corner. Yes, the corner portion provided with the chamfer or the concave portion is disposed in close contact with the base substrate and the adjacent dielectric resonator, and a part of the circuit pattern of the DC circuit portion is disposed in the gap formed by the chamfer or the concave portion. It is characterized by having done.

In the antenna duplexer according to a sixth aspect of the present invention, in the antenna duplexer according to the fourth aspect, the dielectric resonator has a cylindrical shape, and adjacent dielectric resonators are closely arranged.
A part of the circuit pattern of the DC circuit portion is arranged in a gap formed between adjacent dielectric resonators.

According to a seventh aspect of the present invention, there is provided a communication apparatus.
A dielectric filter according to claim 2 or 3, or at least one of the antenna duplexer according to claim 4, 5, or 6 is provided.

In the dielectric filter or antenna duplexer according to the above configuration, a part of a circuit pattern of a DC circuit section for applying a DC voltage to the variable impedance element is disposed between adjacent dielectric resonators. The direct current circuit for controlling the voltage of the variable impedance element and the high frequency circuit which is a filter circuit for transmitting or receiving signals can be separately arranged. Therefore, wiring of a complicated circuit pattern is eliminated, and a portion where the high-frequency circuit section and the DC circuit section intersect can be eliminated, so that high-frequency signal jumps and unnecessary capacitance can be prevented.

Further, since a simple circuit pattern is formed, and the crossing portion between the circuit element and the circuit pattern can be eliminated or reduced, the assembling work becomes easy and the characteristic failure due to a short circuit or the like can be greatly reduced. .

In addition, a chamfer or a concave portion is provided at a corner of a dielectric resonator having a substantially quadrangular cross section, an adjacent dielectric resonator is arranged in close contact, and a direct current for separating a high frequency circuit section and a direct current circuit section is provided. By arranging the pattern of the circuit portion in the gap formed by the chamfer or the concave portion, the size can be further reduced.

Further, if a cylindrical dielectric resonator is used, the pattern of the DC circuit portion can be arranged between adjacent dielectric resonators which are closely arranged.

Further, since the communication device according to the present invention is provided with the dielectric filter or the antenna duplexer having the above characteristics, it is small, inexpensive and has good characteristics.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of an antenna duplexer according to a first embodiment of the present invention will be described with reference to FIGS. 1 is a plan view of an antenna duplexer, FIG. 2 is a cross-sectional view passing through both control terminals in FIG. 1, FIG. 3 is a plan view of a base substrate, and FIG.
Is an equivalent circuit diagram of the antenna duplexer. 1 and 4, the same components are denoted by the same reference numerals, and in FIG. 2, hatching is omitted for clarity of the drawings.

The antenna duplexer shown in FIG. 1 shows a specific structure of an equivalent circuit of the antenna duplexer shown in FIG. 4. The transmission filter has a two-stage band rejection filter, and the reception filter has a three-stage band-pass filter. The filter is configured so that the passband of each filter can be varied by controlling the variable impedance element with a DC voltage. For this reason, the antenna duplexer has a high-frequency circuit section which is a filter circuit for transmitting and receiving signals, and a DC circuit section for controlling the voltage of the variable impedance element.

This antenna duplexer includes dielectric resonators 1 and 2 forming a transmission filter on a base substrate 21, dielectric resonators 3 to 5 forming a reception filter, and PIN diodes D1 to D6 as variable impedance elements. , A capacitor C1 for coupling for forming a filter and a DC circuit for controlling the voltage of the variable impedance element.
C21, inductors L1... L21, and circuit elements of resistors R1 and R2 are arranged.

The base substrate 21 is made of glass epoxy or the like. The surface of the base substrate 21 is a copper electrode for connecting the above-mentioned components including the transmission terminal Tx, the reception terminal Rx, the antenna terminal ANT, the control terminals CONT1, CONT2 and the ground electrode 22. Are formed. Circuit pattern is P
It comprises a DC circuit pattern 23 (shown by hatching in FIGS. 1 and 3) serving as a DC path for controlling the voltage of the IN diodes D1 to D6, and a high-frequency circuit pattern serving as a path for transmission / reception signals. Although not shown,
The terminals Tx, Rx, ANT, CONT1, and CONT2 are formed to extend to the rear surface via the end surface of the base substrate 21. A ground electrode is formed on substantially the entire surface of the rear surface of the base substrate 21 except for a region where each terminal is formed. Although not shown, a resist film is formed on the circuit pattern except for a soldered portion. The antenna duplexer of this embodiment is surface-mounted with the back surface of the base substrate 21 as a mounting surface.

Each of the dielectric resonators 1 to 5 includes a cylindrical dielectric 31 having a substantially rectangular cross section, an outer conductor 32 provided on the outer peripheral surface of the cylindrical dielectric 31, and an inner circumference of the cylindrical dielectric 31. And an inner conductor 33 provided on the surface. The outer conductor 32 is formed at one open end surface of the dielectric 31 (a lower end surface in FIG.
On the other end (hereinafter referred to as a short-circuited end), the inner conductor 33 is electrically short-circuited (conductive). The dielectric resonators 1 to 5 are arranged in a line so that their side surfaces are in close contact with each other, their open end faces are in the same direction, and their axes are parallel to each other. Each inner conductor 33 is connected to a predetermined position of the circuit pattern via the connection terminal 26 to the electrode 22.

The four corners (ridges) of the side surfaces of each dielectric 31 are chamfered by curved surfaces, and each of the dielectric resonators 1 to 3 is chamfered.
5 is placed on the base substrate 21 with the side surfaces of
Gap S between adjacent dielectric resonators and base substrate 21
Is formed.

In the present embodiment, the DC circuit pattern 23 extending from the DC circuit section to the pin diodes D1 to D6 is formed from the short-circuit end face to the open end face of each of the dielectric resonators 1 to 5, respectively. The DC circuit pattern 23 extending from D2 to D6 is provided in the gap S between the adjacent dielectric resonators, and includes a DC circuit element R1,
R2, C22, C23, L2, L3, L6, L7, L8
Are arranged on the short-circuit end face side or near the short-circuit end face side of each of the dielectric resonators 1 to 5, and the circuit element of the high-frequency circuit is arranged on the open end face side. That is, the antenna duplexer of the present embodiment has a structure in which the high-frequency circuit unit and the DC circuit unit are separated so as not to be mixed.

In the configuration of the present embodiment, the open end face side of the dielectric resonator is constituted only by the high-frequency circuit section.
There is no complicated circuit pattern wiring (routing), and there is no portion where the high-frequency circuit and the DC circuit intersect, so that high-frequency signal jumps and unnecessary capacitance are prevented, and the filter characteristics are improved. I have.

Further, since adjacent dielectric resonators are arranged in close contact with each other, and a DC circuit pattern for separating the high-frequency circuit section and the DC circuit section is provided in a gap between the dielectric resonators. It has been downsized.

Further, the circuit pattern is simple, and the number of intersections between the circuit element and the circuit pattern can be eliminated or reduced. As a result, assembling work is facilitated, and characteristic defects due to short circuits and the like are greatly reduced. Is reduced.

Even if the line width of the DC circuit pattern is reduced, the characteristics are not affected even if the line width is reduced. In this embodiment, the chamfer radius of the dielectric resonator is 0.3
mm, and the line width of the DC circuit pattern provided in the gap S between the dielectric resonators is 0.1 mm.

In the above embodiment, the dielectric resonators are arranged in close contact with each other. However, the present invention is not limited to this. If the dielectric resonators are small and chamfering is not enough to secure a sufficient gap S. Is 0.1 mm between adjacent dielectric resonators
A gap of about 0.2 mm may be provided, and a DC circuit pattern may be arranged between them.

Further, in the above embodiment, all the circuit elements for the DC circuit are arranged on the short-circuit end face side or near the short-circuit end face side. However, the present invention is not limited to this. It may be arranged on the open end face side. In short, the circuit patterns and circuit elements may be arranged so that the high-frequency circuit section and the DC circuit section are separated without crossing each other.

In the above-described embodiment, the dielectric resonator having a substantially square cross section as shown in FIG. 2 has been described by chamfering the corners with a curved surface.
As shown in (a), the chamfer of the corner may be flat,
In addition, as shown in FIG.
A curved concave portion may be provided as shown in FIG. Further, as shown in FIG. 6, a cylindrical dielectric resonator may be used. When a cylindrical dielectric resonator is used, the line width of the pattern can be relatively widened.

That is, when the dielectric resonators are arranged in close contact with each other, the external shape of the dielectric resonator may be any as long as the gap S for forming the DC circuit pattern is formed.

The shape of the inner conductor 33 is not limited to a circular cross section, and the shape and dimensions are selected according to the required characteristics.

Next, the circuit configuration and operation of the antenna duplexer of the above embodiment will be described. In the antenna duplexer of the present embodiment, a transmitting circuit is electrically connected between the transmitting terminal Tx and the antenna terminal ANT, and a receiving circuit is electrically connected between the receiving terminal Rx and the antenna terminal ANT. .

The transmission-side circuit comprises a dielectric resonator 1 electrically connected to a transmission terminal Tx via a resonance capacitor C1.
And a dielectric resonator 2 electrically connected to the antenna terminal ANT via the resonance capacitor C2 and the coil 20. The resonance capacitors C1 and C2 are capacitors for obtaining an attenuation pole on the lower side of the pass band. The series resonance circuit of the dielectric resonator 1 and the capacitor C1 is electrically connected to the series resonance circuit of the dielectric resonator 2 and the capacitor C2 via the coupling coil L1. Further, capacitors C5 and C6 are electrically connected in parallel to these two series resonance circuits, respectively.

At the connection point between the dielectric resonator 1 and the resonance capacitor C1, a PIN diode D1 as an impedance element is electrically connected to the dielectric resonator 1 with the cathode grounded via a band variable capacitor C3. Are connected in parallel. At the connection point between the dielectric resonator 2 and the resonance capacitor C2, two PIN diodes D2 and D3 connected in series are electrically connected in parallel with the dielectric resonator 2 via a band variable capacitor C4. It is connected. PIN
The cathode of the diode D2 is a band variable capacitor C4.
In addition, the anode is electrically connected to the anode of the PIN diode D3, and the cathode of the PIN diode D3 is grounded. Band variable capacitors C3, C4
Are capacitors for respectively changing two attenuation pole frequencies of the attenuation characteristic of the transmission side circuit. A choke coil L4 is connected between the cathode of the PIN diode D2 and the ground so that a direct current flows when the PIN diodes D1 and D2 are turned on.

The control terminal CONT1 is electrically connected to the connection point between the anode of the PIN diode D1 and the band variable capacitor C3 via the resistor R1 and the capacitor C22 and the choke coil L2, and is connected to the resistor R1 and the capacitor C22 and the choke. Via coil L3 and PIN
It is electrically connected to a connection point between the anodes of the diodes D2 and D3.

The receiving side circuit includes the dielectric resonator 3 electrically connected to the antenna terminal ANT via the resonance coil L9 and the coil 21, and the resonance coil L10 and the coil L10.
And a dielectric resonator 5 electrically connected to the receiving terminal Rx via the first and second couplings 11, and electrically connected between the dielectric resonators 3 and 5 via coupling capacitors C11, C12, C13 and C14. And a dielectric resonator 4. The resonance coils L9 and L10 are inductances for obtaining an attenuation pole on the higher side of the pass band.

At the connection point between the dielectric resonator 3 and the resonance coil L9, a series circuit of a band variable capacitor C7 and a PIN diode D4 is connected to the dielectric resonator 3 with the cathode of the PIN diode D4 grounded. And are electrically connected in parallel. Dielectric resonator 4 and coupling capacitor C
12 and C13 are connected to a band variable capacitor C8.
And a series circuit of a PIN diode D5 are electrically connected in parallel to the dielectric resonator 4 with the cathode of the PIN diode D5 grounded. At the connection point between the dielectric resonator 5 and the resonance coil L10, a series circuit of a band variable capacitor C9 and a PIN diode D6 is electrically connected to the dielectric resonator 5 with the cathode of the PIN diode D6 grounded. Are connected in parallel.

The control terminal CONT2 is electrically connected to a connection point between the anode of the PIN diode D4 and the band variable capacitor C7 through the resistor R2 and the capacitor C23 and the choke coil L6.
23 and a choke coil L7, are electrically connected to a connection point between the anode of the PIN diode D5 and the band variable capacitor C8.
23 and the choke coil L8, it is electrically connected to the connection point between the anode of the PIN diode D6 and the band variable capacitor C9.

The coil 20 connected between the transmitting side circuit and the antenna terminal ANT, the ground and the antenna terminal ANT
A T-shaped phase circuit is formed by the capacitor 15 connected between the antenna 15 and the coil 21 connected between the receiving side circuit and the antenna terminal ANT.

This antenna duplexer outputs a high-frequency transmission signal input from the transmission circuit system to the transmission terminal Tx from the antenna terminal ANT via the transmission-side circuit, and receives a high-frequency reception signal input from the antenna terminal ANT. The signal is output from the receiving terminal Rx to the receiving circuit system via the side circuit.

When a positive voltage is applied as a control voltage to the control terminal CONT1, the PIN diodes D1, D
2 and D3 are turned on. Therefore, the band variable capacitors C3 and C4 are connected to the PIN diodes D1, D2 and D4.
3, the two attenuation pole frequencies are both lowered, and the pass band of the transmission side circuit is lowered. vice versa,
When a negative voltage is applied as a control voltage, the PIN diodes D1, D2, and D3 are turned off. This allows
The band variable capacitors C3 and C4 are opened,
The two attenuation pole frequencies are both higher, and the passband of the transmitting circuit is higher. As described above, the transmission-side circuit has two different passband characteristics by grounding or opening the band variable capacitors C3 and C4 by controlling the DC voltage applied to the control terminal CONT1. be able to.

On the other hand, when a positive voltage is applied as a control voltage to the control terminal CONT2, the PIN diodes D4, D4
5, D6 are turned on. Therefore, the band variable capacitors C7, C8, C9 are grounded via the PIN diodes D4, D5, D6, respectively, and the pass band is lowered. Conversely, when a negative voltage is applied as a control voltage, PI
The N diodes D4, D5, D6 are turned off. As a result, the band variable capacitors C7, C8, and C9 are opened, and the pass band is increased. As described above, the receiving side circuit can have two different pass band characteristics by grounding or opening the band variable capacitors C7 to C9 by controlling the DC voltage applied to the control terminal CONT2. it can.

In this embodiment, an antenna duplexer having two dielectric filters, a transmission filter and a reception filter, has been described. However, the present invention is not limited to this, and one dielectric filter may be used. Further, the number and the circuit configuration of the dielectric resonators constituting each filter are not limited to this embodiment either, and any frequency variable type dielectric filter using an impedance variable element and an antenna duplexer may be used. . Further, a variable capacitance diode (varactor diode) or a field effect transistor (FET) may be used as the variable impedance element.

Next, FIG. 7 shows the configuration of a communication device according to a second embodiment of the present invention. In FIG. 7, 122 is an antenna, 123 is an antenna duplexer, 124 is a transmission filter,
Reference numeral 125 denotes a reception filter, 126 denotes a transmission circuit, and 127 denotes a reception circuit. Antenna terminal A of antenna duplexer 123
NT is the antenna 122, the transmission terminal Tx is the transmission circuit 12
6, the receiving terminals Rx are connected to the receiving circuit 127, respectively, to constitute a communication device.

Here, as the antenna sharing device 123. The antenna duplexer described in the first embodiment can be used. Further, as the transmission filter 124 or the reception filter 125, a frequency-variable dielectric filter according to the present invention can be used. By using the dielectric filter or the antenna duplexer according to the present invention, it is possible to obtain a small, inexpensive communication device having good characteristics.

[0051]

As described above, according to the dielectric filter or antenna duplexer of the present invention, a part of the circuit pattern of the DC circuit portion is disposed between the adjacent dielectric resonators. The DC circuit section and the high-frequency circuit section can be arranged separately. Therefore, the wiring of the circuit pattern can be simplified, and the portion where the high frequency circuit section and the DC circuit section intersect can be eliminated, so that high frequency signal jumps and unnecessary capacitance are prevented, and the filter characteristics are improved. Can be planned.

Further, a simplified circuit pattern is obtained,
Since intersections between circuit elements and circuit patterns can be eliminated or reduced, assembling work is facilitated, and characteristic defects due to short circuits and the like can be significantly reduced, and manufacturing costs can be reduced.

Further, by providing a chamfer or a concave portion at a corner of a dielectric resonator having a substantially square cross section, or by using a cylindrical dielectric resonator, adjacent dielectric resonators are closely arranged and arranged. The pattern of the DC circuit portion for separating the high-frequency circuit portion and the DC circuit portion can be arranged in the gap formed between the adjacent dielectric resonators, and the size can be further reduced.

Further, by using the dielectric filter or the antenna duplexer according to the present invention, it is possible to obtain a small, inexpensive communication device having good characteristics.

[Brief description of the drawings]

FIG. 1 is a plan view of an antenna duplexer according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view passing through both control terminals of FIG.

FIG. 3 is a plan view of the base substrate according to the first embodiment of the present invention.

FIG. 4 is an equivalent circuit diagram of the antenna duplexer according to the first embodiment of the present invention.

FIGS. 5A to 5C are cross-sectional views showing modified examples of a dielectric resonator according to another embodiment of the present invention.

FIG. 6 is a sectional view of a cylindrical dielectric resonator according to another embodiment of the present invention.

FIG. 7 is a block diagram of a communication device according to a second embodiment of the present invention.

FIG. 8 is a plan view of a conventional antenna duplexer.

[Explanation of symbols]

 1-5 Dielectric resonator 21 Base substrate 23 DC circuit pattern S Clearance C1... C23 Capacitor D1... D6 PIN diode L1... Control terminal 123 Antenna duplexer 124 Transmit filter (transmitter circuit) 125 Receive filter (receiver circuit)

Claims (7)

[Claims] 1. A plurality of dielectric resonators, a voltage-controllable impedance variable element electrically connected to at least one of the dielectric resonators, and a coupling or impedance variable element for coupling each dielectric resonator. A circuit element for voltage control;
A base substrate on which the respective components are mounted and on which a circuit pattern for connecting the respective components is formed, wherein a part of a circuit pattern of a DC circuit unit for applying a DC voltage to the variable impedance element is adjacent to a dielectric substrate. A dielectric filter, which is disposed between body resonators. 2. The dielectric resonator according to claim 1, wherein the at least one corner has a chamfered or recessed portion provided with a substantially quadrangular cross section, and the corner having the chamfered or recessed portion is adjacent to the base substrate. 2. The dielectric filter according to claim 1, wherein the dielectric filter is disposed in close contact with a dielectric resonator, and a part of the circuit pattern of the DC circuit unit is disposed in a gap formed by the chamfer or the recess. 3. 3. The dielectric resonator has a cylindrical shape, adjacent dielectric resonators are closely arranged, and a part of a circuit pattern of the DC circuit portion is formed between the adjacent dielectric resonators. The dielectric filter according to claim 1, wherein the dielectric filter is disposed in the gap formed. 4. A dielectric resonator for a transmission filter, a dielectric resonator for a reception filter, and a voltage-controllable impedance variable electrically connected to at least one of the dielectric resonators for each filter. An element, a circuit element for coupling of each dielectric resonator or a voltage control of an impedance variable element, and a base substrate on which a circuit pattern for mounting the respective components and connecting the respective components is formed, An antenna duplexer wherein a part of a circuit pattern of a DC circuit unit for applying a DC voltage to an impedance variable element is arranged between adjacent dielectric resonators. 5. The dielectric resonator has a cylindrical shape having a substantially square cross section in which at least one corner is provided with a chamfer or a concave portion, and the corner having the chamfer or the concave portion is adjacent to the base substrate. The antenna duplexer according to claim 4, wherein the antenna is arranged in close contact with a dielectric resonator, and a part of the circuit pattern of the DC circuit unit is arranged in a gap formed by the chamfer or the recess. 6. The dielectric resonator has a cylindrical shape, adjacent dielectric resonators are closely arranged, and a part of a circuit pattern of the DC circuit portion is formed between the adjacent dielectric resonators. The antenna duplexer according to claim 4, wherein the antenna duplexer is arranged in the space defined. 7. A dielectric filter according to claim 1, 2 or 3, or at least one of the antenna duplexer according to claim 4, 5 or 6. A communication device characterized by the above-mentioned.