JPS59110202A - Branching filter using band-pass filter - Google Patents

Abstract

PURPOSE:To decrease the number of parts by specifying geometric coefficients of BPFs equipped with input/output capacity-coupled devices forming a branching device and eliminating the need for a branching circuit. CONSTITUTION:Band-pass filters BPF1-BPF3 forming the branching device are comb line type BPFs each composed of a dielectric resonator. In this case, the decrease rate of geometric coefficients from the center resonator to the initial- stage resonator is set larger than that from the center resonator to the final- stage resonator. Further, capacity elements C1.0.1, C2.0.1, C3.0.1, and C4.0.1 which forms the input/output coupled circuits of the respective BPFs are coupled directly with branch points. Consequently, the need for a branching circuit is eliminated and the number of parts is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a duplexer for very high frequency waves or microwaves using a bandpass filter. (Hereinafter, a bandpass filter is abbreviated as BPF.) Conventionally, as shown in FIG. or a microwave duplexer is in practical use.In Fig. 1, R1
or Rn (n is the order of BPF) is a resonant circuit, C1,
2, Oa, >,...Ccn-bow, 7? is the interstage coupling capacitance, and Cσ, l and On, tn−h are the input/output coupling capacitances. In Fig. 2, R1 to Rn are resonant circuits, J, a, Ma, 3%...''M(71-
13,7L is the crotch magnetic field coupling coefficient, C6,1 and C,nc
n? is the input/output coupling capacitance.

In a conventional duplexer using such a PF, B
Since PF' has an equivalent length, the branch point BRN for connecting an external circuit such as an antenna and the center frequency f as shown in the third diagram.
Branch circuits BC+ and BCa made of semi-rigid cables are interposed between the input and output terminals of BPF 1 and BPF' with center frequency fa, respectively, and each electrical length is

and saw, o<J! a<in 1/4 and λf/4
〈ノ、〈λt (gradient is the wavelength within the jurisdiction) I: Selection, branching, outline B
The impedance viewed from the branch circuit BCa side from RN % is assumed to be infinite with respect to the frequency ff, and the impedance viewed from the branch point BRN to the branch circuit Bet side is assumed to be infinite and zero with respect to the frequency f, 1, and It is necessary to configure the fas so that they do not interfere with each other. In this way, the conventional duplexer shown in Figure 3 requires a branch circuit, which increases the number of component parts, makes the overall shape complex and large, and requires a relatively large amount of time and effort for assembly and adjustment. There are drawbacks such as the need for

The present invention reduces the number of component parts by directly connecting the input/output terminals of the BPP to the branching point without intervening a branch circuit between the branching point and the input/output terminals of the BPF, and the overall shape is simple and small, making it easy to assemble. The purpose is to realize a simple duplexer for ultra-high frequency waves or microwaves.

FIG. 4 is a sectional view showing one embodiment of the present invention, that is, BB sectional view in FIG. 5, and FIG. 5 is an AA sectional view in FIG. The housing, PAR is a partition wall made of a conductor, and BPFI to BPF4 are comline type BPFs each made of a dielectric resonator.
and R1/, 1 to R9, 7L are components of a dielectric resonator, for example, as shown in the enlarged cross-sectional view in FIG. A rod-shaped inner conductor S having an axial length equal to the tube wavelength is fitted into the inner conductor S, and together with the housing CAS and the partition wall PAR, a dielectric resonator is constructed. (1, + or Or, t
n-〇, (b, I to G (71-1) % G3.
H to G3fy+-++ and GEI to G Q, (
'7L-r) is the air gap between the dielectric resonators, SGR+, + to SCR+11 and 5CRa, / to 5CRa, n
are setscrews for the dielectric resonator components Rr, + to Rr, n and Ra, 1 to Rj, %, and are not shown in the figure for the dielectric resonator components RJ, I to R4,
o Ctn, and R9, l to Rqn are also fixed in position within the housing CAS by similar setscrews;
I%Ct,n,Cnpr)lICa,o,H%C
J-71, f7L-+) %03.11.1 % CJ
, n, tns) % CQ, n, + and sales n, (n啼)
is an input/output coupling capacitance element consisting of a suitable capacitor or an electrode plate that forms a coupling capacitance between it and the internal conductor of each initial stage and final stage dielectric resonator. T, or T is the input/output coaxial terminal, Tc is the common input/output coaxial terminal, and the drawn cotton LO
T Th via input/output coupling capacitive element Cto, +% O
It is connected to the branch point of G01, cz, a, r and CLt, ol. The leader line LOT I has a characteristic impedance equal to the characteristic impedance of the external circuit connected to the common input/output coaxial terminal, and is made of a strip line or coaxial line.

In the duplexer of the present invention, the geometric coefficients for each BPF are determined as follows. That is, in general, the BP
The geometric coefficients of F' are shown in Figure 7 (the horizontal axis is the order n of the BPF, the vertical axis is the size of the geometric coefficient g), and the distance from the central resonator to the first and final stage resonators (towards this point) is shown by the solid line. (The decreasing state reaching the first stage side and the decreasing state reaching the final stage side are configured to be symmetrical with respect to the center.) In , the coupling capacitance or magnetic field coupling coefficient between each resonator from the central resonator to the first stage resonator on the branch point side is calculated as Measures such as increasing the coupling capacitance or magnetic field coupling coefficient appropriately The geometric coefficients associated with each resonator from the central resonator to the first stage resonator are made smaller than the geometric coefficients associated with each resonator from the central resonator to the first stage resonator. By adjusting the ratio appropriately, the frequency f +
In addition to making the coupling characteristics good for the signals of
In PFλ, the coupling characteristics for fa are good, and f(,
Impedance for fa, f% is close to infinity/IB
In PFJ, the coupling characteristics for 3 are good, fl,
, fax fg+ is close to infinity.The BPF9 is formed so that the coupling characteristics to fl are good and the impedance to fl or fa is close to infinity. Therefore, even if BPFr to BPF' are directly connected to a branch point without going through a branch circuit, fl to f% will not interfere with each other, and f to f will be connected to each corresponding BPFr to B.
It is possible to perform demultiplexing and coupling to each PF'% separately, and
Since no branch passage is required, the overall shape can be made simple and compact, and assembly is easy.

8 and 9 are equivalent circuit diagrams of the duplexer of the present invention.
The figure shows the case where electric field coupling is made between each dielectric resonant circuit configuring each BPF, R:, l or R'+rIs R'2
．． 1 to RJ, n, R'J, I to RS, 71x
R'(II to R'vn are resonances og each, C't, a,
+,,C'+,n4n-+),(4),1%Ca,n,
+n+t+,C10,a,+,C';,n,tnar)
s C'17.6.1% O'et, n 2 qr) is the input/output coupling capacity, aS, >, c-91... From the grave, rt is the groin coupling capacity, T7 or T- is Input terminal, T
Y is a common input terminal.

Figure 9 shows the case where the dielectric resonant circuits constituting each BPF are magnetically coupled, and MIJ % Ma, 1...
・M(7L-1) is the magnetic coupling coefficient, other signs are the 8th
It is similar to the figure.

As shown in FIG. 6, the constituent elements of the dielectric resonator in the BPF constituting the duplexer of the present invention are formed by inserting a rod-shaped conductor S into the hole H bored in the dielectric. The internal conductor may be formed by attaching a metal coating such as silver or copper to the inner wall surface of the hole H, or by attaching a metal coating to the inner wall surface of the hole H and further fitting a rod-shaped conductor into the inner wall surface of the hole H. Alternatively, a helical coil may be embedded in the dielectric material to serve as an internal conductor. The dielectric material may be formed into a cylindrical shape instead of a rectangular parallelepiped, or an adjacent dielectric resonator may be used as an internal conductor. A BPF' made of a dielectric resonator may be configured by making them closely contact each other without providing a gap therebetween, or by uniformly filling the casing CAS with a dielectric material.

Instead of configuring the BPF with a dielectric resonator, the overall shape will inevitably become somewhat larger, but the dielectric in the casing CAS is replaced with air, and the interior is made of a rod-shaped conductor or a cylindrical conductor. A resonator may be formed by the conductor, the casing CAS, and the partition wall PAR.

Although FIGS. 4 and 5 illustrate the case where a comline type BPF is used, the present invention can also be practiced using an ink-digital type BPF in which the input/output coupling circuit is a capacitive coupling circuit. , some BPF.

For example, BPFr and BPFa are formed using a comline type BPF', and the remaining BPF is formed using an ink digital type BPF.
The present invention can also be carried out by forming it using the following methods.

FIG. 10 is an equivalent circuit diagram showing another embodiment of the present invention, and B
PFr and BPF4 have the geometric coefficients shown with solid lines in FIG. 7. BPF% LC is the compensation inductance, BR
N is the branch point, and if we now consider the case where the compensation inductance LG is omitted, in this case apr, (or BP
The input/output coupling capacitance of F& ) is BPF& (or BPFE
), resulting in deterioration of voltage standing wave ratio characteristics and transmission characteristics. However, when inserting the compensation inductance LC in parallel to the branch point BRN as in this embodiment, the BP
When looking at Pr or BPF, the capacitive admittance in the non-resonant region is compensated for by the compensating inductance LC (in this case, the thickness of LC should be selected appropriately23), and the branch point becomes low. A parallel resonant circuit of the load Q is formed, and there is no possibility of interference between BPF'r and BPF. Therefore, as in the previous embodiment, there is no need to interpose a branch circuit between the BPF and the branch point, and the overall shape is simple and compact, making assembly easy.

In the embodiment shown in FIGS. 4 and 5, the BPF is 4.
In the embodiment shown in FIG. 10, the case where two BPFs are directly connected to the branch point j is illustrated, but in any embodiment, the present invention can be implemented using any number of BPFs greater than or equal to two. You can.

[Brief explanation of the drawing]

1 to 3 are diagrams showing a conventional duplexer, FIGS. 4 and 5 are sectional views showing an embodiment of the present invention, and FIGS. 6 and 7 are configurations of a duplexer according to the present invention. 8 and 9 are equivalent circuit diagrams of the duplexer according to the present invention, and FIG. 10 is an equivalent circuit diagram showing another embodiment of the present invention. In each figure, BPF I to BPF6: band pass filter, BC+ and BCJ: branch path, BRN:
Branch point, CAS: housing, PAR: partition wall, D: rectangular parallelepiped made of dielectric, H: hole, S: rod A large internal conductor, T1 to Tφ: input/output coaxial terminal, TC: common input/output coaxial terminal, LOT :Leader line, R11 (\shiR+翫Ra, l,%shiRa,n %Ri,t or Ra,n and R
No qI% L, Rq, x: Resonator components, G+
, I to G, prompt-〇-GaI, G-C-circle-/)
, G3. I to Gj, (7L-1) and GQ, f to G Ll, cqc-+): void, SCR, . to 5ORtTL and 5CRa, + to 5CRr,
*: Set screw, Ot, Ct, n, (rL+g, OJ
, O,1JajyL, (ytx]%CL'-1-G3.
'O-Cnfυ, Cη, of and CtAn, (fLtr
) 'It is an input/output coupling capacitive element. Figure 9 Figure 10 M (71-1), 71

Claims (2)

[Claims] (1) The rate of decrease in the geometric coefficient associated with each resonator from the central resonator to the first stage resonator is calculated by the geometric coefficient associated with each resonator from the central resonator to the final stage resonator. In addition to increasing the rate of decrease in A duplexer using a bandpass filter characterized by comprising: (2) One input/output coupling circuit of each of a plurality of bandpass filters formed using capacitive coupling circuits is directly coupled to a branch point, and a compensating inductance element is connected in parallel to the branch point. A duplexer using a bandpass filter characterized by comprising: