JPS5819002A - Polarized type band pass filter - Google Patents

Abstract

PURPOSE:To improve the leading characteristics of the attenuation area, by disposing a plurality of semicoaxial type dielectric resonator in channel shape, and indirectly coupling the resonators. CONSTITUTION:A BPF is formed with a shield case 1, inner conductors 21-26, dielectric substances 31-36, interstage coupling capacitor forming conductors 41-410, and section shield 7. A coupling element 9 is coupled with a leakage magnetic field produced at an air gap of a resonator including the inner conductors 22 and 25, and coupling element 10 consists of an electrode rod supported and inserted at the air gap of the resonator including the inner conductors 21, 26 to form the coupling capacitor. With suitable degree of coupling of the coupling elements 9 and 10, the attenuation pole to the attenuation area can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polarized bandpass filter (hereinafter referred to as a bandpass filter abbreviated as BPP) using a half-open axial dielectric resonator.

FIG. 1 is a diagram showing an example of a conventional BPP, and is a cross section cut along a horizontal plane (hereinafter referred to as yJ<plane cross-sectional view (1)). In the figure, I is a seal 1 + case that absorbs the external conductor, 21 to 2b are internal conductors, each lower end is in contact with the bottom wall of the shield case 1, and each upper end is placed between the earthen wall of the shield case 1 as appropriate. A gap is provided. 31 to 3b 1. is a rectangular dielectric,
Together with the inner conductors 21 to 2 and the seal 1ζ case l, a semi-coaxial dielectric resonator is formed. 41 or 4ID
is a conductor piece for forming interstage coupling capacitance, and one end is the inner conductor 2I.
An interstage coupling capacitance is formed between the opposed conductor pieces 1 to 2b, which are attached to the open ends of the conductors 1 to 2b. 5I
and 5 are input/output coupling capacitors, 6I and 62 are input/output coaxial terminals, and 7 is a partition shield wall.

FIG. 2 is an equivalent circuit diagram of the BPF shown in FIG.
Or L6 is each semi-coaxial type! The inotaftance of the previous resonator, CI and cq are the input and output capacitors 5I and 5z.
The capacitance, Cz or Cm, is the conductor piece 41 or 41
5, the interstage coupling capacitance formed≧disappears.

(2) In such a conventional BPF, the normal h range is Wagner.
It exhibits shape characteristics or Chepinev-type characteristics, the attenuation region is Wagner-type characteristics, and the rise characteristics of the attenuation region are poor, and in order to make the rise characteristics good, it is necessary to increase the number of stages (order) of the quadrupole. As a result, the overall size is large, the insertion loss is large, and there are drawbacks such as a large amount of time and effort required for manufacturing and adjustment.

An object of the present invention is to realize a polarized bandpass filter that has good rise characteristics in the attenuation region, is small in size, has low input and loss, and can be easily and quickly adjusted during manufacturing. .

3 is a horizontal cross-sectional view (cross-sectional view taken along the line C-C in FIG. 4) showing one embodiment of the present invention; FIG. 4 is an elliptical cross-sectional view taken along the line A-A in FIG. 3; The figure is a cross-sectional view of the B-8 section in FIG. 3. In each figure, 1 is a shield case forming an external conductor; 2. or 2b is an internal conductor, 31 or 3G
is a rectangular parallelepiped dielectric (3) electric body, 41 to 410 are conductor pieces for forming interstage coupling capacitance, 51 and 52 are input/output coupling capacitors → f, 61 and υ6z are input/output coaxial terminals, 7 is a partition seal IS wall This is provided to prevent the forward resonator from coupling with the return resonator, and the above configuration is the same as that shown in Figure 1. 8I to 8b are tuning screws, Separate each I
By tightening this rotation, the resonance frequency of each resonator can be finely adjusted individually. (Adjusting screws 8 and 8 are not shown) 9 and 10 are indirect coupling elements which are the gist of the present invention, and element 9 is an open part of both dielectric resonators including internal conductors 2z and 25, that is, an internal conductor. 22. and 2
6, a gap is formed between the upper end surfaces of the dielectrics 3z and 3, and the earthen wall of the shield case 1, and is composed of a loop that couples with the leakage magnetic field generated in this gap. is connected to the partition shield wall 7, and its intermediate portion is inserted into a hole 11 bored in the partition shield wall 7. In order to prevent the coupling loop 9 from contacting the periphery of the hole 11 (4) and causing a short circuit, an insulator (not shown) is interposed between the coupling loop 9 and the hole 11 .

Next, the element 10 is inserted into a hole 12 formed in the partition shield wall 7 at a location corresponding to each open part of both dielectric resonators including the internal conductors 2I and 2b through an insulator 13. Therefore, a coupling capacitance is formed between one end of the electrode rod and the internal conductor 21 and between the other end of the electrode rod and the internal conductor 26, respectively.

FIG. 6 shows the polar type B of the present invention shown in FIGS. 3 to 5.
In the basic equivalent circuit diagram of PF, Mr or L& is the inductance of each dielectric, CI and C7 are the capacitances of input/output coupling capacitors 5I and 52, and C2 to C
6 is the coupling capacitance between the legs formed by the conductor pieces 41 to 4+o, M+ is the mutual inductance between the resonator including the coupling loop 9 and the internal conductor 22, and M2 is the mutual inductance between the resonator including the coupling loop 9 and the internal conductor 25. The mutual inductance, Oc is the total capacitance of the coupling capacitance between the coupling element 10 and the internal conductor (5) and the coupling capacitance between the coupling element 1o and the internal conductor 26 open, and A, B, O, and D are the indirect coupling elements 9 and 10. It is the connection point of

Figure 7 shows the equivalent path diagram shown in Figure 6 with 70 square diagrams, where P and P7 are phase circuits formed by resonators and coupling capacitors (the amount of phase is 19
0', i.e., +270"), and is a so-called impedance inverter. The ±90° shown in the figure is the phase amount in the resonator of the transmission signal, and the signal with a frequency higher than the passband is +90', but above the passband. The phase 1 of a signal with a high frequency is -90''. Other symbols are the same as in FIG.

In the BPF of the present invention configured as described above, in the signal transmitted through the half-open shaft dielectric resonator circuit via the groin coupling capacitance (referred to as the signal transmitted through the main circuit under μ), the frequency is lower than the passband. The phase amount between points A and D of a signal with a high The phase amount of the A and D booths is -90'X
6 + (-90'X5) knee 990'' (-990
+720'knee 270'). On the other hand, the signal transmitted from point A to point D via the indirect coupling capacitance element 10 is! <A and D related to morning wave number
A phase advance of 90'+7) is generated between the points, and a phase difference of 180' is generated between the signal transmitted from point A through the main circuit to point D. In the attenuation range, the amplitude of the signal transmitted to point D via the main circuit is at point A (i). By smoothing, the amplitude of the signal transmitted to point D via element 10 is made equal to the amplitude of the signal transmitted to point D via the main circuit, causing both signals to cancel each other out, and the signal is attenuated in the attenuation range. It is possible to generate extremes.

Next, among the signals transmitted through the main circuit, the phase amount between points B and C of a signal with a higher frequency than the passband is +90'X4 + (-90''X3) = +90° for both voltage (7) and current. , among the signals transmitted through the main circuit, the phase amount between points B and C of the signal whose frequency is lower than the passband is -90'X4 + (-90°X3) = -630°(-
630" + 360'--270").

On the other hand, the signal transmitted from the point B to the point 0 via the indirect coupling loop 9 includes the internal conductors 2z and 2g. Since the current phase becomes -90', an attenuation pole can be generated in the attenuation region by appropriately adjusting the degree of coupling of the coupling loop 9.

Note that the signal in the passband transmitted through the main circuit is the signal 1 in the passband transmitted through the indirect coupling elements 9 and 10; the amplitude is sufficiently large, so the influence of the cancellation effect (8) at point 0 and point D is The loss is negligible.

The transmission characteristics of the polarized BPF' of the present invention can be approximately expressed by the following equation.

・・・・・・(1) When n is an even number, When n is an odd number, ・・・・・・(3) However, in each of the above formulas, L: Signal attenuation in the passband S: Passband Allowable voltage standing wave ratio (VSWR) (
9) n: Number of stages (order) of the electrostatic resonator, which is 6 in the second embodiment.

f6f f.

x = −(−−−) Bw+c fa f Bwr+ : Bandwidth of allowable VSWR fo : Common 4-pin frequency f ; Arbitrary transmission frequency fc : Cutoff frequency f-5 : Frequency that gives an attenuation pole Furthermore, in equation (2) Re means taking the real part, (3
) in the equation. bn means taking the imaginary part.

FIG. 8 is a curve diagram showing the transmission characteristics (10) of the conventional BPP and the BPI of the present invention, in which the horizontal axis represents the transmission frequency f in MHz, and the vertical axis represents the attenuation amount ATT in dB. As is clear, the characteristics of the present invention BP[i' (solid line) have a much steeper rise in the attenuation curve than the characteristics of the conventional BPF shown in FIGS. 1 and 2 (dashed line), and p In Fig. 8, fl is the lower limit passing frequency, and f2 is the upper limit passing frequency.

The above explanation is based on the case where a polarized BPF is configured with six tenn-axis dielectric co-opters and two indirect coupling circuits, but the number of semi-coaxial dielectric co-opters and the indirect coupling circuit The number of indirect coupling circuits can be increased or decreased as appropriate, and the types of indirect coupling circuits and their combinations can also be appropriately selected. For example, the indirect coupling element 9 shown in FIGS. 3 to 5 (2)
may be formed using a capacitive element, and the indirect coupling element 10 may be formed using a coupling loop, or the pixel element may be formed using a capacitive element or a coupling loop. Further, the present invention can be practiced by forming an indirect coupling circuit by drilling a magnetic field coupling hole in the part of the partition shield wall corresponding to the open part of the half-open axial dielectric resonator instead of the coupling loop.

[Brief explanation of the drawing]

Figure 1 is a diagram showing an example of a conventional bandpass filter, Figure 2 is a diagram showing an example of a conventional bandpass filter.
3 to 5 are diagrams showing an embodiment of the present invention, and FIG. 6 is a basic equivalent circuit diagram,
FIG. 7 is a block diagram thereof, and FIG. 8 is a curve diagram showing each transmission characteristic of the conventional bandpass filter and the bandpass filter of the present invention. 3
1 to 3b: dielectric, 41 to 410; conductor pieces for forming interstage coupling capacitance, 5I and 52; input/output coupling capacitors, 61 and 6z: input/output coaxial terminals, 7: partition shield wall, 8I to 8I,: tuning Screws, 9 and 10:
Indirect coupling element, 11 and 12: pore, 13: insulator, L
l to r 几: resonator inductance, CI and C: input/output coupling capacitance, C2 to CL: interstage coupling capacitance, M+ and Mz: mutual inductance between the indirect coupling element and the resonator, Cc: indirect Total coupling capacitance between coupling element and internal conductor, A, B, C and D; coupling point of indirect coupling element, P
l to Pq: Phase circuit. (13) Figure 1 Figure 2

Claims (1)

[Scope of Claims] A plurality of semi-coaxial frost-proof body resonators are arranged in a U-shape, and are cascade-connected via a coupling capacitance, and inside the plurality of semi-coaxial frost-proof body resonators. Any non-cascaded semi-solid axial dielectric resonators can be connected via coupling capacitance elements, coupling loops or coupling holes provided in the open gaps of these half-open axial dielectric resonators. What is claimed is: 1. A polarized bandpass filter characterized in that the filter is formed by indirectly coupling two polarized bandpass filters.