JPH0131322B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a bandpass waver, and particularly to a bandpass waver using a dielectric resonator.

[Prior art and its problems]

FIG. 2 is a diagram showing an example of the configuration of a conventional dielectric resonator bandpass filter (hereinafter referred to as DR BPF), in which a is a front sectional view, and b is a plan view seen from above with the cover removed. In FIG. 1, 1 to 5 are dielectric resonators, 6 to 10 are support stands for the dielectric resonators, and 11 to 15 are metal screws for adjusting the resonance frequency of the dielectric resonators, respectively. Reference numeral 16 designates a metal chassis (casing) of the bandpass wave device, 17 a metal cover, and 18 and 19 designate input/output connectors, which are electromagnetically coupled to the dielectric resonators 1 and 5, respectively. Probes 20 and 21 are attached for this purpose. However, these connectors have a different appearance than the others.

FIG. 3 is a diagram showing an example of the characteristics (relationship between no-load Q and frequency) of typical dielectric resonators currently used. As can be easily seen from FIG. 2, in general, dielectric resonators with a higher relative dielectric constant ε _r have a lower no-load Q value. Features expected of DR BPF include reduced insertion loss and smaller size. If you try to increase the no-load Q by using a dielectric resonator with a small relative permittivity ε _r , you will have to use a dielectric material to obtain the same relative bandwidth compared to using a dielectric resonator with a large ε _r . The inter-resonator distances S ₁ to _{S 4} become large, and as a result, the shape of the DR BPF becomes large. Therefore, when considering the feature of miniaturization of the shape, in the conventional DR BPF configuration example, an ε _r of about 38 to 40 is used for all dielectric resonators making up the DR BPF. However, even if you do this,
Conventional wave devices have a problem of large insertion loss.

As an example, using a dielectric resonator with ε _r = 40,
Ripple is 0.01dB, type is Tiebishiev type, center frequency is 4GHz, ripple band is ±20M
Consider configuring a DR BPF with characteristics of 5 Hz and 5 steps. DR given the above characteristics
The insertion loss of BPF is given by filter theory as [insertion loss] = 4.343 × center frequency / ripple band × ₅ 〓 ^{n = 1} g _o ... (1). Here, g _o is the value determined by filter theory, and in the case of the above example, g ₁ =
0.7563, g ₂ = 1.3049, g ₃ = 1.5773, g ₄ = 1.3049, g ₅
=0.7563. Therefore, if all five dielectric resonators have an unloaded Q of 6000 as shown in Figure 3, the insertion loss from equation (1) is [insertion loss] = 4.343 x 4000/40 x (0.7563 + 1 .3049+1
.5773+1.3049+0.7563)/6000≒0.41dB…(2)

FIG. 4 is a diagram showing the relationship between frequency (GHz) and insertion loss, and the value at point A (square mark) indicates the above-mentioned insertion loss value. However, in reality, the configuration shown in Figure 2
When a DR BPF is manufactured, it has the disadvantage that it is inferior to equation (2). When we investigated the cause of this, we found that it was because the no-load Q of the dielectric resonators (1 and 5 in Figure 2) coupled with the input/output circuit decreased due to conductor loss in the input/output circuit. Divided. The degree of decrease varies depending on the fractional band, but as shown in the characteristic example
For 40MHz band at 4GHz, no-load Q of 6000
is approximately 2500. Therefore, the actual insertion loss is [insertion loss] = 4.343×4000/40×(0.7563/2500
+1.3049+1.5773+1.3049/6000+0.7563/2500)≒0.
57dB...(3) Point B (triangle mark) in FIG. 4 indicates the above insertion loss value. Therefore, equations (2) and (3) show that as the no-load Q at both ends decreases, the insertion loss deteriorates by 0.16 dB, which is the difference between 0.57 dB and 0.41 dB. The same applies to points C and D at 8 GHz.

[Purpose of the invention]

Therefore, the purpose of the present invention is to reduce the size of the
The objective is to obtain a DR BPF with improved insertion loss without losing much of the merits of the DR BPF. More specifically, the aim is to obtain a DR BPF with low insertion loss at the input and output ends.

[Structure of the invention]

The dielectric resonator bandpass wave device of the present invention includes a plurality of dielectric resonators 1a, 2, 3, 4, and 5a and a metal chassis 16 containing them, at least one of the dielectric resonators 1a and 5a on the input/output circuit side for coupling with the outside is , a dielectric resonator band-pass waver is obtained which is characterized in that the dielectric resonators 2, 3, and 4 have a higher no-load Q than the remaining dielectric resonators 2, 3, and 4.

〔Example〕

In the configuration of the embodiment of the present invention shown in FIG.
Components that are the same as those in the figures are provided with the same reference numerals. For example, 2, 3, and 4 are dielectric resonators each having an unloaded Q of 4000, which are specifically used in the present invention. As these resonators, for example, dielectric resonators with ε _r =30 as shown in FIG. 3 are used. As shown in Figure 3, the unloaded Q of the dielectric resonator with ε _r = 30 is
There are approximately 12,000 in the 4GHz band. Even if the conductor loss of the input/output circuit is taken into account, the fractional band of the above characteristic example can be approximately 6000. Therefore, if such dielectric resonators are used as dielectric resonators 1a and 5a at both ends, [insertion loss]=4.343×4000/40×(0.7563+1.304
9+1.5773+1.3049+0.7563)/6000≒0.41dB, resulting in a value as shown at point A in FIG. In this way, it is possible to prevent deterioration of insertion loss due to a decrease in the no-load Q of the dielectric resonators at both ends, which was a problem in the conventional configuration example. Note that since ε _r of the dielectric resonators 1a and 5a at both ends of FIG. 1 is smaller,
Although the shape is slightly larger than the other dielectric resonators 2, 3, and 4, the loss is improved as described above, and it is extremely effective in practice.

5 and 6 are diagrams showing the configurations of two other embodiments of the present invention, and FIG. 5 shows a configuration in which only the dielectric resonator 1a on one side is replaced with a high no-load Q one. , Figure 6 shows two pieces a, 2a, 4 on both sides.
This shows a configuration in which four elements a and 5a can be replaced.
Both are extremely effective.

〔Effect of the invention〕

As described above, the present invention minimizes the increase in shape and improves insertion loss.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a dielectric resonator bandpass filter (DR BPF) that is an embodiment of the present invention.
Figure 2 shows the configuration of a conventional DR BPF, and Figure 3 shows the configuration of a conventional DR BPF.
The figure shows the relationship between no-load Q and frequency of a typical dielectric resonator. 5 and 6 are diagrams showing the configurations of two other embodiments of the present invention. Explanation of symbols: 1 to 5 and 1a, 2a, 4a,
5a is a dielectric resonator, 6-10 are support stands, 11-
15 is a metal screw (for adjusting resonance frequency), 16 is a metal chassis, 17 is a metal cover, 18 and 19 are input/output connectors, and 20 and 21 are probes, respectively.

Claims (1)

[Claims] 1. In a dielectric resonator bandpass wave device consisting of a plurality of dielectric resonators arranged in series and a metal chassis containing them, the dielectric resonator on the input/output circuit side for coupling with the outside is at least one,
A dielectric resonator band-pass wave device characterized by having a higher no-load Q than the remaining dielectric resonators.