JPS5810003B2 - circulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circulator, and particularly to a circulator using microstrips.

Recently, microstrip circuits have been applied to many microwave circuits, and microstrip circulators have become available that are comparable to conventional triplex strip line type circulators.

There are various types of microstrip line circulators, and when classified by the type of substrate used for the microstrip, there are two types: those using a ceramic substrate and those using a ferrimagnetic substrate.

Recently, due to improvements in ferrimagnetic materials and advances in substrate manufacturing technology, many circulators have been manufactured using ferrimagnetic materials as substrates.

FIGS. 1 and 2 are a front view and a sectional view showing a microstrip circulator using a conventional ferrimagnetic substrate.

1 and 2, the ferrimagnetic substrate 1, which functions as both a non-reciprocal element and a substrate, has an internal structure consisting of a circular joint 2a, transmission lines 2b and 2d, and a capacitive piece 2C. A conductor 2 is formed, and this capacitive piece 2c is provided protruding from the transmission lines 2b and 2d,
A branch line is constituted by these transmission lines 2b, 2d and the capacitive piece 2c.

Further, a magnet 4 for applying a magnetic bias perpendicularly to the outer conductor 3 and the ferrimagnetic substrate 1 is attached to the ferrimagnetic substrate 1 .

After metal is deposited on the ferrimagnetic substrate 1, only the surface thereof is etched to form the inner conductor 2, leaving the metal on the side facing the outer conductor 3 as it is.

Next, the structure will be further described in the case where yttrium-iron-gannet (hereinafter abbreviated as rYIGj) is used as the ferrimagnetic substrate 1.

First, the thickness of the YIG substrate is 0.635 m, which is the same as the ceramic substrate often used in general microwave integrated circuits.
m, and the relative dielectric constant ε of the YIG substrate is 14, and the conductor width of the characteristic impedance line of 50Ω provided on the ferrimagnetic substrate is the one published by Horizon House.The m
icrowave englneers hand b
ookand buyer's guide, 1968
．． If calculated using the graph of P95, it will be about 0.35rr.

Since the characteristic impedance of a strip line generally used in microwave circuits is 50Ω, the characteristic impedance of the connection point of the circulator with the external circuit is also selected to be 50Ω to make the connection easy. 20 width is 0.35 mm.

The microstrip line circulator shown in Figure 1 is
When used in a microwave circuit, coaxial connectors,
It is necessary to connect to a ceramic substrate, a substrate using Teflon glass fiber, etc., but as mentioned above, the internal conductor width is as narrow as 0.35 mm, so discontinuities occur in the electrical connection, making it difficult to obtain stable electrical characteristics. In addition, mechanically, there were drawbacks such as the strength of the connection portion being weakened and soldering being extremely difficult.

Considering these points, tl in FIG. 1 is shortened to t2, and the ferrimagnetic substrate 1 is extended to the position of the capacitive piece 2c.
There is also a method of reducing the external size of the ferrimagnetic substrate, but such a method has the disadvantage that it is not practical when the external size of the ferrimagnetic substrate cannot be arbitrarily selected.

SUMMARY OF THE INVENTION An object of the present invention is to provide a circulator in which the capacitive piece of the internal conductor is provided with a connecting end to an external circuit, thereby eliminating the above-mentioned drawbacks of the conventional circulator.

The present invention provides a circulator consisting of a ferrimagnetic substrate formed with an internal conductor having a junction, a transmission line, and a branch line consisting of a protruding capacitive piece, and an external conductor and magnet attached to this substrate. In,
It is an object of the present invention to provide a circulator characterized in that the capacitive piece is disposed at a connection end between the branch line and an external circuit.

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 3 shows the first embodiment. In FIG. 3, a ferrimagnetic substrate 11 that functions as both an irreversible element and a substrate includes a circular joint 12a, a transmission line 12b, and a capacitive piece 1.
The capacitive piece 12c protrudes from the transmission line 12b and is provided at the connection end between the internal conductor 2 and the external circuit.

Although not shown, the ferrimagnetic substrate 11 is attached with a magnet for applying a magnetic bias perpendicularly to the external conductor and the ferrimagnetic substrate 11.

In the circulator of the first embodiment of the present invention having the above configuration, the capacitive piece 12c of the internal conductor 12 is provided at the connection end with the external circuit.
Since the width of c is much larger than the conductor width of 0.35 mm of the transmission line 2d of the conventional circulator in FIG. gender can be removed.

If the matching condition can be satisfied by providing the capacitive piece 12C on the side edge of the ferrimagnetic substrate 11 given in this manner, there will be no inconvenience caused by shortening the length from 11 to t2 in FIG. 1.

This matching condition can be easily found by the means used in the design of ordinary microwave circuits, and this method will be explained next using an equal number of circuits.

Zo is the impedance of the circulator's external connection circuit.
, the impedance on the circular junction side from the contact point between the branch line and the circular junction 12a is Z2, the capacitance of the capacitive piece 12c is c, and the characteristic impedance and length of the transmission line 12b are 21 and 1, respectively. The equivalent circuit of one branch circuit is as shown in FIG.

In this case, the impedance Z2 on the circular junction side is approximately 1 if the saturation magnetization 4πMs of the ferrimagnetic substrate 1, relative permittivity εS, operating magnetic field, and size of the circular junction are appropriately selected.
The reactance component can be made extremely small in the 0% fractional band.

In FIG. 4, the impedance Z on the circulator side from the connection point A with the external circuit is expressed by equation (1).

In order to achieve matching between the circulator and the external circuit, the following equation (2) needs to be satisfied.

2=2o・・・・・・・・・・・・・・・(2) As a result, Zo=50Ω, Z2=25Ω (As mentioned above, the reactance component becomes small, so to simplify the calculation, the reactance component is Ingredients were ignored.

), Zl and C are calculated as follows.

Therefore, relative dielectric constant εr-14, thickness t=0.635
In the case of a circulator with f = 10 GHz using the ferrimagnetic substrate 11 of
If m is chosen, the wavelength shortening rate is about 34%. From the above formula, Z1=
49.97Ω, C=0.22pF.

In this way, the characteristic impedance of an arbitrary transmission line 12b and the dimensions of the capacitive piece 12C are determined by the above calculation.

FIG. 5 shows a second embodiment, in which the same parts as in the first embodiment shown in FIG. 3 are denoted by the same reference numerals and the explanation thereof will be omitted.

The difference between the second embodiment shown in FIG. 5 and the first embodiment shown in FIG. 3 is that the transmission line 12d is formed in a meandering manner.

The circulator according to the second embodiment of the present invention having the above configuration is effective when the length of the transmission line 12d cannot be shortened by increasing the characteristic impedance of the transmission line 12d.

It should be noted that the present invention is not limited to the above-mentioned embodiment, but has various applications and modifications.For example, in the above-mentioned embodiment, the dielectric constant ε is 14, and the thickness of the ferrimagnetic substrate is 0.
Although the case of 635 mm has been explained, if the relative dielectric constant ε is larger and the thickness of the ferrimagnetic substrate is thinner, the width of the transmission line will be smaller than 0.35 mm, so the present invention cannot be applied. produce a greater effect.

Further, although the present invention has been described in outline with respect to a circulator, the principles of the present invention can be applied to an isolake that terminates one terminal of a circulator to exhibit the above-mentioned functions and effects.

Furthermore, in addition to etching the ferrimagnetic substrate to form the internal conductor, a metal plate having an internal conductor, a transmission line, and a capacitive piece may be attached to the substrate, and the material of the substrate is limited to the ferrimagnetic substrate. Any suitable substrate can be used.

As explained above, in the present invention, the capacitive piece of the internal conductor is provided at the connection end with the external circuit to increase the width of the conductor, which facilitates connection with the external circuit by soldering etc. This has the effect of providing stable characteristics due to electrical characteristics caused by discontinuity of the connection portion.

[Brief explanation of the drawing]

1 and 2 show a front view and a sectional view of a conventional circulator, FIGS. 3 to 5 show an embodiment of a circulator according to the present invention, and FIG. 3 shows a front view and a sectional view of a conventional circulator. FIG. 4 is an equivalent circuit diagram of FIGS. 3 and 5, and FIG. 4 is a front view of the second embodiment. 11... Ferrimagnetic substrate, 12...
Internal conductor, 12a... Junction, 12b, 12d
...Conduction line, 12c...Capacitive piece.

Claims (1)

[Claims] 1 Consists of a ferrimagnetic substrate on which an internal conductor is formed that has a junction, a transmission line, and a branch line consisting of a protruding capacitive piece, and an external conductor and magnet attached to this ferrimagnetic substrate A circulator, characterized in that the capacitive piece is disposed at a connection end between the branch line and an external circuit.