JPS633205Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to widening the bandwidth of a diode switch configured with a finline.

FIG. 1 shows an example of the structure of a diode switch constructed using a conventional finline.

A dielectric plate 2 is placed approximately in the center of the wide surface of the waveguide 1 in parallel to the electric field, and the surface of the dielectric plate 2 has
Metal film 4 with slits 3 along the radio wave propagation direction
is covered.

Furthermore, diodes 5 are connected to the metal film 4 at predetermined intervals by bonding, soldering, etc. so as to bridge the gap 3.

The diode switch of the configuration example shown in FIG. 1 switches the polarity of the bias applied to the diode 5 in forward and reverse directions to switch between blocking and passing radio waves propagating through the fin line.

That is, in a forward bias state, the impedance exhibited by the diode 5 becomes a low impedance, thereby short-circuiting the microwave current flowing along the slit 3, resulting in a cutoff state, whereas in a reverse bias state, the diode 5 exhibits a high impedance. Therefore, a passing state is obtained without affecting the microwave current.

Further, usually, a plurality of diodes 5 (two in the figure) are connected at predetermined intervals to improve isolation characteristics and reflection characteristics.

Incidentally, a diode switch configured with a finline is often used in a high frequency band because the diode 5 can be easily attached, it can be easily converted into a waveguide, and the loss is relatively low. However, as the frequency becomes higher, the impedance that the diode 5 presents to the microwave in the reverse bias state becomes lower. Therefore, there was a drawback that the reflection characteristics in the state of passing through the switch deteriorated.

In order to eliminate this drawback, this idea covers the dielectric plate surface on the side where the diode is mounted and the opposite surface with a metal film with a slit similar to the surface on which the diode is mounted. The narrow gap at the position facing the diode mounting part is short-circuited with a metal wire or the like to prevent a drop in the impedance of the diode mounting part in a reverse bias state and to obtain good reflection characteristics.

FIG. 2 shows an embodiment of this invention, in which a metal film 4 with a narrow gap 3 is adhered to both sides of a dielectric plate 2, and a metal film 4 facing the position where a diode 5 is installed is attached to the dielectric plate 2. The membrane 4 is provided with a metal wire 6,
It has a structure in which a metal wire 6 bridges the gap 3. By appropriately determining the length of the metal wire 6, the metal wire 6 has an inductive reactance with respect to the microwave propagating through the fin line.

Further, the metal wire 6 is connected in parallel to the diode 5 for microwaves propagating through the finline.

Therefore, by appropriately determining the value of the inductive reactance exhibited by the metal wire 6, a parallel resonance state is possible together with the capacitive reactance of the diode 5, resulting in a high impedance.

In this case, the microwaves propagating through the fin line are not significantly reflected at the diode mounting portion, and good transmission characteristics can be achieved.

Further, although FIG. 2 shows an example in which two diodes 5 are used, the invention is not limited to this, and a large number of diodes 5 may be used in order to obtain even better reflection and isolation characteristics.

Further, as shown in FIG. 3, the width of the slit 3 provided in the metal film 4 connecting the metal wire 6 is widened,
The magnitude of the inductive reactance exhibited by the metal wire 6 may be changed. Furthermore, the metal wire 6 can also be formed integrally with the metal film 4 using the same photo-etching method as the metal film 4.

In the finline diode switch according to this invention, a metal film with the same slits as the surface is coated on the surface facing the dielectric plate surface on the side where the diode is mounted, and the metal film is coated on the surface opposite to the dielectric plate surface on the side where the diode is mounted. By short-circuiting the above-mentioned gap at the position with a metal wire or the like, it is possible to prevent a decrease in the impedance of the diode mounting part in a reverse bias state and obtain good reflection characteristics.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the structure of a conventional finline diode switch, Fig. 2 is a perspective view showing the structure of a finline diode switch according to this invention, and Fig. 3 is a perspective view showing the structure of a finline diode switch according to this invention. FIG. 7 is a perspective view showing the structure of another embodiment. In the figure, 1 is a waveguide, 2 is a dielectric plate, 3 is a slit,
4 is a metal film, 5 is a diode, and 6 is a metal wire. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

Claims (1)

[Scope of utility model registration request] A dielectric plate is placed approximately in the center of the wide surface of the waveguide in parallel to the electric field, and a metal film with a narrow gap along the radio wave propagation direction is coated on both sides of the dielectric plate. In a fine-line diode switch, a diode is mounted on one surface so as to bridge the gap, and a bias circuit for changing the bias state of the diode is provided. A finline diode switch is characterized by a thin metal wire attached to bridge the gap between the two.