KR940007970B1 - High-frequency noise protect device of magnetron - Google Patents

Abstract

The preventor improves productivity, reduces components, and attenuates microwave. The preventor includes a concaved anode which is placed around a cathode, an antenna seal which seals a part of the anode, and a magnetron which connects the anode, and has an output antenna lead, and a choke (24) has a slant of λ/4 between maximum height and minimum height. The maximum height (A) of slanted choke (24) is 4.7-6.2 mm. The minimum height (B) of slanted choke (24) is 2.9-3.1 mm.

Description

Magnetron Harmonic Noise Control

1 is a half sectional view showing a general magnetron.

2 is a longitudinal sectional view showing a conventional output unit.

3 is a half sectional view showing a conventional choke.

4 is a longitudinal sectional view showing an output of the present invention.

5 is a perspective view showing a choke which is a main part of the present invention.

6 is a longitudinal sectional view showing another embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

6: antenna feeder 7: antenna seal

24: choke

The present invention relates to a harmonic noise prevention device of a magnetron that can suppress harmonic noise generated when a high frequency is supplied from a magnetron to a cavity in a wide range.

In general, the magnetron generating high frequency has a shape as shown in FIG. 1, and a series cathode (filament) 1 is installed in the axial direction at the center thereof, and an anode 2, which is a radial anode structure, is installed around the center. It is a kind of two-pole vacuum tube.

Here, the upper yoke 3a and the lower yoke 3b are provided to apply the magnetic flux to the working space between the cathode 1 and the anode 2, and the magnets 4 and the magnetic poles 5 are disposed on the upper and lower surfaces of each yoke. There is a magnetic circuit installed in order, and the antenna lead 6, the antenna seal (7), the antenna ceramic (8) and the antenna cap (9) to send the high frequency energy delivered to the anode (2) to the outside (cavity) ) Is installed.

In addition, a heat dissipation fin 10 is installed to dissipate heat generated by the collision of hot electrons to the outside in the anode vane 2a, and the choke coil 11 for preventing the undesired high frequency components generated in the working space from flowing back to the power source. The high pressure capacitor 12 and the like can be protected by the filter box 13.

Therefore, the microwave energy transmitted to the anode vane 2a in the above-described working mechanism of the magnetron is transmitted to the antenna seal 7, the antenna ceramic 8, the antenna ceramic 8, the antenna cap 9, the antenna lead 6, and the like. Energy is sent to the outside through the output.

In the case of sending microwave energy through these outputs, the magnetron for microwave ovens has a fundamental frequency of 2.45 GHz, which is a frequency band used for satellite broadcasting, which acts as a noise. A choke 14 structure having a quarter length of a specific harmonic wavelength is provided between (6).

However, the choke structure for this particular harmonic can be suppressed in the microwave magnetron having the characteristic that the length A is fixed and the fundamental operating frequency varies depending on the load impedance as shown in FIGS. 2 and 3. Since the frequency range is limited, in order to compensate for this, several chokes of different lengths have to be installed, resulting in an increase in mold manufacturing cost and a decrease in productivity.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described drawbacks, and its object is to provide a function capable of attenuating microwaves outside of the magnetron intrinsic frequency band by π-1 mode or the like.

According to the aspect of the present invention for achieving the above object, the choke is provided between the antenna seal and the lead provided in the output portion of the magnetron, the inclined surface of the upper maximum height and the minimum height is lambda / 4 Provided is a harmonic noise suppression device of a magnetron by installing an excitation choke.

Hereinafter, the present invention will be described in more detail with reference to FIGS. 4 and 5 of the accompanying drawings.

FIG. 4 is a longitudinal sectional view showing an output port of the present invention, and FIG. 5 is a perspective view showing a choke which is a main part of the present invention. The present invention provides an antenna for suppressing a characteristic in which a fundamental operating frequency varies depending on load impedance. An inclined surface that changes linearly is formed on the top of the choke 24 provided between the seal 7 and the antenna lead 6.

At this time, the length of the maximum height and minimum height of the inclined surface is λ / 4.

In addition, the length A of the maximum height of the upper side of the choke 24 is within the range of 4.7-6.2 mm, and the length B of the minimum height is of the range of 2.9-3.1 mm. Although installed so as to face, it may be installed to face downward as in the embodiment shown in FIG.

According to the present invention configured as described above, when the choke 24 having the inclined shape having the linearly changed upper side is installed on the antenna seal 7 of the output unit, the maximum of the electric inclined choke 24 among the microwaves sent to the outside through the antenna is provided. The frequency of the region of the height λ / 4 is attenuated up to the frequency of the region of the choke 24 with the lowest height of the electrically inclined choke 24.

This will be described in more detail with reference to one embodiment as follows.

EXAMPLE

If the maximum height of the choke is 6.25 mm and the minimum height is 3 mm, the attenuation band is up to 12 GHz, and the fundamental wave is 2,400 GHz. Even if the fundamental wave comes out (in both cases, it is not normal operation), it can be attenuated at the height of 6mm.

In the case of the pile having the 6.7 harmonic region, the attenuation can be attenuated at a portion of 5.09 mm and 4.36 mm, respectively.

As described in the above embodiment, the present invention can attenuate the microwave in the frequency band of λ / 4 by the simple structure of forming an inclined surface having a linear change on the top of the choke 24 at the output side.

Therefore, it is possible to reduce the number of parts, because it can have a function to attenuate microwaves outside the magnetron intrinsic frequency band by the π-1 mode, etc., which was not able to attenuate when a conventional sized choke is installed. The workability is improved to reduce the production cost.

Claims (3)

A cathode, a cylindrical anode disposed around the cathode, a vane radially disposed on an inner surface of the anode, an antenna seal hermetically sealed to a portion of the anode, and electrically connected to one end of the anode and antenna seal A magnetron consisting of an output antenna lead extending through an inner space of the antenna, comprising: a choke having a maximum height and a minimum height having a length of λ / 4 between the antenna seal and the antenna lead and a continuous inclined plane of λ / 4 therebetween Harmonic noise prevention device of the magnetron, characterized in that by installing the. 2. An apparatus for preventing harmonics of magnetrons according to claim 1, wherein the maximum height (A) of the inclined choke (24) is formed to be 4.7-6.2 mm. The harmonic noise preventing device of a magnetron according to claim 1, wherein the choke (24) minimum height (B) having an inclined shape is formed at 2.9-3.1 mm.