JPH1075139A - Diode limiter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily separate a target signal within a close distance reflection signal by thinning the I-layer thickness of a PIN diode successively from an initial stage side in a transmission direction and setting the I-layer thickness of a PIN diode of a final stage to a prescribed thickness. SOLUTION: A preceding stage PIN diode 1 and a succeeding stage PIN diode 2 are arranged to a comb-like type waveguide 26. Assuming that a close distance reflection signal level to be the maximum of 1mW, the diode of the I-layer thickness of 1.0μm is arranged in a succeeding stage. As the diode 1 of a preceding stage, power resistance characteristics and the limiting level of about 50dB at the time of high power input are taken into consideration, and the I-layer thickness is turned to 16μm. Since limiting operation start power is decided by setting the I-layer thickness of the diode 2 to the prescribed thickness, in the case of a radar device or the like, the target signals can be separated from the close distance reflection signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a diode limiter used for a radar device or the like.

[0002]

2. Description of the Related Art For example, as shown in FIG.
The microwave oscillated by the magnetron is sent to the circulator 2
2, the reflected wave reflected by the target is received by the antenna 23, guided to the diode limiter 24 by the action of the circulator 22, and further transferred to the receiver 25 for signal processing. Have been. The diode limiter 24 is for protecting the receiver 25 from a microwave directly reflected by the antenna 23 or a microwave having a large energy inputted by leaking the circulator 22 directly. Recently, a PIN diode is used as the diode limiter 24 which is mainly used, the impedance is changed by self-bias, and the circuit is short-circuited at high power to provide a limiter function. There are two types. .
One is such that a front-stage PIN diode 27 (pill package type) and a rear-stage PIN diode 28 (pill package type) are arranged inside a comb-shaped waveguide 26 as shown in FIG. Used when used. The other one is a micro-strip line 29 as shown in FIG.
(Flat package type), and is used when a microstrip line is used as a transmission line.

[0003]

In the diode limiter as described above, the withstand power characteristic of the limiter and the limiting level characteristic at the time of high power input for preventing the destruction of the receiver are sufficiently considered. Since the limiting start point is not considered at all, the radar apparatus and the like have the following problems. The radar short-range reflection signal includes a sea-surface reflection signal and a target signal (buoy, etc.) superimposed thereon, but the diode limiter starts to operate due to the high power level of the short-range reflection signal. Since the signal after passing through the diode limiter is suppressed, it becomes difficult to separate the target signal in the receiver. SUMMARY OF THE INVENTION It is an object of the present invention to provide a diode limiter that solves the above-mentioned problems and easily separates a target signal in a short-range reflection signal.

[0004]

In order to achieve the above object, according to the present invention, the I-layer thickness of the PIN diode is sequentially reduced from the first stage side in the transmission direction, and the limiting operation starting point of the diode limiter is set to a predetermined transmission power. In this case, the I-layer thickness of the last PIN diode is set to a predetermined thickness.

[0005]

For example, in a radar device, the signal after passing through the diode limiter is not suppressed by selecting the I-layer thickness of the last-stage PIN diode so that the above-mentioned predetermined transmission power becomes a point higher than the short-range reflection signal level. Thus, the target signal can be separated in the receiver.

[0006]

FIG. 1 shows an embodiment of the present invention.
In this embodiment, a first-stage PIN diode 1 and a second-stage PIN diode 2 are arranged in a comb-shaped waveguide 26, and a PIN diode chip 3 having a mesa structure is housed in a pill package as shown in FIG. Was. FIG. 3 shows input power versus limiting level characteristics when the I-layer thickness of the PIN diode is taken as a parameter. The thinner the I layer, the lower the power for starting the limiting operation.
In this embodiment, assuming that the short-range reflection signal level is 1 mW at the maximum, a PIN diode having an I-layer thickness of 1.0 μm is arranged at the subsequent stage, and the PIN diode at the preceding stage has power-resistant characteristics and a limiting level at the time of high-power input. About 50
The thickness of the I layer was set to 16 μm in consideration of dB. FIG. 4 shows the limiting characteristics in the above case. Input signal 1
It can be seen that there is no signal suppression at mW. As another example, assuming that the short-range reflection signal level is 10 mW at the maximum, the limiting characteristics of the diode limiters in which the I-layer thickness of the preceding PIN diode is 16 μm and the I-layer thickness of the succeeding PIN diode is 10 μm are arranged. This is shown in the data of FIG. It can be seen that there is no signal suppression at an input signal of 10 mW.

Therefore, in a radar apparatus, a short-range reflection signal level (generally 1 mW or 10 m) determined by the output level of the radar apparatus and the characteristics of the radar antenna.
By using a diode limiter having a different starting point for the limiting operation in accordance with W), the signal can be faithfully transmitted to the receiver side, and the signal can be separated because there is no signal suppression.

[0008]

As described above, the starting power of the limiting operation can be determined by setting the I layer thickness of the PIN diode of the diode limiter to a predetermined thickness. There is an advantage that the target signal can be separated from the distance reflection signal.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a comb-shaped waveguide type diode limiter according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a mesa structure of the PIN diode 14 of FIG.

FIG. 3 is a limiting level characteristic diagram according to a difference in I layer thickness of the PIN diode of FIG. 1;

FIG. 4 is an input power resistance characteristic diagram according to a difference in I layer thickness of the PIN diode of FIG. 1;

FIG. 5 is a configuration diagram of a pulse radar.

FIG. 6 is a cross-sectional view of a conventional comb-shaped waveguide type diode limiter.

FIG. 7 is a front view of a conventional microstrip line type diode limiter.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Front PIN diode 2 ... Rear PIN diode 3 ... PIN diode chip 21 ... Magnetron 22 ... Circulator 23 ... Antenna 24 ... Diode limiter 25 ... Receiver 26 ... Comb-toothed waveguide 27 ...... Front-stage PIN diode (pill package type) 28 ... rear-stage PIN diode (pill package type) 29 ... microstrip line 30 ... front-stage PIN diode (flat package type) 31 ... rear-stage PIN diode (flat package type)

Claims (2)

[Claims] In a diode limiter provided with a plurality of PIN diodes at predetermined intervals on a transmission line in a transmission direction, an I layer thickness of the plurality of PIN diodes is sequentially reduced from a first stage side in a transmission direction. In addition to reducing the thickness, the limiting operation starting point of the diode limiter is set to a predetermined transmission power determined from the I layer thickness vs. operation starting power characteristic of the plurality of PIN diodes.
A diode limiter wherein an I layer thickness of a diode is set. 2. An I-layer thickness of a first-stage PIN diode is 16 μm.
m, the I-layer thickness of the last-stage PIN diode is 1 μm.
2. The diode limiter according to claim 1, wherein the distance is set to m or 10 μm.