JPS62209376A - Plane antenna radar equipment - Google Patents

Abstract

PURPOSE:To miniaturize and simplify constitution, by using a crank shaped microstrip antenna. CONSTITUTION:A circular polarized signal of left-handed rotation is transmitted from the crank shaped microstrip antenna 24 connected to an oscillator 21 at one terminal thereof and reflected from a target to come to a circular polarized signal of right-handed rotation. This receiving signal and the transmitting signal are processed by the mixer connected to the other terminal of an antenna to perform reception and detection. By this constitution, a direction coupler, a circulator or a receiving antenna becomes unnecessary and the constitution of a plane antenna radar equipment becomes simple and small-sized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a radar device configured by combining a planar antenna, an oscillation signal source, and a mixer circuit.

(Prior art and its problems) A radar wave from a Tochi oscillation signal source is emitted from an antenna, a reflected wave from a target object is received, and this is mixed with the oscillation signal in a mixer circuit. The high frequency circuit section of a radar device that obtains speed information and distance information from a mixed output signal generally has a configuration as shown in FIG. 2(a) or in FIG.

In FIG. 2(a), a part of the output signal of the oscillation signal source 11 is branched by the directional coupler 12, and this and the radar reflected wave are mixed by the mixer circuit 15 to obtain the desired signal. A radar reflected wave received by the antenna 14 is supplied to a mixer circuit 15. 16 is an output terminal. .

FIG. 2(b) shows the transmitting antenna 141 and the receiving antenna 1.
42 is an example of a system that uses two separate antennas for transmitting and receiving.

The above two conventional examples require many components such as the directional coupler 12, the circular radar 13, or two antennas for transmission and reception, and are also large in size.
It also has the disadvantage of being expensive.

The present invention aims to solve these problems of the prior art.

(Means for Solving the Problems) The present invention is characterized in that a crank type microstrip antenna is used as an antenna for a radar device.

FIG. 1 shows the configuration of an embodiment of the present invention.

21 is an oscillation signal source, and 25 is a mixer circuit, which are connected to the power feeding terminal 201 and the termination side terminal 202 of the crank type microstrip antenna 24, respectively. Also 2
6 is an output terminal.

Now, the crank type microstrip antenna has a structure as shown in FIG. 3(a). This crank type microstrip antenna will be explained below.

The crank type microstrip antenna is shown in Figure 3 (a).
It is constructed by arranging a large number of conductors 31 in an array.

Figure 3 (Φ) shows the change over time in the direction of the current flowing through each part of the crank-type conductor. The dimensions of the crank are actually determined by the design beam direction of the antenna. Here, in order to make the explanation easier to understand, the length of each side of the crank is determined like the person in Figure 30). If a current with a wavelength of λ flows into a crank-type conductor with a total length of 2 h, the current will flow at A in Figure 3 (b) between t = 0 and t = 3/(4/).
Proceed as shown. Observe how the direction of the electric field generated by this current changes. First, t,,xQ
In the case of , since i4 and 11 are in opposite directions, they cancel each other out and no longer contribute to the electric field.

The same applies to the horizontal components of i2 and i3. 12 and i
Only the contribution from the upward component of 3 remains, creating an upward electric field vector. At t=1/4f, only the contribution of i3 remains, and the direction of the electric field vector points to the left.

Hereinafter, the electric field vector will be determined in the same manner in the case of t = 2/4/, 3/4f. Its direction rotates counterclockwise once every time the current travels a distance λ in the crank-shaped conductor. In other words, a circularly polarized wave is radiated in a direction perpendicular to the drawing (this happens. In the case of A in Fig. 3(b), it is a right-handed circularly polarized wave, and in the case of B in Fig. 3, it is rotated. is reversed, resulting in left-handed circular polarization.

When power is fed to the pair of crank-type strip antennas shown in FIG. 3(a) in the same phase from the left side of the figure, right-handed circularly polarized waves are generated as explained above. Conversely, if power is supplied from the right side, left-handed circularly polarized waves will be generated.

In an actual antenna, these cranks will be connected in a planar array. Basic element 3 shown in FIG. 3(a)
2 are connected in succession to form an array antenna 401 having a central conductor pattern as shown in FIG. 4(a), for example, and a plurality of these antennas are arranged to form a planar array. First? I
(a) is an example in which four array antennas are arranged. It is necessary to feed in-phase power to these array antennas 401,
Power is supplied to each array antenna 401 by a power divider 402 .

Furthermore, the termination side of the array antenna is similarly connected with a power divider. ) in FIG. 4 is an example of a power divider, and a signal inputted from an input terminal 403 is outputted to an output terminal 404 at the same phase and level.

Now, when power is supplied from the terminal 405 of the crank type microstrip antenna shown in FIG. 4(a), it generates right-handed circularly polarized waves as described above, and when power is supplied from the terminal 406, left-handed circularly polarized waves are generated. . Generally, Kunia array antennas are designed to have an electric field distribution that outputs about 10% of the input signal power to the terminal side. Therefore, when designed in this way, a part of the input signal power is output from the terminal 406 when the power is output from the terminal 405, and the same can be said for the reverse case.

Regarding antennas, the transmitting antenna and the receiving antenna are reversible, and the above explanation also applies to the receiving antenna. Therefore, the antenna shown in FIG. 4(a) becomes a right-handed circularly polarized antenna when terminal 405 is used.
06 can be used as a left-handed circularly polarized antenna.The present invention utilizes this property of a crank type microstrip antenna.

FIG. 1 shows an example of the configuration of the present invention. The oscillation signal source 21 is connected to one terminal 205 of the crank type microstrimp antenna 24, and the mixer circuit 25 is connected to the other terminal 206.
is connected. Now, assuming that the terminal 205 corresponds to the terminal 405 and the terminal 206 corresponds to the terminal 406 in FIG. is transmitted as a right-handed circularly polarized signal, and a part of the signal is output from the terminal 206 and input to the mixer circuit 25. At the same time, the left-handed circularly polarized wave signal received by the crank type microstrip antenna 24 is also outputted from the terminal 206, inputted to the mixer circuit 25, mixed with a part of the output signal of the oscillation two signal waves 21, and then outputted from the terminal 26. The mixed signal will be output.

If the terminals 205 and 206 are exchanged, a left-handed circularly polarized wave signal will be transmitted, and a right-handed circularly polarized wave signal will be received and mixed by the mixer circuit 25.

Now, when a circularly polarized signal wave is reflected by an object, it becomes a circularly polarized wave with the opposite direction of rotation. Therefore, for example, a reflected wave of a signal wave sent as a right-handed circularly polarized wave returns as a left-handed circularly polarized wave. That is, by adopting the configuration as shown in FIG. 1, it becomes possible to input the transmitted radar waves and the received radar waves to the mixer circuit 25 simultaneously.

Now, if the oscillation signal source 21 is a fixed frequency signal source, the configuration shown in FIG. 1 can be used as a Doppler radar, and the Doppler signal is output from the terminal 26.

Furthermore, if the oscillation signal source 21 is an oscillator whose frequency is modulated with a sawtooth wave or a triangular wave, the so-called FM-C
It becomes a W radar and can be used as a distance measuring radar.

(Effects of the Invention) As described above, the present invention configures a radar device by connecting an oscillation signal source and a mixer circuit to the two feeding terminals of a planar crank-type microstrip antenna, respectively. This radar device does not require a directional coupler or circulator for oscillation signal source power branching, or a number 1 receiving antenna, etc., which were required in the technology, and is therefore simple in structure, small in size, and inexpensive. can be configured.

Further, the crank type microstrip antenna is a so-called planar antenna, and can be constructed on a single substrate including an oscillation signal source, a mixer circuit, a signal processing circuit, etc., and a flat radar device can be constructed. Therefore, it can be installed almost closely on a wall surface, and also has the advantage of being able to be used without forming a large protrusion when attached to the body of a moving body such as a vehicle.

[Brief explanation of drawings]

FIG. 1 shows an example of the configuration of the present invention, and FIG. 2(a) Φ) shows the configuration of a radar device according to the prior art. Figure 3(a) (
b) is a diagram explaining the principle of a crank type microstrip antenna, and FIG. 4 is an example of its center conductor pattern.
FIG. 4(a) is an overall view, and FIG. 2(b) is an example of the center conductor pattern of the power divider. In the figure, 11.21 is an oscillation signal source, 15.25 is a mixer circuit, 14.141, 142 are antennas, 12 is a directional coupler, 13 is a circuit 1-da, 16.26 is a mixed signal output terminal, 24 is a crank type microstrip antenna, 401 is a crank type microstrip array antenna, 402 is a power divider, 205.206.4
03.404.405.406 is a terminal. Figure 1 Figure 2 Figure 3 Right-handed circularly polarized wave Left-handed circularly polarized wave A n Figure 4 (a) (b)

Claims (1)

[Claims] (1) A planar antenna comprising a crank-type microstrip antenna, an oscillation signal source connected to the feed terminal of the antenna, and a mixer circuit connected to the other end terminal of the antenna. radar equipment.