JPS63122979A - Millimeter wave radar - Google Patents

Abstract

PURPOSE:To obtain a high-performance radar with less temperature resolutions while lowering the cost with reduction in weight and size of the apparatus, by arranging an antenna for receiving noise power of millimeter wave band, a local oscillator, a mixer, a single-throw unipole switch, an amplifier, a signal processing section and the like. CONSTITUTION:When a single-throw unipole switch 11 is turned ON, an antenna 1 is connected to a mixer 4 and receives a noise power of millimeter wave or the like radiated from an object. The noise power is mixed with a signal from a local oscillator 5 by the mixer 4 and the frequency of the signal is converted into an intermediate frequency from the millimeter wave by frequency conversion. After amplified with an amplifier 6, the noise power thus converted to the intermediate frequency is detected with a power meter 7 to be converted into a voltage value and sent to a signal processing section 8. When the single- throw unipole switch 11 is turned OFF, internal noise power generated within the switch 11, the mixer 4 and the amplifier 6 is measured and the noise power from the object is compared with the results as reference to calculate an equivalent noise temperature of the object.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a millimeter wave radar device that receives millimeter wave power.

[Conventional technology]

FIG. 3 is an example of a conventional millimeter wave radar device that receives millimeter wave power. In fig.

(1) is an antenna, (2) is a terminating resistor, and (3) is a single-throw double-pole switch (5) for switchingly connecting the antenna (1) and the terminating resistor (21) to the mixer (4). is a local oscillator connected to the mixer (4), (6) is an amplifier connected to the mixer (4), (7) is a power meter, (8) is a signal processing section, and (9) is a signal processing section ( After receiving the measurement and calibration timing from 8), switch (
3) is a control circuit that switches.

Next, the operation will be explained. The above millimeter wave radar device is
By receiving the noise emitted by an object and calibrating its power with the power of a reference noise source.

This is a device that attempts to measure the equivalent noise temperature of an object.

The noise power in the t'J wave band radiated from the object is transmitted by the antenna (
1) and enters the mixer (4) via a single-throw double-pole switch (3). 1 local oscillator (5) in mixer (4)
The signal frequency is converted from the i'J wave to an intermediate frequency. The noise power converted to an intermediate frequency is amplified by an amplifier (6), detected by a power meter (7), converted to a voltage value, and sent to a signal processing product (8).

On the other hand, switch the single-throw double-pole switch (3) and connect the terminating resistor (
When the mixer (4) is connected to 2), the terminating resistor (
The noise power generated in step 2) is converted into a voltage value and sent to the signal processing section (8) through the path described above. In the signal processing unit (8), the noise power generated by the terminating resistor (2) is compared with the noise power from the object.

Calculate the equivalent noise temperature of the object. The control circuit (9) is.

It functions to switch the single-throw double-pole switch (3) according to the timing of measurement and calibration from the signal processing section (8).

Next, the above operation will be explained theoretically using FIG. As shown in Fig. 4, the noise power En generated from the termination resistor (2) at temperature 'ro is En = K-To-B ------
-+13 where K is Boltzmann's constant and B is the amplifier (6)
This is a band tank. Output noise power E from amplifier (6)
out is Eoui = G-K(To+'re)B
...-+2 where G is the amplifier circuit a1 gain e're is the equivalent noise temperature of the amplifier (6).

The amplifier circuit α1 in FIG. 4 is considered as an integrated form of the single-throw double-pole switch (3), the mixer (4), and the amplifier (6) in FIG. 3, and its equivalent noise temperature 're is.

Te"To×(LswXF-Lee -・-+3
Furthermore, eLaw is the insertion loss of the single-throw bipole switch (3), and F is the noise figure including the mixer (4) and amplifier (6).

Here, if you connect the single-throw double-pole switch (3) to the antenna (reverse side), you can receive the radiation noise from the object.

Noise power E'O output from output terminal A of amplifier circuit α1
ut is E'out "" G-K (Ta+Te)
-------(4) Here, Ta is the equivalent noise temperature of the object.

From equations (2), (3), and (4), it is clear that e
By determining the ratio between Eout and E'out, the equivalent noise temperature Ta of the object can be calculated using the temperature 'ro of the termination resistor 2) as a reference. This calculation is performed in the signal processing section (8).

The performance of the millimeter wave radar explained above is based on the temperature resolution ΔTM
It is defined as gi and expressed as . B is the bandwidth, τ is the integration time * T'sys
is the system temperature, C is a constant and C cape ZO. Here T
'sya is 'rsys''ra+'re = Ta+To (LawX F-1) -・-
---(6). Since C9J17 is a constant determined by the radar device, let α be the proportionality constant.

ΔTrm−αX TSyB; αx(Ta”To (LgwX F−1)) −=
(7), and the temperature resolution is the switch loss L 8W
s and the hismixer (determined by the noise figure F of 4. In the conventional example, an example of calculating the system temperature T8 is shown.

TaW250'. The loss sw of the millimeter-wave band single-throw double-pole switch (3) is approximately 2.5 dB, and the noise figure is F −
It is 8dB, and if it is set as To""300'.

TByB-250'+300'K(1-78X&31
1) -3319°K...
・(8) becomes.

[Problem that the invention seeks to solve]

Conventional millimeter wave radar equipment has had the problem of increasing weight and dimensions, as well as increasing the price, since it is necessary to use a terminating resistor (2) whose temperature is controlled to To. Since a bipolar switch (3) is used, there is an insertion loss in the millimeter wave band, and the sw becomes thick.

There was a problem in that the temperature resolution ΔTM, which is the basic performance of radar, deteriorated.

The present invention has been made to solve the above-mentioned problems, and aims to provide a millimeter wave radar device that can reduce the weight and size, reduce the price, and reduce the temperature resolution.

[Means for solving problems]

The millimeter wave radar device according to the present invention does not use a terminating resistor, and the single-throw double-pole switch is replaced with a single-throw single-pole switch.

[For production]

The millimeter wave radar device according to the present invention eliminates the terminating resistor, and instead uses the internal noise power generated when the single-throw single-pole switch is turned OFF as a reference, and when the switch is turned ONL, the noise from the object is By measuring the noise power, the equivalent noise degree of the object is calculated. Single-throw, single-pole switches have lower insertion loss than single-throw, double-pole switches, and can reduce the temperature resolution of millimeter-wave radar.

[Strong example]

FIG. 1 is a block diagram of a millimeter wave radar device showing an embodiment of the present invention. In FIG. 1, +1), +4 to (
9) is similar to the conventional example shown in FIG. υ is a single-throw, single-pole switch connected between the antenna (1) and the mixer (4).

In the millimeter-wave radar of this embodiment, whose operation will be explained next, the single-throw single-pole switches all are ONL.

When the antenna (1) and mixer (4) are connected,
Receives noise power emitted from an object. Note that the signal processing path is the same as that described in the conventional example above.

When the single-throw, single-pole switch αυ is set to 0 FFL/ ), and the internal noise power generated inside the amplifier (6), and the operation of 0 or more based on this is measured as a second
This will be explained theoretically using diagrams. When the noise power of an object is received from the antenna 111 in the same manner as shown in the conventional example above, the noise power Fi:out output from the output terminal A is as follows.

Eout = G-K (TB+Te) B
..."+9 where G is the gain of the amplifier circuit α1, is the Boltzmann constant, Ta is the equivalent noise temperature of the object eTe is the equivalent noise temperature of the amplifier (6), and B is the bandwidth of the amplifier (6) .

The amplifier circuit αQ in FIG. 2 is considered to be an integrated form of the single-throw single-pole switch αυ, the mixer (4), and the amplifier (6) shown in FIG. Also, the equivalent noise temperature Te is 9.

Te = To X (Law X F-t)
----Q (1 Here, To is the temperature tLBW of the amplifier circuit αQ, and the insertion loss of the single-throw single-pole switch α power,
F is the noise figure including the mixer (4) and amplifier (6).

Also, when the single-throw single-pole switch αυ is set to 0FFL/.

The output noise power E'out output from output terminal A is.

E'out= 2GKT6B+GKT6B -・
...It becomes 4υ. As is clear from formula (9), formula 84, and formula Q9.

By calculating the ratio of Eout and E'out, the equivalent noise temperature Ta of the object is determined based on the temperature of the amplifier circuit 'ro.
can be calculated. This calculation is performed by the signal processing section (8)
It will be held in

From the above, it can be seen that the equivalent noise temperature Ta of the object can be measured without using the terminating resistor (2).

Here, the temperature resolution ΔT is calculated from equation (7).

ΔTm1n=αTs =α(Law
In the millimeter wave band, the loss of a single-throw single-pole switch is 1.
About 5 dB, noise figure F = 8 dB.

'fa=250°Km T (assuming 1 depth is 3800K.

T'sys = 250° +300'K (1,41
X 6.31-1) Fable 2619°K
...It becomes α3. Equation (8), (1
From the result of formula 3, *T'sys is 33 in the conventional example.
Since the temperature was 19°K, in this example, T'sys
It can be seen that the temperature resolution ΔT++ox is small and therefore the temperature resolution ΔT++ox is small. Since the S/N ratio of the radar device is determined by the temperature resolution, for one actual m%J, compared to the conventional example, Equation (8) and (Equation 13) are used.

This shows that the BS/N ratio has improved by 1.03 dB.

In the above embodiment, the switching of the single-throw single-pole switch αυ was controlled by the timing of measurement and calibration from the signal processing circuit (8), but the present invention is not limited to this, and for example, switching of the single-throw single-pole switch αυ is controlled manually. ON.

0FFL/But it goes without saying that it's a good thing.

〔Effect of the invention〕

As described above, according to the present invention, since the radar device is configured without using a terminating resistor, it is possible to obtain a millimeter wave radar device with a simple configuration, small size and weight, and a low price. be.

Also, since I configured it using a single-throw single-pole switch.

This has the effect of providing a radar device with low temperature resolution and good performance.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an i-wave radar device according to an embodiment of the present invention, FIG. 2 is a conceptual diagram of a radar device according to the present invention, and FIG. 3 is a block diagram of a conventional i-wave radar device. FIG. 4 is a conceptual diagram of a conventional radar device. In the figure, +11 is an antenna, (4) is a mixer, and (6) is an amplifier. (7) is a power meter, (8) is a signal processing section, (9) is a control circuit, αQ is an amplifier circuit, and aυ is a single-throw single-pole switch. In the drawings, the same or corresponding parts are designated by the same reference numerals.

Claims (1)

[Claims] An antenna that receives noise power in the millimeter wave band radiated from an object, a local oscillator, a mixer that converts the signal frequency received by the antenna into an intermediate frequency using an output signal of the local oscillator, and the antenna and the mixer. a single-throw, single-pole switch connected between the mixer and an amplifier for amplifying the output of the mixer; and an amplifier for amplifying the output of the mixer; The internal noise power at temperature T_0 is introduced through the switch, mixer, and amplifier, and is generated inside the amplifier circuit composed of the single-throw single-pole switch, mixer, and amplifier when the single-throw single-pole switch is OFF. and a signal processing unit that calculates an equivalent noise temperature T_a of the object based on the temperature T_0 of the internal noise power by calculating a ratio between the noise power of the object and the internal noise power. millimeter wave radar equipment.