JPH0549070B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a direction finding device that detects the direction of incoming radio waves.

[Prior Art] Fig. 3 is a block diagram of a conventional direction finding device, in which 1 and 2 are element antennas for receiving incoming radio waves;
3 is a phase detector, 4 is a console, and 5 and 6 are signal cables connecting between the element antennas 1 and 2 and the phase detector 3.

Next, the operation of this device will be explained. The incoming radio waves received by the element antennas 1 and 2 are sent to the signal cables 5 and 6.
The signal is guided to the phase detection receiver 3 via.

If the signal input to one terminal of the phase detection receiver 3 is V ₁ = E ₁ sinωt ...(1) and the signal input to the other terminal is V ₂ = E ₂ sin (ωt + φ) ...(2), As shown in equation (3), the output signal Vout is expressed as a function of the phase difference φ of the incoming radio waves received by the element antenna (1) and Vout=K(E ₁ E ₂ ) cosφ ...(3) (2) It can be done. The console (4) reads Vout expressed by equation (3), and immediately converts Vout to a phase difference φ.

On the other hand, as is clear from Fig. 3, there is a relationship between the phase difference φ and the arrival direction θ of the radio wave as shown in equation (4), and in the console (4), θ=sin ^-1 [λ・φ/2πd]... ...(4) λ: By calculating the above equation, the direction of the arriving radio wave can be determined and displayed.

[Problems to be Solved by the Invention] The conventional direction finding device is configured as described above, and the phase of the incoming radio waves received by the element antennas 1 and 2 is measured using the phase detection receiver 3. Phase measurement is generally more difficult than amplitude measurement, and the frequency characteristics of the element antennas 1 and 2 and the phase detection receiver 3, as well as the twisting and bending temperature characteristics of the signal cables 5 and 6, cause errors during phase measurement. There was a drawback that the direction of radio waves could not be detected accurately.

This invention was made to solve the above-mentioned problems, and eliminates the need to directly detect the phase of an incoming radio wave using the phase detection receiver 3 as in the past, and instead uses the element antennas 1 and 2. By combining the received electric fields into multiple fields and measuring the amplitudes of the multiple fields in the same time plane with an amplitude receiver, the phase of the arriving wave received by both element antennas 1 and 2 is calculated with high precision. The purpose is to

[Means for solving the problem] A direction finding device according to the present invention includes element antennas 1 and 2.
Using multiple amplitude receivers, the phases of multiple semi-fixed or fixed phase shifters connected to either one or the other element antenna are set to be different in advance, and the phase of the radio waves arriving at This method calculates the phase of the radio waves arriving at the element antennas 1 and 2 from the amplitude changes of multiple composite reception vectors, and calculates the direction of arrival of the radio waves from the phase using equation (4) above. be.

[Function] The direction finding device according to the present invention has element antennas 1 and 2.
When determining the phase of radio waves arriving at The accuracy of phase measurement, which was a problem with the phase comparison method, can be dramatically improved, and the instantaneous detection characteristic of the conventional method can also be maintained.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention, in which 1 is a first element antenna, 2 is a second element antenna, 4 is a console, 5 and 6 are signal cables, and 7 is a diagram showing an embodiment of the present invention.
is the first power divider, 8 is the second power divider, 9
a, 9b, 9c are first, second and third couplers, 1
0a, 10b, 10c are first, second, third amplitude receivers; 11a, 11b, 11c are first, second,
third semi-fixed or fixed phaser, 12, 13, 14
are the T ₁ , T ₂ , and T ₃ receiving channels.

The operation of one embodiment of the direction finding device of the present invention configured as described above will be described.

The signal received by the first element antenna 1 is S1,
The signal received by the second element antenna 2 is assumed to be S2.

The signal S1 is distributed by the first power divider 7 via the signal cable 5, and is distributed to a plurality of couplers 9a, 9b,
Input to one terminal of 9c.

The signal S2 is distributed by the second power divider 8 via the signal cable 6, and then passed through a plurality of semi-fixed or fixed phase shifters 11a, 11b, 11c whose phases are known, and then connected to the couplers 9a, 11c, respectively. 9b, 9c
is input to the other terminal of The respective signals phase-shifted by a plurality of semi-fixed or fixed phase shifters 11a, 11b, 11c are converted into S _2a , S _2b , S _2c
shall be.

In each of the combiners 9a, 9b, and 9c, the signal S1 and the signals _S2a , _S2b , and _S2c are vector-synthesized to output signals _T1 , _T2 , and _T3 having different amplitudes. Multiple amplitude receivers 10a, 10b, 1
At 0c, output signals T ₁ , T ₂ and T ₃ from the couplers 9a, 9b and 9c are received. The console 4 reads the signals T ₁ , T ₂ , and T ₃ with different levels within the same time plane, processes them, and calculates the incoming radio waves received by the first element antenna 1 and the second element antenna 2. Calculate relative phase.

Immediately from this result, the calculation of equation (4) is performed on the console 4, and the direction of the incoming radio wave can be determined.

Figure ₂ is a diagram for explaining _the method of calculating the relative phase _of incoming radio waves.
The reception level of each of a, 10b, and 10c is T ₁ ,
It is expressed as T ₂ and T ₃ .

The observed values p, q, r are rotated by S2 around 01 in Fig. 2, and along with this, the resultant vectors T ₁ , T ₂ , T ₃
is expanded and contracted using 0 as a fixed point.

Therefore, the observed values p, q, and r exist on the circumference indicated by the broken line in the figure, and α is the phase difference between the semi-fixed or fixed phase shifters 11b and 11a, and β is the phase difference between the semi-fixed or fixed phase shifts 11b and 11a.
Since the value corresponds to the phase difference between 1c and 11b, the center of rotation 01 of the circles C and S2 can be calculated from the observed values p, q, and r. Thereby, the composite vector T for any phase can also be determined.

The relative phase of S1 and S2 can be calculated from the maximum and minimum values of the amplitude of T and the phases when the maximum and minimum values are reached.

Specifically, in Figure 2, if the phase at which the combined vector T gives the maximum value is Δ ₀ , then the relative phase of the incoming radio waves (relative phase of S ₁ and S ₂ X = φ _o - φ ₀ ) can be calculated using the following formula. It can be obtained by calculation.

X=tan ^-1 sinΔ ₀ /cosΔ ₀ +S ₂ /S ₁ (5) If the relative phase of S ₁ and S ₂ can be calculated, the direction of arrival of the radio wave can be immediately determined using equation (4).

Here, the process of deriving the relative phase X of S ₁ and S ₂ will be explained below.

In Fig. 2, the composite electric field vector in the initial state
The amplitude and phase of T〓 ₂ are E ₀ and φ ₀ , and the amplitude and phase of the n-th vector S〓 _2b of interest are E _o and φ _o .

When the phase of this n-th vector S〓 _2b is set and fixed at φ _o +β, the composite vector T〓 ₃ is expressed by the following equation.

T〓 ₃ = [E ₀ e ^j 〓 ⁰ −E _o e ^j 〓 ⁿ ]＋E _o e ^j( 〓 ⁿ⁺ 〓 ⁾ If we set X=φ _o −φ ₀ , then T〓 ₃ = {E ₀ −E _{o e} ^{j (} 〓 ^n- 〓 ⁰⁾ ＋E _o e ^j( 〓 ^n- 〓 ⁰⁺ 〓 ⁾
｝e ^j 〓 ⁰ = {E ₀ +E _o e ^jX [e ^j 〓−1]}e ^j 〓 ⁰ = {E ₀ e ^-jX +E _o [e ^j 〓−1]｝e ^j( 〓 ^0+X) = (E ₀ cosX + E _o cosβ−E _o ) + j (−E ₀ sinX + E _o sinβ) e ^j(X+ 〓 ⁰⁾ |T ₃ | ² = (E ₀ cosX−E _o ) ² +2E _o (E ₀ cosX − _{E o ) cosβ} ^＋ _{E o} ² ₊ ^E ₀ ² _sin ^{2 _ _} _{_}
/E ₀ ] ² + 2 [E _o /E ₀ ] {[cosX−E _o /E ₀ ]cosβ−sinX
_sinβ } Here ^, if ^k ₌ E _o ^/ E ₀ and Y ² = (cosX−k) ^{2 +} sin ² −sin
Xsinβ) |T ₃ | ² /T ₂ ² =Q, then Q=Y ² +k ² +2kYcos (β+Δ ₀ ) (5) where tanΔ ₀ = sinX/cosX−k (6) is obtained.

If the ratio of the maximum and minimum of Q is γ, then from equation (5), γ ² = (Y+k) ² / (Y-k) ² Therefore, γ = ± [Y+k/Y-k] (7) In equation (7), When the sign on the right side is positive, the unknowns k and X are found from equations (6) and (7).

From equation (7), Y=[γ+1/γ−1]k is expanded to become (cosX−k) ² −sin ² X=[γ+1/γ−1] ² k ² (8).

Solving the simultaneous equations from equations (6) and (8), k=Γ/(1+ΓcosΔ ₀ +Γ ² ) ^1/2 (9) X=tan ^-1 [sinΔ ₀ /cosΔ ₀ +Γ] (10) However, Γ= γ-1/γ+1 (γ is the ratio of maximum and minimum) The maximum and minimum ratio γ is γ=S ₁ +S ₂ /S ₁ -S _2Therefore , Γ=γ-1/γ+1=S ₁ +S ₂ /S ₁ −S ₂ −1/S ₁ +S ₂ /
S ₁ −S ₂ +1=S ₂ /S ₁ , and equation (10) becomes X=tan ⁻¹ sinΔ ₀ /cosΔ ₀ +S ₂ /S ₁ (11).

[Effects of the Invention] As described above, according to the present invention, instead of using a phase receiver, the relative phase of an incoming radio wave is calculated from data on changes in the output level of a plurality of amplitude receivers. Therefore, the relative phase can be determined with high accuracy while maintaining the instantaneous search function, and a highly accurate direction finding device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the present invention, FIG. 2 is a diagram illustrating the relationship between composite vectors of a plurality of receiving channels, and FIG. 3 is a block diagram of a conventional direction finding device. In the figure, 1 and 2 are element antennas, 3 is a phase detection receiver, 4 is a console, 5 and 6 are signal cables,
7, 8 are power dividers, 9a, 9b, 9c are combiners, 10a, 10b, 10c are amplitude receivers, 11
a, 11b, 11c are semi-fixed or fixed phase shifters, 1
2, 13, and 14 are T ₁ , T ₂ , and T ₃ receiving channels. It should be noted that the same or corresponding parts in the figures are indicated by the same reference numerals.

Claims (1)

[Claims] 1 It has first and second element antennas that receive incoming radio waves, and a circuit that detects the relative phase of the signals received by the first and second element antennas, and calculates the direction of arrival of the radio waves from the relative phase. A direction finding device comprising a console that distributes signals received by the first element antenna, and a second power divider that distributes signals received by the second element antenna. , a plurality of semi-fixed or fixed phase shifters that make the phases of the plurality of signals distributed by the second power divider different, and a plurality of semi-fixed or fixed phase shifters that receive different phase deviations, respectively. a plurality of combiners that vector-combine the respective output signals and the respective signals distributed by the first power divider;
A plurality of amplitude receivers receive a plurality of signals with different levels output from the plurality of couplers, and the relative phase and direction of arrival of the signals arriving at the first and second element antennas are calculated from the difference between the respective different reception levels. A direction finding device characterized by having a console for.