JP2608559B2 - Radio arrival direction detection method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a phase difference detection type radio wave arrival direction detecting method, and relates to one set of antenna pairs at a predetermined interval and another set of antennas. The present invention relates to a method of arranging pairs orthogonally and detecting a direction of an incoming radio wave from a combined value of reception outputs of each pair of antennas.

(Prior Art) As a method of detecting the arrival direction of a radio wave, there are conventionally a method of roughly dividing and measuring an electric field strength of a reception radio wave, and a method of using a phase difference between reception radio waves at two points separated by a certain distance.

The method of measuring the electric field strength uses the directivity of the receiving antenna, imparts a sharp directional characteristic to the receiving antenna, and changes the directional direction by scanning operation such as mechanical rotation or change in electrical phase. The direction of arrival is detected by the change in the received electric field strength.

On the other hand, the method using the phase difference uses that the phases of the received radio waves at two points change according to the distance between the two reception points and the radio wave arrival direction. To explain this using an equation, assuming that the interval between the receiving antenna pair A1 and A2 is d and the angle between the arrival direction of the radio wave and the straight line connecting the antenna pair is θ in FIG. Is the wavelength of the radio wave
given that, Becomes There is a method using an adcock antenna as a method for obtaining the arrival direction of a radio wave using this equation, and this method obtains the arrival direction from the electromotive force induced in the antenna and the difference between the antennas.

(Problems to be Solved by the Invention) In the method for detecting the direction of arrival of a radio wave, the method using electric field strength uses the directivity of the receiving antenna.
Requires mechanical or electrical scanning. On the other hand, in the method using the phase difference, the directivity of the receiving antenna is not used, but the sign of the direction θ cannot be determined with only one antenna pair as can be seen from the equation (1) and FIG.
That is, even with the same arrival direction θ, θ _A1 , θ _A2 (| θ _A1 | = |
There is a possibility of two directions of θ _A2 | = | θ |), and the rotation operation of the antenna is required to determine one.

Therefore, an object of the present invention is to detect the direction of an incoming radio wave from any direction without requiring the above-described scanning operation regardless of mechanical or electrical, and further to detect the phase difference, the radio wave arrival direction It does not provide a detection method.

(Means for Solving the Problems) In order to achieve this object, the radio wave arrival direction detecting method of the present invention uses the same directivity characteristics at the quarter wavelength interval of the arrival radio wave.
Two pairs of antennas each having two antennas are provided.
The antennas of each set are arranged so that the straight lines connecting the positions of the two antennas are orthogonal to each other, and a phase delay of π / 2 is given to one of the two antennas of each of the two antenna pairs. The radio wave arrival direction is detected by a logical product of two sets of spare values of the radio wave arrival direction determined from the normalized power of the composite wave of the antenna reception output of each set.

(Example) The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 (a) is a schematic block diagram showing the configuration necessary for implementing the detection method according to the present invention, and FIG. 1 (b) shows the relationship between the arrangement of two antenna pairs and the direction of arrival of radio waves.

In FIG. 1 (a), the delay circuits 1 and 2 are inserted into the outputs of the antennas A2 and B2, which are one of the antenna pairs A1 and A2 and B1 and B2, respectively. Next, the antenna reception outputs of the respective sets are combined by combiners 3 and 4, and the powers of the combined waves are obtained by power measuring devices 5 and 6. At this time, the power of the combined wave is normalized by the measured power from the separately provided reference antenna C via the power measuring device 7, and the phase difference detectors 8, 9 are obtained from the normalized power values.
Then, the phase difference between the two antenna reception waves in each set is detected, and the two radio wave arrival directions are determined by the direction determiners 10 and 11 based on the phase difference. Next, one direction is finally determined by taking the logical product of the common direction from the two directions obtained for each set by the logical product circuit 12.

Next, each component will be described. As shown in FIG. 1 (b), in the method of the present invention, another pair of antennas B1 and B2 is connected to the pair of antennas A1 and A2 shown in FIG. By arranging the straight lines so as to be orthogonal to each other, the rotating operation required by the conventional method is not required. That is, the directions of the angles θ _A1 and θ _A2 are determined by the antenna pairs _A1 and _A2 , and the directions of the angles θ _B1 and θ _B2 are determined by the antenna pairs B1 and B2. The direction θ _A1 = θ _B1 common to both is determined as the direction of arrival of the radio wave.

In the phase difference detection method, two antenna outputs are combined in each set of antenna pairs, and the power (square of the amplitude) of the combined wave is obtained.
, The phase difference between the two antenna reception waves in each set is obtained.

In the antenna pair A1 and A2, assuming that the received waves of the antennas A1 and A2 are E _A1 and E _A2 , respectively, E _A1 = E _QA1 exp {−j (ωt + _A + _QA )} (2) E _A2 = E _QA2 exp { −j (ωt + _AQ )} (3) However, E _QA1 and E _QA2 are amplitudes, _A is a phase difference between two antennas depending on the arrival direction of the radio wave and the distance between the antennas, and it is expressed by equation (1), and _QA is a common phase. At this time, the power P _{A of the} combined wave is P _A = α (E _A1 + E _A2 ) (E _A1 + E _A2 ) ^* (* means conjugate) = α (| E _A1 | ² + | E _A2 | ² + E _A1 E _A2 ^* + E _A1 ^* E _A2 ) = α (E _QA1 ² + E _QA2 ² + 2E _QA1 E _QA2 cos _A ≈ 2α E _Q ² (1 + cos _A ) (4) where α is the strength of the radio wave at the receiving point. And a constant related to the antenna gain, and is set as E _QA1 ≒ E _QA2 = E _Q.

Next, in order to remove the influence of the radio wave reception situation at the receiving point, the reception output power of the reference antenna C having the same directional characteristics as the antenna A1, P _c = αE ² _QC ≒ αE ² _Q (5) normalizing the synthetic wave power P _a) of, that is, put anew P _a this by dividing the composite wave power P _a of the formula (4) in the received output power P _C of the reference antenna, P _a = 2 (1 + cos _A ) (6) From the equation (1), the phase difference _A depends on the radio wave arrival direction θ _A. Equation (6) is expressed as shown in FIG. Therefore, until this time, the phase difference from the normalized power P _A
A cannot be determined in a one-to-one relationship. The present invention solves this problem by the following method.

According to FIG. 3 (a), the phase difference _A is nπ ≦ _A ≦ (n + 1) π (n = 0, ± 1, ± 2 ...)
(8) corresponding one-to-one and if it normalized power P _A and the phase difference _A in the range of. Therefore, first, the distance d between the two antennas
Is set to d = λ / 4. Second, the output of one of the two antennas, for example, π / 2 + is applied to antenna A2.
Give a delay of 2mπ (m = 0,1,2 ...). This is λ /
Equivalent to a delay of 4.

 Equation (6) is rewritten as follows by these.

That is, E _A1 = E _QA1 exp {-j (ωt + _QA )} E _A2 = E _QA2 exp {-j (ωt + π / 2 ± 2mπ + _QA )} The combined power corresponding to equation (4) is P _A = α (E _A1 + E _A2 ) (E _A1 + E _A2 ) ^* = α (| E _A1 | ² ＋ | E _A2 | ² ＋ E _A1 E _A2 ^＊ ＋ E _A1 ^* E _A2 ) ＝ α 〔E _QA1 ² ＋ E _QA2 ² ＋ 2E _QA1 E _QA2 cos { _A − (π / 2 ±
2mπ)}] ^{_{= 2αE Q 2 (1 + cos}} {A - (π / 2 ± 2mπ)} ] ^{_{= 2αE Q 2 (1 + cos}} {A - (π / 2)} = 2αE Q 2 (1 + sin A) , and the formula (6 The normalized power corresponding to) is P _A = 2 (1 + sin _A ) (9).

At the same time Figure 3 (a) shown relationship was changed in FIG. 3 (b) illustrated relationship, the relationship between the normalized power P _A and the phase difference _A is that obtained in a one-to-one relationship. And furthermore, From the relationship, as shown in FIG. 4 (a), two directions θ _A1 and θ _A2 can be obtained as possible radio wave arrival directions.

On the other hand, the phase difference _B is similarly obtained from the antenna pair B1 and B2 by the normalized power P _B = 2 (1 + sin _B ) (11) of the composite wave, and then Thus, two directions θ _B1 and θ _B2 shown in FIG. 4 (b) are obtained.
Then, θ = (θ _A1 or θ _A2 ) and (θ _B1 or θ _B2 ) (13) is determined as the actual arrival direction of the radio wave.

Note that the reference antenna C for power measurement may be provided separately from each set of antenna pairs, or one of the antenna pairs may be substituted.

Further, in the method of the present invention, when the antennas having the same directivity characteristics are used between the two pairs of antennas, one of each pair of antennas is shared, that is, each of the two isosceles sides has four sides of the incoming radio wave. It is also possible to dispose a total of three antennas having the same directivity characteristics at each apex of a right-angled isosceles triangle having a length of one-half wavelength.

(Effects of the Invention) Use of the method of the present invention as described above brings about the following effects and advantages.

First, since the directivity of the antenna is not used when detecting the direction of arrival of a radio wave, it is actually only necessary to set up two pairs of antennas having the same directivity characteristics.

Secondly, since the scanning operation is unnecessary regardless of whether it is mechanical or electrical, the detection device is simplified.

Thirdly, the scanning operation is unnecessary and the incoming radio wave from any direction can be detected effectively.

Fourth, the present invention relates to a phase difference detection type method, which can be easily converted to a phase difference by measuring the power of the composite wave.

In addition, when adjusting the direction of the parabolic antenna during transmission using microwaves, the direction of the parabolic antenna can be adjusted automatically by using the method of the present invention by utilizing the radio wave of a direct-current telephone in the short-wave or extremely short-wave band. Can be expected.

[Brief description of the drawings]

FIG. 1 shows a schematic block diagram (a) necessary for carrying out the detection method according to the present invention and a diagram (b) showing the relationship between the arrangement of two antenna pairs and the direction of arrival of radio waves. FIG. 3 is a diagram for conceptually explaining a phase difference detection type radio wave arrival direction detection method. FIG. 3 shows the phase difference between two antennas and the power of the composite wave of the antenna reception output. FIG. 4A shows the relationship (a) and the relationship (b) between the phase difference and the power of the composite wave when the antenna interval and the phase delay according to the present invention are given. FIG. FIG. 4B shows the relationship between the synthesized wave power and the phase difference between the antennas, and the phase difference and the direction of arrival of the radio wave. FIG. 4B shows the antenna pairs A1, A2 and B1, B2
2 shows the relationship between the combined wave power and the phase difference, and the relationship between the phase difference and the radio wave arrival direction. 1,2 delay circuit, 3,4 synthesizer 5,6,7 power measuring instrument 8,9 phase difference detector 10,11 direction determiner 12 logical product circuit

Claims (1)

(57) [Claims] 1. A pair of antennas having two antennas having the same directivity characteristic arranged at a quarter wavelength interval of an incoming radio wave is provided, and straight lines connecting positions of the two antennas of each pair are orthogonal to each other. Each pair of antennas is arranged, and one of the two antennas of each pair of the two pairs of antennas has an output of π.
/ 2 phase delay, and the direction of arrival of the radio wave is detected by the logical product of two sets of predicted values of the direction of arrival of the radio wave determined from the normalized power of the composite wave of the antenna reception output of each set. Direction of arrival detection method.