JPH07128382A - Antenna measuring method - Google Patents

Abstract

PURPOSE:To measure the exciting amplitude and phase of each element of a phased array antenna in a short time. CONSTITUTION:The phase of a phase shifter 2 for an element antenna 1 is set M times between O to 2pi radian at a constant interval, e.g. 2pim/M (M: a natural number depending on the form of the phase shifter, m=O, M-1). An amplitude/phase receiver 7 measures the amplitude and the phase of combined radiation field of the phased array antenna to determine a complex combined field vector Em. M measurements of complex combined field vector Em are then multiplied by exp (-j2pim/M) (exp: exponential function, j<2>=-1) and an arithmetic average of M products of Em.exp (-j2pim/M) is determined thus obtaining the exciting amplitude and phase of a relevant element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a plurality of element antennas, each element is connected to a variable phase shifter, and the phase of these phase shifters is controlled to electronically perform beam scanning or pattern shaping. In an array antenna, that is, in a phased array antenna, the present invention relates to an antenna measurement method capable of accurately measuring the excitation amplitude phase of each element antenna in the operating state of all element antennas.

[0002]

2. Description of the Related Art Generally, a phased array antenna is basically constructed as shown in FIG. That is, in FIG. 6, 1 is an element antenna, 2 is a phase shifter, 3 is a power distribution circuit, 4 is a transmitter, 5 is a pickup antenna for measurement,
6 is a receiver for measurement, and 8 is a phased array antenna.

Next, the operation will be described. FIG. 6 shows an example of transmission, in which the signal power generated by the transmitter 4 is distributed to a desired distribution ratio by the power distribution circuit 3 and sent to each phase shifter 2. Then, the phase is changed by the phase shifter 2 controlled to have a desired amount of phase shift, and radiated from the element antenna 1 to obtain desired antenna characteristics. The case of reception is the same as the case of transmission except that the transmitter and the receiver are exchanged.

In the phased array antenna 8 described above, there are variations in characteristics among the various configurations.
In order to obtain the desired antenna characteristics, it is necessary to accurately know the excitation amplitude phase of each element antenna 1 including these variations.

Therefore, the phase of the phase shifter of each element is changed, the combined electric field of the phased array antenna is measured by the pickup antenna 5, and the phase giving the maximum to minimum ratio r ² and the maximum value of the change of the electric field level is measured. There has been a method in which the amount of change Δ ₀ is obtained and the amplitude and phase of each element antenna are obtained in all array operating states. This conventional method will be described with reference to FIG.
First, in the full array operation state of FIG. 6, the combined electric field vector E ₀ exp (j
φ ₀ ) is represented by the sum of the electric field vectors of the element antennas 1 as shown in FIG. Here the electric field vector of the n-th antenna element 1 (hereinafter the n-th element) to E _n exp (j
_If this phase φ _n is changed as φ _n ), the electric field vector of all array synthesis changes according to the rotation of the electric field vector of the n-th element. By measuring only the change in the amplitude of the composite electric field vector, the relative amplitude phase E _n /
E ₀ , φ _n −φ ₀ are obtained as follows. Nth
The combined electric field vector when the phase of the element is changed by Δ is represented by “Equation 1”.

[0006]

[Equation 1]

Here, the variable X is defined as follows.

[0008]

[Equation 2]

If "Equation 1" is transformed using "Equation 2", the following is obtained.

[0010]

[Equation 3]

Next, the variable K is defined by the following equation.

[0012]

[Equation 4]

When the absolute value of "Equation 3" is obtained using "Equation 4", the following equation is derived.

[0014]

[Equation 5]

The definition of Y and Δ _{0 in} "Equation 5" is shown in the following equation.

[0016]

[Equation 6]

[0017]

[Equation 7]

That is, the combined power level changes with cosine as shown in "Equation 5" due to the phase change of the n-th element. Here, if the ratio of the maximum value and the minimum value of the change in cosine is r ² , then from Equation 5

[0019]

[Equation 8]

[0020] In addition, from “Equation 5”, −Δ ₀ is cos
It is the amount of phase change that gives the maximum value of ine change. These r and Δ ₀ are quantities obtained by measuring the relative electric power of “Equation 5”, and from this r and Δ ₀ , the relative amplitude of the n-th element (K =
E _n / E ₀ ) and the relative phase (X = φ _n −φ ₀ ) are determined as follows. From "Number 8"

[0021]

[Equation 9]

Is satisfied. Considering the case of the plus sign in “Equation 9”, the following equation holds.

[0023]

[Equation 10]

[Mathematical formula-see original document] Also, the following equation is established from "Equation 7".

[0025]

[Equation 11]

[0026]

[Equation 12]

Therefore, "Equation 10", "Equation 11", "Equation 1"
Eliminating Y from 2 ″ gives the following system of equations for K and X.

[0028]

[Equation 13]

[0029]

[Equation 14]

By solving "Equation 13" and "Equation 14", a solution of the relative amplitude K and the relative amplitude X can be obtained by the following equation.

[0031]

[Equation 15]

[0032]

[Equation 16]

However, P in "Equation 15" and "Equation 16" is given by the following equation.

[0034]

[Equation 17]

The above is the case where the right side of "Equation 9" has a positive sign, but in the case of a negative sign as well, the following equation is similarly obtained.

[0036]

[Equation 18]

[0037]

[Formula 19]

That is, if the phase of the n-th element is changed by the phase shifter 2 and the change of the combined power level is measured by the pickup antenna 5, a cosine-like level change with respect to the phase change (corresponding to "Equation 5") is obtained. Then, the maximum / minimum ratio r and the maximum point Δ ₀ are obtained from the data. By calculating "Equation 15", "Equation 16" or "Equation 18" and "Equation 19" using these r and Δ ₀ , the relative amplitude and phase of the element antenna 1 with the phase changed can be determined. . By repeating the same measurement, data processing, and calculation for all element antennas 1 with the same initial setting, the relative amplitude and phase of all element antennas 1 can be known. Also, "Equation 15", "Equation 16" and "Equation 18", "Equation 19"
As to which of the two solutions of (1) should be adopted, the above-mentioned measurement is performed again for all the element antennas by changing the default phase distribution and K and X are obtained, and K is compared with the result of the first time. It can be decided by choosing the same solution.

[0039]

The conventional antenna device measures the excitation amplitude and phase of the element antenna by the above-described measurement method, and the solution can be obtained only by the amplitude measurement value of the synthetic radiated electric field. , "Equation 15", "Equation 1"
6 ”,“ Equation 18 ”, and“ Equation 19 ”, whichever of two sets of solutions should be adopted, the above-mentioned measurement is performed again for all the element antennas by changing the initial phase distribution and K and X Therefore, it is necessary to select a solution in which K is the same as that of the first result, and the same measurement needs to be repeated twice or more.

The present invention has been made in order to solve the above-mentioned problems, and the calculation is performed using not only the amplitude measurement value of the combined radiation electric field but also the phase measurement value, and the calculation is performed twice by the conventional method. The present invention provides an antenna measurement method in which a solution is obtained by a single measurement of what needs to be repeatedly measured.

The antenna measuring method according to the present invention also provides an antenna measuring method capable of specifying the presence / absence of a failure of the phase shifter and the failure location from the amplitude / phase measurement value of the combined radiation electric field.

[0042]

In the antenna measuring method according to the present invention, the set phase Δ of the phase shifter of the element antenna of interest is Δ = 2πm / M (M is a natural number, m determined by the type of phase shifter, etc.) = 0, ..., M−1), the amplitude and phase of the combined radiated electric field of the phased array antenna are measured by setting M times at equal intervals between 0 and 2π (radian), and the complex combined electric field is measured. The vector E _m is obtained, and the excitation amplitude and phase of the element antenna of interest are calculated from the M complex combined electric field vector measurement values E _m .

In the antenna measuring method according to the present invention, the set phase Δ of the phase shifter of the element antenna of interest is Δ = 2π.
m / M (M is a natural number determined by the type of phase shifter, m = 0,
, M-1), the amplitude and phase of the combined radiated electric field of the phased array antenna are measured by setting M times at equal intervals between 0 and 2π (radian), and the complex combined electric field vector E _m Then, the complex composite electric field vector E _m is subjected to discrete Fourier transform, the spectrum thereof is obtained, and the presence or absence of the phase shifter failure and the failure location are specified from the distribution of the spectrum.

[0044]

In the antenna measuring method according to the present invention, the set phase Δ of the phase shifter of the element antenna of interest is Δ = 2πm / M (M
Is a natural number determined by the type of phase shifter, m = 0, ..., M
-1), M at equal intervals between 0 and 2π (radian)
The complex composite electric field vector E _m is obtained by measuring the amplitude and the phase of the composite electric field of the phased array antenna once set to the ex of the M complex composite electric field vector measurement values E _m .
p (-j2πm / M) (exp () is an exponential function, j ² =
-1), and M E _m · exp (−j2πm
/ M) is calculated to calculate the amplitude and phase of the target element antenna by calculating the arithmetic mean, and conventionally it is necessary to change the initial phase distribution and measure repeatedly twice or more to determine the solution. On the other hand, the solution can be obtained by one measurement.

In the antenna measuring method according to the present invention, the set phase Δ of the phase shifter of the element antenna of interest is Δ = 2.
πm / M (M is a natural number determined by the type of phase shifter, m =
0, ..., M-1), the amplitude and phase of the combined radiated electric field of the phased array antenna are measured by setting M times at equal intervals between 0 and 2π (radian), and the complex combined electric field vector seeking E _m, and discrete Fourier transform of the complex composite electric field vector E _m, the spectrum calculated and is able to identify the presence and fault location of the failure of the phase shifter from the distribution of the spectrum.

[0046]

【Example】

Example 1. Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is an element antenna, 2 is a phase shifter, 3 is a power distribution circuit, 4 is a transmitter, 5 is a pickup antenna, and 7 is an amplitude phase receiver.

Next, the operation will be described. First, in the full array operation state of FIG. 1, the combined electric field vector received by the pickup antenna 5 is represented by the sum of the electric field vectors of the element antennas 1 as shown in FIG. Here, if the electric field vector of the n-th element antenna 1 (hereinafter referred to as the n-th element) is set to E _n exp (jφ _n ) and this phase φ _n is changed, the electric field vector of the total array synthesis is the electric field vector of the n-th element. Changes according to the rotation of. The combined electric field vector when the phase of the n-th element is changed by Δ is represented by “Equation 1”. Δ in “Equation 1” is set at equal intervals between 0 and 2π as follows.

[0048]

[Equation 20]

Substituting "Equation 20" into "Equation 1",

[0050]

[Equation 21]

By setting the phase of the phase shifter 2 to the value shown in "Equation 20" and measuring the combined electric field with the amplitude phase receiver 7,
It is possible to measure M complex composite electric field vectors E _m . Multiplied by exp (-j2πm / M) to the M number of E _m, performs the following operation.

[0052]

[Equation 22]

Therefore, the electric field vector of the element n is

[0054]

[Equation 23]

It can be expressed as follows, and the amplitude E _n and phase φ _n of the element n can be known. Here, “Numeral 23” is E _m · e
This corresponds to obtaining the arithmetic mean value of xp (−j2πm / M). By repeating the same measurement, data processing and calculation for all the element antennas 1, the amplitude and phase of all the element antennas can be known.

In the above-mentioned measurement method, the conventional antenna measurement method measures the amplitude fluctuation of the composite electric field, and the combination of the two solutions to be obtained is obtained from "Equation 15", "Equation 16" and "Equation 18".
In order to determine which of 9 "should be adopted, it is necessary to change the default phase distribution and measure again for all element antennas, and to select the solution from the comparison of the two solutions. According to the method, a desired solution can be obtained with one measurement, so that the measurement time can be shortened and the ambiguity of the measurement result associated with the determination of two solutions can be removed.

Example 2. “Equation 23” in the above antenna measurement method is equivalent to obtaining the spectrum of the component of frequency 1 when E _m (m = 1 ... M−1) is regarded as time series data. Therefore, by obtaining the spectrum of the high-order frequency component, it is possible to identify the presence or absence of a failure of the phase shifter and the failure location. The principle will be described below.

FIG. 3 shows an example of the structure of a general phase shifter 2.
FIG. 3 shows the case of a 5-bit phase shifter. In FIG. 3, 9 is a 180 degree variable phase shift circuit, 10 is a 90 degree variable phase shift circuit, 1
Reference numeral 1 is a 45 degree variable phase shift circuit, 12 is a 22.5 degree variable phase shift circuit, 13 is a 11.25 degree variable phase shift circuit, and 14 is a control circuit for controlling each of the variable phase shift circuits. Figure 3 below
Will be explained. When there is no failure in the phase shifter 2, the actual phase set value for the set phase for the control circuit 14 is shown in FIG.
It changes as shown in (a).

Example 1. Similarly to, the phase of the phase shifter 2 is set to the value shown in "Equation 20", and the combined electric field is set to the amplitude phase receiver 7
It is possible to measure M complex composite electric field vectors E _m . For this the M E _m exp (-
j2πmk / M) (k = 1 ... M-1) are multiplied and the following calculation is performed.

[0060]

[Equation 24]

E (k) in "Equation 24" is E _m (m =
When 1 ... M-1) is regarded as time-series data, it is equivalent to obtaining the spectrum of the component of frequency k by discrete Fourier transform.

When there is no failure of the phase shifter 2 as shown in FIG. 4A, the amplitude of the spectrum E (k) is, as shown in FIG. 5A, the amplitude E _n of the element antenna 1 at k = 1. Next to
It becomes 0 for other k.

On the other hand, when the phase shifter 2 has a failure, for example, when the 45 ° variable phase shift circuit 11 has a failure, the control circuit 1
The actual phase set value for the set phase to 4 changes, for example, as shown in FIG. In the case of FIG. 4B, the amplitude of the spectrum E (k) is shown in FIG.
As shown in (b), spectra appear at k = 5, 13, 21, and 29.

As shown in FIGS. 4 and 5, the generation position and amplitude of the spectrum E (k) (k ≠ 1) due to the failure of the phase shifter are uniquely determined by the failure site and the failure content. Therefore, by obtaining the spectrum E (k) from "Equation 24", it is possible to specify the presence or absence of a failure of the phase shifter and the failure location.

In the above description, the phased array antenna of FIG. 1 was taken as an example, but as is clear from the description of the measurement theory, the antenna measuring method according to the present invention is the type of element antenna, the arrangement configuration of element antennas, and the configuration of the feeding circuit. It can be applied to all phased array antennas regardless of type or type.

[0066]

As described above, according to the present invention, a desired solution can be obtained by a single measurement, so that the measurement time can be shortened and the ambiguity of the measurement result associated with the determination of two solutions can be eliminated. You can

According to another invention of the present invention, the set phase Δ of the phase shifter of the element antenna of interest is Δ = 2πm
/ M (M is a natural number determined by the type of phase shifter, m = 0,
.., M-1), the amplitude and phase of the composite electric field of the phased array antenna are measured by setting M times at equal intervals between 0 and 2π (radian), and the complex composite electric field vector E _m is calculated. Then, the above M complex composite electric field vector measurement values E are obtained.
By performing the discrete Fourier transform by regarding _m as time-series data, M spectra are obtained, and it is possible to specify the presence / absence of a failure of the phase shifter and the failure location from the distribution of the spectrum.

[Brief description of drawings]

FIG. 1 is a diagram showing a circuit configuration of an element antenna amplitude / phase measurement according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an electric field vector of an element antenna and a combined electric field vector.

FIG. 3 is a diagram showing a configuration of a general phase shifter.

FIG. 4 is a diagram showing a relationship between a phase setting value for a control circuit of a phase shifter and an actual setting phase.

FIG. 5 is a diagram showing a distribution of a spectrum E (k).

FIG. 6 is a diagram showing a circuit configuration of a conventional element antenna amplitude / phase measurement.

[Explanation of symbols]

 1 element antenna 2 phase shifter 3 power distribution circuit 4 transmitter 5 pickup antenna 6 receiver 7 amplitude phase receiver 8 phased array antenna 9 180 degree variable phase shift circuit 10 90 degree variable phase shift circuit 11 45 degree variable phase shift circuit 12 22.5 degree variable phase shift circuit 13 11.25 degree variable phase shift circuit 14 Control circuit

Claims (2)

[Claims] 1. An antenna measuring method for measuring an amplitude and a phase of an excitation current or an excitation voltage of each element antenna of a phased array antenna having a plurality of element antennas and a phase shifter connected to each element antenna. , Set the phase of the phase shifter of the element antenna of interest to 2πm /
M (M is a natural number determined by the type of phase shifter, m = 0, ...
., M-1), M times are set at equal intervals between 0 and 2π (radian), the amplitude and phase of the combined radiated electric field of the phased array antenna are measured, and the complex combined electric field vector E _m is obtained. , The above M complex composite electric field vector measurement values E
_m is multiplied by exp (−j2πm / M) (exp () is an exponential function, j ² = −1), and the M number of Em · ex
An antenna measuring method characterized by calculating an amplitude and a phase of a target element antenna by obtaining an arithmetic mean of p (-j2πm / M). 2. An antenna measuring method for measuring an amplitude and a phase of an exciting current or an exciting voltage of each element antenna of a phased array antenna having a plurality of element antennas and a phase shifter connected to each element antenna. , Set the phase of the phase shifter of the element antenna of interest to 2πm /
M (M is a natural number determined by the type of phase shifter, m = 0, ...
., M-1), M times are set at equal intervals between 0 and 2π (radian), the amplitude and phase of the combined radiated electric field of the phased array antenna are measured, and the complex combined electric field vector E _m is obtained. , The above M complex composite electric field vector measurement values E
An antenna measurement method for determining the presence / absence of a phase shifter failure and the failure location from the spectrum distribution by performing a discrete Fourier transform by regarding _m as time-series data.