JP4782394B2 - Axial ratio measuring apparatus and axial ratio measuring method - Google Patents

Description

  The present invention relates to an axial ratio measuring device and an axial ratio measuring method for measuring the axial ratio of a circularly polarized antenna.

  As a method for measuring the axial ratio of a circularly polarized antenna, Example 1 is a method for obtaining an axial ratio from the amplitude and phase of a radio wave, and Example 2 is a measured antenna that rotates a linearly polarized antenna and periodically changes it. There is a method for obtaining the axial ratio from the difference between the maximum value and the minimum value of the received power.

As a method of Example 1, a measurement method as described in Non-Patent Document 1 below has been proposed. FIG. 5 shows the measuring apparatus. This measuring apparatus includes a linearly polarized wave transmitting antenna 6, a receiving antenna 1 to be measured, and a detector 12 that detects the amplitude and phase of received power received by the receiving antenna 1 to be measured. This axial ratio measurement method disclosed in Non-Patent Document 1 uses the linearly polarized transmitting antenna to calculate the complex amplitude of the output obtained when the surface is vertically polarized in the plane perpendicular to the main beam direction and when vertically polarized. Assuming that ₁ exp (jφ ₁ ) and E ₂ exp (jφ ₂ ), when E ₁ = E ₂ , 3π / 2 <φ ₂ −φ ₁ <π / 2, the following formula 7

When E ₁ = E ₂ and π / 2 <φ ₂ −φ ₁ <3π / 2, the following equation 8

When E ₁ ≠ E ₂ ,

The angle θ [rad] formed by the axial ratio R [dB] and the major axis of the ellipse can be calculated.

As a method of Example 2, a measurement method as in Patent Document 2 below has been proposed. FIG. 6 shows the measuring apparatus. This measuring device is installed at a suitable distance in the main beam direction of the transmission antenna 6 from the linearly polarized transmission antenna 6 provided with a rotation device that rotates in a plane perpendicular to the main beam direction of the antenna. 6 includes a circularly polarized antenna under test 1 that receives radio waves radiated from the antenna 6, and a measuring instrument 11 that can measure the received power of the antenna under measurement 1 over time, such as a network analyzer capable of single frequency time axis measurement. Is done. The axial ratio measuring method disclosed in Patent Document 2 rotates the transmitting antenna 6 and selects the maximum value and the minimum value from the received power measurement values of the antenna 1 to be measured that periodically change with the rotation. This is a measurement method in which the difference between the maximum value 8 and the minimum value 9 is taken and the difference 10 is used as the axial ratio.
Antenna Engineering Handbook The Institute of Electronics, Information and Communication Engineers, Ohmsha, 1st Edition, 10th Edition P436-P437 JP-A-6-94764

  However, the conventional measuring apparatus as shown in Example 1 requires an apparatus that measures the amplitude and the phase at the same time, and it is difficult to accurately measure the phase particularly in the millimeter wave frequency band. For this reason, there was a problem in the measurement accuracy of the axial ratio R [dB].

  Further, in the measurement apparatus as shown in Example 2, the axial ratio R [dB] can be calculated, but the angle θ [rad] formed by the major axis of the ellipse in the radiation characteristics of the circularly polarized antenna cannot be calculated. The radiation characteristics of the circularly polarized antenna could not be grasped.

  Therefore, the present invention can improve the measurement accuracy of the axial ratio R [dB], provide an economical axially polarized antenna ratio measuring apparatus, and grasp the radiation characteristics of the circularly polarized antenna. It is an object of the present invention to provide an axial ratio measuring apparatus and an axial ratio measuring method that can be used.

  As a result of repeated studies on the conventional problems, the present inventor does not calculate the axial ratio R [dB] from the amplitude and phase in two directions perpendicular to each other as in the prior art, but only the amplitude in three independent directions. Thus, the inventors have found a method for calculating an angle θ [rad] formed by the axial ratio R [dB] and the long axis of the ellipse.

That is, axial ratio measuring apparatus of the present invention, and the measured antenna, disposed from the antenna under test at a suitable distance to the main beam direction of該被measuring antenna, radiated power emitted from the antenna under test of the axial ratio measuring apparatus for a circular polarization antenna using a reception probe for receiving linearly polarized component, and rotates the received probe the main beam direction perpendicular to a plane of the antenna under test, any The reception power P _{α of the} reception probe when the plane of polarization of the reception probe is aligned with a second direction rotated by an angle α in a specific direction from the first direction, and the specific direction from the second direction. The received power P _{+ β} of the receiving probe when the plane of polarization of the receiving probe is aligned with a third direction rotated by an angle β in the direction, and an angle β opposite to the specific direction from the second direction. Only Characterized by including the axial ratio calculating means for calculating the axial ratio R with the rolling received power _P-beta of the receiving probe when combined the plane of polarization of the received probe to the fourth direction Is. Further, the axial ratio calculating means, before and Ki受 transmission power P _alpha, and the received power P _{+ beta,} using said received power _P-beta, and the said first direction of polarization ellipse major axis An angle θ calculating means for calculating the angle θ formed is provided.

According to the present invention, the axial ratio calculating means, the received power P _alpha, the received power P _{+ beta,} with the said received power _{P -β, P + β = P} - β ≠ P α and, P _alpha When> P _{+ β} and cos (α−β) = sin (α + β), the following formula 10

By calculating the said axial ratio R the angle _{θ, P + β = P -} β ≠ P α and, and P ₊ β> P α, when cos (α-β) = sin (α + β), the following Equation 11

To calculate the axial ratio R and the angle θ, and when P _{+ β} ≠ P _{− β} ,

To calculate the axial ratio R and the angle θ .

Further, the angle alpha, the angle beta, the match to the relative angle between the measured antenna and the receiving probe, a rotation control means for generating a rotation control signal for controlling the relative angle obtained from said rotation control signal Rotational recording means for recording relative angles in association with each other. The axial ratio measuring method of the present invention is installed at an appropriate distance from the antenna under measurement in the main beam direction of the antenna under measurement , and receives the linearly polarized component of the radiated power radiated from the antenna under measurement. using the received probe to a second direction wherein the receiving probe is rotated in the main beam direction perpendicular to the plane of the antenna under test, rotated by an angle α from any first direction to a particular orientation the received power P _alpha of the receiving probe when the combined polarization of the received probe, the polarization plane of the receiving probe from the second direction to a third direction rotated by an angle β to the particular orientation When the plane of polarization of the reception probe is aligned with the received power P _{+ β} of the reception probe and the fourth direction rotated from the second direction by an angle β opposite to the specific direction. Before Receiving a probe of the received power _P-beta and was respectively _{measured, P + β = P - β} ≠ P α and, and P α> P ₊ β, when cos (α-β) = sin (α + β), the number of the following 1
3

To calculate the axial ratio R and the angle θ formed by the long axis of the polarization ellipse and the first direction, and P _{+ β} = P _−β ≠ P _α and P _{+ β} > P _α and cos (α When -β) = sin (α + β), the following formula 14

To calculate the axial ratio R and the angle θ, and when P _{+ β} ≠ P _{− β} ,

To calculate the axial ratio R and the angle θ .

  According to the present invention, the axial ratio R [dB] is calculated from the received power of the independent three-direction polarization planes of the reception probe, thereby improving the axial ratio measurement accuracy and excellent in economic efficiency. An axial ratio measuring apparatus can be provided.

  Hereinafter, an axial ratio measuring device of the present invention is explained based on a drawing. FIG. 1 is an example of a configuration diagram of an axial ratio measuring apparatus according to the present invention. According to FIG. 1, a receiving probe that is installed at an appropriate distance in the main beam direction of the antenna to be measured 1 from the antenna to be measured 1 and receives a linearly polarized component of the radiated power radiated from the antenna 1 to be measured. 2 and a rotating device 7 that rotates in a plane perpendicular to the main beam direction. The antenna under measurement 1 and the reception probe 2 are connected to the output terminal and the input terminal of the scalar network analyzer 3, respectively. The scalar network analyzer 3 is controlled and processed by the controller 4, and the control and measurement values of the controller 4 are displayed by the display 5.

  In this configuration, since only the amplitude of the received power is measured, the scalar network analyzer 3 that is cheaper and more economical than the vector network analyzer that simultaneously measures the amplitude and phase is used.

  Hereinafter, the method for measuring the axial ratio of the present invention will be described. A radio wave radiated from the antenna 1 to be measured is received as received power by the receiving probe 2 and output to the controller 4 via the scalar network analyzer 3. At this time, the rotation direction of the receiving probe 2 can be set by controlling the rotating device 7.

  First, the polarization plane of the reception probe 2 is rotated in a certain arbitrary direction α, and the radiated power of the antenna 1 to be measured is measured. Next, the radiation power of the antenna 1 to be measured is measured by rotating the polarization plane of the reception probe 2 in the -β and + β directions with the α direction as the main axis. The measurement order in the α, −β, and + β directions is not limited. And based on the measured radiation power, an axial ratio is calculated based on the following principles.

Hereinafter, the principle of calculating the axial ratio of the present invention will be described. Arbitrary elliptical polarization is considered from the synthesis of left-handed circular polarization and right-handed circular polarization. FIG. 2 shows left-hand circular polarization and right-hand circular polarization, and FIG. 3 shows elliptical polarization. The x-axis electric field component E _x and the y-axis electric field component E _y of the elliptically polarized wave shown in FIG.

Can be expressed as Here, E _R and E _L indicate the amplitudes of the electric fields of right-handed circular polarization and left-handed circular polarization, respectively.

Next, as shown in FIG. 4, the received power in the arbitrary polarization direction α is P _α , and the received power when the arbitrary polarization direction α is rotated to + β around the main axis is rotated to P _{+ β} and −β. When the received power is P _−β , P _α , P _{+ β} , and P _−β are the following formula 17

It is represented by Therefore, the angle θ [rad] formed by the axial ratio R [dB] and the major axis is P _{+ β} = P _−β ≠ P _α , P _α > P _{+ β} and cos (α−β) = sin (α + β) When the following number 18

Calculated _{by, P + β = P - β} ≠ P α and, and P ₊ β> P α, when cos (α-β) = sin (α + β), the following equation 19

When P _{+ β} ≠ P _{− β} , the equation 20

Can be calculated.

The axial ratio R [dB] was evaluated by the axial ratio measuring device of the present invention. Actually, a millimeter-wave band circularly polarized antenna was used as the antenna to be measured, and the radiated power of the radiated radio wave was measured five times to calculate the average and variation of the axial ratio R [dB]. Here, as measurement conditions in the axial ratio measuring apparatus, the three-directional polarization planes, α, + β, and −β of the receiving probe were set to + π / 4, + π / 4, and −π / 4, respectively. The measurement results are shown in Table 1.

From the measurement results, the received power P _α in the polarization direction α = 33.10 ± 0.03 [dB], the received power P _{+ β in} the polarization direction _{+ β} = 32.30 ± 0.05 [dB], and the polarization direction− The received power of _{β was} P _−β = 33.40 ± 0.04 [dB]. Therefore, an axial ratio R [dB] = 1.19 ± 0.11 and an angle θ = 0.19 ± 0.06 [rad] formed by the major axis were obtained from the power value [W] of the measurement result.

In addition, the axial ratio was evaluated based on the conventional example 1 with respect to the conventional method for measuring the axial ratio. The measurement sample and conditions are the same as described above. As a result, as shown in Table 1, the linearly polarized transmission antenna is rotated by π / 2 in a plane perpendicular to the main beam direction, and the complex amplitude of the output obtained in the horizontal polarization and the vertical polarization is E _1. = 41.20 ± 0.25 [V / m], φ ₁ = 1.59 ± 0.04 [rad], E ₂ = 46.80 ± 0.19 [V / m], φ ₂ = 0.08 ± 0.02 [rad]. Therefore, an axial ratio R [dB] = 1.22 ± 0.39 and an angle θ = 0.22 ± 0.18 [rad] formed by the major axis were obtained.

  As described above, when the axial ratio measurement result obtained by the axial ratio measuring apparatus of the present invention is compared with the axial ratio measurement result obtained by the conventional technique, a large variation occurs in the axial ratio measurement result obtained by the conventional technique. This variation occurs because the amplitude and phase values vary, but as shown by the axial ratio measurement result of the present invention, the axial variation R [dB] when the amplitude variation is ± 0.05 [dB] or less. Has a small effect of ± 0.11 [dB]. Therefore, the variation in the axial ratio measurement results according to the prior art is due to the low phase measurement accuracy. Similarly, the angle θ formed by the major axis varies greatly due to the low phase measurement accuracy.

  From the above results, it has been clearly recognized that the axial ratio measuring apparatus of the present invention has less fluctuation and higher measurement accuracy than the conventional method.

It is the schematic for demonstrating the axial-ratio measuring apparatus in this invention. It is the schematic for demonstrating left-handed and right-handed circularly polarized wave. It is the schematic for demonstrating elliptical polarization. It is the schematic for demonstrating the polarization plane of 3 directions in this invention. It is the schematic for demonstrating the axial ratio measuring apparatus by the example 1 of a prior art. It is the schematic for demonstrating the axial ratio measuring apparatus by the example 2 of a prior art.

Explanation of symbols

1 antenna to be measured 2 reception probe 3 scalar network analyzer 4 controller
5 Display
6 Transmitting antenna 7 Rotating device
11 Network analyzer

Claims (5)

And the measured antenna, the installed from the measured antenna at a suitable distance to the main beam direction of該被measuring antenna, a receiving probe configured to receive the linearly polarized component of the emitted radiation power from the antenna under test In the axial ratio measuring apparatus for a circularly polarized antenna using the antenna, the receiving probe is rotated in a plane perpendicular to the main beam direction of the antenna to be measured, so that an angle from an arbitrary first direction to a specific direction is obtained. The reception power P _{α of the} reception probe when the plane of polarization of the reception probe is aligned with the second direction rotated by _α, and the third direction rotated by the angle β from the second direction to the specific direction the received power P _{+ beta} of the receiving probe when combined the plane of polarization of the receiving probe, the receiving-flop to a fourth direction rotated by an angle beta from the second direction to the specific direction and opposite to the Axial ratio measuring apparatus characterized by comprising axial ratio calculating means for calculating the axial ratio R by using the received power _P-beta of the receiving probe when combined the plane of polarization of the over drive. The axial ratio calculating means includes a front Ki受 transmission power P _alpha, and the received power P _{+ beta,} using said received power _P-beta, the angle between the first direction and the polarization ellipse major axis 2. The axial ratio measuring device according to claim 1, further comprising angle θ calculating means for calculating θ. The axial ratio calculating means, the received power P _alpha, and the received power P _{+ beta,} with the said received power _P-beta, and _{P + β = P -β ≠ P} α, P α> P + β and, cos (α-β) = sin (α + β)
When the following number 1
By calculating the said axial ratio R the angle _{θ, P + β = P -} β ≠ P α and, and P ₊ β> P α, when cos (α-β) = sin (α + β), the following Number 2
To calculate the axial ratio R and the angle θ, and when P _{+ β} ≠ P _{− β} ,
The axial ratio measuring apparatus to that請 Motomeko 2 wherein the calculating means calculates the said angle θ and the axial ratio R. The angle alpha, the angle β, the match to the relative angle between the measured antenna and the receiving probe, a rotation control means for generating a rotation control signal for controlling the relative angle, relative angle obtained from said rotation control signal The axial ratio measuring device according to any one of claims 1 to 3, further comprising: a rotary recording unit that records them in association with each other. Is placed at a suitable distance from the antenna under test in the main beam direction of該被measurement antenna, using the reception probe to receive the linearly polarized component of the emitted radiation power from the antenna under test, the received probe When the plane of polarization of the receiving probe is aligned with a second direction rotated by an angle α in a specific direction from an arbitrary first direction after being rotated in a plane perpendicular to the main beam direction of the antenna under measurement. Received power P _{α of the} receiving probe and the second direction from the second direction
Received power P _{+ beta} of the receiving probe when combined the plane of polarization of the received probe in a third direction rotated by an angle beta to a particular orientation, wherein the particular orientation in the second direction and GyakuMuko
Comes to the angle beta by rotating the fourth of the receiving probe when combined the plane of polarization of the received probe in a direction received power _P-beta and was respectively _{measured, P + β = P - β} ≠ P α and, P _α > P _{+
When β} and cos (α−β) = sin (α + β), the following equation 4
To calculate the axial ratio R and the angle θ formed between the major axis of the polarization ellipse and the first direction, and P _{+
When β} = P _{− β} ≠ P _α , P _{+ β} > P _α, and cos (α−β) = sin (α + β), the following formula 5
To calculate the axial ratio R and the angle θ, and when P _{+ β} ≠ P _{− β} ,
The axial ratio R and the angle θ are calculated by the axial ratio measuring method.