JPH05312871A - Antenna gain measuring device - Google Patents

Abstract

PURPOSE:To enable the simple and correct measurement of the relative gain of a measured antenna in any environment by setting space propagation loss, obtained by two gain-known antennas, as the reference value, and comparing space propagation loss, measured in the same environment by making one of the antennas into the measured antenna, with the reference value. CONSTITUTION:The distance between the feeding points of a transmitting antenna 2 and a receiving antenna 3 using a standard dipole antenna is set to the fixed distance D1. A moving vehicle 9 with the antenna 2 mounted thereto is moved within a range of the moving distance D set in such a way as to be sufficiently shorter than the distance D1 and sufficiently longer than a quarter of the measured wavelength, and the preset n-number of digital data is measured and processed (7) so as to be set as the reference value of received power. The antenna 2 or the antenna 3 is then changed into the measured antenna, and the received power is measured by the same operation and compared with the reference value to obtain the relative gain of the measured antenna. The power gain can be thereby measured simply without using special environment such as a radio dark room or an open site.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for measuring the power gain or directivity pattern of an antenna under test without using an anechoic chamber or an open site.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 7, in order to measure the power gain of an antenna under test, a standard dipole antenna as a transmitting antenna 12 in a so-called anechoic chamber 10 whose inner wall is entirely covered with a radio wave absorber, and Standard dipole antennas are used as the receiving antennas 13, respectively, and the distances between the feeding points of the transmitting antennas 12 and the receiving antennas 13 are set to a constant inter-antenna distance D3. The polarization planes are matched, and the radiation directivity of each antenna is arranged so that the directions in which the radiation power patterns are maximized face each other, and are defined by the high-frequency signal generator 11 via the transmission power supply line 15 at the measurement frequency. A high frequency signal of a level is applied to the transmitting antenna 12. At this time, the reception power generated in the reception antenna 13 is measured by the electric field strength measuring device 14 via the reception power supply line 16, and this reception power is set as the reference reception power P11.

In some cases, the reference received power P
The angles of the transmitting antenna 12 and the receiving antenna 13 in the horizontal plane or the heights of the antennas are finely adjusted so that 11 is maximized, and the maximum received power value obtained here is set as the reference received power P11. Next, the transmitting antenna 12 is replaced with a measured antenna, and the distances between the feeding points of the transmitting antenna 12 and the receiving antenna 13 are opposed to each other at the same inter-antenna distance D3 as when the reference received power P11 is measured, and the high frequency A high frequency signal of a specified level is applied to the transmitting antenna 12 at the frequency at which the signal generator 11 performs the measurement. When the transmitting antenna 12 is rotated 360 degrees in the horizontal plane about the feeding point while confirming the received power generated in the receiving antenna 13 with the electric field strength measuring device 14 in the same manner as when measuring the reference received power P11. The maximum received power P12 of the antenna under measurement obtained in step 1 is measured.

From the above measurement, the reference received power P1
1, the maximum received power P1 of the antenna under measurement
From the value of 2, the gain G11 of the antenna under measurement for the full-half-wavelength antenna can be obtained. Below, the reference received power P11 and the maximum received power P1 of the antenna under test P1
An equation for obtaining the gain G11 of the antenna under measurement for the full-half-wavelength antenna from 2 and is shown in.

G11 = 10 · log (P12 / P11) (dBd) ... Next, a conventional method for measuring the power gain of the antenna to be measured using the open site will be described with reference to FIG. An open site for measuring electromagnetic noise radiated from an electronic device has a distance of 3 (m), 10 (m), or 30 (m) between the turntable on which the EUT is installed and the receiving antenna 13 which receives the electromagnetic noise. m) Installed separately, the entire floor is covered with the metal plate 17. In addition, in the straight line connecting the turntable and the receiving antenna 13, and in the periphery thereof, there is no obstacle other than the metal plate 17 on the floor surface that reflects electromagnetic waves.

Here, in order to measure the power gain of the antenna to be measured, first, a standard dipole antenna is used as the transmitting antenna 12 and a standard dipole antenna is used as the receiving antenna 13, and each of the transmitting antenna 12 and the receiving antenna 13 is measured. The distance between the feeding points in the horizontal plane is previously set to be constant, and the distance between the antennas is set to D3 so that the polarization planes of the respective antennas of the transmitting antenna 12 and the receiving antenna 13 coincide with each other and the radiation of each antenna is radiated. The respective antennas are arranged so that the directions in which the electric power pattern becomes maximum face each other, and the high frequency signal of the specified level is applied to the transmitting antenna 12 by the high frequency signal generator 11 via the transmitting power feeding wire 15. On the other hand, the receiving side inputs the high frequency signal received by the receiving antenna 13 into the electric field strength measuring device 14 via the receiving power supply line 16 and measures the received power.

Here, the received power received by the receiving antenna 13 is radiated from the transmitting antenna 12 and directly reaches the receiving antenna 13, and is radiated from the transmitting antenna 12 and is once reflected by the metal plate 17. Since the reflected wave 19 that reaches the receiving antenna 13 and the two waves are combined, the propagation of the direct wave 18 and the reflected wave 19 that reach the point of the receiving antenna 13 by moving the receiving antenna 13 up and down. The distances are adjusted differently, so that the phase of each wave changes, and the received power that is the composite wave also changes.

Then, the reference reception power P21 is measured as the reception power when the reception antenna 13 is moved up and down to maximize the reception power. Next, the transmitting antenna 12 is replaced with the antenna under measurement, and the same operation as the operation for obtaining the reference received power P21 is performed, and the maximum reception of the antenna under measurement which is a value when the received power becomes maximum is performed. Electric power P22
To measure.

By the above measurement, the gain G21 of the measured antenna for the full half-wavelength antenna can be obtained from the value of the maximum received power P22 of the measured antenna when the measured reference received power P21 is used as a reference. The following is an equation for obtaining the gain G21 of the antenna under measurement for the perfect half-wavelength antenna from the reference received power P21 and the maximum received power P22 of the antenna under measurement.

G21 = 10 · log (P22 / P21) (dBd) ...

[0011]

However, in the conventional technique shown in FIG. 7, an expensive anechoic chamber, which is an expensive facility, is required to measure the power gain of the antenna, so that the experiment can be easily performed. In addition, there is a problem that the frequency band in which measurement can be performed is limited due to the radio wave absorption characteristics of the radio wave absorber used in the anechoic chamber.

Further, in the prior art shown in FIG. 8, a special environment called an open site is required to measure the power gain of the antenna, and the open site originally causes electromagnetic noise radiated from electronic equipment. Since it is a facility for measurement, it is installed in a place away from the urban area to make it less susceptible to the effects of urban noise. For this reason, the laboratory for developing the antenna and the place where the open site is located are often distant from each other in terms of distance, and there is a problem that the characteristics of the power gain of the antenna cannot be easily evaluated.

An object of the present invention is to solve the conventional problems as described above, and the relative gain of the antenna under test can be easily measured in any environment without using equipment such as an anechoic chamber or an open site. It is to realize the device.

[0014]

In order to solve the above problems, the present invention outputs a high frequency signal generator, a plurality of antennas with known power gains, and a detection output signal proportional to the level of a received high frequency signal. And a pulse signal generator for generating a trigger signal for the A / D converter, which comprises: And a data processing device having a function of storing a plurality of the digital data and a function of calculating the median value of the received power from the plurality of stored digital data, without being restricted by the measurement environment. It is possible to measure the spatial propagation loss including the power gain of the antenna under any environment.

[0015]

In the antenna gain measuring apparatus configured as described above, two antennas having known gains are first used, and the results obtained by using these antennas as the transmitting antenna and the receiving antenna are measured. The spatial propagation loss including the antenna power gain is used as the reference value, and then the spatial propagation loss including the antenna power gain is measured when either the transmitting antenna or the receiving antenna is used as the antenna under test in the same environment. By comparing the measurement results of these two, the power gain of the antenna under measurement can be obtained.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing the configuration of an embodiment of an antenna gain measuring apparatus according to the present invention. When measuring the power gain of the antenna under test in FIG. 1, first, a standard dipole antenna is used as the transmitting antenna 2 and the receiving antenna 3 in order to measure the median value P1 of the reference receiving power. The distance between the feeding point and the feeding point of the receiving antenna 3 is set to a predetermined constant inter-antenna distance D1, and the transmitting antenna 2
Also, the polarization planes of the respective antennas of the receiving antenna 3 are made to coincide with each other, and the radiation directivities of the respective antennas are arranged so as to face each other in the direction in which the radiation power pattern becomes maximum. Next, by the high-frequency signal generator 1, the transmission feeder line A2
A high-frequency signal of a specified level at the measurement frequency is applied to the transmitting antenna 2 via.

On the other hand, the high frequency signal received by the receiving antenna 3 is input to the electric field strength measuring device 4 via the receiving power feed line A6. The electric field strength measuring device 4 has a function of outputting a detection output signal proportional to the level of the input high frequency signal, and the detection output signal is converted into an analog / digital converter 5
(Hereinafter referred to as A / D converter 5), the level of the detection output signal is digitalized in synchronization with the trigger signal generated by the pulse signal generator 6 by using the A / D converter 5. Convert to data. Then, the digital data is stored in the storage means in the data processing device 7.

Here, in order to measure the median value P1 of the received power as a reference, while the preset N digital data are measured, the mobile trolley 9 on which the transmission antenna 2 is mounted is transmitted by the mobile trolley 9. Compared with the inter-antenna distance D1 between the feeding point of the antenna 2 and the feeding point of the receiving antenna 3, the wavelength λ of the frequency at which the measurement is performed is sufficiently short.
The operation of moving within the range of the moving distance D2 set to a sufficiently long distance with respect to 1/4 of the above is continued. Generally, the transmitting antenna 2 or the receiving antenna 3 as in an open site
In an environment other than an ideal environment in which there are no obstacles that reflect radio waves around, the radio waves emitted from the transmitting antenna 2 are obstructed around the transmitting antenna 2 or the receiving antenna 3,
A plurality of waves arrive at the receiving point through a plurality of paths after being reflected by the floor and the ceiling, and so-called multiple wave propagation occurs. Therefore, the received power received by the receiving antenna 3 is a combination of these multiple waves, and the mobile carriage By moving 9 within the range of the moving distance D2, the so-called fading in which the level of the received power rapidly changes occurs.

Based on the N pieces of the digital data measured by the above-mentioned operation and stored in the storage means in the data processing device 7, the data processing device 7 performs arithmetic processing and the center of the reference received power. The value P1 is calculated. After that, the transmission antenna 2 is changed from the standard dipole antenna to the antenna under measurement, and the same operation as the operation for obtaining the median value P1 of the reference received power is performed to perform the operation P2. Ask for.

Next, the relationship between the received power and the power gain of the antenna will be described with reference to FIG. FIG. 2 is an explanatory diagram showing a standard channel model. The transmission power of the transmission device A1 is Pt (dBm), and the loss of the transmission power supply line A2 is Lft (d
B), the power gain of the transmitting antenna A3 is Gt (dBi),
The spatial propagation loss A4 is Γ (dB), the power gain of the receiving antenna A5 is Gr (dBi), and the loss of the receiving power feed line A6 is Lf.
r (dB), the reception power of the receiving device A7 is Pr (dBm)
Then, the transmission power Pt and the loss L of the transmission power supply line are
The following relationships are established among ft, the power gain Gt of the transmitting antenna, the spatial propagation loss Γ, the power gain Gr of the receiving antenna, the loss Lfr of the receiving feed line, and the receiving power Pr.

Pr = Pt−Lft + Gt−Γ + Gr−Lfr (dBm) When the standard propagation path model is applied to the measurement shown in FIG. 1, the median value P1 of the reference received power obtained in the first measurement is obtained. And the median value P2 of the received power of the measured antenna obtained in the next measurement is the power gain of the standard dipole antenna used as the transmitting antenna 2 in the first measurement, Gt1 (d
Bi), assuming that the power gain of the antenna under measurement used as the transmission antenna 2 in the next measurement is Gt2 (dBi), the transmission power Pt and the loss Lf of the transmission power feed line in both measurements.
Since t, the spatial propagation loss Γ, the power gain Gr of the receiving antenna, and the loss Lfr of the receiving feed line are all equal, the following relationship holds.

P1 = Pt−Lft + Gt1−Γ + Gr−Lfr (dBm) P2 = Pt−Lft + Gt2−Γ + Gr−Lfr (dBm) ∴P2−P1 = Gt2−Gt1. And the median value P2 of the received power of the measured antenna is the difference between the power gain Gt1 of the standard dipole antenna and the power gain Gt2 of the measured antenna.

In this embodiment, the standard dipole antenna is used as the transmitting antenna 2 and the standard dipole antenna is used as the receiving antenna 3 in order to measure the median value P1 of the reference received power. The power gain of the antenna to be measured can be obtained in the same manner as described above by using antennas having known power gains other than the standard dipole antenna as the transmitting antenna 2 and the receiving antenna 3.

Next, with reference to FIG. 3, an embodiment of a method for obtaining an instantaneous received power value and a method for calculating the received power median value from the measured received power instantaneous value according to the present invention will be described. FIG. 3 shows a mobile cart 9 on which a transmitting antenna 2 is mounted in order to measure the reference median value P1 of the received power or the median value P2 of the received power of the antenna under test in the measuring apparatus shown in FIG. Showing a detection output signal output from the electric field strength measuring device 4 in proportion to the level of the high frequency signal received by the receiving antenna 3 and input to the electric field strength measuring device 4 while moving The detected output signal is input to the A / D converter 5. The horizontal axis represents time T, and the trigger signal generated by the pulse signal generator 6 is input to the A / D converter 5 at timings T1, T2, T3, T4 to TN. In the A / D converter 5, the voltage level of the detection output signal is converted into digital data in synchronization with the timing when the trigger signal is input, and the digital data is stored in a storage means in the data processing device 7. To be done.

That is, the voltage level Va1 of the detection output signal at time T1, the voltage level Va2 of the detection output signal at time T2, and the voltage level VaN of the detection output signal at time TN are converted into digital data, respectively, and the data It will be stored in the storage means in the processing device 7. Here, since the voltage level of the detection output signal and the level of the high frequency signal input to the electric field strength measuring device 4 are in a proportional relation, the data processing device 7 receives the digital data from the receiving antenna 3 at the receiving antenna 3. The received power of the high frequency signal can be calculated.

That is, in the data processing device 7,
From the voltage level Va1 of the detection output signal at time T1 to the received power Pa1 at that time, from the voltage level Va2 of the detection output signal at time T2 to the received power Pa at that time
2. Voltage level VaN of detection output signal at time TN
From this, the received power PaN at that time can be calculated.

Further, in the data processing device 7, when the N pieces of data of the received powers Pa1 to PaN obtained by the measurement and the calculation are rearranged in descending order of the received power level, the received power located at the center is obtained. , The median value Pa which is the 50% value in the cumulative distribution of the received power is obtained. For example, if the number of data N is 101,
The median value Pa of the received power is the 51st received power counted from the largest received power level when 101 measured received powers are rearranged in descending order of received power level.

Next, based on FIGS. 4A and 4B, A / D
An embodiment of the pulse signal generator 6 that generates the trigger signal when the timer pulse is used as the trigger signal of the converter 5 will be described. FIG. 4A is an explanatory diagram showing an embodiment of the circuit configuration of the pulse signal generator 6 according to the present invention.

Transistors Q1 and Q2 and variable resistance R1,
A signal generated by the astable multivibrator circuit composed of R2, capacitors C1 and C2, and resistors R3 and R4 is generated by turning on and off the transistors Q1 and Q2.
Since the FFs operate so that they are always in the opposite operation states, the signal at the point A temporarily indicates that the transistor Q2 is OF
If it is F, the transistor Q1 is ON,
At this time, the capacitor C1 is charged by the variable resistor R1 and the time until the potential at the connection point between the capacitor C1 and the variable resistor R1 rises to the potential for turning on the transistor Q2, that is, the time constant determined by the variable resistor R1 and the capacitor C1. H for the period of T11, which is the time obtained by multiplying
i, then the transistor Q2 turns on, and at the same time the transistor Q1 turns off. This time, the capacitor C2 is charged by the variable resistor R2 and the capacitor C2 and the variable resistor R
It becomes Low only during the time period until the potential at the connection point with 2 rises to the potential at which the transistor Q1 is turned on, that is, the period T12, which is the time constant obtained by multiplying the time constant determined by the variable resistor R2 and the capacitor C2, 2 The above states are alternately repeated to become the signal at the timing of the signal B1 at the point A shown in FIG.

The signal is split into two, one of which is directly I
The signal input to C2, and the other signal is a signal whose logic is inverted with a delay time T13 with respect to the signal at point A by a circuit composed of a resistor R5, a capacitor C3 and an inverting amplifier IC1 having hysteresis. B shown in (b)
The signal becomes a timing signal of the point signal B2 and is input to the IC2. Since IC2 is an AND circuit, the output signal is Hi only during the delay time T13 and is Low during the other periods.
Becomes a signal of a repetition cycle T14, that is, a signal at the timing of the output signal B3 shown in FIG. The output signal B3 is used as a trigger signal for the A / D converter 5. The repeating cycle T14 is a period in which the T11 and the T12 are added.

FIG. 6 shows a case where the inter-antenna distance D1 which is the distance between the feeding point of the transmitting antenna 2 and the feeding point of the receiving antenna 3 in the measurement shown in FIG. 1 is changed within the range of the moving distance D2. In this example, the change in received power is actually measured. In FIG. 6, the vertical axis represents the received power level measured by the electric field strength measuring device 4, and the horizontal axis represents the passage of time. Here, the radio waves emitted from the transmitting antenna 2 are reflected by surrounding obstacles, floors and ceilings, etc., and propagate as multiple waves, causing fading in which the received power at the receiving point changes rapidly. Since this fading changes in inverse proportion to the frequency of measurement or the moving speed of the moving carriage 9, the output signal B3 of FIG. 4 (b) which is the trigger signal of the A / D converter 5 is suitable for measurement. It is necessary to set the period T14.

Next, an embodiment of the measurement table will be described with reference to FIGS. 5 (a) and 5 (b). The measurement table is driven by a power source such as a motor to perform a first rotary motion 26 at an arbitrary angular velocity within a predetermined range centered on a first center point 24, and the above-mentioned first turntable 21. The first center point 24 on the first turntable 21
The first rotational movement 2 is interlocked with the first rotational movement 26 about a second center point 25 located at a position away from
Second rotational movement 2 in the opposite direction to 6 and at the same angular velocity
And a second turntable 22 for performing No. 7.

Here, the object to be measured 23 is installed on the second turntable 22 so that the front surface of the object to be measured 23 faces right as shown in FIG.
The first rotary motion 26 of the first turntable 21 is performed counterclockwise, and after a certain time elapses, the first turntable 21 moves to the first center point 2
If it is rotated 90 degrees counterclockwise about 4, the second center point 2 which is the center of the second turntable 22 will be described.
5 is the first center point 2 due to the first rotational movement 26.
4. The second turntable 22 also rotates 90 degrees counterclockwise about the first rotation movement 26.
Since the second rotary motion 27 is performed in the opposite direction of the first rotary motion 26 and at the same angular velocity as the first rotary motion 26, the second turntable 22 is centered on the second center point 25. It rotates 90 degrees clockwise, resulting in the positional relationship shown in FIG. 5 (b).

That is, the object 23 to be measured can move its position while always facing in a constant direction by the first rotary motion 26 and the second rotary motion 27 linked with the first rotary motion 26. Is possible. In addition, the second turntable 22 can also perform a rotary motion independently of the second rotary motion 27 linked to the first rotary motion 26, and thus is shown in FIG. In order to set the radiation directivity of the respective antennas of the transmitting antenna 2 and the receiving antenna 3 so that the directions in which the radiated power patterns are maximum oppose each other when performing the measurement, they are input to the electric field strength measuring device 4. It is also possible to rotate only the second turntable alone so that the received power becomes maximum while observing the level of the high frequency signal.

Therefore, if the transmission table 2 shown in FIG. 5A is used instead of the moving carriage 9 shown in FIG. 1 and the transmitting antenna 2 is used as the DUT 23, the moving distance D2 is automatically set. It is possible to continuously perform the movement operation within the range. Although the first turntable 21 and the second turntable 22 are illustrated as circular tables in FIGS. 5A and 5B, the shapes of the first turntable 21 and the second turntable 22 are not limited to square or rectangular. The result is obtained.
Further, in FIG. 5A, the first rotary motion 26 is shown as a counterclockwise rotation and the second rotary motion 27 is shown as a clockwise rotation. Similar results are obtained when the first rotary movement 26 is clockwise rotation and the second rotary movement 27 is counterclockwise rotation.

In the description of the embodiments according to the present invention, the method of measuring the power gain of the antenna to be measured by using the antenna to be measured as the transmitting antenna has been described. However, the antenna has input impedance, power gain, directivity, etc. Since the various characteristics are reversible, it is possible to obtain the power gain of the measured antenna even when the measured antenna is used as the receiving antenna, as in the embodiment.

[0037]

As described above, the present invention provides a high frequency signal generator, a plurality of antennas having known power gains, and an electric field having a function of outputting a detection output signal proportional to the level of a received high frequency signal. In an electric field intensity measuring system having an intensity measuring device, an A / D converter for converting the detection output signal into digital data, a pulse signal generator for generating a trigger signal of the A / D converter, and a plurality of the digital data are provided. Since it is configured to have a means for individually storing and a data processing device having a function of calculating a median value of received power from the plurality of stored digital data, a special environment such as an anechoic chamber or an open site is used. Can measure the spatial propagation loss including the power gain of the antenna in the environment where the measurement is actually performed in any environment. It becomes bets, gain there is an effect that it becomes possible to obtain a power gain of the antenna under test by the measurement result comparison of the antenna and the antenna under test of known value.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of an embodiment of an antenna gain measuring apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing a standard channel model.

FIG. 3 is an explanatory diagram showing a method for measuring an instantaneous value of received power and a method for obtaining a median received power according to the present invention.

FIG. 4A is an explanatory diagram showing an example of a circuit configuration of a pulse signal generator according to the present invention. (B) is an explanatory view showing the timing of signals generated by the pulse signal generator according to the present invention.

5A and 5B are explanatory views showing the configuration and operation of the measurement table according to the present invention.

FIG. 6 is an explanatory diagram showing changes in actually measured reception power.

FIG. 7 is an explanatory diagram showing a conventional antenna gain measuring method using an anechoic chamber.

FIG. 8 is an explanatory diagram showing a conventional antenna gain measurement method using an open site.

[Explanation of symbols]

 1, 11 High-frequency signal generator 2, 12, A3 transmitting antenna 3, 13, A5 receiving antenna 4, 14 Electric field strength measuring device 5 A / D converter 6 Pulse signal generator 7 Data processing device 9 Moving carriage 21 First Turntable 22 Second turntable 24 First center point 25 Second center point 26 First rotary motion 27 Second rotary motion A2,15 Transmit power supply line A6,16 Receive power supply line A4 Spatial propagation loss D1, D3 Distance between antennas D2 Moving distance

Claims (4)

[Claims] 1. A high-frequency signal generator for generating a preset high-frequency signal or a high-frequency signal whose output level can be varied, two or more antennas having a known power gain at a measurement frequency, and a received high-frequency signal. In an electric field intensity measuring system having an electric field intensity measuring device for measuring the level of the signal, an analog / digital converter for converting a detection output signal from the electric field intensity measuring device into digital data, and an input to the analog / digital converter. A pulse signal generator for outputting a trigger signal for converting the detected detection output signal into digital data, and a data processing device for processing the digital data from the analog / digital converter. Characteristic antenna gain measurement device. 2. The data processing device comprises:
A means for storing a plurality of digital data converted by the digital converter, and having a function of calculating a median value or an average value of electric field strength measurement values from the plurality of stored digital data. An antenna gain measuring device according to claim 1. 3. The gain measuring device for an antenna according to claim 1, wherein the pulse signal generator has a timer pulse generating function capable of arbitrarily setting a pulse signal. 4. The electric field strength measuring system is provided with a first turntable that is driven by a motor or the like to perform a first rotary motion, and is provided on the first turntable and has the first center point. Has a second center point formed at another position, and has a second turntable that performs a second rotary motion at the same angular velocity in the opposite direction to the first rotary motion, and 2. The antenna gain measuring apparatus according to claim 1, wherein the second turntable is rotatable independently of the first turntable rotating movement.