JPH02254372A - Method and system for measuring antenna gain - Google Patents

Abstract

PURPOSE:To enable highly accurate measurement of a gain by receiving radio waves sent from a reference antenna and an antenna to be measured alternately within a short period of time to determine a gain of the antenna to be measured from a reception level. CONSTITUTION:Radio waves transmitted from an antenna 1 to be measured and a reference antenna 2 are received with a receiving antenna 5 to be introduced to a spectrum analyzer 6 respectively. Then, the analyzer 6 detects reception levels of respective radio waves received. The analyzer 6 is accessed by a control circuit 9 at a short time interval. As a result, reception level detection values of the radio waves from antennas 1 and 2 obtained from the analyzer 6 are introduced to a circuit 9 within a short period. When this one set of reception level detection values are loaded, the circuit 9 calculates a difference between the reception level detection values to store a data thereof into the circuit 9. Then, a gain of the antenna 1 is calculated from all reception levels and reception level differences obtained while the antenna 5 turns.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an antenna gain measurement method used to measure the gain of an antenna installed in a wireless base station, a wireless transmitter/receiver, etc. Regarding measurement systems.

(Prior Art) Conventionally, the comparison method is generally well known as a method for measuring the gain of an antenna. In this comparison method, standard antennas with known gains are prepared in addition to the 4pj constant antenna, and radio waves are sent out alternately by replacing these antennas. Then, each radio wave transmitted from these antennas is received by one receiving antenna, a difference in reception level is detected, and the gain of the antenna to be measured is calculated from this difference in reception level. Furthermore, as a standard antenna, V
In the HF and UHF bands, dipole antennas and 3-element Yagi antennas are used.
A Uda antenna is used, and a standard horn antenna is used in the microwave band.

(Problem to be Solved by the Invention) However, in a general space other than an anechoic chamber, the propagation characteristics of radio waves constantly change over time due to the influence of the surrounding topography and the like. For this reason, the conventional 1Il system replaces the antenna under test and the standard antenna during measurement and alternately transmits radio waves.
In the lj determination method, the radio wave propagation conditions change between when the antenna under test transmits radio waves and when the standard antenna transmits radio waves, and the component of this change in propagation conditions appears in the reception level difference, so it is necessary to perform highly accurate measurements. was difficult.

SUMMARY OF THE INVENTION The present invention addresses the above points and aims to provide an antenna gain measuring method and a measuring system thereof, which can reduce the influence of time changes in radio wave propagation characteristics and perform highly accurate a11 determination.

[Structure of the Invention] (Means for Solving the Problem) The present invention receives radio waves transmitted from a standard antenna with a known gain and an antenna to be measured using a common receiving antenna, and detects the radio waves from the antenna to be measured based on the reception level difference. In the antenna gain measurement method for determining the antenna gain of an antenna, the radio waves sent from the standard antenna and the radio wave sent from the antenna under test are alternately switched within a short period of time to receive each, or the standard antenna and the antenna under test are received separately. Radio waves are alternately switched and transmitted from the -1 constant antenna within a short period of time, and the gain of the Al11 constant antenna is determined from the reception level or reception level difference of these radio waves.

Further, the antenna gain measurement system of the present invention arranges standard antennas with known gains in close proximity to all fixed antennas, and also arranges standard antennas with known gains in close proximity to all fixed antennas.
A transmitting device for respectively transmitting radio waves having a predetermined frequency interval close to each other from the IJ standard antenna, one receiving antenna for receiving the radio waves transmitted from the standard antenna and the antenna to be measured, and a measuring device. , This measuring device alternately switches and raises each reception level of the radio waves from the standard antenna and the JPI standard antenna received by the above-mentioned receiving antenna within a short period of time, and determines the antenna to be measured based on the reception level or the reception level difference. It is designed to calculate the gain of .

Furthermore, in another antenna gain measurement system of the present invention, a standard antenna with a known gain is placed close to the antenna to be measured, and a transmitting device transmits radio waves of the same frequency from these standard antennas and the ΔP1 constant antenna within a short period of time. and a 1p1 constant device;
This measurement device detects each reception level of the radio waves from the standard antenna and the antenna under test received by the reception antenna in synchronization with the radio wave switching and transmission operation by the transmission device, and detects the reception level or reception level. The gain of the antenna under test is calculated from the difference.

(Function) As a result, according to the present invention, from the reception level or reception level difference of each radio wave of the standard antenna and the antenna to be measured that are transmitted or received alternately within a short period of time, that is, substantially simultaneously,
The gain of the antenna under test will be calculated. That is, the antenna gain is determined from each radio wave propagated with substantially equal propagation characteristics from the standard antenna and the m11pr constant antenna. Therefore, even if measurements are made under conditions where the propagation characteristics of radio waves change over time, the gain of the antenna under test can be determined with little influence from changes in the propagation characteristics over time. Measurement becomes possible.

(Example) FIG. 1 is a schematic configuration diagram of an antenna gain measurement system according to a first example of the present invention.

In the figure, 1 is the antenna to be measured, and this
A standard antenna 2 is provided at a position close to the fixed antenna 1. This standard antenna 2 consists of, for example, a dipole antenna, and its gain is already known.

A signal generator 3.4 as a transmitting device is connected to the antenna to be measured 1 and the standard antenna 2, respectively.

These signal generators 3.4 each generate a transmission signal of frequency f1+f2. The frequencies fl+f2 are set to values close to each other and separated by a minimum frequency difference (for example, several hundred kHz) that can be separated by a spectrum analyzer 6 on the receiving side, which will be described later.

On the other hand, a receiving antenna 5 is installed at a position a predetermined pressure apart from the antenna to be measured 1 and the standard antenna 2. This receiving antenna 5 is fixed to a rotary table 7, and is rotated at a constant speed in a circular orbit in a horizontal plane by a drive mechanism including a motor 8. A received signal obtained by the receiving antenna 5 is introduced into a spectrum analyzer 6. The spectrum analyzer 6 detects the signal level of the received signal for each frequency by alternately switching the frequency between fl and fl. The reception level detection data obtained by the spectrum analyzer 6 is introduced into the control circuit 9.

By the way, the control circuit 9 has, for example, a microprocessor as a main control section, and has reception frequency switching control means 9a, rotation control means 9b, and gain calculation means 9C as its functions. Among these, first the rotation control means 9b
At the time of measurement, a drive signal is output to the drive mechanism including the motor 8 to move the receiving antenna 5 continuously through 360° at a constant speed.
It is something that is rotated. While the receiving antenna 5 is rotating, the reception frequency switching control means 9a changes the reception level of the radio wave (frequency f1) from the antenna under test 1 detected by the spectrum analyzer 6 and the radio wave (frequency f1) from the standard antenna 2.
The reception level of frequency f2) is switched at a predetermined period and introduced alternately.

This introduction period is set to a value (for example, several tens of m5ec) that is sufficiently shorter than the time corresponding to the rate of change over time of the propagation characteristics of radio waves. The gain calculating means 9c stores data on the reception level and reception level difference each time the reception level detection value from each antenna 1, 2 is introduced from the spectrum analyzer 6 at the above-mentioned period. Then, the gain of the antenna to be measured 1 is calculated based on the data of the received level and the received level difference according to a predetermined arithmetic expression.

Next, the operation of the system configured as above will be explained according to the measurement procedure. With the antenna to be measured 1 and the standard antenna 2 installed at their respective predetermined positions, first adjust the signal generator 3.4 to set the oscillation frequencies to fl and f, respectively.
1, and the antenna under test 1 and the standard antenna 2 transmit radio waves at frequencies f, , f2. As described above, the frequencies '1nf2 are set to values separated from each other by the minimum frequency difference (several hundred kHz) that can be separated by the spectrum analyzer 6. On the receiving side, when a measurement start instruction is input to the control circuit 9 by operating the DJ constant start button on the operation panel, the control circuit 9 starts the measurement operation according to a preset control procedure, and first starts driving the motor including the motor 8. A drive signal is output to the mechanism to drive the drive mechanism. Therefore, the rotary table 7 starts rotating, and thereby the receiving antenna 5 starts receiving the radio waves transmitted from the antenna to be measured 1 and the standard antenna 2 while rotating at a constant speed.

Now, the antenna under test 1 and the standard antenna 2
When the radio waves transmitted from the transmitter are received by the receiving antenna 5, each received signal is introduced into the spectrum analyzer 6, respectively. At this time, each of the above antennas 1 and 2
As described above, the frequencies fl and f2 of the radio waves sent out have a frequency difference that can be resolved by the spectrum analyzer 6. Therefore, the spectrum analyzer 6 detects the reception level of each of the received radio waves. On the other hand, at this time, the spectrum analyzer 6 is accessed by the control circuit 9 at short time intervals (approximately several tens of times 5 CCs), and as a result, the detection value of the reception level of the radio waves from each antenna 1 and 2 obtained by the spectrum analyzer 6 is short-term. The signals are respectively introduced into the control circuit 9 within a certain period of time. That is, the reception level detection values of the radio waves received from each antenna 1.2 substantially simultaneously are introduced into the control circuit 9, respectively. When this set of reception level detection values is loaded, the control circuit 9 first calculates the difference between these reception level detection values. The data of these reception levels and reception level differences are stored in a storage section within the control circuit 9.

Thereafter, similarly, while the receiving antenna 5 rotates 3GO',
At regular intervals, the detected values of the reception levels of the radio waves from each antenna 1.2 obtained substantially simultaneously by the spectrum analyzer 6 are introduced into the control circuit 9. and,
Each time this set of reception level detection values is introduced, the difference between them is calculated and stored in the storage section within the control section 9. and,
For example, from the detection values of all reception levels and reception level differences obtained during one rotation of the reception antenna 5,
, 2 are calculated, and these values are also stored in the storage section in the control circuit 9 as the gain of the antenna under test 1. Further, the calculated gain is outputted from the control circuit 9 to a display device or a storage device (not shown), and is displayed or recorded on these devices. In this way, the gain of the antenna under test 1 is measured.

In this way, in this embodiment, the gain of the antenna under test 1 is calculated from the reception level of the radio waves from each antenna 1.2 that are received by the receiving antenna 5 at the same time. The influence of time changes can be almost ignored. Also, since the detection of the reception level of the radio waves sent out from the antenna under test 1 and the reception level of the radio waves sent out from the standard antenna 2 are performed almost simultaneously, each antenna 1 and 2 can be replaced and the Compared to conventional measurement methods that detect the reception level of radio waves, this method allows highly accurate gain measurements even in locations where radio wave propagation characteristics change over time.

FIG. 2 shows the configuration of an antenna gain measurement system according to a second embodiment of the present invention.

In this figure, the same parts as in FIG. 1 are given the same reference numerals and detailed explanations will be omitted.

Signal generators 11 and 12 that generate transmission signals of the same frequency f3 are connected to the antenna under test 1 and the standard antenna 2, respectively. On the other hand, the control circuit 10 on the reception side has a microprocessor as a main control section, and has as its functions a transmission timing switching control means 10a, a rotation control means 10b, and a gain calculation control means 10c. Among these, the transmission timing switching control means 10a is
A switching control signal for alternately switching the transmission timing of the radio waves of the antenna under test 1 and the standard antenna 2 is generated at a predetermined short period corresponding to the minimum sampling period of the spectrum analyzer 6. This switching control signal is transmitted from a transmitting section 13 provided on the receiving side to a receiving section 15 provided on the transmitting side via a wired line 14.

The receiving section 15 supplies a switching drive signal to each signal generator 11.12 in accordance with the switching control signal, thereby alternately switching the signal generation timing of each signal generator 11.12 at the short cycle.

Further, the rotation control means 10b of the control circuit 10 outputs a drive signal for rotating the receiving antenna 5 in steps in synchronization with the switching control signal. still,
The gain calculation means 10c of the control circuit 10 has the same gain calculation function as the gain control means 9c provided in the control circuit 9 of FIG.

With such a configuration, when a measurement start instruction is input to the control circuit 10, the control circuit 10 generates a switching control signal. This switching control signal is modulated by the transmitter 13 and then sent to the receiver 15 on the transmitting antenna side via the wired line 13.
transmitted to. Then, the receiving section 15 supplies a switching drive signal to each signal generator 11.12 in accordance with the switching control signal, and this switching drive signal causes the signal generation timing of each signal generator 11.12 to be alternately changed in a short cycle. Can be switched. Therefore, from the antenna under test 1 and the standard antenna 2, the same frequency
3 radio waves are transmitted.

On the other hand, on the receiving antenna side, the antenna under test 1
The radio waves alternately sent from the standard antenna 2 are sequentially received by the receiving antenna 5, and the reception levels of the radio waves are detected by the spectrum analyzer 6 in the order of reception. Further, at this time, the spectrum analyzer 6 is accessed by the control circuit 10 in synchronization with the switching cycle of the transmission radio waves. Therefore, the reception level detection values of each received radio wave obtained by the spectrum analyzer 6 are sequentially introduced into the control circuit 10. Then, the control circuit 10 detects the detected value of the received level of the radio wave sent from the antenna under test 1, the detected value of the received level of the radio wave sent from the standard antenna 2, and the difference in the received level between the antenna under test 1 and the standard antenna 2. is detected, and the gain of the antenna under test 1 is calculated based on these data according to a predetermined arithmetic expression.

In this embodiment, radio waves of the same frequency are alternately switched and transmitted from the antenna under test 1 and the standard antenna 2 in short cycles, and the receiving antenna side detects the reception levels of these radio waves. Since the gain of the antenna under test 1 is calculated based on the reception level and the reception level difference, the gain can be calculated from the reception level of the radio waves transmitted from the antenna under test 1 and the standard antenna 2 at substantially the same time. Therefore, the influence of time-dependent changes in radio wave propagation characteristics can be substantially ignored, and thereby the gain Al1 can be determined with high precision.

Furthermore, in this embodiment, since radio waves of the same frequency are transmitted from the fixed antenna 1 and the standard antenna 2, there is no difference in the frequency of radio waves between the antennas 1.2 as in the first embodiment. This makes it possible to further improve measurement accuracy. Furthermore, in this embodiment, since the receiving antenna 5 is rotated stepwise in synchronization with the switching timing of radio wave transmission of the antenna under test 1 and the standard antenna 2, the angle of the receiving antenna 5 is fixed, that is, Each radio wave from the antenna under test 1 and the standard antenna 2 can be received at the same angle. Therefore, measurement errors due to changes in the angle of the receiving antenna 5 that occur when the receiving antenna 5 is continuously rotated at a constant speed are eliminated, thereby further improving measurement accuracy.

Note that the present invention is not limited to the above embodiments. For example, in the second embodiment, signal generators 11 and 12 are provided for each of the antenna under test 1 and the standard antenna 2, and these signal generators 11 and 12 are alternately operated in accordance with a switching control signal sent from the receiving antenna side. By operating the antennas 1 and 2, radio waves are sent out alternately.In addition, as shown in FIG. It may also be configured such that radio waves are alternately transmitted from the antenna under test 1 and the standard antenna 2 by switching the changeover switch 17 in accordance with a switching control signal sent from the receiving antenna side.

Furthermore, in the second embodiment, the transmission timing of radio waves from each antenna 1.2 is controlled by transmitting a switching control signal from the receiving antenna side to the transmitting antenna side. The transmission timing may be controlled. However, in this case, it is necessary to transmit a transmission timing switching control signal to the receiving antenna side.

Further, as the transmitter, for example, a frequency synthesizer using a PLL circuit may be used, and the configuration of the control circuit, measurement procedure, measurement contents, etc. may be modified in various ways without departing from the gist of the present invention. .

[Effects of the Invention] As detailed above, according to the present invention, the radio waves transmitted from the standard antenna and the radio waves transmitted from the antenna to be measured are alternately switched within a short period of time and received respectively, or Radio waves are alternately switched and transmitted from the standard antenna and the antenna under test within a short period of time, and the gain of the antenna under test is determined from the reception level or difference in reception level of these radio waves, thereby improving the radio wave propagation characteristics. It is possible to provide an antenna gain measurement method that can perform highly accurate measurements by reducing the influence of changes over time.

Further, a standard antenna with a known gain is arranged close to the antenna to be measured, and a transmitting device for transmitting radio waves having a predetermined frequency interval close to each of these standard antennas and the antenna to be measured, and the above-mentioned standard antenna. It is equipped with one receiving antenna that receives radio waves transmitted from the antenna and the antenna under test, respectively, and a measuring device. Detects by alternately switching the reception level within a short period of time,
By calculating the gain of the antenna to be measured from the reception level or reception level difference, an antenna gain measurement system that can perform highly accurate 1t)I determination by reducing the influence of time-dependent changes in radio wave propagation characteristics has been created. can be provided.

Furthermore, a standard antenna with a known gain is placed close to the antenna under test, and a transmitting device alternately switches and transmits radio waves of the same frequency from these standard antennas and the antenna under test within a short period of time, and comprising one receiving antenna that receives radio waves transmitted from the antenna and the antenna to be measured, respectively, and a measuring device,
This measurement device detects each reception level of the radio waves from the standard antenna and the antenna under test received by the reception antenna in synchronization with the radio wave switching and transmission operation by the transmission device, and the reception level between the reception levels is Also by calculating the gain of the antenna to be measured from the level difference, it is possible to provide an antenna gain ΔII constant system that can reduce the influence of time-dependent changes in radio wave propagation characteristics and perform highly accurate measurements.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an antenna gain measurement system according to a first embodiment of the present invention, FIG. 2 is a schematic configuration diagram of an antenna gain measurement system according to a second embodiment of the present invention, and FIG. FIG. 4 is a main part configuration diagram for explaining another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Antenna to be measured, 2... Standard antenna, 3°4.11, 12.16... Signal generator, 5... Receiving antenna, 6... Spectrum analyzer, 7...
Turntable, 8...Motor, 9, 10...Control circuit, 9
a... Reception frequency switching control means, 10a... Transmission timing switching control means, 9b, 10b... Rotation control means, 9c, 10c... Gain calculation means, 13... Transmission unit, 14...・Wired line, 15... Receiving section, 17...
・Choice switch.

Claims (4)

[Claims] (1) An antenna gain measurement method in which radio waves transmitted from a standard antenna and an antenna to be measured whose gains are known are each received by a common receiving antenna, and the antenna gain of the antenna to be measured is determined from the reception level difference. An antenna characterized in that the radio waves transmitted from the antenna and the radio waves transmitted from the antenna to be measured are alternately switched and received within a short period of time, and the gain of the antenna to be measured is determined from the reception level or the difference in reception level. Gain measurement method. (2) An antenna gain measurement method in which radio waves transmitted from a standard antenna and an antenna to be measured whose gains are known are each received by a common receiving antenna, and the antenna gain of the antenna to be measured is determined from the reception level difference. and the antenna to be measured, alternately switching and transmitting radio waves within a short period of time, respectively receiving the radio waves transmitted from these antennas, and determining the gain of the antenna to be measured from the reception level or the difference in reception level. An antenna gain measurement method characterized by: (3) a standard antenna with a known gain placed close to the antenna under test; a transmitting device for respectively transmitting radio waves having a predetermined frequency interval close to the standard antenna and the antenna under test; One receiving antenna that receives radio waves transmitted from the standard antenna and the antenna to be measured, respectively, and each reception level of the radio waves received by the receiving antenna from the standard antenna and the antenna to be measured is alternately switched within a short period of time. 1. An antenna gain measurement system comprising: a measurement device that detects the received signal and calculates the gain of the antenna to be measured from the reception level or the reception level difference. (4) A standard antenna with a known gain placed in close proximity to the antenna under test, and a transmitter that alternately switches and transmits radio waves of the same frequency from these standard antennas and the antenna under test within a short period of time. , one receiving antenna that receives the radio waves transmitted from the standard antenna and the antenna under test, respectively, and the reception level of each radio wave from the standard antenna and the antenna under test received by this receiving antenna as a radio wave by the transmitting device. An antenna gain measuring system comprising: a measuring device that detects each in synchronization with the switching and transmitting operation of the antenna and calculates the gain of the antenna to be measured from the received level or the received level difference.