Communications: radio wave antennas – Antennas – With coupling network or impedance in the leadin
Reexamination Certificate
2001-03-05
2002-09-10
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
With coupling network or impedance in the leadin
C342S380000
Reexamination Certificate
active
06448939
ABSTRACT:
BACKGROUND OF THE INVENTION
The present inventions relates to an array antenna receiving apparatus for removing interference by controlling directivity of an antenna, and especially, to an array antenna receiving apparatus for conducting calibration of a plurality of radio receiving sections.
In a cellar mobile communication system and so forth, in order to aim at high speed and high quality of a signal, and increase of a capacity of members, a method of forming a reception directivity pattern has been investigated, in which, using an array antenna receiving apparatus consisting of a plurality of antenna elements, a reception gain is increased for a direction along which a desired signal comes, and a reception gain is decreased for interference from other users and interference due to a delay wave.
By the way, in the array antenna receiving apparatus, since generally an amplitude variation and a phase variation in a radio receiving section for each antenna element are individually different from each other, it is necessary to compensate those amplitude variation and phase variation in forming the reception directivity pattern. This operation called calibration.
In the array antenna receiving apparatus for conducting this kind of calibration, for example like a calibration device in an array antenna radio receiving apparatus disclosed in JP-A-46180/1999, amplitude and phase information for compensation is obtained by inputting known calibration signals to each radio receiving section and measuring an amplitude variation and a phase variation.
FIG. 6
is a block diagram showing one arrangement example of a conventional array antenna receiving apparatus for conducting calibration.
As shown in
FIG. 6
, this conventional example is constructed of an array antenna
601
consisting of a plurality of antenna elements
602
-
1
to
602
-N, multiplex circuits
603
-
1
to
603
-N for multiplying calibration signals by signals received at the antenna elements
602
-
1
to
602
-N and outputting them, which are provided in accordance with the antenna elements
602
-
1
to
602
-N, respectively, radio receiving sections
604
-
1
to
604
-N for conducting reception processing of signals output from the multiplex circuits
603
-
1
to
603
-N, which are provided in accordance with the antenna elements
602
-
1
to
602
-N, respectively, a detection circuit
611
to which signals output from the radio receiving sections
604
-
1
to
604
-N are input, for detecting amplitude information and phase information of the signals received at the antenna elements
602
-
1
to
602
-N based on the input signals, user signal processing sections
605
-
1
to
605
-M, provided by the number of users, for correcting the signals output from the radio receiving sections
604
-
1
to
604
-N using the amplitude information and phase information detected at the detection circuit
611
, and outputting them as demodulation signals for every user, a signal generator
607
for calibration, which generates calibration signals, a radio transmitting section
608
for calibration, which applies frequency conversion to the calibration signals generated at the signal generator
607
for calibration, and outputting them, and power level variable circuit
609
for outputting the calibration signals output from the radio transmitting section
608
for calibration at arbitrary power levels, and the calibration signals output from the power level variable circuit
609
are multiplied by the signals received at the antenna elements
602
-
1
to
602
-N in the multiplex circuits
603
-
1
to
603
-N.
In the antenna elements
602
-
1
to
602
-N constituting the array antenna
601
, restrictions are not especially imposed on directivity within a horizontal plane and a perpendicular plane for a single antenna element, and for example, omini (non-directivity) and dipole (dipole directivity) can be given. The antenna elements
602
-
1
to
602
-N are placed so that reception signals of the respective antenna elements
602
-
1
to
602
-N have a correlation with each other, and receive signals in which desired signals and a plurality of interference signals are multiplied.
In the multiplex circuits
603
-
1
to
603
-N, the calibration signals output from the power level variable circuit
609
are multiplied by the signals received at the antenna elements
602
-
1
to
602
-N in a radio band by means of code multiplexing and so forth for example, and are output to the radio receiving sections
604
-
1
to
604
-N. In addition, a multiplexing method here is not limited to the code multiplexing. Also, the calibration signals multiplied at the multiplex circuits
603
-
1
to
603
-N can be extracted.
The radio receiving sections
604
-
1
to
604
-N are constructed of a low-noise amplifier, a band-limitation filter, a mixer, a local dial device, an AGC (Auto Gain Controller), a quadrature detector, a low band pass filter, an analog/digital converter and so forth. Here, in the radio receiving section
604
-N for example, a signal output from the multiplex circuit
603
-N is input thereto, and amplification, frequency conversion from a radio band to a base band, quadrature detection, analog/digital conversion and so forth of the input signal are conducted, and the signal is output to the user signal processing sections
605
-
1
to
605
-M and the detection circuit
611
. Generally, to make power levels of output signals constant independent of power levels of input signals for each of the radio receiving sections
604
-
1
to
604
-N, an AGC that is a non-linear circuit is used.
In the detection circuit
611
, signals output from the radio receiving sections
604
-
1
to
604
-N are input thereto, and calibration signals are extracted from the input signals, and thereby, amplitude and phase information of the signals received at the antenna elements
602
-
1
to
602
-N is detected. The detected amplitude and phase information is output to the signal processing sections
605
-
1
to
605
-M. Here, the amplitude and phase information of the signals received at the antenna elements
602
-
1
to
602
-N is detected by investigating variation quantity of amplitude and phase of the calibration signals in the radio receiving sections
604
-
1
to
604
-N.
In the user signal processing sections
605
-
1
to
605
-M, the signals output from the radio receiving sections
604
-
1
to
604
-N and the amplitude and phase information detected at the detection circuit
611
are input thereto, and the signals output from the radio receiving sections
604
-
1
to
604
-N are corrected based on the amplitude and phase information detected at the detection circuit
611
, and thereby, a reception directivity pattern is formed such that, for each user, a reception gain is increased for a direction along which a user signal comes, and a reception gain is decreased for interference from other users and interference due to a delay wave, and demodulation signals received by means of the reception directivity pattern are output.
In the signal generator
607
for calibration, calibration signals are generated in a base band, and the generated calibration signals are output to the radio transmitting section
608
for calibration.
In the radio transmitting section
608
for calibration, the calibration signals in the base band, which were output from the signal generator
607
for calibration, are input thereto, and digital/analog conversion, frequency conversion from a base band to a radio band and so forth are applied to the input calibration signals, and these calibration signals are output to the power level variable circuit
609
as calibration signals having a frequency band same as the signals received at the antenna elements
602
-
1
to
602
-N.
In the power level variable circuit
609
, the calibration signals output from the radio transmitting section
608
for calibration are output to the multiplex circuits
603
-
1
to
603
-N at arbitrary power levels.
Below, an operation of the array antenna receiving apparatus arranged as described above will
Clinger James
NEC Corporation
Wong Don
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