EMC’09/Kyoto
22R3-3
Receive Antenna for Radiated Emission Test Site
Validation Method above 1 GHz
Chiharu Miyazaki#1, Katsuyuki Tanakajima*2, Hiroshi Yamane#3, Jiro Kawano#4
#1
Mitsubishi Electric Corporation
5-1-1 Ofuna, Kamakura, Kanagawa247-8501, Japan
#2
Intertek Japan K.K.
3-2 Sunayama, Kamisu, Ibaraki 314-0255, Japan
#3
NTT
3-9-11 Midori-cho, Musashino, Tokyo 180-0012, Japan
#4
VCCI
7F NOA Bldg., 2-3-5 Azabudai, Minato, Tokyo 106-0041, Japan
Abstract— The validation method of the radiated emissions test
site above 1 GHz has been published as CISPR16-1-4 in 2007[1].
The authors think that further discussions are necessary about
this site validation method. In this paper, we describe the matter
of the influences of the directivity of a receivH antenna, based on
the measurement results.
Key words: site validation method; site VSWR; radiated
emission; receive antenna; CISPR; VCCI
In CISPR 16-1-4 (2007), the site validation test shall be
performed within a test volume in the shape of a cylinder. The
diameter of the cylinder (D) is the largest diameter required to
accommodate an EUT. The site VSWR is determined for each
required transmit antenna location shown in Fig. 1. The
transmit antenna shall have a dipole-like radiation pattern. The
acceptance criterion for the site validation is SVSWR of 6dB or
less.
I. INTRODUCTION
The radiated emission measurements above 1 GHz shall be
performed in the free space. The radiated emission test site
validation method above 1 GHz has been discussed in CISPR
SC-A. CISPR16-1-4 (2007) has been published and the site
validation method above 1GHz by the site voltage standing
wave ratio (VSWR) has presented in this international
standard. VCCI Technical Sub-committee investigated this
site validation method and extracted the problems of this site
validation method. The problem is the directivity of a receive
antenna. This paper shows this problem, based on the
measurement results.
If the test volume diameter is larger than 1.5m, the site
validation test at the center position (C1 to C6) is required in
addition to the front, the right and the left position. At each
required position, six measurements, such as F1 to F6, on a
line to the receive antenna reference point are required. In the
site validation test, absorbers are placed midway between the
perimeter of the test volume and the receive antenna.
II. RADIATED EMISSION TEST SITE VALIDATION METHOD
ABOVE 1 GHZ
A. Transmit Antenna Positionfor Site Validation Method
R1 to R6
Reference point
D
C1 to C6
F1 to F6
d
B. Receive Antenna for Test Site Validation
The site validation method evaluates a given test volume
for the specific combination of the site, the receive antenna,
the test distance and the absorbing material placed on the
ground plane. The receive antenna shall be the same type as
used for EUT emission measurements. Therefore, if there are
some receive antennas for EUT emission measurements at the
same frequency, the site validations have to be performed with
each receive antenna. A lot of time is needed to measure the
site VSWR with each receive antenna. The site VSWR is
changed by the directivity of the receive antenna. [2], [3] The
receive antenna that will be used for EUT emissions
measurements must be linearly polarized. But the directivity
of the receiving antenna is not specified. We need the
maximum site VSWR of the test site. If the receive antenna
that can get the maximum site VSWR is already known, the
site validations with each receive antenna might be
unnecessary. Only one site validation with the receive antenna
that can get the maximum site VSWR is needed. Accordingly,
VCCI examined the relationship between the site VSWR and
the directivity of the receive antenna.
L1 to L6
Fig. 1 Required location for site validation test
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EMC’09/Kyoto
22R3-3
III. RELATIONSHIP BETWEEN SITE VSWR AND DIRECTIVITY OF
RECEIVE ANTENNA
A. Measurement of Site VSWR
The relationship between the site VSWR and the directivity
of the receive antenna was examined with several receive
antennas. The measurement system of the site VSWR is shown
in Fig. 2. The diameter of the test volume was 2.0 m.
Absorbers (3.0 m × 3.0 m) were placed on the site floor. The
transmit antenna was set to the fabricated antenna moving
system. The accuracy of the fabricated antenna moving system
is about ± 0.5 mm. The frequency step of the measurement was
50 MHz. The height of the transmit and the receive antennas
was 1.0 m. The frequency range of these measurements was
from 1 GHz to 6 GHz.
B. Receive Antenna for Site Validation
The site VSWR was measured by using four receive
antennas with different directivities. The receive antennas that
were used for this measurements were a log-periodic dipole
arrays antenna (LPDA) and three double-ridged-guide
antennas (DRGA 1, DRGA 2, DRGA 3). Figure 3, 4, 5, 6 show
the 3 dB beamwidths of these antennas. And Fig. 7 shows T3dB
of these antennas. T3dB is the minimum 3 dB beamwidths of
both the E-plane and H-plane values at each frequency. DRGA
1 has the narrowest beamwidth. LPDA has the widest
beamwidth. And the beamwidths of DRGA 2 and DRGA 3 are
almost the same up to 3.5 GHz. Above 3.5 GHz, the
beamwidths of DRGA 3 are wider than that of DRGA 2.
Receive antenna mast
<Test site>
Transmit
antenna
Receive
antenna
Styrene
foam
Cable 3
3m
Network Cable 2
analyzer
PC
h1, h2
Site floor
2m
Diameter of Test Volume
Pre-amp.
Cable 1
Absorber
(3.0 × 3.0 m)
Antenna
moving system
Fig. 2 Measurement system of site VSWR (Center position)
3 dB beam width [deg]
100
3 dB beam width [deg]
100
DRGA1(E-plane)
DRGA1(H-plane)
80
80
60
60
40
40
20
20
0
0
1
2
3
4
Frequency [GHz]
5
6
1
Fig. 3 3 dB beamwidth of receiving antenna(DRGA1)
2
DRGA2(E-plane)
DRGA2(H-plane)
3
4
Frequency [GHz]
5
Fig. 4 3 dB beamwidth of receiving antenna(DRGA2)
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3 dB beam width [deg]
100
And when the same type receive antennas (DRGA) were used,
the receive antenna with a wider directivity was able to get a
higher site VSWR. At 1.35 GHz, the 3 dB beamwidths of
DRGA 1 is 40 degree and that of DRGA 2 and DRGA 3 are 68
degree. Figure 11 shows the deviations of the site VSWR when
three DRGA antennas were used as the receive antenna. The
reference values of these deviations were the site VSWR that
were gotten by using DRGA 1. This figure shows that the
deviations of DRGA 2 and DRGA 3 are almost the same up to
DRGA3(E-plane)
DRGA3(H-plane)
80
60
40
20
Site VSWR [dB]
5
0
1
2
3
4
Frequency [GHz]
6
5
4
㻰㻾㻳㻭㻝
Max. site VSWR : 3.5 dB
3
Fig. 5 3 dB beamwidth of receiving antenna(DRGA3)
2
3 dB beam width [deg]
100
1
80
0
1
60
2
3
4
Frequency [GHz]
5
6
40
Fig. 8 Measurement results of site VSWR (Receive antenna : DRGA1)
20
LPDA(E-plane)
LPDA(H-plane)
Site VSWR [dB]
5
0
1
2
3
4
Frequency [GHz]
5
6
4
㻰㻾㻳㻭㻞
Max. site VSWR : 4.7 dB
Fig. 6 3 dB beamwidth of receiving antenna(LPDA)
3
T3dB [deg]
100
DRGA1
DRGA3
DRGA2
LPDA
2
1
80
0
60
40
1
3
4
Frequency [GHz]
20
Fig. 9 Measurement results of site VSWR (Receive antenna : DRGA2)
0
1
2
3
4
Frequency [GHz]
5
2
Site VSWR [dB]
5
6
6
㻰㻾㻳㻭㻟
Max. site VSWR : 4.4 dB
4
Fig. 7 T3dB of receiving antenna
5
3
C. Measurement Result of Site VSWR
Figure 8, 9, 10 show the measurement results of the site
VSWR when DRGA 1, DRGA 2, DRGA 3 were used as the
receive antenna, respectively. These figures show that the site
VSWR is changed by the directivity of the receive antenna. [2],
[3] But these figures show the same frequency characteristics.
In these results, the maximum site VSWR got at the same
transmit antenna position (center position : C1 – C6), the same
frequency (1.35 GHz) and the same polarization (vertical).
Copyright © 2009 IEICE
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2
1
0
1
2
3
4
Frequency [GHz]
5
6
Fig. 10 Measurement results of site VSWR (Receive antenna : DRGA3)
EMC’09/Kyoto
22R3-3
3.5 GHz. Above 3.5 GHz, the deviations of DRGA 3 are
bigger than that of DRGA 2. These tendencies look like that of
the deviations of the directivities between DRGA 2 and
DRGA3 very well. The site VSWR and the directivities of the
receive antennas have a very strong relationship. When the
same type receive antennas (DRGA) were used, it is enough
only to measure the site VSWR in the case of using the
receiveantenna with the widest directivity because the site
VSWR inthe case of using the receive antenna with the widest
directivity is larger than that in the case of using the other
receive antenna.
Deviation [dB]
3
DRGA2
DRGA3
Antenna elements
Fig. 13 Log-periodic dipole arrays antenna (LPDA)
IV. CONCLUSION
The radiated emissions test site validation method above 1
GHz was examined in the frequency range from 1GHz to 6
GHz and the following conclusions were obtained.
Max. deviation
(4.6GHz)
2
Direction of the
transmit antenna
1
x
The site VSWR was measured by using four receive
antennas with different directivities. The site VSWR
and the directivities of the receive antennas have a
very strong relationship. The site VSWR is changed by
the directivity of the receive antenna. When the same
type receive antennas (DRGA) were used, it was
confirmed that the site VSWR in the case of using the
receive antenna with a wide directivity was larger than
that in the case of using the receive antenna with a
narrow directivity in the frequency range from 1 GHz
to 6 GHz. Therefore it is enough only to measure the
site VSWR in the case of using the receive antenna
with the widest directivity because the site VSWR in
the case of using the receive antenna with the widest
directivity is larger than that in the case of using the
other receive antenna.
x
The differences of the site VSWR by the receive
antennas with different shapes (DRGA 2, LPDA) were
measured Although the directivity of LPDA is wider
than that of DRGA 2, the site VSWR in the case of
using LPDA is smaller than that in the case of using
DRGA 2. The reason is that the minimum value of the
standing wave cannot be accurately measured by
LPDA because the antenna elements of LPDA are
distributed in the direction where the transmit antenna
is moved. Therefore, it is necessary to pay attention
enough when LPDA is used as the receiving antenna.
0
-1
1
2
3
4
Frequency [GHz]
5
6
Fig. 11 Deviation of site VSWR
Site VSWR [dB]
5
㻸㻼㻰㻭
Max. site VSWR : 4.4d B
4
3
2
1
0
1
2
3
4
Frequency [GHz]
5
6
Fig. 12 Measurement results of site VSWR (Receive antenna : LPDA)
On the other hand, when LPDA were used as the receive
antenna, the frequency characteristics of site VSWR changed
(see Fig. 12). In this results, the maximum site VSWR got at
the different frequency (4.50 GHz) and the different
polarization (vertical). Although LPDA has the widest 3 dB
beamwidths at the range from 1GHz to 6 GHz, the site VSWR
in the case of using LPDA is smaller than that in the case of
using DRGA 2 as shown in Fig. 9 and Fig. 11. The reason is
that the minimum value of the standing wave cannot be
accurately measured by LPDA because the antenna elements
of LPDA are distributed in the direction where the transmit
antenna is moved (see Fig. 13). Therefore, it is necessary to
pay attention enough when LPDA is used as the receive
antenna.
ACKNOWLEDGMENTS
This investigation was performed by VCCI Technical Subcommittee.
REFERENCES
[1]
[2]
[3]
Copyright © 2009 IEICE
456
CISPR 16-1-4 (Ed.2), “Radio disturbance and immunity measuring
apparatus – Ancillary equipment – Radiated disturbances,” Feb. 2005.
C. Miyazaki, K. Tanakajima, H, Muramatsu, J. Kawano,”Investigation
of Radiated Emissions Test Site Validation Method above 1 GHz,”
International Symposium on EMC, IEEE, Portland, USA, Aug. 2006.
Voluntary Control Council for Interference by Information Technology
Equipment (VCCI), “CISPR/A/602/CDV Investigation of site VSWR
method ~ Radiated emissions test site validation method from 1GHz to
18GHz
~,”
VCCI
Technical
report,
VCCI-VT026,
http://www.vcci.or.jp.