LAPLACE INSTRUMENTS LTD RF300 USER GUIDE
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LAPLACE INSTRUMENTS LTD
RF300 LARGE LOOP ANTENNA
USER GUIDE
Serial Number 9072
Issue 5 May 2010
LAPLACE INSTRUMENTS LTD RF300 USER GUIDE
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INDEX
Introduction 3
Packing list 3
Assembly 5
Calibration loop 12
Calibration 13
Operation 14
In use with the
EMCEngineer software 14
Appendix A...Calibration data 16
Appendix B… CISPR16 20
LAPLACE INSTRUMENTS LTD RF300 USER GUIDE
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Introduction
The RF300 large loop antenna has been developed to meet the requirements of
EN55015, section 9.9.1, which refers to CISPR16-1-4, section 4.6.1. This specifies the
limits for magnetic field induced current for luminaires with lamp operating
frequencies in excess of 100Hz.
Construction of the RF300 is as detailed in annex C of EN55016. This antenna is fully
compliant with the standard and details of the calibration factors are included in this
manual. These antenna factors should be added to the results to obtain correct
measurements that can be compared directly with the limits.
Test setup and limits should be conducted as required by EN55015, section 4.4.
Packing List
On receipt of the RF300, check the contents of the packages against the diagram shown
in fig 1.
Identify each component and check for shortages.
See also list overleaf.
Qty 4 Corner posts Qty 3 loops
Qty 4 Base extensions
Qty 3 Loop
transducers
Switch unit
with cable
Central pillar
Qty 4 Post stabilisers
Qty 8 long +
8 short wood
screws
Qty 5
tiewraps
10dB
attenuator
Qty 1 5m
cable
Qty 3
loop
leads
Qty 4 Corner posts Qty 3 loops
Qty 4 Base extensions
Qty 3 Loop
transducers
Switch unit
with cable
Central pillar Central pillar
Qty 4 Post stabilisers
Qty 8 long +
8 short wood
screws
Qty 5
tiewraps
10dB
attenuator
Qty 1 5m
cable
Qty 3
loop
leads
LAPLACE INSTRUMENTS LTD RF300 USER GUIDE
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Qty Item
3 Large loops fitted with connectors at each end
4 Corner posts
4 Base extensions
4 Post stabilisers
1 Central pillar
1 Switch unit
1 Short co-ax patch cable fitted with BNC connectors
3 Loop transducers
5 Tiewraps
8 1¾ x 8 wood screws
8 1” x 8 wood screws
1 5m BNC - BNC lead
3 2m BNC-BNC lead fitted with ferrite absorbers
1 10dB in-line BNC attenuator
LAPLACE INSTRUMENTS LTD RF300 USER GUIDE
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Assembly
1. Establish an appropriate area to erect the RF300. This needs to be a clear area at
least 4m square with a flat floor and a ceiling height of at least 3m.
2. In the centre of this area, stand the central pillar and fit the base extensions as shown
in fig 2.
Figure 2.
Base assembly.
Set centre and base
extensions
Figure 2.
Base assembly.
Set centre and base
extensions
3.Attach corner post stabilisers with 2 short brass screws as shown in fig 3a and then
slot the corner posts into the square hole at the end of each base. Secure each with the
long brass wood screws as shown in fig 3b.
Figure 3a
Screw post
stabilisers to
post bases
Figure 3a
Screw post
stabilisers to
post bases
Figure 3b
Secure posts to
base extensions
Figure 3b
Secure posts to
base extensions
LAPLACE INSTRUMENTS LTD RF300 USER GUIDE
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Figure 4
Loop assembly
Figure 4
Loop assembly
4. Prepare the 3 loops. The configuration of these loops is as shown in fig 4 and fig 5.
The connectors on each end of the loop are mated with the sockets either side of each
loop transducer. The retaining ring on each connector needs to be screwed firmly to the
socket but take care. These rings will bind and be difficult to turn unless the loop is
aligned properly. Force is not necessary, simple jiggle the loop into alignment and the
ring will turn easily.
Screw loops connectors into
transducer sockets. Do not
force, adjust alignment to ease
tightening
BNC outlet for cable to selector
unit
Figure 5
Loop transducer connection
Screw loops connectors into
transducer sockets. Do not
force, adjust alignment to ease
tightening
BNC outlet for cable to selector
unit
Figure 5
Loop transducer connection
LAPLACE INSTRUMENTS LTD RF300 USER GUIDE
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5. The first loop to mount is the horizontal loop. To mount the loops, at least two
people are required. Do not try to do this single handed....it will only end in tears.
Mount the loop in the recesses at the top of each corner post with the loop transducer
close to (within 5 cm) of a corner post. See fig 6.
Slight ‘drooping’ of the loop between the posts has no effect on the performance of the
antenna.
Rest horizontal loop
on top of posts
Position transducer
close to one post
Figure 6
Mounting of horizontal loop
Rest horizontal loop
on top of posts
Position transducer
close to one post
Figure 6
Mounting of horizontal loop
6. The second loop is now fitted. Figs 7, 8, 9 show the details.
This loop is fitted inside the first (horizontal) loop, orientated so that it fits in the lower
‘slot’ in the central pillar (fig 9) and is held between the ‘ears’ on the corner posts (fig
8). Arrange the loop so that the transducer is within 20 cm of the central pillar.
For the moment, the loop will sag and generally not hold its shape. This will be
resolved later.
LAPLACE INSTRUMENTS LTD RF300 USER GUIDE
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Install first vertical loop.
Note orientation of
central post. Position
transducer near bottom
Figure 7
Mounting of second
loop
Install first vertical loop.
Note orientation of
central post. Position
transducer near bottom
Figure 7
Mounting of second
loop
Figure 9
Central post configuration
Second loop
Third loop
Figure 9
Central post configuration
Second loop
Third loop
Add tywrap as
shown
Figure 8
Attachment of loops to
posts
Add tywrap as
shown
Figure 8
Attachment of loops to
posts
Add tywrap as
shown
Figure 8
Attachment of loops to
posts
LAPLACE INSTRUMENTS LTD RF300 USER GUIDE
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7. The final loop is now fitted INSIDE the other two. See fig 10.
This fits in the upper slot in the central pillar, between the corner post ‘ears’ and under
the other vertical loop at the top. Again arrange the loop so the transducer is close to
the central pillar.
Adjust loops to
optimum
configuration and
add tywrap at peak
Figure 10
Mounting of third loop
Adjust loops to
optimum
configuration and
add tywrap at peak
Figure 10
Mounting of third loop
LAPLACE INSTRUMENTS LTD RF300 USER GUIDE
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8. The loops can now be adjusted for best shape and position. Generally the vertical
loops will tend to sag into the lower half of the antenna. These are held up in position
by using the tiewraps as shown in fig 8 on each corner post to take some on the weight
of the loop. The top of the vertical loops can be adjusted for best shape and the two
loops fastened together with the fifth tiewrap. With care, the tiewraps can be adjusted
to produce reasonable circles for each loop.
Note that the exact shape is not critical. Deviation from perfect circles is inevitable but
this has no significant effect on antenna performance. EN55015 states in section 7.2
that even the position of the UUT in the antenna is not critical.
9. Within the loop, construct a wooden stand or table to suit the products to be tested.
This is not included with the RF300 because it needs to be matched to individual
customers requirements. The stand should hold the product roughly central within the
loop.
10. Connect the loop transducers to the switch unit as shown in fig 11. The 3
transducer cables are identified by having thick RF absorber filters along their length.
Fit the cables so that these filters are nearest to the switch unit.
The switch unit is intended for floor mounting, or may be mounted on a suitable table
if preferred. The short co-ax cable acts as a patch cable to switch each input, one at a
time, to the output.
The output from the switch unit is connected direct to the analyser or receiver.
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Figure 11
Connections to
selector unit
To analyser
Horiz
(X)
Vert
(Y)
Vert
(Z)
Loop transducers
Ferrite absorbers are
at this end of cables
Select loop
using link cable
Figure 11
Connections to
selector unit
To analyser
Horiz
(X)
Vert
(Y)
Vert
(Z)
Loop transducers
Ferrite absorbers are
at this end of cables
Select loop
using link cable
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Calibration loop
The RF300C calibration loop is manufactured to comply with CISPR16.
Full details of the use of this loop are provided in this standard.
LAPLACE INSTRUMENTS LTD RF300 USER GUIDE
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Calibration data
See appendix A
The calibration data for each loop is virtually identical. The following details therefore
apply to all three axes, although full data for each axis is given in the appendix.
For reference, the ‘ideal’ curve is shown in graph 1. This is taken directly from
EN55016, annex C, Figure C8.
The antenna factor data for the RF300 are also given.
This ‘antenna factor’ correction data effectively converts the output from the RF300
(measured in dBuV) directly to dBuA.
The data can be used with any analyser or receiver capable of EMC measurements.
The estimated measurement uncertainty is 3dB.
For a detailed explanation of the calibration of the RF300 and discussion of changes to
CISPR15 (EN55015) and CISPR16, see appendix B
If using the SA1002 or SA3000 analyser:
The RF300 is listed under the normal Inputs menu. Just select this device and the
software automatically applies the appropriate correction factors so that the trace reads
correctly in dBuA and can be compared directly with the EN55015 limits.
Further details are given overleaf.
LAPLACE INSTRUMENTS LTD RF300 USER GUIDE
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Operation
Details of the measurements and limits are given in EN55015, section 4.4. A copy of
this should be consulted if performing compliance tests.
The UUT should be mounted on a wooden frame or table in the centre of the antenna.
The position is not critical.
Connecting cables to the EUT should leave the volume enclosed by the loops in such a
way as to be kept away from the loops to avoid capacitive coupling. See Fig C6 in
CISPR16.
Each axis (loop) should be measured in turn. Each should meet the requirements of the
standard. The loops are individually selected by connecting the short patch lead to the
appropriate input socket as shown in fig 11.
Measurement with the SA1002 or SA3000 and EMCEngineer Windows software.
1. Select the RF300 item under the input menu. The vertical scale will indicate units
of dBuA. (If this item is not available, you need a later version of the software.
Contact your supplier)
2 Under the limits menu, select the EN55015 ......... 2m loop antenna limit line.
3. Connect the switch unit to the analyser input.
4. With the UUT switched off, check the background signal level. At frequencies
below 1MHz, the background can be very strong. If strong signals do exist, check that
the analyser is not in compression by changing the input attenuator setting on the
analyser and comparing scans. Apart from the base line, the traces should overlay. If
this happens then it is OK to use the analyser with that attenuator setting. If not,
increase the attenuation and try again.
5. If the background is strong, it is advisable to either find a ‘quieter’ location or screen
the room.
6. Switch the UUT on. Check the levels of signal over the background levels using the
techniques used for conventional radiated testing as described in the user guide.
The levels displayed are fully compensated for the RF300 characteristics and can be
compared directly with the limit lines.
7. ALWAYS check for compression (overload) when taking measurements. The
amplitude of the reading on the screen cannot be used directly as a guide for
compression because the readings have been adjusted for the RF300 characteristics.
If it is suspected that the signals are too strong even with the attenuator switched in,
install the 10dB attenuator in the input lead to the switch unit. This additional
LAPLACE INSTRUMENTS LTD RF300 USER GUIDE
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attenuator can be automatically compensated for in the software by adjusting the preamp settings on the screen.
8. If the background and the product is ‘quiet’, and especially at frequencies above
20MHz, use 0dB attenuation.
LAPLACE INSTRUMENTS LTD RF300 USER GUIDE
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APPENDIX A
CALIBRATION DATA
1. CISPR16 ‘ideal’ plot
2. Calibration data.
3. RF300 actual sensitivity plots and RF300 correction
plot (Antenna Factor)
LAPLACE INSTRUMENTS LTD RF300 USER GUIDE
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EN55015 Standard antenna response
CISPR16 LLA (2m diameter)
60
65
70
75
80
85
90
95
100
105
110
0.01 0.1 1 10 100
Freq (MHz)
Validation factor (dBohms)
LAPLACE INSTRUMENTS LTD RF300 USER GUIDE
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Calibration data
Calibration sources
Laplace Instruments Ltd, RF300C calibration loop to CISPR16, annex C5.
Laplace Instruments Ltd, SA1002 Spectrum analyser s/n 1010
Calibration: Laplace: 16.03.2009
Marconi TF2016A signal generator, s/n 118032/004
Calibration: Checked against Marconi TF2019A, s/n 118449-169
Advantest R4131D calibrated by Schaffner, 20.11.02 and checked against
Marconi TF2019A, s/n 118449-169
Marconi TF2019A, serial number 118449-169, calibrated by Industrial
Calibration Ltd, 22.06.07
Freq.
Calibration
Freq. EN
MHz 9072A 9072B 9072C MHz Average Max Min Range Freq 55015 Freq A.F
0.01 37.68 37.68 36.68 0.01 37.35 37.68 36.68 1.00 0.01 46 0.01 8.65
0.04 48.68 47.68 48.68 0.04 48.35 48.68 47.68 1.00 0.04 46.5 0.04 -1.85
0.10 55.68 55.68 55.68 0.10 55.68 55.68 55.68 0.00 0.10 46.5 0.10 -9.18
0.20 62.68 62.68 62.68 0.20 62.68 62.68 62.68 0.00 0.20 46.5 0.20 -16.18
0.50 69.68 69.68 69.68 0.50 69.68 69.68 69.68 0.00 0.50 46 0.50 -23.68
1.00 71.68 71.68 71.68 1.00 71.68 71.68 71.68 0.00 1.00 45.5 1.00 -26.18
2.50 71.68 71.68 71.68 2.50 71.68 71.68 71.68 0.00 2.50 44 2.50 -27.68
5.00 67.68 67.68 67.68 5.00 67.68 67.68 67.68 0.00 5.00 41 5.00 -26.68
10.00 62.68 62.68 62.68 10.00 62.68 62.68 62.68 0.00 10.00 37.5 10.00 -25.18
15.00 60.68 59.68 59.68 15.00 60.01 60.68 59.68 1.00 15.00 35 15.00 -25.01
20.00 55.68 55.68 55.68 20.00 55.68 55.68 55.68 0.00 20.00 32.5 20.00 -23.18
25.00 55.68 55.68 55.68 25.00 55.68 55.68 55.68 0.00 25.00 30.5 25.00 -25.18
30.00 52.68 52.68 53.68 30.00 53.01 53.68 52.68 1.00 30.00 28 30.00 -25.01
LAPLACE INSTRUMENTS LTD RF300 USER GUIDE
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Actual output plots for the loops
Output
Output RF300 s/n 9072
0
10
20
30
40
50
60
70
80
0 0 1 10 100
Frequency (MHz)
Output (dBuV)
Antenna factor
Antenna factor s/n 9072
-30
-25
-20
-15
-10
-5
0
5
10
15
0.01 0.10 1.00 10.00 100.00
Frequency (MHz)
Antenna factor (dB)
LAPLACE INSTRUMENTS LTD RF300 USER GUIDE
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Appendix B
Technical Report Laplace Instruments Ltd January 2010
RF300 Large loop antenna, an analysis of changes to the standards
These changes are due to the amendments to CISPR15 and CISPR16
The latest versions are now …..
CISPR15:2006 + A2:2009 and
CISPR16-1-4:2007 + A1:2008
The key changes related to LLAs are:
1. Sections related to the construction and specification of LLAs are moved from CISPR15 to
CISPR16. Note that in the new CISPR15, the requirements for the LLA are referred to Section
4.7.1 in the new CISPR16, which does not exist! It seems that the reference should be to Section
4.6.1. The same error is repeated in CISPR16 which again refers in Annex C to the non-existent
section 4.7.
2. The definition of the calibration data has been re-defined.
Note 1.
The details of the LLA were given in Annex B of CISPR15. These are now transferred to Annex C of
CISPR16. Most of the content has remained the same, but Table 1 summarises the changes.
Previous
CISPR15
New
CISPR16
Notes
Significant changes
Annex B Annex C Description, construction and
validation of LAS
Both annexes combined into one.
Annex C
Clause B1 Clause C1 Introduction Loop antenna named LAS (Loop
Antenna System
Clause B2 Clause C2 Construction of LAS Additional requirements for cables
and connectors.
Clause C3 Construction of loop Information previously included with
diagrams now included in text. Note
low R for inner conductor is required.
Clause B3 ----- Positioning of the LAS Requirement for minimum distance to
nearby objects,…… not included in
new CISPR16
Clause B4 Clause C4 Validation New definition for validation factor.
(see below).
Figure B1 Figure C1 General view None
Figure B2 Figure C2 Position of slits None
Figure C3 Construction of slits None
Figure C5 Metal box for current probe None
Figure B3 Figure C4 Example slit construction None
Figure B4 Figure C8 Validation factor Converted from dBuA to dB(Ω). See
below.
Figure C7 Positions of calibration loop None
Figure C9 Construction of calibration
loop
None
Figure C1 Figure C11 Sensitivity vs diameter None
Figure C2 Figure C10 Conversion factors between
loop current and magnetic
field strength at a distance.
Factors for magnetic field with
electric field added. Factors for
distance 30m removed.
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Note 2
CISPR15 gave the verification data as a plot of loop current in dBuA vs frequency for the standard test
signal (1V, open circuit voltage with a source impedance of 50ohm). This seems to be a straightforward
method, especially as the limits are quoted in dBuA, so it’s a direct correlation between the calibration
loop and the limits.
CISPR16 is essentially the same information, but presented differently. It specifies the relationship
between the source voltage (1V, as specified above) and the output current in the loop as measured by
the current probe. Note that the current probe has a transfer characteristic of 1V/A. The relationship
between volts and current is ohms, hence the use of dB(ohms) as the ‘validation factor’.
The result is therefore a conversion factor scaled in dB(Ω) to convert current to voltage,
CISPR16 defines the validation factor dB(Ω) = 20*log(Vs/Ii) where Vs is the source voltage and Ii is
the loop current.
Vs = 1V = 1,000,000uV
Under ‘old’ CISPR15, for Ii @ 100KHz = 46dBuA = 200uA
So the new CISPR16 value is 20*log(1000000/200) = 74 dB(Ω)
and
Old CISPR15 for Ii @ 30MHz = 29dBuA = 29uA
So the new CISPR16 value is 20*log(1000000/29) = 91 dB(Ω)
These calculations confirm the relationship between the CISPR15 plot and the CISPR16 validation
factor.
The plots in the standards assume a current probe with a 1V/A transfer function. Such probes are ‘active’
but provide a flat frequency response. The RF300 uses passive probes which have a non-flat frequency
response. This is not important if the probe is ‘inside’ the calibration loop and has a linear transfer
function with amplitude. These factors hold true for the probe that is used. So the RF300 antenna uses an
antenna factor correction to produce a calibration that agrees with the validation factor. This antenna
factor is supplied with each antenna, and is equivalent to the correction factors as supplied with all EMC
antennas, test cells, LISNs and other types of transducer.
Using the antenna factor data with the RF300 enables the output to be compared directly with the limits
as specified in EN55015.
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