PRAXSYM PM-2458 User manual

PM-2458
2.4/5.3/5.8GHz Broadband
Wireless Power Meter
User’s Manual

Warranty concerns or claims should be pursued with the company from
which the product was purchased.
PRAXSYM warrants that all items will be free from defects in material and
workmanship under use as specified in this guide for a period of one year
from date of delivery. PRAXSYM further agrees to repair or replace, at its
discretion, any failure which upon PRAXSYM's inspection appears to be a
result of workmanship or material defect. In no case, shall PRAXSYM's li-
ability for breach of warranty exceed the purchase price of the items in
question. PRAXSYM's liability on any claim of any kind, for any loss con-
nected with, or resulting from the use of, performance or breach thereof,
installation, inspection, operation or use of any equipment furnished by
PRAXSYM, shall in no case exceed the purchase price of the goods which
give rise to the claim.
Illustrations by Mike Gorman, Prairie Wind Communications, Inc.
Phone: [phone] / Email: [email protected]
Copyright © 2004 Castle Rock Microwave, LLC
PM-2458
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PRAXSYM
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Tableof C ontents
Introduction to the PM-2458 1
Using the PM-2458 2
Measuring Transmitter Power 5
Measuring Transmission Line Loss 7
Measuring VSWR of Antenna and Terminations 9
Specifications 11
Appendix — VSWR Table 13
Appendix—Notes 15

PM-2458
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Introduction to the PM-2458
The PM-2458 is a handheld broadband power meter capable of detect-
ing forward and reflected power in a microwave radio system. The me-
ter is capable of detecting various types of wireless broadband modula-
tion schemes in the license exempt 2.4, 5.3, and 5.8GHz frequency
bands.
The meter was designed with the system integrator and installer in
mind. It is the perfect tool for the verification of transmitter power,
transmission line loss characteristics, and antenna performance.
Key features of the PM-2458:
-affordability
-portability
-tri-band use in the microwave bands (2.4, 5.3, and 5.8GHz)
-verification of system installation

Using the PM-2458
The PM-2458 ships with a durable nylon case that is secured with hook
and loop flaps. The package is designed such that the meter can be used
while still in the nylon case. The flaps that cover and protect the meter
can be secured behind the unit while it is in use. This is shown on the
front cover of this manual.
Packaged with the meter is a male-to-male type “N” adapter (in the left
pocket), a 50Ωtermination (right pocket), and a 2W 10dB attenuator (in
the pocket above the meter).
Most transmitters have a female type “N” connector on them. The double
male adapter can be used to connect the meter directly to the transmitter.
The meter should always have a 50Ωload on its output when connected
to a transmitter. Depending on the type of test, this can be an antenna or
the 50Ωtermination included in the kit. The 20dB attenuator is included
for use when the device under test transmits a signal higher than 20dBm
in amplitude. When using the 10dB attenuator it is a good idea to change
the offset to “+10” in the MODE settings (page 4). Note that the input to
the 2W 10dB attenuator should not exceed 33dBm (2W). If an attenuator
with a higher power rating is used, the input into the attenuator can be
increased such that the output of the attenuator does not exceed 20dBm.
The attenuator offset should be set for “+00” when no attenuator is used.
PRAXSYM
50Ωtermination
2W 10dB attenuator
Male-to-male adapter
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The meter should always be inserted into the system in the forward power
direction. Use the arrow labeled “FORWARD SIGNAL” as a guide when
connecting the meter.
Pressing and quickly releasing the ON-OFF button turns the meter on.
The meter will display “Below Range” if it is not connected to a source that
is within it’s dynamic range (0 to 20dBm).
Once the meter is connected to a source, and a 50Ωtermination is placed
on it’s output, the forward and reflected power can be measured. If the
meter is not properly terminated the forward power measurement may be
inaccurate.
If the signal applied to the meter exceeds 20dBm, the meter will read
“Exceed Range”.
VSWR is automatically calculated and displayed according to the forward
and reflected measurements. The accuracy of the VSWR measurement de-
pends on several variables (forward and reflected power levels, attenua-
tion in the transmission line, etc).
Button Description
ON-OFF: Turns the unit ON or OFF. Unit also powers down five min-
utes after last key depression. Powers up to the last state that it was
in.
SELECT: Used with MODE key to make selections.
MODE: First push - Displays remaining battery life.
Second push - Allows selection of the unit of power
(dBm or mW) on the display.
Third push - Allows selection of the frequency band of
interest (2.4, 5.3, or 5.8GHz).
Fourth push - Allows selection of the inline attenuator
offset (0dB, 10dB, 20dB, or30dB).
Fifth push - Exits MODE and returns to selected moni-
toring state (FWD or REFL.)
Depressing FWD or REFL also exits MODE at any time.
FWD: Displays forward power and VSWR. A right-pointing arrow in
PM-2458
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the upper right of the display indicates the meter is measuring forward
power. The power measurement is displayed continuously. The VSWR
is displayed for two seconds on the bottom display line and
then is replaced for one second by the band indi- cator (“2.4G,”
“5.3G,” or “5.8G”) and the in-line attenu- ator setting (“+00,” “+10,” “+20”,
or “+30”).
REFL: Similar in function to the FWD button, except it displays the reflected
power and shows a left-pointing arrow in the upper right of the display.
PRAXSYM
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Measuring Transmitter Power
The meter should be connected to the transmitter according to the
“FORWARD SIGNAL” label on the meter (see the illustration on the opposite
page). Depending on the gender of the type “N” connector on the transmit-
ter it may be necessary to use the double male type “N” adapter. The meter
should be terminated with the 50Ωload included in the kit.
Turn the PM-2458 on by pressing the ON-OFF button. Select the frequency
band of interest by pressing the MODE button until the frequency list is
shown. Use the SELECT button to scroll through, and select the appropriate
band. A small arrow should be displayed beside the band (2.4, 5.3, or 5.8).
Press the FWD button to read the forward power. A small right-pointing ar-
row will appear in the upper right side of the display. This is the amplitude
of the signal (in dBm or mW, depending on the unit selected in the MODE
menu) in the forward direction.
The meter is designed to detect signals between 0 and 20dBm in the for-
ward direction, and –20 to 17dBm in the reflected. Damage can occur to the
meter if the forward power into the meter (without the attenuator) exceeds
36dBm.
Most broadband radio transmitters deliver less than 100mW (20dBm). The
2W 10dB attenuator can be used for sources that are between 20 and
30dBm in amplitude. Remember to apply the appropriate offset in the
MODE setting (+10 if the attenuator included in the kit is used). If the out-
put of the transmitter exceeds 33dBm (2W), an attenuator of the appropri-
ate power rating and insertion loss should be used to lower the signal to a
level below 20dBm. Using the MODE button an offset can be configured for
attenuators up to 30dB. If an attenuator is not used, the offset should be set
to “+00”.
While the forward power is displayed constantly on the top line of the dis-
play, the bottom line alternates between the VSWR and the frequency band
and offset settings.
NOTE: A good way to verify proper operation of the 50Ωtermination
(included in the kit) is to make sure that the a VSWR of 1.2:1 is displayed
when the meter is connected according to the diagram on the opposite
page. If the VSWR is not 1.2:1 the termination should be replaced.
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PRAXSYM
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Measuring Transmission Line Loss
Measure the forward power of the transmitter as shown on the previous
pages. Use the 50Ωtermination included in the kit as the load. Make note of
the forward power reading.
Disconnect the meter from the transmitter. NOTE: The transmitter should
always be powered down when there is no load present, or when connect-
ing the meter or transmission line. Connect the transmission line directly to
the transmitter with the proper amount of attenuation (if necessary).
Move the PM-2458 to the opposite end of the transmission line. Connect the
meter as shown on the opposite page. Take another forward power read-
ing. Subtract this forward power reading from that taken directly off the
back of the transmitter. This is the amount of signal lost due to attenuation
in the transmission line and terminations.
This value can be compared to the loss specifications of the transmission line
and connectors to verify that the coax is properly terminated.
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PRAXSYM
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Measuring VSWR of Antenna and Termina-
tions
To measure the VSWR of an antenna, place the meter into the system be-
tween the transmission line and the antenna. Use the “FORWARD SIGNAL”
arrow on the meter to orient the meter properly. The arrow will point to-
wards the antenna when it is properly inserted. The double male type “N”
adapter can be used if the antenna has a female type “N” connector.
Apply power to the transmitting device. The meter will display the VSWR so
long as there is sufficient power reaching it (between 0 and 20dBm). In other
words, if the transmit power of the radio minus the transmission line loss is
less than 0dBm, the meter will read “Below Range”. Likewise, if for some rea-
son the power at the meter exceeds 20dBm it will display “Exceed Range”.
The best return loss* that the meter can read accurately in any of the bands is
roughly 20.8dB. This correlates to a VSWR of roughly 1.2:1. Most antenna
manufactures in the license-exempt broadband wireless market advertise a
VSWR of 1.5:1. Therefore, a defective or damaged antenna feed should be
pretty evident using the PM-2458 as they will indicate a VSWR higher than
1.5:1.
It is possible to measure the VSWR (or return loss) of a transmission line termi-
nation by placing the meter between it and the radio. It is necessary to prop-
erly terminate the far-end termination with the 50Ωtermination, and typically
a type “N” double female adapter (not included). These measurements are
often only accurate for the ‘local’ terminations, or the terminations that are
physically close to the meter. The two-way transmission line loss may mask
any reflections further down the transmission line or at the far-end termina-
tions (i.e. make the VSWR look better than it really is). The problem becomes
more pronounced as the two-way loss of the transmission line approaches
the dynamic range of the meter, which is 20dB. Therefore, it is best to have
as little transmission line loss as possible when attempting to measure return
loss or VSWR of a termination with the meter. A VSWR vs. return loss table is
included in the Appendix.
NOTE: Reflections are usually due to bad terminations, kinks in the transmis-
sion line, bend radii which are too tight, or moisture in the line or connectors.
*Return loss is simply the forward power minus the reflected power.
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PRAXSYM
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Electrical Specifications
Frequency Range: 2.4-2.4835 GHz, 5.150–5.350 GHz, 5.725–5.850 GHz
Forward Power Measurement Range:
0 dBm to 20 dBm (no in-line attenuation)
10 dBm to 30 dBm (10 dB inline attenuator)
20 dBm to 40 dBm (20 dB inline attenuator)
30 dBm to 50 dBm (30 dB inline attenuator)
Reflected Power Measurement Range:
-20 dBm to 17 dBm (no in-line attenuation)
-10 dBm to 27 dBm (10 dB inline attenuator)
0 dBm to 37 dBm (20 dB inline attenuator)
10 dBm to 47 dBm (30 dB inline attenuator)
Power Measurement Accuracy: +/- 0.5 dBm (with a 1.2:1 LOAD)
Insertion Loss: 0.4 dBm @ 2.4 GHz, 0.75 dBm @ 5.8 GHz
VSWR Measurement Range:
1.2:1 to 6.0:1 (2.4GHz)
1.2:1 to 6:0:1 (5.3GHz)
1.2:1 to 6.0:1 (5.8GHz)
Environmental Specifications
Temperature Range: -10 to 50 deg C
Humidity: 0 to 95% RH non-condensing
Altitude: 0 to 15,000 feet
Mechanical Specifications
RF Connectors: Type “N” female (input, output)
Display: 2 lines by 8 characters, LCD – not illuminated
Keypad: Five keys – see definition on page 3
Enclosure: Black ABS
PM-2458
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Mechanical Specifications (cont’d)
Power Source: 2 AA alkaline batteries – industrial grade
Size: 4.9 x 2.7 inches (exc. N connector)
Weight: 10 ounces
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PRAXSYM

VSWR
Return Loss
(dB)
Reflected
Power (%)
Transmiss.
Loss (dB)
1 oo 0 0
1.01 46.1 0.005 0.0002
1.02 40.1 0.01 0.0005
1.03 36.6 0.022 0.0011
1.04 34.1 0.04 0.0018
1.05 32.3 0.06 0.0028
1.06 30.7 0.082 0.0039
1.07 29.4 0.116 0.0051
1.08 28.3 0.144 0.0066
1.09 27.3 0.184 0.0083
1.1 26.4 0.228 0.01
1.11 25.6 0.276 0.0118
1.12 24.9 0.324 0.0139
1.13 24.3 0.375 0.016
1.14 23.7 0.426 0.0185
1.15 23.1 0.488 0.0205
1.16 22.6 0.55 0.0235
1.17 22.1 0.615 0.026
1.18 21.6 0.682 0.0285
1.19 21.2 0.75 0.0318
1.2 20.8 0.816 0.0353
1.21 20.4 0.9 0.0391
1.22 20.1 0.98 0.0426
1.23 19.7 1.08 0.0455
1.24 19.4 1.15 0.049
1.25 19.1 1.23 0.053
1.26 18.8 1.34 0.056
1.27 18.5 1.43 0.06
1.28 18.2 1.52 0.064
1.29 17.9 1.62 0.068
1.3 17.68 1.71 0.073
1.31 17.4 1.81 0.078
1.32 17.2 1.91 0.083
1.33 17 2.02 0.087
1.34 16.8 2.13 0.092
1.35 16.53 2.23 0.096
1.36 16.3 2.33 0.101
1.37 16.1 2.44 0.106
PM-2458
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Appendix—VSWR Table

VSWR
Return Loss
(dB)
Reflected
Power (%)
Transmiss.
Loss (dB)
1.38 15.9 2.55 0.112
1.39 15.7 2.67 0.118
1.4 15.55 2.78 0.122
1.41 15.38 2.9 0.126
1.42 15.2 3.03 0.132
1.43 15.03 3.14 0.137
1.44 14.88 3.28 0.142
1.45 14.7 3.38 0.147
1.46 14.6 3.5 0.152
1.47 14.45 3.62 0.157
1.48 14.3 3.74 0.164
1.49 14.16 3.87 0.172
1.5 14 4 0.18
1.55 13.3 4.8 0.21
1.6 12.6 5.5 0.24
1.65 12.2 6.2 0.27
1.7 11.7 6.8 0.31
1.75 11.3 7.4 0.34
1.8 10.9 8.2 0.37
1.85 10.5 8.9 0.4
1.9 10.2 9.6 0.44
1.95 9.8 10.2 0.47
2 9.5 11 0.5
2.1 9 12.4 0.57
2.2 8.6 13.8 0.65
2.3 8.2 15.3 0.73
2.4 7.7 16.6 0.8
2.5 7.3 18 0.88
2.6 7 19.5 0.95
2.7 6.7 20.8 1.03
2.8 6.5 22.3 1.1
2.9 6.2 23.7 1.17
3 6 24.9 1.25
3.5 5.1 31 1.61
4 4.4 36 1.93
4.5 3.9 40.6 2.27
5 3.5 44.4 2.56
6 2.9 50.8 3.08
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PM-2458
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Notes

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PRAXSYM
Notes

Version 052405
PRAXSYM