A.H. Systems SAS-512-2 User manual

A.H. Systems SAS-512-2 Log Periodic Antenna
SAS-512-2
Log Periodic Antenna
Operation Manual
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A.H. Systems SAS-512-2 Log Periodic Antenna
TABLE OF CONTENTS
INTRODUCTION
Introduction ............................................................................................................. 3
Intended Purposes...................................................................................................
Optional Equipment.................................................................................................5
OPERATING INSTRUCTIONS
Assembly Instructions .............................................................................................6
Mounting Instructions...............................................................................................6
Operating Instructions..............................................................................................8
SPECIFICATIONS
Specifications .......................................................................................................... 9
Typical Data...........................................................................................................10
Calculations...........................................................................................................11
Convertion Factors.................................................................................................12
MAINTENANCE
Maintenance Procedures ......................................................................................13
Annual Calibration..................................................................................................13
Warranty................................................................................................................ 1
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A.H. Systems SAS-512-2 Log Periodic Antenna
INTRODUCTION
The SAS-512-2 Log Periodic Antenna (also known as a log periodic dipole array) is a
compact, lightweight antenna that has been designed to ensure maximum gain, low
VSWR and high power handling capabilities. This compact design is an ideal solution for
EMC testing where the reduced size of the antenna is preferred to minimize chamber wall
coupling and increasing the half power beamwidth to a more acceptable angle that will
cover the whole device under test. Constructed of lightweight aluminum, the SAS-512-2
Log Periodic Antenna has been manufactured to operate over a very wide bandwidth.
Weighing in at just 1.5 pounds this Log Periodic Antenna is one of the lightest antennas
commercially available.
The SAS-512-2 Log Periodic Antenna is the standard workhorse of any EMC compliance
test house. The SAS-512-2 has an excellent Front to back ratio and cross-polarization
properties that is required per CISPR 16-1 that greatly reduces measurement uncertainty.
This Linearly polarized antenna is an ideal solution for radiated emissions and normalized
site attenuation.
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A.H. Systems SAS-512-2 Log Periodic Antenna
INTENDED PURPOSES
The log periodic antenna is intended for general laboratory use in a wide variety
of industrial and scientific applications and has been designed to be used in the
process of generating, controlling and measuring high levels of electromagnetic
Radio Frequency (RF) energy. It is the responsibility of the user to assure that
the device is operated in a location which will control the radiated energy such
that it will not cause injury and will not violate regulatory levels of
electromagnetic interference.
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A.H. Systems SAS-512-2 Log Periodic Antenna
OPTIONAL EQUIPMENT
The following is a recommend accessory list for the SAS-512-2 Log Periodic
Antenna:
CONNECTING ACCESSORIES:
PAM-0202
This preamplifier has a broad frequency range and at least 30 dB of gain. An
ideal solution for improving overall system sensitivity for various emissions
testing requirements.
SAC-211
Standard N(m) to N(m) RF cable made with RG-21 /U and optional ferrite
loading that can be made to your specified length. Other cable types available
upon request.
Adapters
Need an Adapter? We stock those as well.
MOUNTING ACCESSORIES:
AEH-510
Azimuth and elevation head to assist the test engineer in orientating biconical
antenna at the device under test.
ATU-510
Each tripod leg is independently adjustable in angle and length to facilitate
antenna height setting. The tripod legs have a rubber tip on one end for indoor
or hard surface use, and a metal spike on the other end for outdoor soft surface
(such as dirt) use.
LPM-510
The optional Log Periodic Tripod mount (LPM-510) mounts the antenna near
the CG of the antenna.
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A.H. Systems SAS-512-2 Log Periodic Antenna
OPERATING INSTRUCTIONS
ASSEMBLY INSTRUCTIONS
The SAS-512-2 Log Periodic Antenna is shipped fully assembled. If an optional
Log Periodic Tripod mount (LPM-510) was purchased, that will also be pre-
assembled and mounted to the antenna.
MOUNTING INSTRUCTIONS
The SAS-512-2 is a lightweight, rear mount Log Periodic Antenna. Attach the
antenna to the azimuth and elevation head (AEH-510) through the screw hole in
the antenna base. The azimuth and elevation head (AEH-510) mounts to the
tripod (ATU-510) top and allows the antennas to be rotated 360 degrees and
tilted between horizontal and vertical polarization. Each tripod leg is
independently adjustable in angle and length to facilitate antenna height setting.
The tripod legs have a rubber tip on one end for indoor or hard surface use, and
a metal spike on the other end for outdoor soft surface (such as dirt) use.
Four extra holes are pre-drilled into the booms (at the approximate CG point) of
the antenna for an optional Log Periodic Mount (LPM-510). This allows an
optional center mount of the antenna where applications require it.
Mount the antenna such that the elements are parallel to the ground for
horizontal polarization testing, or perpendicular to the ground for vertical testing.
The horizontal beamwidth of the log periodic is approximately 5 degrees and it
should be pointed or aimed in the direction that the received signal is coming
from.
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A.H. Systems SAS-512-2 Log Periodic Antenna
EMISSIONS TESTING MEASUREMENT POINT:
For 3 and 10 meter testing, the measurement is made from the center of the
antenna radiating elements and is annotated by a measurement point sticker
(per ANSI C63.5).
IMMUNITY TESTING MEASUREMENT POINT:
Measurement is made from the tip of the antenna and typically preformed at a 1
meter distance. (3 meters per IEC 61000- -3)
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A.H. Systems SAS-512-2 Log Periodic Antenna
OPERATING INSTRUCTIONS
Once the antenna is mounted to a mast or tripod, connect an N-type coaxial
cable from the antenna to a receiver or RF generator. The cable should be
matched to 50 ohms, relatively low loss and adequately shielded against
leakage such as RG-21 /U or better. For certain applications where an
increased dynamic range is required, an optional preamplifier (PAM-0202) may
be used to increase the total system sensitivity.
The Log Periodic Antenna is in the horizontal polarization when the antenna
elements are parallel to the ground, and vertical polarization when the elements
are perpendicular to the ground.
To minimize impedance mismatch errors, it is recommended that high-quality
in-line attenuators be used to reduce reflections. Connect the attenuator at the
antenna end of the transmitting cable, or when receiving connect the attenuator
at the measuring instrument or preamplifier input.
Dress the cables straight back from the antenna connector at least 1 meter
before being dressed vertically down to the ground plane. Signal cables that
are dressed orthogonal to the antenna elements will have minimal coupling to
the antenna field, but the cable shields may carry external currents caused by
impedance imperfections. Also, portions of the cables that are not straight down
or straight back will couple to the antenna fields.
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A.H. Systems SAS-512-2 Log Periodic Antenna
SPECIFICATIONS
ELECTRICAL SPECIFICATIONS
Frequency Range .........................................................................190 Mhz – 2 GHz
Antenna Factor....................................................................................11 to 30 dB/m
Antenna Gain..................................................................................................6.5 dBi
Maximum Continuous Power...................................................................1000 Watts
Average Beamwidth............................................................................................. 5°
Average Beamwidth (H-Field)............................................................................100°
Impedance (nominal)..........................................................................................50W
Average VSWR........................................................................1.62:1 typ. 2.6:1 max
Maximum Radiated Field..............................................................................200 V/m
Connector........................................................................................N-Type (female)
Mounting............................................................................................1/ -20 (female)
PHYSICAL SPECIFICATIONS
Weight ...........................................................................................................2.2 lbs.
(1 kg)
Size (L x W x H)...........................................................................33.3" x 29.5" x 2.5"
(84.6cm x 74.9cm x 6.3cm)
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A.H. Systems SAS-512-2 Log Periodic Antenna
TYPICAL DATA
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A.H. Systems SAS-512-2 Log Periodic Antenna
CALCULATIONS
EMISSIONS TESTING
Individual calibration data for the log periodic antenna is supplied at
appropriate distances (3, and 10 meter) to comply with various emissions test
requirements. For emissions measurements, add antenna factor plus cable
loss to receiver reading in dBV to convert to field strength in dBV/meter.
F eld Strength(dBuV/m) = SA(dBuV) + AF(dB/m) + cable loss (dB)
SA = Spectrum Analyzer or Receiver voltage reading
AF = Antenna Correction Factor
CL = Cable Loss in dB
IMMUNITY TESTING
For Immunity measurements, the generated electric field strength can be
calculated by:
FS = Approximate Field Strength in (V/m)
P = Power in watts
g = Numeric Gain
d = Distance in meters
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A.H. Systems SAS-512-2 Log Periodic Antenna
TYPICAL CONVERSION FORMULAS
LOG -> LINEAR VOLTAGE FIELD STRENGTH & POWER DENSITY
dBV to Volts V = 10 ((dBV – 120) / 20) dBV/m to V/m V/m = 10 (((dBV/m) -120) / 20)
Volts to dBV dBV = 20 log(V) + 120 V/m to dBV/m dBV/m = 20 log(V/m) + 120
dBV to Volts V = 10 (dBV / 20) dBV/m to dBmW/m2dBmW/m2 = dBV/m – 115.8
Volts to dBV dBV = 20log(V) dBmW/m2 to dBV/m dBV/m = dBmW/m2 + 115.8
dBV to dBV dBV = dBV +120 dBV/m to dBA/m dBA/m = dBV/m – 51.5
dBV to dBV dBV = dBV - 120 dBA/m to dBV/m dBV/m = dBA + 51.5
LOG -> LINEAR CURRENT dBA/m to dBpT DBpT = dBA/m + 2
dBA to uA A = 10 (dBA / 20) dBpT to dBA/m dBA/m = dBpT – 2
A to dBA dBA = 20 log(A) W/m2 to V/m V/m = SQRT(W/m2 * 377)
dBA to A A = 10 (dBA / 20) V/m to W/m2W/m2 = (V/m)2 / 377
A to dBA dBA = 20log(A) T to A/m A/m = T / 1.25
dBA to dBA dBA = dBA + 120 A/m to TT = 1.25 * A/m
dBA to dBA dBA = dBA -120 E-FIELD ANTENNAS
LOG -> LINEAR POWER Correction Factor dBV/m = dBV + AF
dBm to Watts W = 10((dBm – 30)/10) Field Strength V/m = 30 * watts * Gain numeric
meters
Watts to dBm dBm = 10log(W) + 30 Required Power Watts = (V/m * meters)2
30 * Gain numeric
dBW to Watts W = 10(dBW / 10) LOOP ANTENNAS
Watts to dBW dBW = 10log(W) Correction Factors dBA/m = dBV + AF
dBW to dBm dBm = dBW + 30 Assumed E-field for
shielded loops
dBV/m = dBA/m + 51.5
dBm to dBW dBW = dBm - 30 dBpT = dBV + dBpT/V
TERM CONVERSIONS
dBm to dBVdBV = dBm + 107 (50)
dB  V = dBm + 10log(Z) + 90
CURRENT PROBES
dBV to dBm dBm = dBV – 107 (50)
dBm = dB  V – 10log(Z) – 90
Correction Factor dBA = dBV – dB(ohm)
dBm to dBA dBA = dBm – 73 (50)
dB  A = dBm – 10log(Z) + 90
Power needed for injection probe given voltage(V) into
50 load and Probe Insertion Loss (IL)
dBA to dBm dBm = dBA + 73 (50)
dBm = dB  A + 10log(Z) – 90
Watts = 10 ((IL + 10log(V2/50))/10)
dBA to dBV dBV = dBA + 3 (50)
dB  V = dB  A + 20log(Z)
dBV to dBA dBA = dBV – 3 (50)
dB  A = dB  V – 20log(Z)
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A.H. Systems SAS-512-2 Log Periodic Antenna
MAINTENANCE
MAINTENANCE PROCEDURES
Proper antenna maintenance should include:
Visual inspection of RF connectors
Check for bent and loose elements
Check for loose or missing hardware
Corrosion near the element joints
At least once a month it is a good idea to wipe down the antenna with a damp
rag.
ANNUAL CALIBRATION
To ensure reliable and repeatable long-term performance, annual re-calibration
of your antennas, preamplifiers and current probes by A.H. Systems
experienced technicians is recommended. Our staff can calibrate almost any
type or brand of antenna.
It is always up to the user to determine the appropriate interval for calibration
certification based on the requirements of the end users specific
test/application. The calibration of EMC antennas is important for those
conforming to compatibility standard. Radiated emissions testing for
electromagnetic compatibility (EMC) requires the measurement of electric field
(E-field) strength, which is compared with a limit level. The output voltage of an
antenna is converted to E-field strength via its antenna factor, the measurement
of which must include the uncertainty components related to that particular
antenna, taking into consideration the environment in which the antenna is to be
used for the testing. Most standards will specify the appropriate interval for re-
calibration of your EMC antenna.
In some cases these antennas are used for a manufacturers pre-compliance
testing, field monitoring, surveillance and/or other applications where the exact
field intensity of the received signal is not of importance. For those customers a
yearly re-calibration is not necessary, however it is recommended that an
interval for maintenance be performed.
For more information about our calibration services or to place an order for
antenna calibration visit our website at http://www.AHSystems.com
or call 1(818) 998-0223.
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A.H. Systems SAS-512-2 Log Periodic Antenna
WARRANTY INFORMATION
A.H. Systems Inc., warrants that our Antennas, Sensors and Probes will be free from
defects in materials and workmanship for a period of three (3) years. All other products
delivered under contract will be warranted for a period of two (2) years. Damage caused
by excessive signals at the product's input is not covered under the warranty. A.H.
Systems' obligation under this warranty shall be limited to repairing or replacing, F.O.B.
Chatsworth, California, each part of the product which is defective, provided that the
buyer gives A.H. Systems notice of such defect within the warranty period commencing
with the delivery of the product by A.H. Systems.
The remedy set forth herein shall be the only remedy available to the buyer, and in no
event shall A.H. Systems be liable for direct, indirect, incidental or consequential
damages.
This warranty shall not apply to any part of the product which, without fault of A.H.
Systems has been subject to alteration, failure caused by a part not supplied by A.H.
Systems, accident, fire or other casualty, negligence, misuse or normal wear of
materials.
Except for the warranty set forth above, there are no other warranties, expressed or
implied, with respect to the condition of the product or it's suitability for the use intended
for them by the buyer.
For prompt service, please contact our service department for a Return Material
Authorization Number before shipping equipment back to us.
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