Atec AHA118 User Manual

Features

Frequency Range – 1 to 18 GHz

Increased Sensitivity with a Built in Preamp

Two-year Warranty

Individual Calibration

Description

Active Horn Antenna

AHA-118

The model AHA-118 Active Horn Antenna is basi­cally the AH-118 Horn Antenna with an integrated
preamplifier. The preamplifier has a nominal gain of
20 dB for the entire frequency range. The preamplifier
improves the effective system noise performance for
emissions testing as explained below. The antenna
AH-118 is linearly polarized and has a frequency
range of 1-18 GHz.

This antenna is constructed using lightweight alumi­num with a corrosion resistant conductive coating.
The rear mounting plate of the AHA-118 has 1/4 inch
x 20 threads. These threads allow the antenna to be
mounted on a model AT-100 antenna tripod or any
tripod with similar mounting arrangement. The an­tenna is powered by an external DC supply, which is
shipped with it.

The output of the antenna is connected to the preampli­fier by a short low loss cable, which can be removed.
This arrangement makes it possible to (1) insert a filter
before the amplifier and (2) use the antenna alone for
transmission. The filter insertion capability is impor­tant and is required in presence of a high-level signal
(such as fundamental frequency), which possibly could
saturate the amplifier if the filter is not used. The
transmitted signal flow is in opposite direction and
uses a higher power level. Both conditions could
damage the preamplifier if not removed.

Each antenna is individually calibrated. The correc­tion factors and certificate of calibration is shipped
with the antenna. The data also includes separate
antenna factors and amplifier gain.

Application

This antenna is suitable for accurately receiving low
amplitude radiated emission signals. It is used during
EMC testing for various standards such as FCC part
15, CISPR, and FAA for EMC emissions.

For obtaining valid data during the test, it is impera­tive to maintain signal level above the noise floor. In
a typical setup, a receiving antenna is connected to a
preamplifier that is located next the spectrum ana­lyzer. The output of the preamplifier is then fed to the
spectrum analyzer. In this arrangement, since the
location of the preamplifier is far from the antenna,
the interconnecting cable is long. A combination of
factors such as a long cable, increasing cable loss
(especially for frequencies above 1 GHz), and high
antenna factors reduce the signal level to below the
noise floor of the preamplifier; and that produces
invalid readings. Boosting the signal at the antenna,
prior to its attenuation by long cables keeps it from
falling below the noise floor.

Com-Power Corporation (949) 587 - 9800 www. com-power.com [e-mail]

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Specifications

Frequency Range: 1 GHz - 18 GHz
VSWR: 2.0 :1
Polarization: Linear
Output Impedance: 50 Ohm
Connector types

Antenna output: N (f)
Preamplifier input: N (f)
Preamplifier output: N (f)

Power input: 18 VDC, 500 mA
Weight: 7 lbs. (3.1 kg)
Size: 10.2" X 9.5" X 5.6" (25.9 cm x 24.1 cm x 14.2 cm)

Mechanical outline

Antenna output to preamplifier input side view

Tripod
Mounting
Block

Preamplifier
Housing

Preamplifier input

Typical Antenna Factors

60.0

50.0

40.0

Antenna output

10.2"

Preamplifer output side view

Tripod
Mounting
Block

Preamplifier
Housing

Front View

9.5"

10.2"

Preamplifier output

5.6"

30.0

20.0

AH-118
AHA-118

10.0

Antenna Factors (dB/m)

0.0

-10.0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Freque ncy (MHz)

All values are typical values unless specified.
All specifactions are subject to change without notice.

Com-Power Corporation 20621 Pascal Way, Lake Forest, California 92630 (949) 587 - 9800 www.com-power.com Rev 1201

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