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Atec EMCO-3101-02-03 User Manual

Conical log spiral

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M O D E L 3 1 0 1

Model 3101

200 MHz – 1 GHz

Model 3102

1 GHz – 10 GHz

Model 3103

100 MHz – 1 GHz

EMCO’S BROADBAND CONICAL LOG SPIRAL ANTENNAS

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minimal pattern change over their wide operating frequency
range of 100 MHz to 10 GHz. All antennas in this series have
moderate gain and low VSWR. Three models offer you a choice
in size, frequency range, and polarization.

Once used exclusively for MIL-STD and SAE testing, conical
log spiral antennas are effective for other types of measure-
ments too. For example they can be used for close-in “quick-
looks” to find the spectral characteristics of RF emissions. For
immunity testing , conical log spirals generate reasonable field
strengths with modest power input. By placing conical log
spiral antennas in a vertical position with respect to the ground
plane, they also can be used as omni-directional, horizontally
polarized antennas for electromagnetic site surveys.

EMCO Conical Log Spiral Antenna Features

Circular or Linear Polarization

EMCO’s conical log spiral antennas will receive both circular
polarized and linear polarized fields (with a 3 dB variance for
linear fields) under normal operating conditions.

Low VSWR

Average VSWR for the Model 3101 is 2.4:1. The Model 3102
averages a 1.6:1 VSWR and the Model 3103 averages
1.9:1 VSWR.

Compact Size

The compact size of EMCO’s conical log spiral antennas makes
them ideal for use in anechoic chambers and shielded
enclosures where space is limited and proximity effects must
be minimized.

Quality Construction

EMCO’s conical log spiral antennas are made with spiral
windings of coaxial cable attached to the outside of a fiberglass
cone. Outside windings improve heat dissipation. This cone is
attached to a delrin rod equipped with an aluminum base. The
antenna mounting base accepts standard 1/4 in x 20 threads
from an EMCO tripod or most other tripods.

Choosing Your Model: Three Models
with Frequency Ranges of 100 MHz to 10 GHz

100 MHz to 1 GHz

The Model 3103 conical log spiral antenna is similar to Models
3101 and 3102 except that it has the lowest frequency range
and it is largest in size. Length is 102.0 cm (40 in) diameter is
66.0 cm (26.0 in). The design is patterned on NASA drawings.

200 MHz to 1 GHz

The Model 3101 conical log spiral antenna was designed by
the Department of Defense for MIL-STD-461E measurements.
The original drawings provide the basis for our Model 3101.
Length is 81.3 cm (32.0 in) and diameter is 33.0 cm (13.0 in).

1 to 10 GHz

The Model 3102 conical log spiral antenna is similar to the
Model 3101 but has a higher frequency range and is smaller in
size. Length is 38.1 cm (15 in) and diameter is 12.7 cm (5.0 in).

Circular Polarization

Extremely Low VSWR

Compact Size

Unique Applications

Quality Construction

Conical Log Spiral