ALYX ANTENNA GUIDE
CURTAIN ANTENNA FOR SHORTWAVE RADIO BROADCASTING


GENERAL DESCRIPTION


photo curtain antenna The curtain antenna is a dipole array, consisting of rows and columns of dipoles. The number of rows can be 1, 2, 3, 4 or 6; the number of columns is usually 2 or 4.

The curtain antenna is a high gain directional antenna, designed for medium and long range communications.

The dipoles are horizontally polarized and a reflector screen is placed behind the dipole array to provide a directive beam.

Curtain antennas are available in two sizes. A low-band array covers the 6, 7, 9 and 11 MHz bands and a high-band array covers the 11, 13, 15, 17 and 21 MHz bands (or 13-26 MHz bands).

The number of dipole columns defines the azimuth beamwidth. For a 2-wide dipole array, the beamwidth is around 50°, for a 4-wide dipole array around 30°. The main beam can be slewed by 15 or 30° so that a maximum coverage of 90° can be achieved.

The number of dipole rows and the height of the lowest element above ground determine the elevation angle and consequently the distance of the service area. A 2-row high array has a typical takeoff angle of 20° and is used for medium range communications, while a 4-row high array has a typical takeoff angle of 10° and is used for long range communications.

The curtain antenna is designed for connection to a 300 ohm balanced open wire feeder.

TYPICAL RADIATION PATTERNS
Azimuth pattern Elevation pattern
typical azimuth pattern curtain antenna typical elevation pattern curtain antenna


TYPICAL COVERAGE MAP
typical coverage map curtain antenna


TECHNICAL SPECIFICATIONS
ELECTRICAL
Azimuth pattern directional
Frequency ranges 6-26 MHz
Gain 12.5-22.5 dBi
Input impedance 300 ohm balanced
Polarization horizontal
Power ratings up to 500 kW carrier with 100% modulation
VSWR 1.5 : 1 or less
Specifications may change without notice

THIS TYPE OF ANTENNA IS AVAILABLE FROM
Manufacturer Type number Power Level
Antenna Products Corporation HR2/2/.4

H
HR2/4/.5

H
HR4/4/.5

H
Kintronic Laboratories, Inc. DCA Series
M H
TCI Model 611

H
Thomson Broadcast & Multimedia HR

H
Transradio SenderSysteme Berlin HR Series

H


ABBREVIATIONS

Abbreviation Explanation
Power Level L low 1-5 kW
M medium 10-50 kW
H high 100-500 kW