photo Ampegon Antenna Systems HR When sectional coverage is desired, directional antennas are the proper choice. Curtain antennas provide not only high antenna efficiency, but also highest tolerances when faced with unfavorable environmental conditions.

As per ITU Regulations, a special alphanumeric code is used to describe curtain antennas. In its most general form, the antenna is denoted by AHRS m/n/h, whereby:

A aperiodic

H horizontal polarisation of the antenna

R existence of a reflector screen

S the possibility of beam slewing

m number of half-wave elements in a horizontal row (typical range 2, 4 or 6)

n the number of dipoles stacked vertically in horizontal rows (typical range 2, 4 or 6)

h height of the lowest dipole above ground in wavelengths of the bottom row of dipoles (typical range 0.25 - 1.0)

State of the art design allows curtains to be operated over the frequency range of one octave, covering up to six adjacent frequency bands out of the shortwave broadcasting spectrum as defined by WARC.


photo Ampegon Antenna Systems HR Fixed curtains consist of half-wave, folded, open and multiple wire cage dipoles. The dipole feeding system is based on broadband design, which means dipoles are switched in parallel to subgroups. These subgroups are switched in parallel to subsystems, until the common feed point (input of the slewing switch) is reached.

Dipoles and their feeding system as well as the reflector screen are suspended to towers or masts in such a way that they can be lowered separately for maintenance.

A counterweight system is fixed directly to ground at one end, and at the other end, fixed to ground by a follow-up mechanism. This counterweight system makes sure that strong winds cannot damage the dipoles, the feeding system or the reflector screen.

Curtains may be arranged back-to-back or side-by-side and may be suspended individually or cellectively between suitably dimensioned guyed or self-supported towers.

In case a large range of azimuth needs to be covered with radio signals, the curtains may be installed in either a star or a polygon shape.



photo Ampegon Antenna Systems HR The Rigid Dipole Technology combines design principles as implemented in rotatable shortwave antennas with the advantages of curtain antennas. The resulting integrated system consists of rigid dipoles and a self supporting structure with central shaft.

The components of the rigid "curtain" antenna are easily accessible. The system maintainability is greatly simplified due to the fact that there are no moving parts like halyards, steel ropes, counterweights etc.


Antenna Type Range (in km) Frequency Range Radiation Pattern Typical Gain (dBi)
Up to 1300 1000 to 4000 2000 to 6000 3000 to 8000
AHR(S) 2/2/h
(Fixed Curtain)


up to six adjacent frequency bands directional 14 - 16
AHR(S) 4/2/h
(Fixed Curtain)

up to six adjacent frequency bands directional 15 - 21
AHR(S) 4/4/h
(Fixed Curtain)

X up to six adjacent frequency bands directional 18 - 24
The height (h) is according specific performance requirements.
The stated range is assuming single-hop transmission and can be seen as a rough guideline for design purposes. In any case the range is dependent on specific ionospheric propagation conditions.
Specifications may change without notice