Renkus-Heinz STXLA/9 - Manual (Page 8)

Line Array User’s Manual Line Array User’s Manual
ALL LA SYSTEMS
RH Engineering has developed an acoustic lens of the “path length refractor” type in order to change the output of a
horn/driver into a planar wavefront. A schematic of the HF section of a Renkus-Heinz Line Array Module looks like
this:
Renkus-Heinz line array modules use pattern control techniques that have been borrowed from microwave research.
Since microwaves have characteristics similiar to high frequency sound waves, these techniques are useful for
creating continuous HF wavefronts. The Path Length Equalization Technology used in this device has a significant
advantage over other techniques (such as reflectors and obstacle arrays). Reflectors and obstacle arrays operate
over a relatively narrow bandwidth: perhaps four octaves. This limitation is due to the transition from the “ray
model” (reflection) to the “wave model” (refraction and diffraction) that occurs as wavelengths become long in
relation to the reflector or the obstacles.
The path length refractor, however, can generate planar wavefronts over a wide operating band. When higher
frequencies pass through the device, it operates on the “ray model,” as illustrated below:
When the “wave model” takes over due to the longer wavelengths, the path length refractor lens functions as
closely spaced array of diffraction slots, as illustrated on the next page.
For maximum splay (i.e. 5° in “uptilt” position or 4° in “downtilt” position) align the middle hole on the Tie Bar with the
bottom hole on the receiving tube.
LANDING THE SYSTEM AND LOADING OUT
Carefully lower the array onto the dolly.
Align the front edge of the dolly (the one without a supporting ledge) and the front edge of the lowest module.
8 25