Loop design
As a rule, an induction loop as a rectangle encloses the area to be supplied. Generally, the loop is laid on the floor. Depending on room size, room geometry and other environmental and/or general conditions, special loop designs and loop amplifiers are required.
Basically, loop systems can be divided into two types: Perimeter loops and phased arrays.
The perimeter loop
A perimeter loop is not very complex, is easy and inexpensive to install, and requires only one amplifier channel to operate.
Perimeter loops are particularly suitable in rooms where there is
- no metal structure,
- no other inductive hearing system is operated in the vicinity and
- confidentiality is not a necessity.
In large perimeter loops, the level response varies significantly: the level decreases significantly from the edge to the center. Once metal structures are present, the metal losses drastically reduce the field strength in the middle of the loop.
A larger perimeter loop can therefore only be used if no metal structure is present. Otherwise, a perimeter loop can only be reasonably used in small spaces.
Furthermore, there are variations of the perimeter loop in which several loops of this type are combined. This form is usually referred to as an eight, figure 8 or single array. The advantage of this is that the subdivision into smaller areas reduces the required loop current and metal losses are better compensated. Its disadvantage: In the area of the parallel conductors, no usable magnetic field is available for the listener.
Another special form is the stop loop, also called cancellation loop. Here, a small loop segment limits the magnetic crosstalk in one direction. The design of this requires careful planning and the use of a simulation program is recommended in this context.
The Phased Array
The phased array is a combination of two overlapping loops driven by two amplifier channels. One amplifier channel is driven with a 90° phase shift. Phased arrays can homogeneously supply large areas even if a metal structure is present.
With a special design, phased arrays can greatly limit magnetic crosstalk in the horizontal plane.
For the design, careful planning and the use of a simulation program is necessary.
AUDIOropa Pro Loop inductive loop amplifiers
AUDIOropa’s portfolio of Pro Loop loop amplifiers provides a wide range of devices for almost any application.
The range includes single-channel loop amplifiers for perimeter loops in the power class from 2 A to 15 A. For phased arrays, two-channel loop amplifiers are available in the power class from 5 to 15 A.
The amplifiers prove to be reliable, robust, durable and offer an all-round convincing audio quality. A convenient operating concept allows users to tap into the full flexibility that these systems offer in terms of adaptation to the respective room and application conditions.
