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The RLA4G is a cross loop receiving antenna for fixed outdoor installation. It operates broadband as a
non-tuned active antenna with an integrated amplifier. The power is supplied via the HF cable. The two
loops consist of coaxial cables for the symmetrical control of two differential current amplifiers with a low-
impedance input. The utilization of the latest components in the two amplifier branches guarantees very
low intrinsic noise values and high intermodulation resistance. The two reception loops are arranged at an
angle of 90° to one another. By adjusting the amplifiers, an electronic rotation of the receiving direction is
possible. The outer jacket of the antenna elements is grounded on the amplifier housing and shields the
actual loops (inner conductor) against interference radiation.
The amplifier is installed in a sealed aluminum housing. The HF currents of the antenna elements are lead
waterproof into the housing via RP-TNC coaxial connectors. The HF derivation to the RX takes place via a
sealed TNC housing bushing. The bottom of the housing has tabs with holes for screwing the antenna
onto flat construction elements (beams, straight roof surface, mast head with flat sheet metal or similar).
In addition to the HF connections of the amplifier, the antenna elements are also attached to a connection
housing (common ground point, HF voltage and current zero point). It is connected to the amplifier housing
via a connection rod. This means that all metal parts are at the same low-impedance potential and can be
grounded via the amplifier housing (lightning protection).
If lightning protection is not necessary (observe the relevant regulations!), grounding is not necessary to
operate the antenna. The connection to the receiver via the antenna cable is sufficient. However,
grounding can be useful to derive interference. On the other hand, it can also cause faults if the grounding
point is chosen unfavorably (e.g. equipotential bonding of the power supply, which often leads to high
interference currents).
So-called ground loops can occur if the antenna is (supposed to be) grounded (multiple, spatially spaced
ground connections, e.g. lightning rods and antenna cables), which can act as a reception loop. In this
case, further measures are necessary, such as choking the antenna cable (e.g. winding it onto a ferrite
toroid) or special grounding of the receiver end or the receiver. These measures are heavily dependent on
the environment and the additional wiring of your electronics and their necessity / effectiveness must be
determined empirically.
Power supply to the RLA4G is only possible via the HF cable ("remote power supply"). Any remote supply
device that can be looped into the antenna cable and that can supply the required voltages and currents
(see technical data) is suitable for this. The fed voltage's level can be modulated with a data signal in order
to electronically control the direction of reception (for example using control units RSW2 or RSW3, see
description of these devices).
The RLA4G must be assembled vertically with the connection housing facing up. Slight deviations from the
vertical are permitted. The reception diagram is then eight-shaped in the horizontal (bidirectional with 2
wide reception lobes and two sharp zeros). Without a control unit (remote supply with constant voltage),
the main reception direction is approximately transverse to the direction of the connection socket for the
antenna cable (the zeros are approximately in the axial direction of the socket).
This direction also corresponds to the 0° setting on the control unit. The RLA4G is not suitable for direction
finding. The absolute deviation of the setting compared to the actual reception direction can be several
10°s. The purpose of the electronic rotatability is the orientation towards maximum suppression of
interference signals, as well as the reception of useful signals, which are at the zero position for antennas
with a fixed reception direction without the possibility of rotation.
If the degree display on the control unit should approximately correspond to the actual cardinal direction
(max. reception or zero point), the antenna must be "northed" once during assembly.
VERSION
DATE
1.4
24.11.2021
Operator Manual
K & M Burkhard Reuter
NAME
RLA4G/GS
B. Reuter
4
8
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