User manual

To achieve the most reliable possible link to the model , what we want to avoid are
situations in which the transmitter and receiver antennas are end-on
to each other. For the transmitter, the advice to the pilot is simple. A single receiver
antenna will inevitably be pointed at the transmitter some of the time and thus in
a relatively weak orientation for reception. This is where diversity comes in. If the receiver
has two active antennas positioned at right angles to each other, they can never both be
pointed at the transmitter simultaneously. The receiver just has to select the antenna that
is giving the better signal right now.
Diversity improves the reliability of the RF link in other ways. If the two receiver antennas
are well separated, at least one should have a clear view of the transmitter, minimizing the
risk of signal blanking by conductive materials on board the model. As well, with antennas
at right angles, one of them should be somewhere near parallel to the transmitter antenna,
thus roughly aligning polarization for a stronger signal. Conductive materials such as foil
coverings, batteries, metal components and carbon fiber can absorb and shield the
incoming radio signal. Radio systems on 2.4GHz have a very short wave length and are
susceptible to this. Receiver antennas need to be placed so that this effect is minimized.
In summary
What all this means for the installation of a receiver is simple.
If the receiver has dual diversity antennas, make sure the active tip portions are
separated as far as practical from each other and from conductive stuff like battery, wiring
and carbon fiber. 3 Align these portions so they are at right angles
to each other and reasonably straight. The coax cable portion of the antennas can
be curved to achieve this but must not be sharply bent.
If a satellite is connected, it should be well away from the main receiver, not right
next to it. Align it so the satellite antenna(s) and at least one main receiver
antenna are roughly at right angles.
Take all this seriously but don't get paranoid. The installation doesn't have to be
perfect to support an adequately strong RF link. Our modern receivers do a
remarkable job of picking up the signal, even with just a simple single antenna.
Diversity is not essential in most cases but can be thought of as extra security for
when the going gets tough.
And, as always, range testing is essential. It should be done very thoroughly
before the first flight of a new installation, with reception tested from all
directions by walking around the model. If control becomes erratic from any
direction at 25m range it’s time to review and improve the installation. Once the
setup is proven, a quick range check at 30 paces before the first flight of the day
is all that’s needed to check that things are working as they should.