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WiNRADiO G39DDC User’s Guide
15
Grounding
Grounding requirements and the following related comments do not
typically apply to antennas which do not require ground as a
counterpoise to the “live” terminal. For example, typical VHF/UHF
antennas such as discones or HF magnetic field loop antennas do not
require grounding of the receiver. In general, antennas with two output
terminals do not usually require that the receiver be grounded. However,
some of these antennas, such as dipoles or inverted "V" antennas, have
balanced outputs, and will require impedance matching to the WiNRADiO
receiver’s unbalanced 50 ohm input.
In all other cases, to obtain the maximum possible performance from your
receiver, you may also like to experiment with grounding. In some situations,
signal reception may be significantly enhanced with improved grounding.
Unfortunately, results are not always predictable due to variations in individual
installations, so some trial and error experiments may be required in the
search for the ultimate in performance.
With long-wire antennas, good grounding is absolutely essential. If you don't
apply any external additional grounding with the receiver, then you are relying
on grounding provided via the power supply or via the computer’s USB
interface. Such grounding may not be optimum as it may introduce noise to the
receiver’s input due to “ground loops”, where the useful signal is sharing the
ground path with undesirable interference.
A "good" ground for a receiver is one that provides a low impedance path to
ground for radio signals in the frequency range of interest. A metal cold water
pipe located in close proximity to a possible ground connection point could
provide good results. If no such point exists, a copper stake hammered into
the ground may be required. Copper earth stakes can be obtained from
electrical supply outlets.
Assuming a typical installation where the coaxial cable to the receiver enters
the building at some point, an opportunity may exist to make a connection
between the outer shield of the coaxial cable and the suitable ground point. In
order for the grounding to be effective, the connection between the ground
point and the coaxial cable outer should preferably be no more than a few
meters in length. A low impedance connection (such as braid removed from a
section of coaxial cable) should be used to make the connection.