Transmitting
 All
avalanche transceivers transmit on one antenna. However, the
Ortovox 3+ has a unique feature
wherein it selects which antenna it will transmit on
based on the transceiver's
physical orientation. This can potentially increase the range at which searcher
will receive the 3+'s signal.
The major benefit of multiple antennas occurs during searching as explained on this
page.
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| Steve Uncovers a Victim |
Single antenna transceivers typically have a long
range when the searching beacon is in-line with the transmitting beacon's
flux lines, but they have a significant loss
in range when the antenna's are not aligned. Single-antenna beacons cannot display
a directional indicator, although some
single-antenna beacons do display a distance
indicator.
Two-antenna transceivers have two antennas mounted perpendicularly. They compare
the relative strength of the signal that is received on each antenna to calculate the
location of the buried beacon. This allows the transceiver to guide you to the victim
by displaying a directional indicator.
Two-antenna beacons retain a strong signal even when they are turned 90°, because the
second antenna is then aligned with the transmitting beacon's
flux lines. Two-antenna transceivers, as with
single-antenna transceivers, are unable to resolve spikes.
Three-antennas transceivers have the advantages of two-antenna beacons (i.e., they
can display a directional indicator). They also have a tiny, vertically-mounted third
antenna which only turns on when you get near the victim. The third antenna greatly
reduces, or eliminates, spikes (where the beacon mistakenly
points to a location a meter or two from the victim).
More About Multiple Antenna Beacons
The Tracker DTS was the
first transceiver with two antennas. It quickly gained the reputation as the easiest
avalanche beacon—it certainly was. The DTS uses its two antennas to display a directional
indicator that points you toward your buried friend. Yes, some professionals discounted
the Tracker as being for novices, but ease-of-use is important when your best
friend is dying. The ARVA Advanced,
ARVA Evolution+, and the
Barryvox 3000 also have
two antennas and as with the Tracker DTS, these beacons will quickly lead you to the
victim. The Ortovox X1 also has
multiple antennas (either two or three), but in my testing it performed relatively poorly.
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The ARVA Evo3,
ARVA 3Axes,
Ortovox 3+,
Ortovox S1,
Mammut Pulse, Pieps
DSP, Pieps DSP Advanced,
and Tracker2 have three antennas.
These avalanche transceivers not only offer the directional and distance benefits of
two-antenna beacons, but they almost eliminate spike problems.
You won't notice the spike handling when searching for a beacon a few inches under
the snow (as is typical during practice), but bury it under a meter or two of snow and
the difference is significant. Three antennas on a searching beacon ensure that antennas
are pointed in three-dimensions (i.e., up/down, left/right, and forward/back). The beacon
can then use the relative strength of the signal on each antenna to precisely locate
the transmitting beacon. The
Ortovox Patroller,
Ortovox D3 and newer
Ortovox X1s also have three antennas,
but in my testing they did not accurately resolve spikes. The DSP (and probably others)
has a 4th antenna that is only used during its self test.
In my testing, having two-or-more antennas is the most important factor in performing
a rapid coarse search in a variety of conditions
with a variety of rescuers. And three-antennas greatly improve the
fine search in all but very shallow burials.
I know some old-timers will disagree, but only until they do serious tests with multi-antenna
transceivers. I was a hardcore Ortovox
F1 fan and swore that multiple antenna transceivers were for dummies—until I used
one and discovered the benefits. That isn't a sales pitch, rather it is based on
my experiences with many beacons.
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