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Antennas

Konrad Roeder edited this page Sep 3, 2022 · 3 revisions

This section focuses on mobile antennas for the LoRa APRS Tracker

image Photo courtesy Klaus Kitzmantel, OE5KKP DL9KX

Technical terms

Polarization

LoRa APRS uses vertical polarization exclusively. Vertical antennas are the best way to get an omni-directional pattern. They're vertically polarized. Yagi antennas are very directional, meaning they can produce gain in a certain direction. They're generally horizontally polarized. There are large signal losses when the polarization of the transmit antenna and the receive antenna don't match. It does not make sense for mobile units to transmit horizontal polarization. Therefore iGates and Trackers have pretty much standardized on using vertical polarization

Antenna gain

dBi - Gain over isotropic, a point source

SWR

Standing wave ratio

Antenna mounts

Magnetic

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Trunk lip

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Fender bracket or through roof

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Antennas

More height means more gain

5/8 wave or taller

Low-cost 1/4 wave

Rubber ducky

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