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Updated Antennas (markdown)

Konrad Roeder 2022-09-03 18:00:02 +00:00
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Antennas.md

@ -7,18 +7,25 @@ Photo courtesy Klaus Kitzmantel, OE5KKP DL9KX
## 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
## Antenna gain
dBi - Gain over isotropic, a point source
##SWR
## SWR
Standing wave ratio
# Antenna mounts
## Magnetic
![image](https://user-images.githubusercontent.com/3480859/188282326-2c194436-3a0c-4c41-87c6-98ec59d1d144.png)
![image](https://user-images.githubusercontent.com/3480859/188282391-62f4bb0f-df4a-4e58-a46d-758b992156c7.png)
## Trunk lip
![image](https://user-images.githubusercontent.com/3480859/188282459-aa4df731-5ea5-42ea-8ea0-af2b8ff60224.png)
![image](https://user-images.githubusercontent.com/3480859/188282504-31a925dd-6308-4269-9b3c-75147a08a32b.png)
## Fender bracket or through roof
![image](https://user-images.githubusercontent.com/3480859/188282571-8df790eb-81cf-4c56-9b48-7cc857874a3b.png)
# Antennas
More height means more gain
@ -28,6 +35,8 @@ More height means more gain
## Low-cost 1/4 wave
## Rubber ducky
![image](https://user-images.githubusercontent.com/3480859/188282669-dbee7e16-7b79-4bdc-be57-e47d1ecfbb12.png)