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900mhz antenna

aiidanwings

Senior Member
#1
I'm using the HK 900mhz fpv system. So far its been almost great. The only issue I have is when in a high bank angle the signal dies. Is this because of the stock antennas?
 

earthsciteach

Moderator
Moderator
#2
Yes, this is pretty typical of the stock antennas. I think you will be really happy with a couple of circ polarized antennas. Did you order the $57 system? I'm considering that one.
 

aiidanwings

Senior Member
#3
This is the 200mw system.

I figured that if Voyager is transmitting from 11.5 billion miles away with a 20 watt system, I should be fine with this. So far, I'm very impressed.

Of course NASA has a bigger rx than I do...
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#4
. . . and also correct for polarization. your whip antenna when your plane is upright is vertical polarization. When it's banked(at say 90 degrees) becomes horizontally polarized. In a perfect world a horizontally polarized signal will be completely rejected by a vertically polarized antenna -- meaning no signal through -- but even steep angles will cut your signal sharply.

All this goes away with circular polarization(like made by the cloverleaf antennas). a left-hand circular polarized signal is left hand polarized no matter what orientation it's in. It also has a fair match with Vertical & Horizontal antennas. What it won't match is either a right hand polarized, or reflected left hand polarized signal (which helps cut out multi-path noise), so make sure both sides match.

switch for a cloverleaf, and you'll hold signal to full range no mater what attitude your plane takes.
 

Tritium

Amateur Extra Class K5TWM
#5
Even a simple dipole made for 900MHz would prevent the issue you describe if the two legs were oriented correctly.

Thurmond