1090 MHZ AERIAL
The measurements are not absolutely critical but stick to them as close as possible
SIMPLE 1090 MHZ ANTENNA WHICH
WORKS VERY WELL
You can use one of the cheap r.f amplifiers like the one below, make sure its suitable for use at 1090 MHZ
If you are using the original aerial that came with the rtl dongle for ads-b reception then it is to long, you need to optimise it for 1090 mhz i.e cut it down to about 69 / 70 mm.
136.963 MHZ VERTICAL DIPOLE
|
|
|
A SIMPLE J POLE ANT FOR 1090
MHZ
|
|
|
I made it out of 1mm brass tube - I soldered it at the two bottom corners (or you could just try to bend it) it can then be placed inside a piece of plastic tubing
The good thing about this ant is that it does not require a ground plane - place it as high as you can
SLIM JIM ANT FOR AIS ON 162 MHZ
|
|
I MADE THIS OUT OF COPPER TUBING - ABOUT 2 MM IN DIAMETER - SOLDERED AT ALL OF THE CORNERS AS IT WAS TO FLIMSY TO BEND |
|
COLLINEAR ANT FOR 1090 MHZ
This ant is very cheap and easy to make and performed a lot better than I thought it would - I made it out of enamelled covered copper wire about 2.5 mm thick - not sure what the 'swg ' was
Brass/copper tubing would make it more robust but I think there would be problems with the 'bends' it will tend to flatten out
MORE SIMPLE COLLINEAR ANT FOR 1090 MHZ
1090 MHZ QUAD ANTENAE
A FILTER FOR 1090 MHZ
This filter may help if you have break-through / interference from a nearby transmission - there will be a slight insertion loss - it must be tuned exactly to 1090 MHz - otherwise you will have an un-acceptable insertion loss
DIPOLE LENGTH CALCULATOR
So you want to make a dipole for the 14 MHz (20 metres) ham radio band?
example - 466 / 14.025 MHz = 33.226 feet - so a 14 MHz ham radio band dipole has a total length of 33 feet - each leg is 33/2 = 16.6 feet
There are two local oscillators in most lnb's, switched with a 22 khz tone - without the tone a 'universal' lnb will default to the 9.75 g/hz lo - giving a range of 10.7 - 11.7 g/hz - the 22 khz tone should allow it to receive in the 11.7 - 12.75 g/hz range ( using either 12/18 volt supply ) 18 volt supply will also change the polarisation. i have not tried yet to super impose a 22 khz one onto the line as 10.7 - 11.7 g/hz is sufficient range for the 10 g/hz band i am still experimenting with things
* please check your specific lnb to confirm maximum voltages and frequecy range etc *
Note the transmissions are RHCP but using the dish above will reverse the polarisation so you must wind the helix so it is LHCP
This
patch antenna is based on the design by 9a4qv
note
: the 7 mm spacer not only sets the distance between the patch and the
reflector but also provides earthling ( a build up of static on the patch
during humid weather / thunderstorms could damage your pre-amplifier or dongle
) at the operating frequency of the antenna this metal spacer will appear
as a high impedance and it will not impair the signal
I tested
the antenna in the first instance - to check for shorts etc using a 1090 MHz
signal as it’s a reliable guaranteed signal source - it received planes out to
260 miles on a regular basis ( nooelec lna at the ant and 4 metres of cable feeding to a
nooelec bias tee dongle ) but the antenna is not designed for this frequency or
mode but it does outperform a normal vertical ant - the ant will definitely
work ok on l band signals but it needs the pre-amp and/or a clear view of the satellite
it's important to note that the patch and reflector will present a short cct at the co-ax socket which will cause a problem for a tee bias dongle, in which case replace the metal spacer with a plastic one, the chances of having a build up of static which might damage the dongle, are I would think quite remote anyway
A dc blocker (1000pf capacitor would do) would be needed if you elected to keep the metal spacer or are using a j pole ant or something similar
|
|
|
