Airnav antenna and AIS (VHF)

[tobydude2]

Hi.
Can the Airnav antenna (1090 MHz antenna) and a AIS (VHF antenna for ship traffic) be mounted on the same pole?

[Runway 31]

No reason why not

Alan

[tobydude2]

No reason why not

Thanks.
Just wondered as the instruction manual for the AIS antenna say:
"Caution:
• The AIS receiver generates and radiates a small amount of radio frequency electromagnetic
energy, in accordance with CE and FCC regulations while in operation. This equipment must be
installed and operated according to the instructions contained in this manual. Failure to do so can
result in personal injury and / or AIS receiver malfunction.
• The antenna should not be located near or operated in conjunction with any other VHF transmitting equipment. The required antenna impedance is 50Ω.
"

[Runway 31]

I am no expert on the matter

However the receivers are receive only so there should be no issue although happy to be corrected by someone with knowledge on the matter and what you detailed mentions transmission equipment.  I would however keep them a reasonable distance apart.

Alan

[tobydude2]

I guess the Airnav wave isn´t "any other VHF transmitting equipment."

thanks

[Runway 31]

No both antennas are receive only therefore I cannot see any issues

Alan

[nikhil]

The best thing to do is have vertical separation. Keep the AIS antenna the highest since you need to see ships as far as possible. The ADS-B antenna can be lower since aircrafts naturally have height.

A 1.5 to 2 meter separation should be good.

[tobydude2]

The best thing to do is have vertical separation. Keep the AIS antenna the highest since you need to see ships as far as possible. The ADS-B antenna can be lower since aircrafts naturally have height.

A 1.5 to 2 meter separation should be good.

It got mounted like this. (for now).
It seems to work. Will try a 2 meter separation at a later time. :)
Got the AIS antenna today. :)
Thanks for the tip..

[Aerotower]

for the AIS you only need one side (180º) or a 360º view?

[wiedehopf]

AIS doesn't matter if it has a small blind spot towards land. (Receiving ship transmissions)

Still mounting it via an offset bracket might improve antenna performance.
Apparently 1/4 wavelength, that's 46cm for AIS, is optimal from what i can gather.

But even a 10cm bracket would probably be an improvement.

On the other hand a bracket and the antenna mounted at an offset will most likely increase wind loading of the mast.
Optics of the mast without an offset bracket are also much easier on the eye :)

[tobydude2]

AIS doesn't matter if it has a small blind spot towards land. (Receiving ship transmissions)

Still mounting it via an offset bracket might improve antenna performance.
Apparently 1/4 wavelength, that's 46cm for AIS, is optimal from what i can gather.

But even a 10cm bracket would probably be an improvement.

On the other hand a bracket and the antenna mounted at an offset will most likely increase wind loading of the mast.
Optics of the mast without an offset bracket are also much easier on the eye :)

Thanks.
I Will make som changes and get some distanse to the pole.

[tobydude2]

for the AIS you only need one side (180º) or a 360º view?

Hi
I only need 180 degree view.

[rayjak]

It does not matter if the 2 antennas are close. I have the same setup and have tryed to move them around without any diffrence in signal quality.
Mine are one on top ot the other.

[skybird]

In fact,  on a 40' mast-above 237' AMSL=277'/84meters,  I have the AIRNAV RADAR-EXTENDER A12-1090 & its' mast-head mounted 1090 pre-amplifier (using Westflex-103 cable to the indoor 12-volt power-supply) - in use since 2010.   My location is in Essex-U.K.

As can be seen from the attached photo,  alongside and close to the 1090Mhz antennae is also mounted a DIAMOND D-777 VHF(Civil) + UHF(Military) Airband antennae with a  DD Amtek LNA-DUAL-AIR-O in-line low-noise dual air-band amplifier 112-170 & 218-410Mhz mast-mounted half-way up the mast - in use since 2014.

As well is an equivalent SSS-Air 117 To 140 MHz Receiving Antenna, with its' narrow-band pre-amp near the
bottom of the mast - in use since 2010.

These three antennas are within 12-inches from the centre-mounted AIRNAV antennae and  there has been
no known change to the AIRNAV radar-pattern of between 214 to 300NM range - dependent on aircraft-range
and height,  as well as the condition of the aircrafts' transmission equipment and radio-weather conditions.

The 40'/12.2Metre mast allows for clearance of local housing + with generally low-level surrounding areas, thus  allowing for a good level of receiving ADSB signals - even when light-aircraft etc., are at around 30NM and low-heights  and often on the ground too.

Due to the location where high-winds including even hurricane-force have been experienced,  the need for
two-sets of five guy-lines - has proven an invaluable investment - with little or no-known movement of the mast tops.  These guys use a combination of both Kevlar & covered-steel lines to each of the ground-points.

The heavy-weight of the mast + pre-amps + antennas + heavy co-axial cables + guy-lines does take a while to erect to the full 40' height,  but with the assistance of a Tirfor-winch and a scaffold-pole erected close to the mast,  takes the strain very well to allow for clamping and other needs - whilst raising the mast vertically.

As said elsewhere,  any small radio-radiation from receive-only radio-equipment,  will not affect the reception of the aerials or receivers,  as can barely even be found outside of those radios,  but obviously where a transmitter is used in the close-locality of a similar-mast and radio-station,  there could well-be an issue in interference  and  possibility even damage to such equipment.

A 137Mhz Turnstile antennae for weather-satellite reception,  as well as a second AIRNAV RADAR-EXTENDER antennae can also be seen in the distance  as well as a portable-mast for experimental purposes.