Which antenna is this?

[mandm]

On the bottom of the aircraft there’s these two things sticking out, anyone know what they are?

I was reading about connecting an antenna to my Garmin gdl50 to improve adsb coverage and some forums mentioned using the old antenna from DME/ADF but not entirely sure what’s what.

 

[dmspilot]

The small metal rod is DME or transponder, but probably DME. The white one is marker beacon.

 

[Kritchlow]

The metal one looks a bit naughty if you ask me…

 

[luvflyin]

View attachment 121169

On the bottom of the aircraft there’s these two things sticking out, anyone know what they are?

I was reading about connecting an antenna to my Garmin gdl50 to improve adsb coverage and some forums mentioned using the old antenna from DME/ADF but not entirely sure what’s what.

The little one is Transponder. The other one I’m pretty sure is Marker Beacon. Is this pic your plane? What year is it?

 

[mandm]

The little one is Transponder. The other one I’m pretty sure is Marker Beacon. Is this pic your plane? What year is it? Paging @Pilawt

Yes it’s a 1969 PA28R180

 

[luvflyin]

Yes it’s a 1969 PA28R180

It’s the Marker Beacon

 

[xander75]

ps the GDL30/50 have very good antenna's already, I have the same and the on device antenna gives me great adsb coverage both vertically and horizontally. To note, I have it positioned on top of the cockpit dash by the front window, its not in the way of anything and shows everything I need to see for safe flight and awareness.

If you'd stack it in the rear cabin or bagage compartment of the cherokee maybe you'd want an external antenna. If so, I would use the hole there from the unused antenna but get one that is meant for the device and the radio service you'd need. Location wise, mind you that radar/beacon tends to come from surface to air, hence a bottom mounted one is preferred. gps on the other hand comes from space to surface, hence a top mounted one more preferred. ADSB can be from top or bottom obviously, the direction of energy of the waves is important to consider, hence the type of antenna matters, its amplification capabilities etc.

Sometimes I feel folks think of Antenna's are just a piece of metal sticking out picking up waves, there is a lot more to it...
(eg look at your mobile phone reception when you are right near a tower, it ain't that great, its because of the waves being directed in certain ways, same with wifi and same with localizer/glideslope/ils! (this all comes from my prior hardware dev experience in the mobile/5G space so not talking from powerpoint wisdom

 

[RyanB]

The metal one is the transponder antenna. The other behind it is marker beacon.

 

[Domenick]

For my Warrior II, I think the metal monopole antenna is for my Narco AT150 transponder AND my Narco DME-890. They can share it because their frequencies overlap.

Sometimes the monopole antenna is housed in a fin covering.

 

[mandm]

ps the GDL30/50 have very good antenna's already, I have the same and the on device antenna gives me great adsb coverage both vertically and horizontally. To note, I have it positioned on top of the cockpit dash by the front window, its not in the way of anything and shows everything I need to see for safe flight and awareness.

If you'd stack it in the rear cabin or bagage compartment of the cherokee maybe you'd want an external antenna. If so, I would use the hole there from the unused antenna but get one that is meant for the device and the radio service you'd need. Location wise, mind you that radar/beacon tends to come from surface to air, hence a bottom mounted one is preferred. gps on the other hand comes from space to surface, hence a top mounted one more preferred. ADSB can be from top or bottom obviously, the direction of energy of the waves is important to consider, hence the type of antenna matters, its amplification capabilities etc.

Sometimes I feel folks think of Antenna's are just a piece of metal sticking out picking up waves, there is a lot more to it...
(eg look at your mobile phone reception when you are right near a tower, it ain't that great, its because of the waves being directed in certain ways, same with wifi and same with localizer/glideslope/ils! (this all comes from my prior hardware dev experience in the mobile/5G space so not talking from powerpoint wisdom

The main reason I’m pondering this topic is because the Bluetooth would randomly disconnect from my devices in flight with the Garmin GDL30. On foreflight that means no traffic and it would reconnect a minute or so later automatically. For my Garmin gps it would not reconnect but that device has built in gps so you wouldn’t realize you aren’t receiving weather and traffic data and I would have to manually reconnect the device even though it is set to automatically connect.

So with that I think the GDL30 is overheating or not enjoying the direct sun exposure, I put mind in the same spot that you do as well on the glareshield. I am fine with it there with exception for the sun exposure. Another note is that the GDL30 manual IIRC says not to put the device near the compass (within 12”?) and with it being on the glareshield it is probably 4-5” away from the compass but I don’t notice any issues with that.

I have not had any problems lately though, maybe because it’s cooler ambient temperatures now?

Another annoyance is that the GDL30 will only connect to 2 Bluetooth devices. While I use foreflight on my iPhone and that works for me, if I decide to use my iPad then I would have to disconnect a device. And if I go flying with a buddy then of course that’s one more device needing adsb.

So I am considering if I can mount the GDL30 somewhere that will still give full functionality, I have an external gps antenna that I just got, but I want to make sure the adsb traffic and weather is not affected. I guess there is only a GPS port on the GDL30 but when I read the manual it seemed like you could also hook up an external adsb antenna as well, but I’m not seeing how unless the gps external antenna port are shared with the gps and adsb and same antenna / frequency?

Then next would be for a permanent power installation so I don’t have to take it with me and charge it all the time, and then linking to my Garmin gps to free up one more Bluetooth spots. The GDL30 battery is pretty good, the Garmin gps battery is not. Anyway thinking out loud on future improvements and all comments / suggestions help me come up with an idea to move forward with.

 

[kshaw]

DMEs and the transponder use the same type of antenna, so it could be either. If you are having problems with either, it is a good time to upgrade the RG-58 coaxial cable to RG-400.

 

[xander75]

The main reason I’m pondering this topic is because the Bluetooth would randomly disconnect from my devices in flight with the Garmin GDL30. On foreflight that means no traffic and it would reconnect a minute or so later automatically. For my Garmin gps it would not reconnect but that device has built in gps so you wouldn’t realize you aren’t receiving weather and traffic data and I would have to manually reconnect the device even though it is set to automatically connect.

So with that I think the GDL30 is overheating or not enjoying the direct sun exposure, I put mind in the same spot that you do as well on the glareshield. I am fine with it there with exception for the sun exposure. Another note is that the GDL30 manual IIRC says not to put the device near the compass (within 12”?) and with it being on the glareshield it is probably 4-5” away from the compass but I don’t notice any issues with that.

I have not had any problems lately though, maybe because it’s cooler ambient temperatures now?

Another annoyance is that the GDL30 will only connect to 2 Bluetooth devices. While I use foreflight on my iPhone and that works for me, if I decide to use my iPad then I would have to disconnect a device. And if I go flying with a buddy then of course that’s one more device needing adsb.

So I am considering if I can mount the GDL30 somewhere that will still give full functionality, I have an external gps antenna that I just got, but I want to make sure the adsb traffic and weather is not affected. I guess there is only a GPS port on the GDL30 but when I read the manual it seemed like you could also hook up an external adsb antenna as well, but I’m not seeing how unless the gps external antenna port are shared with the gps and adsb and same antenna / frequency?

Then next would be for a permanent power installation so I don’t have to take it with me and charge it all the time, and then linking to my Garmin gps to free up one more Bluetooth spots. The GDL30 battery is pretty good, the Garmin gps battery is not. Anyway thinking out loud on future improvements and all comments / suggestions help me come up with an idea to move forward with.

That is so interesting Michael! I never had an overheat issue or BT disconnect, while it is right next to the mag compass showing rather accurately still!
Maybe its a solution to get a suction cup type holder and put it behind the passenger window near the baggage compartment so it faces outside, but is far enough from
the cockpit?
I have mine hardwired to the bus so it goes by the avionics master, but yeah having it on battery and needing to charge, it always runs out when you can least 'afford' it!