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What Do Localizer Antenas Look Like?

Sun Apr 22, 2001 12:45 pm

Today while sitting near the threashold of the runway at my local airport I started wondering where the DME/Localizer antenas were. I always thought that the localizer antena is an assembly of wires spanning the width of the runway. All I could see behind me(with a fence around it)was a rather large box with red and white squars painted on it and a pole about 5-8 meters tall right beside it. Was that it?
 
Buff
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RE: What Do Localizer Antenas Look Like?

Sun Apr 22, 2001 10:33 pm

The localizer transmitter is almost always at the departure end of the runway. It provides a much more stable signal to an aircraft all the way to the touchdown zone - theoretically. That's why backcourse approaches have higher minima and are harder to track "close in" because you are nearly overtop of the transmitter on short final.

An exception to this statement is the Track Guidance Localizer (or whatever it's called now!) which is not lined up with the runway centreline. It's purpose is to give precise track information to get the aircraft in close enough to execute a visual manoeuvre to finally land the aircraft, or to get it into the valley where it can intercept an ILS or other approach aid. These devices are usually found in mountainous areas.

Best Regards,

Buff
 
Pilot1113
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RE: What Do Localizer Antenas Look Like?

Mon Apr 23, 2001 2:18 pm

That red and white shed you saw is the ILS.

The localizer actually looks like this (colored red):

= = =
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- Neil Harrison

P.S. I tried with just text. I'll scour the 'net for some pics.
 
notam-j
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RE: What Do Localizer Antenas Look Like?

Mon Apr 23, 2001 3:26 pm

Great question! I think many people know what an ILS, VOR and DME are but aren't sure what they actually look like.

Most of us know that a VOR station is that round building with the cone on top. The cone part of the VOR is actually the DME equipment.

There are several parts of an ILS, but the two that give you horizontal and vertical guidance are the Localizer and Glideslope antennas respectively. The Localizer looks like an array of antennas opposite the approach end of the runway. They look like this: http://www.airportSystem.com/14el_LocAntenna2.html

Click for large version
Click here for full size photo!

Photo © Michael Glick



As for the Glideslope antenna, it is the tall pole next to the white and red checkered building. It looks like this: http://www.airportSystem.com/BandGSAntenna2.html

Click for large version
Click here for full size photo!

Photo © Chris White



For an ILS there can also be up to three marker beacons along the approach and are further away from the airport. They provide the pilot verification as to how far away from the runway they are. They look like this: http://www.airportSystem.com/MarkerBeacon2.html

There are also several lighting configurations that go along with an ILS.

Click for large version
Click here for full size photo!

Photo © Miguel Snoep



Hope this helps answer your question, and stay curious.  Big grin

If only I had a nickel for every Boeing vs Airbus posting...
 
Guest

RE: What Do Localizer Antenas Look Like?

Tue Apr 24, 2001 7:55 am

So you guys are saying that the localizer was is at the oppisite side of the runway? Here in town we have a localizer/dme system on runway 26..........does this mean that the antena is acctually at the threashold of runway 08? Why?
 
JETPILOT
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RE: What Do Localizer Antenas Look Like?

Tue Apr 24, 2001 8:15 am

If the localizer wasnt on the other end of the runway then you would have a station passage,reverse sensing, and ambuguity when you passed the localizer. The sensitivity would be so high the instrument would be unreliable.

JET
 
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apuneger
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RE: What Do Localizer Antenas Look Like?

Tue Apr 24, 2001 5:59 pm

Great topic. So, if I'm right, the localizer antenna and the glideslope antenna are located quite far away from each other?

Localizer
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| | GS (or on the left side)
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| Direction of ILS approach

Ivan

PS: Damn, had to edit this post 10 times before it looked allright
Ivan Coninx - Brussels Aviation Photography
 
flybulldog
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RE: What Do Localizer Antenas Look Like?

Fri Apr 27, 2001 5:03 am

So what is the outer marker?
 
Pilot1113
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RE: What Do Localizer Antenas Look Like?

Sun Apr 29, 2001 2:48 pm

The Outer Marker is usually an NDB.

The OM is, in most cases, the initial approach fix for an instrument approach. This is where you'd start the time for a non precision approach, run down the checklist, and get situated for the approach.

- Neil Harrison

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