[Scan-DC] Antenna pattern for DCA @ 119.1 MHz?

[Andrew Clegg]

Fascinating. Maybe an outer marker for one of the cross runways?

Andy

> On Dec 8, 2014, at 21:02, Albert LaFrance <albert.lafrance at coldwar-c4i.net> wrote:
> 
> Some years ago I came across a little FAA radio facility of some kind, with
> two short towers, tucked away in a South Arlington residential neighborhood
> near DCA:
> <https://goo.gl/maps/VF2SP>
> 
> Albert
> 
>> -----Original Message-----
>> From: Scan-DC [mailto:scan-dc-bounces at mailman.qth.net] On Behalf Of
>> djoneses
>> Sent: Monday, December 08, 2014 10:36 AM
>> To: 'Andrew Clegg'; 'Scan-DC at mailman.qth.net'
>> Subject: Re: [Scan-DC] Antenna pattern for DCA @ 119.1 MHz?
>> 
>> Andy:
>> 
>> Although I do not know the exact answer to your question, my thought has
>> all been that the 119.1 tower frequency transmitter is not located at DCA.
>> And since the controllers have the ability to select transmitter sites,
> they may
>> choose a different transmitter site based on traffic direction.
>> Additionally there probably is some antenna uptilt. -- could be very minor
>> only a few degrees -- but combined with the antenna location, this results
> in
>> a weak signal
>> 
>> On the other hand, the helo transmitter site may be local to DCA and the
>> antenna may have a truer horizontal pattern since it only needs to serve
>> aircraft at relatively low altitudes (compared to approaching fixed wing
>> aircraft) and in the local area.
>> 
>> I often wondered if the 119.1 tower transmitter is not located at the FAA
> Falls
>> Church site.  Maybe a little foxhunting is in order.
>> 
>> David
>> 
>> -----Original Message-----
>> From: Scan-DC [mailto:scan-dc-bounces at mailman.qth.net] On Behalf Of
>> Andrew Clegg
>> Sent: Monday, December 08, 2014 9:57 AM
>> To: Scan-DC at mailman.qth.net
>> Subject: [Scan-DC] Antenna pattern for DCA @ 119.1 MHz?
>> 
>> I've noticed that the 119.1 MHz tower frequency from DCA is surprisingly
>> weak. I can barely hear the tower 4 miles away from a rooftop up 220 ft.
>> Even in the parking lot at Gravelly Point, the signal isn't exactly
> gangbusters.
>> The planes come in fine at both. On the other hand, the 134.35 MHz
>> simulcast frequency that the tower uses to communicate with helicopters
>> comes in loud and clear 4 miles away, and the 257.6 MHz simulcast channel
> in
>> the milair band comes in reasonably well too.
>> Does someone on the list know if by chance the 119.1 MHz DCA antenna has
>> a significant electrical uptilt that keeps the pattern along the horizon
> very
>> low? That would seem odd, because even ~10 miles away, where the tower
>> first starts communicating with inbound planes, the planes are at a
> relatively
>> low elevation as seen from the airport. But I can't seem to figure out why
>> 119.1 is so weak. Maybe the 119.1 antenna on the southeast side of the
>> tower and blocked to the west (where I am) and the north (where Gravelly
>> Point is)?
>> That would seem odd too.
>> Any ideas? This has puzzled me for several years.
>> 73,Andy
>> 
>> __________________________________________________________
>> ____
>> Scan-DC mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/scan-dc
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Scan-DC at mailman.qth.net
>> 
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> 
>> 
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> Version: 2015.0.5577 / Virus Database: 4235/8701 - Release Date: 12/08/14
>> 
>> __________________________________________________________
>> ____
>> Scan-DC mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/scan-dc
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Scan-DC at mailman.qth.net
>> 
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
> 
> ______________________________________________________________
> Scan-DC mailing list
> Home: http://mailman.qth.net/mailman/listinfo/scan-dc
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Scan-DC at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html