Ye old analog antennas atop the Empire State building
- Thread starter pucho812
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YES - there ARE a LOT of antennas up there, and on many sky scrapers, water towers, and other tall buildings nearby! The trick is to avoid interference between them, especially considering signals are strongest at the antenna and all antennas couple to some degree with other objects, especially a mess of aluminum tubing in the near field. Yep - LOTS of RF floating around up there !!
But then ... um ... ahem ... why "analog" antennas? Digital signals are just radio signals and use the same antennas! You may recall the silly nonsense RadioShack and other vendors promulgated when TV went all (mostly) digital a few years ago. They simply reprinted the packages and sold a GAZILLION of the same old analog antennas labeled as "Digital" antennas. Man what a fraud. Many ham radio operators do both digital and analog operation with the same equipment - using the same antennas they always used - with the digital component managed by a computer or dedicated TNC device. Radios and antennas are pretty much the same (with some new features added to facilitate subtle differences in signal processing, but the process and antennas are the same as ever.) I suspect a a large number of those old antennas on the Empire State Building now emit digital signals! Go figure, eh?
(I am NOT being critical, old man - just commenting as we walk the same trail together...)
- James - K8JHR
________________________________________________________
Parenthetically, this is a photo from Google Maps showing three towers near me. Each holds ten to twelve different antennas. The red arrow indicates the tower my friends and I maintain as part of a 17 station linked repeater system. A computerized traffic controller resides in a shed at the base of the tower. We also have antennas on the tower to the left. As mentioned above, avoiding interference is a major concern!
Happy trails. JHR
But then ... um ... ahem ... why "analog" antennas? Digital signals are just radio signals and use the same antennas! You may recall the silly nonsense RadioShack and other vendors promulgated when TV went all (mostly) digital a few years ago. They simply reprinted the packages and sold a GAZILLION of the same old analog antennas labeled as "Digital" antennas. Man what a fraud. Many ham radio operators do both digital and analog operation with the same equipment - using the same antennas they always used - with the digital component managed by a computer or dedicated TNC device. Radios and antennas are pretty much the same (with some new features added to facilitate subtle differences in signal processing, but the process and antennas are the same as ever.) I suspect a a large number of those old antennas on the Empire State Building now emit digital signals! Go figure, eh?
(I am NOT being critical, old man - just commenting as we walk the same trail together...)
- James - K8JHR________________________________________________________
Parenthetically, this is a photo from Google Maps showing three towers near me. Each holds ten to twelve different antennas. The red arrow indicates the tower my friends and I maintain as part of a 17 station linked repeater system. A computerized traffic controller resides in a shed at the base of the tower. We also have antennas on the tower to the left. As mentioned above, avoiding interference is a major concern!
Happy trails. JHR
Brian Roth
Well-known member
Depending on when that Empire State picture was taken, it's possible those antennas were radiating analog TV signals.
I clearly recall the "mad shuffle" the broadcasters in my hometown of Okla. City (#45 market in the USA) went through years ago during the digital transition. Each of the main network stations (NBC, ABC, etc) each had their own 1500'-ish tall tower (exception....CBS and PBS shared the same tower).
In addition to the TV transmission antenna on each, various FM radio and other radiators were also on each tower. Due to the fact that you can only hang so much stuff on each tower structure, the stations had to erect new towers to accommodate the new antennas required for their new UHF assignments while maintaining the older analog facilities at the "overlap time" while they were simulcasting analog signals on one channel and digital on another.
Stations banded together to construct new 1500' towers with shared facilities. After the transition I know of at least one....maybe more?...of the original decades old 1500' foot tall towers were dismantled.
I could ramble on about this since broadcast radio and TV has always been a sideline in my professional journey.
Bri
I clearly recall the "mad shuffle" the broadcasters in my hometown of Okla. City (#45 market in the USA) went through years ago during the digital transition. Each of the main network stations (NBC, ABC, etc) each had their own 1500'-ish tall tower (exception....CBS and PBS shared the same tower).
In addition to the TV transmission antenna on each, various FM radio and other radiators were also on each tower. Due to the fact that you can only hang so much stuff on each tower structure, the stations had to erect new towers to accommodate the new antennas required for their new UHF assignments while maintaining the older analog facilities at the "overlap time" while they were simulcasting analog signals on one channel and digital on another.
Stations banded together to construct new 1500' towers with shared facilities. After the transition I know of at least one....maybe more?...of the original decades old 1500' foot tall towers were dismantled.
I could ramble on about this since broadcast radio and TV has always been a sideline in my professional journey.
Bri
Brian Roth
Well-known member
What was once the tallest man-made structure on the planet was torn down. Too bad the video is pretty low rez.
https://www.news9.com/story/5e35a3f...a:-kwtv-to-take-down-historic-broadcast-tower
As I recall, the tower was engineered to be able to go to 2000' tall if they decided to extend it. Notice the double guy wires on each span. I stood at the base of it and it was MASSIVE! As is common with those Okla. City towers, it had an elevator running up the middle.
Bri
https://www.news9.com/story/5e35a3f...a:-kwtv-to-take-down-historic-broadcast-tower
As I recall, the tower was engineered to be able to go to 2000' tall if they decided to extend it. Notice the double guy wires on each span. I stood at the base of it and it was MASSIVE! As is common with those Okla. City towers, it had an elevator running up the middle.
Bri
pucho812
Well-known member
I said analog as the picture was from the 1960’s
Yeah ... no worries ... good topic! Sorry if I sounded critical - not my intention. I just wanted to mention the terrible fraud perpetrated by so many antenna vendors.
I do not do tower work, myself, and got dizzy just watching the video Brian mentions. I have a friend who is a station engineer for several TV and radio stations ... and he won't go up there, either !
Good stuff. James
pucho812
Well-known member
No worries. Was just making things clear from my post. I can’t imagine working on those. I hate heights. I also can’t imagine how hard it would be to stay with in broadcast frequency with so many antennas so close together.
Brian Roth
Well-known member
I am with you re. the fake advertising for "digital TV antennas". Most folks on this forum are smart enough to know it's total BS.
I've been dabbling here with antenna setups for over the air reception (OTA) since Cox Cable is a total ripoff. Maybe I should start a thread about that....
I've never been comfortable with heights and WAY less now that I'm Olde. <g> Interestingly, back in Okla. City, the majority of the guys doing tower maintenance were Native Americans and seemed totally fearless. I used to contract as the "studio audio guy" for a small FM station, but was involved a bit with the transmitter and 300' tower. The station contracted with a small company (maybe 3 or 4 guys) for things like tower painting and changing the bulbs. They were all part of the same family and specialized in that work.
Did I say fearless?? indeed.
Bri
Brian Roth
Well-known member
There's a fascinating Youtube channel that often discusses engineering of radio and TV transmission. Dad is a long time radio station guy and he and his son nerd out on topics like this. Here's one that I found quite interesting.
Bri
PermO
Well-known member
I've been watching that channel, cool stuff !
I like doing antenna work, I like being outside and I like the massive scale of these projects.
This was two years ago in Antwerp, It's an offshore transformer station for windfarms.
I like doing antenna work, I like being outside and I like the massive scale of these projects.
This was two years ago in Antwerp, It's an offshore transformer station for windfarms.
pucho812
Well-known member
ruffrecords
Well-known member
Astonishing.
Cheers
Ian
Cheers
Ian
Brian Roth
Well-known member
Interesting project! As I recall, you work in the broadcast business....or am I thinking of someone else from that region of the world?
Bri
Brian Roth
Well-known member
As a followup to the post from @MicMaven ....here are two other tower climber videos I ran across awhile back. The first is cool because of the drone footage. The second shows the climber WAAAY above the clouds from the vantage point of his GoPro. Both guys are changing the bulb in the tower beacon. Notice that both are using safety equipment.
Bri (who gets nervous on a short 2 step ladder changing a light bulb in the house )
Bri (who gets nervous on a short 2 step ladder changing a light bulb in the house )
pucho812
Well-known member
I have been told those tower guys make lots of money just for changing a bulb. But at thousands of feet, yeah they should and no I do not want that gig.
I
Brian Roth
Well-known member
While on this Tower Topic (one reason I like these geek-ish discussions in the Brewery vs....ahhh...other stuff)...
Many people don't know about the designs of "radio towers". Most are just metal structures that have mechanically attached antenna elements for TV, FM, Cellular, etc. applications. The tower is strictly to elevate the antennas....and the tower is tied to ground via a whole bunch of copper buried in the dirt below to deal with lightning strikes.
AM radio towers are a totally different story. The entire steel structure IS the antenna. The tower is isolated from ground via an heavy-duty porcelain insulator at the base and the transmitter's output signal is hard wired to the metal structure.
The height of the tower is selected to be "tuned" to the frequency of the AM signal. An AM antenna for, say, 540 kHz is a lot taller than one at 1600 kHz.
A single tower radiates in an omnidirectional pattern....give or take. However, multiple towers of the proper heights and proper spacing can be fed from the transmitter with different amounts of power to each tower through "phasor" circuits (BIG A$$ inductors and capacitors) to change the pattern of the transmission to a cardioid, figure-8, and many variants.
Geeks like me are used to seeing these AM tower arrays as we drive around the countryside. You see two or more towers of the same height spaced in some sort of pattern.
Here's a pic of the three tower array of KOMA (now different call letters) just south of my hometown of Okla. City.
http://www.fybush.com/sites/2004/site-040122.html
These arrays can get really crazy. There's a station in Dallas that uses TWELVE towers to generate the required AM directional signal pattern.
The steel structures are quite electrically "hot" with the RF energy from the transmitter. Geerling Dad and son (I mentioned them in post #9) demo how an AM tower can cook a wiener!
Bri
Many people don't know about the designs of "radio towers". Most are just metal structures that have mechanically attached antenna elements for TV, FM, Cellular, etc. applications. The tower is strictly to elevate the antennas....and the tower is tied to ground via a whole bunch of copper buried in the dirt below to deal with lightning strikes.
AM radio towers are a totally different story. The entire steel structure IS the antenna. The tower is isolated from ground via an heavy-duty porcelain insulator at the base and the transmitter's output signal is hard wired to the metal structure.
The height of the tower is selected to be "tuned" to the frequency of the AM signal. An AM antenna for, say, 540 kHz is a lot taller than one at 1600 kHz.
A single tower radiates in an omnidirectional pattern....give or take. However, multiple towers of the proper heights and proper spacing can be fed from the transmitter with different amounts of power to each tower through "phasor" circuits (BIG A$$ inductors and capacitors) to change the pattern of the transmission to a cardioid, figure-8, and many variants.
Geeks like me are used to seeing these AM tower arrays as we drive around the countryside. You see two or more towers of the same height spaced in some sort of pattern.
Here's a pic of the three tower array of KOMA (now different call letters) just south of my hometown of Okla. City.
http://www.fybush.com/sites/2004/site-040122.html
These arrays can get really crazy. There's a station in Dallas that uses TWELVE towers to generate the required AM directional signal pattern.
The steel structures are quite electrically "hot" with the RF energy from the transmitter. Geerling Dad and son (I mentioned them in post #9) demo how an AM tower can cook a wiener!
Bri
Brian Roth
Well-known member
A more technical discussion of high power AM transmitters and towers from the Geerlings:
Bri
Bri
Quite right. Many amateur radio stations shunt feed 80 to 140 ft towers as vertical ground plane antennas. My friends and I have operated a "contest" station with a 130 ft tower as antennas on the 160 meter ham band (1.800.0 to 2.000.0 MHz) with up to 120 separate ground wires as a quarter-wave resonant vertical ground plane antenna. We also use a number of shorter vertical antennas made from smaller sections as a steerable 4-square array on the 80 meter ham band. One of the guys programmed a rotary phase controller which has an marker indicating the direction around the compass where the peak signal is, knowing there are deep nulls in all other directions. These are very powerful tools in contests and working DX (long distance, i.e., foreign) stations. Such large scale antennas the operator the big dog in the hunt, especially worked against a substantial ground plane.
At home I have a 43 foot monopole that works several bands with a remote transmatch (impedance matching network) concealed in a fiberglass landscape feature - i.e., a fake rock - which works a treat as the transmatch network is situated at the feed point, minimizing loss in the coaxial transmission line. It has 65 50-foot long ground radials and works a treat on a modest suburban lot. Not as big as a tower, but not wimpy, either.
Of course, that is just one of several aluminum structures in my back yard "antenna farm".
The local fawn and fawna have no idea it is a fake rock!
Just saying ... James
Brian Roth
Well-known member
James....cool to chat with an antenna geek here...lol. Your recent projects are far beyond what I've been doing in decades. My last hobby thing was in the late 80's. On a whim I bought a Kenwood R-5000 Rx and installed an Eavesdropper trapped dipole antenna for the SW bands on my roof.
I still have both....but while the Kenwood still seems OK, i believe there is something kaput on the RF front end. Dunno if it's worth sending to someone to test/repair.
The Eavesdropper is wound up in a box somewhere in the garage.
Bri
I still have both....but while the Kenwood still seems OK, i believe there is something kaput on the RF front end. Dunno if it's worth sending to someone to test/repair.
The Eavesdropper is wound up in a box somewhere in the garage.
Bri
