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JB[_3_] · September 17th 08, 02:40 AM posted to rec.radio.amateur.antenna

dittos

"Sal M. Onella" wrote in message
news

"JoeSch" wrote in message
...
Thank you all for replying. Sorry to take so long to get back here.
I momentarily put the project aside because, after missing the first
game, (I posted the first message about an hour before game time,
lol), the Jets will be carried on my cable stations for the next two
weeks. Add the bye week into that and I had a couple of weeks to get
this thing together-there was no super-immediate rush. But I am going
to build this in the next week or so.

As far as Channel 2 going to UHF in February, the Jets regular season
ends in December, so an antenna that is useful until February will
take of this season nicely. Any post season playoff games by the
Jets, (should they get into the playoffs), will be broadcast
nationally, so I won't need the antenna for that. I'll worry about
next season when it happens. However, don't be surprised if next
September you see a thread about building a UHF antenna for the new
Channel 2 New York.

I have high hopes for this project giving me some kind of watchable,
albeit possibly snowy signal. Here's why. Several years ago I
dangled a piece of twin lead from my second floor window to the ground
and got both the sound and an extremely, extremely snowy picture of
Channel 4 New York, (which carried the Jets at that time). The house
I lived in was a few miles farther inland than the one I lived in now,
and it was just a simple 12 foot piece of twin lead out the window,
but I got SOMETHING. Ths project will be on a pole, on a roof, on a
house closer to the water using an antenna scientifically optimized
for Channel 2, so I think the chances of getting something watchable
are very good. There must be something more at play here than just
"line-of-sight" from here to the Empire State Building, at least at
this frequency. Besides, friends driving down to New York tell me
that they pick up FM stations on their car radios about 20 miles down
the road from here. FM frequencies are a little bit higher,
(therefore more straight line), than Channel 2. Though the
requirements for FM reception and TV reception are not the same, it
still indicates that I am not too far out of range for this
frequency.

I have found an interesting project from the US Patent Office, so it
is between that and Sal's Yagi. I am leaning toward the Yagi, so I
will be back with more questions in the next day or two. Just a few
questions:

A) What is the gain of Sal's Yagi compared to a single dipole?

SAL ADDS: YOU'LL GET GAIN OF SIX TO EIGHT DB (NOT SHOUTING. USING CAPS
TO OFFSET, SINCE THE STUPID PROGRAM DIDN'T MAKE THE RIGHT MARKS.)

B) In sound, there is a rule for Sound Pressure Level which says
"double the distance, 6 dB down in decibels". In other words, If I
have a Sound Pressure Level of 100 dB at ten feet, if I move back to
twenty feet my SPL goes down to 94 decibels. Does a similar rule
apply to antenna reception, that if get good reception with a certain
antenna from 50 miles away, I need an antenna 6 dB more sensitive to
get similar reception from 100 miles away?

IT'S WORSE THAN THAT, UNFORTUNATELY, SINCE THE SIGNAL DOESN'T BEND MUCH
AROUND THE EARTH'S CURVATURE. IT WOULD BE TRUE FOR DISTANCES OF 5 AND 10
MILES, RESPECTIVELY, SINCE THE EARTH'S CURVATURE DOESN'T COME INTO PLAY AT
THOSE DISTANCES. (YOUR SOURCE IS ABOUT 1200 FT UP IN THE AIR.)

A PHENOMENON CALLED "DUCTING" WILL SOMETIMES TRUMP THE EARTH'S CURVATURE.
TV SIGNALS CAN GET TRAPPED IN ATMOSPHERIC LAYERS AND BE RETURNED TO EARTH
MUCH STRONGER THAN THE THEORY PREDICTS. DUCTS ARE MORE COMMON IN WARM
AIR,
SO FOOTBALL SEASON IN THE NORTHEAST IS NOT THE TIME TO BE HOPING FOR
DUCTING.

FOR WHAT IT'S WORTH, WCBS-2 IS ALREADY SENDING OUT ITS DIGITAL SIGNAL IN
ADVANCE OF NEXT FEBRUARY -- MOST STATIONS ARE DOING SO. WCBS IS ON
CHANNEL
56 NOW AND WILL DROP TO 33 ON TRANSITION DAY. SEE
http://rabbitears.info/market.php

IT IS CONCEIVABLE THAT A BIG UHF ANTENNA WOULD WORK FOR YOU. IT WORKS FOR
ME, HERE IN SOUTHERN CALIFORNIA, BUT MY DISTANT TRANSMITTERS ARE ON A
6,000
FT MOUNTAINTOP, WHICH IS A SIGNIFICANT ADVANTAGE FOR ME.

"SAL"