themetalman
Member
the higher you go with your diskcone antena. is it better
how high to go
- Thread starter themetalman
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Simply, yes.
However, remember that the higher you go, the more coax you'll need in order to reach your scanner. Therefore, it's important to get some good, low-loss, line ... LMR400 if you can afford it.
However, remember that the higher you go, the more coax you'll need in order to reach your scanner. Therefore, it's important to get some good, low-loss, line ... LMR400 if you can afford it.
themetalman
Member
i am at 20 feet right now..but i am still below the roof.
Al42
Member
Not really. You want to go as high as you need to get the antenna you're trying to listen to (the antenna on the transmitter) above your horizon. Any higher than that won't increase the signal and, in some cases (if the transmitting antenna drops below the main lobe of the antenna), it will actually decrease the signal.themetalman said:
Hi all,
"I went up an additional five feet and it made a huge difference on UHF. VHF didn't notice much difference."
Five feet higher than WHAT? While the rule is "height is might" there comes the point of diminishing returns, all things like coax loss considered. Those five feet may have cleared some obstructions or the antenna could now be five feet off the ground (;->) and here's a short story of a repeater you may find interesting.
There's a 2M ham repeater located at the WNJB transmitter site in Lawrenceville (near Trenton) NJ with the antenna at the 900' level of a 1,000' TV tower. WOW 900', that's AWSOME! True, to a POINT. The tranceiver is a 40W Motorola Micor BUT after passing through 1200' of hard line it's only 2W at the antenna AND a receive preamp is used to compensate for the tremendous loss. Still the repeater covers three states with a bone crushing signal so height IS might, all things considered.
Now here's another point to consider:
"...in some cases (if the transmitting antenna drops below the main lobe of the antenna), it will actually decrease the signal."
That's an extreme case already covered in the never ending story of ham repeaters. If the antenna is located at extreme altitude often it has a "shadow" close in so mobiles under the "umbrella" have a hard time of it. The problem is solved by mounting the antenna upside down so less signal is wasted skyward, rather it shoots down while still the "main lobe" (not exactly the correct term) radiates outward in the normal manner. Like I said, it's an extreme case, we're talking about a transmitter site atop a very high mountain and it's not likely any scanner enthusiasts really want to live above the snow line in the Colorado Rockies unless they own a ski lodge.
One final note of explanation, a beam antenna has a main (forward) lobe and several minor lobes while an omnidirectional antenna has but one and only one lobe, circular. Now if you want to get picky, I'm talking about the azmuthal lobe(s) while you may be thinking elevation (vertical). Now we get into what normally is considered gain, such an omni "gain" antenna has a major (horizontal) and one or more minor (vertical) lobes. The idea is to squash as much signal down toward the horizon as possible. In any case, whether unity or gain no major lobe extends too far below the radials which is exactly why such antennas mounted at extreme altitude are upside down. Still it's an extreme case and cannot be considered in normal, every day communications.
That's the bell, class dismissed. (;->)
"I went up an additional five feet and it made a huge difference on UHF. VHF didn't notice much difference."
Five feet higher than WHAT? While the rule is "height is might" there comes the point of diminishing returns, all things like coax loss considered. Those five feet may have cleared some obstructions or the antenna could now be five feet off the ground (;->) and here's a short story of a repeater you may find interesting.
There's a 2M ham repeater located at the WNJB transmitter site in Lawrenceville (near Trenton) NJ with the antenna at the 900' level of a 1,000' TV tower. WOW 900', that's AWSOME! True, to a POINT. The tranceiver is a 40W Motorola Micor BUT after passing through 1200' of hard line it's only 2W at the antenna AND a receive preamp is used to compensate for the tremendous loss. Still the repeater covers three states with a bone crushing signal so height IS might, all things considered.
Now here's another point to consider:
"...in some cases (if the transmitting antenna drops below the main lobe of the antenna), it will actually decrease the signal."
That's an extreme case already covered in the never ending story of ham repeaters. If the antenna is located at extreme altitude often it has a "shadow" close in so mobiles under the "umbrella" have a hard time of it. The problem is solved by mounting the antenna upside down so less signal is wasted skyward, rather it shoots down while still the "main lobe" (not exactly the correct term) radiates outward in the normal manner. Like I said, it's an extreme case, we're talking about a transmitter site atop a very high mountain and it's not likely any scanner enthusiasts really want to live above the snow line in the Colorado Rockies unless they own a ski lodge.
One final note of explanation, a beam antenna has a main (forward) lobe and several minor lobes while an omnidirectional antenna has but one and only one lobe, circular. Now if you want to get picky, I'm talking about the azmuthal lobe(s) while you may be thinking elevation (vertical). Now we get into what normally is considered gain, such an omni "gain" antenna has a major (horizontal) and one or more minor (vertical) lobes. The idea is to squash as much signal down toward the horizon as possible. In any case, whether unity or gain no major lobe extends too far below the radials which is exactly why such antennas mounted at extreme altitude are upside down. Still it's an extreme case and cannot be considered in normal, every day communications.
That's the bell, class dismissed. (;->)
kb2vxa said:
Sorry. The actual antenna height is about 25 feet above the ground. 5 more feet above the roof line is what I was saying.
kb2vxa said:
I actually did experience this with a local PD freq. Signal is weaker than when the antenna was lower. Oh well, guess I can't have it all
It's all good though since I'd rather hear LAPD with 4 bars than Riverside PD with full bars. Best regards,
Hi Brandon and readers,
Just to clarify, that was me quoting someone else, please refer to my original message.
Your experience is most unusual inasmuch as your antenna is so low and was barely off the ground to begin with. Methinks there was some interaction with the roof causing pattern distortion and an aparant gain in that direction. Now the pattern is less distorted (there is always some interaction with nearby objects, trees and such) so the antenna is receiving more or less normally.
BTW, with winter coming we notice better reception with the leaves off the trees, they absorb signals. My geography may be a bit off (taking a guess with the county) but you should be so lucky in SOCAL. Now if my guess is right, those tall palms make great masts, just learn to gather coconuts like a polynesian. (;->)
Radio waves are amazing and unexpected things happen, especially since the higher the frequency the more they behave like light. Just think, if the police car speeding toward you were going fast enough you'd see the antenna glowing, just ask Einstein and Doppler. No, the lights wouldn't disappear into hyperspace. (;->)
Just to clarify, that was me quoting someone else, please refer to my original message.
Your experience is most unusual inasmuch as your antenna is so low and was barely off the ground to begin with. Methinks there was some interaction with the roof causing pattern distortion and an aparant gain in that direction. Now the pattern is less distorted (there is always some interaction with nearby objects, trees and such) so the antenna is receiving more or less normally.
BTW, with winter coming we notice better reception with the leaves off the trees, they absorb signals. My geography may be a bit off (taking a guess with the county) but you should be so lucky in SOCAL. Now if my guess is right, those tall palms make great masts, just learn to gather coconuts like a polynesian. (;->)
Radio waves are amazing and unexpected things happen, especially since the higher the frequency the more they behave like light. Just think, if the police car speeding toward you were going fast enough you'd see the antenna glowing, just ask Einstein and Doppler. No, the lights wouldn't disappear into hyperspace. (;->)
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