Riddle me this Oh Great Antenna Guru's:
Is it possible to have an antenna that is too strong? I have three antennas for my scanner that I can use. And no, I am not using them all at the same time. I did a little reading on that theory and quickly learned it is a bad idea in most cases. So this is plugging one antenna in, then removing it and connecting a different one. Keep in mind I am not using any kind of fancy testing equipment. I don't have any, and probably wouldn't know how to use it if I did. I am just going by how far out I can catch a signal, how it sounds and the RSSI number in the ScanFree logging software.
First antenna is obviously the little rubber one that came with my 325P2 that is 6 inches long. It actually works a lot better then I thought it would. It has no problem picking up local 150, 450 and 800mhz. I live about 5 miles from most of the antennas in my local town, including the one for my county's trunked system. I can even get a fire department from about 15 miles away (156.105mhz). It is kind of scratchy and has a lot of hiss though. RSSI numbers are between 700-850.
Then I have a large TV antenna on a 30 foot tower. I don't know how old it is, it was here when we bought the house about 5 or 6 years ago. Judging from the elements that are on it it looks like it is made for FM, VHF and UHF. So before TV went to digital broadcasts. All the elements are still there and not mangled by the wind. It has a pre amp mounted right under the antenna. It also has a rotor that works. The control box doesn't look too old either. The tower is not all rusty and cable looks like it is in good condition. It seems to be professionally installed. RG59 cable though running into the house. It runs into an amplified two way splitter and the cabling in the house is all RG6. It is not a solid run though, there is one connector in the middle of what I would guess is a 15 foot run across the house. Then another connection to the 6 foot cable I made with the BNC connector to attach to my scanner. So 30 feet of RG59 into an amplifier, about 8 feet of RG6 to a simple F type connector, then another 8 feet or so to another connector and 6 feet of RG6 terminating with a BNC connector.
The tower antenna has RRSI numbers in the 1000-1100 range and managed to snag a 155mhz channel at over 50 miles away. It didn't sound real great though. It will not pick up the next closest trunking tower that is about 20 miles away, even if you point right at it. It is not real great with 450mhz signals either.
And lastly I have a home made OFCD antenna that is described on this site. 1/2" copper tubing, 48 inch top element, 18 inch lower with pvc connectors. If the numbers I just listed are wrong, it is my memory, I designed it to whatever the specs on this website were. It is attached to an unused chimney on the east side of the house (opposite side of the tower antenna). The T junction is 8 feet off the ground and the antenna is spaced about a foot away from the chimney about 21/2 feet from the side of the house. It is just strapped on temporarily for the moment so I could see how well it worked. If i keep using it I will raise it higher. IF I can get up the nerve to climb that high on the ladder lol. I am scared to death of heights. The cable is 25 feet of brand new RG6. Nothing fancy, just the white cable you can get at lowes with the pre installed terminals. That feeds into an amplifier with a single input and single output, not an amplified splitter. RCA 10 db 50-900mhz fixed gain. Then the 6 foot cable I made running into the scanner.
This set up has RSSI number in the 800-950 range. However, it seems to get more hits and is more consistent than the large tower antenna. Also some of the channels are more clear, no static or hiss like with the other two antennas. Some channels are, but not as many. Like the fire station in Blissfield about 15 miles away. The big antenna will get it, but it doesn't sound real great. The dipole seems to get it with more clarity and stays locked on better. This antenna can also get 150mhz signals from Detriot which is about 45 miles away. It actually picks them up better than the larger antenna. It however will not pick up the trunked system 20 miles away either, Just the local one here in town.
Someone in another thread explained to me that the 800mhz system are set up that way on purpose though so they don't spam other areas.
So if you guys were to take a guess, what do you thing is happening here. Is the large antenna too strong for local signals some how? Or are the RSSI numbers really useless data and the dipole is actually more efficient than the large antenna even though the numbers are slightly lower.
My current options are to either raise the dipole and attach it better, or climb the 30 foot tower and run all new cable.
Keep in mind all of the antennas work just fine for all my local stuff, but the dipole seems to be the best. But if I could pick up either of the next closest trunked systems it would open me up to a lot more of the State Police.
I fully understand that antenna's are pretty complicated and my comparisons are about as low tech as it gets. And that I am asking you to make wild guesses without the proper technical information. I am not asking for hard advice and I am not going to hold anyone to their best guess based on the crappy information I gave. Just your shot in the dark opinion on what might be happening. Don't think that if you all tell me to replace the cable on the 30 foot tower that I am going to run out tomorrow, go to lowes and buy cable, and them come home and climb that tower like a monkey. I can't really spend any more money on this for the next month or so and I am not going up that tower unless I can find a safe way to do it. Like some kind of harness or belt that I can attach along the way. I might brave 15 feet or so, but not 30 lol. By the time I got up there I would be shaking too much to actually do anything.
I am open to other options as well as long as they are not crazy expensive. Like mounting an antenna designed for what I am doing, or even paying someone to run new cable on the 30 foot one, depending on what they would charge. I have the tools to strip cable and attach compression fittings and have done that. I just don't like heights is all. And once we get to the 300 dollar mark I would probably opt to buy a second scanner before spending it on a slightly better antenna. Does that make sense? If it is a vastly better antenna that is another thing.
I suppose another option would be a second scanner and antenna specifically set up for 800mhz. That doesn't sound like a cheap venture or anything I could do real soon though.
Is it possible to have an antenna that is too strong? I have three antennas for my scanner that I can use. And no, I am not using them all at the same time. I did a little reading on that theory and quickly learned it is a bad idea in most cases. So this is plugging one antenna in, then removing it and connecting a different one. Keep in mind I am not using any kind of fancy testing equipment. I don't have any, and probably wouldn't know how to use it if I did. I am just going by how far out I can catch a signal, how it sounds and the RSSI number in the ScanFree logging software.
First antenna is obviously the little rubber one that came with my 325P2 that is 6 inches long. It actually works a lot better then I thought it would. It has no problem picking up local 150, 450 and 800mhz. I live about 5 miles from most of the antennas in my local town, including the one for my county's trunked system. I can even get a fire department from about 15 miles away (156.105mhz). It is kind of scratchy and has a lot of hiss though. RSSI numbers are between 700-850.
Then I have a large TV antenna on a 30 foot tower. I don't know how old it is, it was here when we bought the house about 5 or 6 years ago. Judging from the elements that are on it it looks like it is made for FM, VHF and UHF. So before TV went to digital broadcasts. All the elements are still there and not mangled by the wind. It has a pre amp mounted right under the antenna. It also has a rotor that works. The control box doesn't look too old either. The tower is not all rusty and cable looks like it is in good condition. It seems to be professionally installed. RG59 cable though running into the house. It runs into an amplified two way splitter and the cabling in the house is all RG6. It is not a solid run though, there is one connector in the middle of what I would guess is a 15 foot run across the house. Then another connection to the 6 foot cable I made with the BNC connector to attach to my scanner. So 30 feet of RG59 into an amplifier, about 8 feet of RG6 to a simple F type connector, then another 8 feet or so to another connector and 6 feet of RG6 terminating with a BNC connector.
The tower antenna has RRSI numbers in the 1000-1100 range and managed to snag a 155mhz channel at over 50 miles away. It didn't sound real great though. It will not pick up the next closest trunking tower that is about 20 miles away, even if you point right at it. It is not real great with 450mhz signals either.
And lastly I have a home made OFCD antenna that is described on this site. 1/2" copper tubing, 48 inch top element, 18 inch lower with pvc connectors. If the numbers I just listed are wrong, it is my memory, I designed it to whatever the specs on this website were. It is attached to an unused chimney on the east side of the house (opposite side of the tower antenna). The T junction is 8 feet off the ground and the antenna is spaced about a foot away from the chimney about 21/2 feet from the side of the house. It is just strapped on temporarily for the moment so I could see how well it worked. If i keep using it I will raise it higher. IF I can get up the nerve to climb that high on the ladder lol. I am scared to death of heights. The cable is 25 feet of brand new RG6. Nothing fancy, just the white cable you can get at lowes with the pre installed terminals. That feeds into an amplifier with a single input and single output, not an amplified splitter. RCA 10 db 50-900mhz fixed gain. Then the 6 foot cable I made running into the scanner.
This set up has RSSI number in the 800-950 range. However, it seems to get more hits and is more consistent than the large tower antenna. Also some of the channels are more clear, no static or hiss like with the other two antennas. Some channels are, but not as many. Like the fire station in Blissfield about 15 miles away. The big antenna will get it, but it doesn't sound real great. The dipole seems to get it with more clarity and stays locked on better. This antenna can also get 150mhz signals from Detriot which is about 45 miles away. It actually picks them up better than the larger antenna. It however will not pick up the trunked system 20 miles away either, Just the local one here in town.
Someone in another thread explained to me that the 800mhz system are set up that way on purpose though so they don't spam other areas.
So if you guys were to take a guess, what do you thing is happening here. Is the large antenna too strong for local signals some how? Or are the RSSI numbers really useless data and the dipole is actually more efficient than the large antenna even though the numbers are slightly lower.
My current options are to either raise the dipole and attach it better, or climb the 30 foot tower and run all new cable.
Keep in mind all of the antennas work just fine for all my local stuff, but the dipole seems to be the best. But if I could pick up either of the next closest trunked systems it would open me up to a lot more of the State Police.
I fully understand that antenna's are pretty complicated and my comparisons are about as low tech as it gets. And that I am asking you to make wild guesses without the proper technical information. I am not asking for hard advice and I am not going to hold anyone to their best guess based on the crappy information I gave. Just your shot in the dark opinion on what might be happening. Don't think that if you all tell me to replace the cable on the 30 foot tower that I am going to run out tomorrow, go to lowes and buy cable, and them come home and climb that tower like a monkey. I can't really spend any more money on this for the next month or so and I am not going up that tower unless I can find a safe way to do it. Like some kind of harness or belt that I can attach along the way. I might brave 15 feet or so, but not 30 lol. By the time I got up there I would be shaking too much to actually do anything.
I am open to other options as well as long as they are not crazy expensive. Like mounting an antenna designed for what I am doing, or even paying someone to run new cable on the 30 foot one, depending on what they would charge. I have the tools to strip cable and attach compression fittings and have done that. I just don't like heights is all. And once we get to the 300 dollar mark I would probably opt to buy a second scanner before spending it on a slightly better antenna. Does that make sense? If it is a vastly better antenna that is another thing.
I suppose another option would be a second scanner and antenna specifically set up for 800mhz. That doesn't sound like a cheap venture or anything I could do real soon though.