Re: [Repeater-Builder] Antenna on the side of a water tower
I have a partial answer based on experience with a Med 9 (462.950) repeater, that when installed was on the south side of a water tank, probably 90' on the railing around the tank. Needless to say it performance to the north was poor about 90 degrees of coverage was just gone, northwest to northeast. Once out of the shadow of the tank it did fairly well. When finally put on top after much complaining it did OK, except for ground elevation not being high enough. It is what you get when the county takes a free site, when better ones existed. Cheap, free is always better to people who know nothing and dollars count. Steve KB3FPN - Original Message - From: Dave VanHorn To: Repeater-Builder@yahoogroups.com Sent: Friday, January 26, 2007 1:16 PM Subject: [Repeater-Builder] Antenna on the side of a water tower Can anyone point me to something that will show me the antenna pattern for a VHF and UHF antenna mounted on the side of a water tank at different distances from the tank? I've been offered a site, but I can't have top mount, I have to go on the side. I have the mfgr's docs showing pattern with different distances between the loops and the mast, but I don't have any info on how the big metal tank reflection will disturb the pattern. I'm sure there's an optimal distance, but I don't know what it would be.
[Repeater-Builder] Antenna on the side of a water tower.
Wierd, I thought I sent this message already.. Anyway. I've been offered a site, but I would have to mount the antennas on the side of the water tower, not the top. That means within probably 3-6 feet of the side of the big metal can. I have docs from my antenna mfgr for pattern when I adjust the loop-mast spacing, but I need something that will show me what happens with distance between the mast and the water tower. I need this for VHF and UHF. Any pointers?
RE: [Repeater-Builder] Antenna on the side of a water tower.
Dave gave us the model of your antenna,is it the 4 loops on a 20 feets mast antenna? here in Canada it is called the SRL210A4 or SRL210C4 depending if the harness is inside the mast or outside. normally the loop are 36 inches or less from the mast (i dont have my specs near),it will affect your tx pattern also, the most you get far from the tower the best result you will have because of the tower will have a effect of reflector over the antenna you will install,, i just install one at 250 feets and they were install 4 feets from the tower 73/s Dave gervais,ve2ckn Original Message Follows From: Dave VanHorn [EMAIL PROTECTED] Reply-To: Repeater-Builder@yahoogroups.com To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Antenna on the side of a water tower. Date: Fri, 26 Jan 2007 20:19:09 - Wierd, I thought I sent this message already.. Anyway. I've been offered a site, but I would have to mount the antennas on the side of the water tower, not the top. That means within probably 3-6 feet of the side of the big metal can. I have docs from my antenna mfgr for pattern when I adjust the loop-mast spacing, but I need something that will show me what happens with distance between the mast and the water tower. I need this for VHF and UHF. Any pointers? _ Windows Live Spaces: partagez vos photos du Nouvel An! http://discoverspaces.live.com/?loc=fr-CA
RE: [Repeater-Builder] Antenna on the side of a water tower
Dave; Are you able to choose where on the side of the tank (IE, facing a particular direction) or are you stuck with a specific spot? I don't have any charts to reflect this, but a repeater I helped maintain had a remote receiver on a water tower. Unfortunatly, the only spot the antenna could be placed was on the side facing opposite of the area we were trying to improve RX to. It gave us a considerable null in the desired area, with audio being worse into the RX site than the main repeater site. I would suggest 1/2 wave away from the surrounding metal as a minimum, but try and get as far away as you can. -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] Behalf Of Dave VanHorn Sent: Friday, January 26, 2007 1:17 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Antenna on the side of a water tower Can anyone point me to something that will show me the antenna pattern for a VHF and UHF antenna mounted on the side of a water tank at different distances from the tank? I've been offered a site, but I can't have top mount, I have to go on the side. I have the mfgr's docs showing pattern with different distances between the loops and the mast, but I don't have any info on how the big metal tank reflection will disturb the pattern. I'm sure there's an optimal distance, but I don't know what it would be.
Re: [Repeater-Builder] Antenna on the side of a water tower
For a water tower, I would imagine the backside null is rather substantial. A club I was associated with more than 20 years ago tried the side mounting of an 2 meter antenna on the railing of a old style water tower (four legs supporting the Ball. It performed as expected with deep, very noticeable (on the air) nulls off the back. However, if that is all you can get, then go for it. I have seen guys mount a Rohn 25 type tower on the platform where the railing is, mount the antenna on top of the tower section(s) and then the top of the antenna will see over the top of the water tower. I guess it should work. However. I bet there is a mechanical situation that has to be worked out to insure mechanical integrity during high winds. If you can bolt the tower top to the ball, that would help. I have seen that also. Roger W5RD From: Dave VanHorn [EMAIL PROTECTED] Date: 2007/01/26 Fri PM 12:16:39 CST To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Antenna on the side of a water tower Can anyone point me to something that will show me the antenna pattern for a VHF and UHF antenna mounted on the side of a water tank at different distances from the tank? I've been offered a site, but I can't have top mount, I have to go on the side. I have the mfgr's docs showing pattern with different distances between the loops and the mast, but I don't have any info on how the big metal tank reflection will disturb the pattern. I'm sure there's an optimal distance, but I don't know what it would be. Roger White Murphy, Texas
[Repeater-Builder] Antenna on the side of a water tower
Can anyone point me to something that will show me the antenna pattern for a VHF and UHF antenna mounted on the side of a water tank at different distances from the tank? I've been offered a site, but I can't have top mount, I have to go on the side. I have the mfgr's docs showing pattern with different distances between the loops and the mast, but I don't have any info on how the big metal tank reflection will disturb the pattern. I'm sure there's an optimal distance, but I don't know what it would be.
RE: [Repeater-Builder] Antenna on the side of a water tower
Dave, You did not mention where the water tank is located, with respect to the desired coverage area. If it is located to one side of the desired coverage area, then you don't have a problem- just use a directional or offset pattern antenna. Attempting to achieve an omnidirectional pattern with a large-diameter water tank very close behind any other type of antenna is problematic, to say the least! The manufacturer's data on offsetting an omni antenna from a tower are not much help here, since they are usually assuming a skeletal tower of only a few feet in cross section. Check with the antenna manufacturer's tech support folks for advice, since you're certainly not the first repeater operator to have this issue. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Dave VanHorn Sent: Friday, January 26, 2007 10:17 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Antenna on the side of a water tower Can anyone point me to something that will show me the antenna pattern for a VHF and UHF antenna mounted on the side of a water tank at different distances from the tank? I've been offered a site, but I can't have top mount, I have to go on the side. I have the mfgr's docs showing pattern with different distances between the loops and the mast, but I don't have any info on how the big metal tank reflection will disturb the pattern. I'm sure there's an optimal distance, but I don't know what it would be.
