AW: [Repeater-Builder] Height Gain figure
dear friends if anybody is interrested in figure out a radio location then try out the program "radio mobile" http://www.cplus.org/rmw/english1.html you can build networks ... repeatersites ... etc. there are heights data from a space mission where the heights of the whole worlds were measured by radar put your repeater on its location, fill in the data for pwr, antenna gain etc. and see what happens best 73´s de dg9bfc -Ursprüngliche Nachricht- Von: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] Auftrag von Gary Schafer Gesendet: Dienstag, 12. August 2008 02:40 An: Repeater-Builder@yahoogroups.com Betreff: RE: [Repeater-Builder] Height Gain figure > -Original Message- > From: Repeater-Builder@yahoogroups.com [mailto:Repeater- > [EMAIL PROTECTED] On Behalf Of Dave Gomberg > Sent: Monday, August 11, 2008 8:37 AM > To: Repeater-Builder@yahoogroups.com > Subject: Re: [Repeater-Builder] Height Gain figure > > At 16:42 8/10/2008, Dick wrote: > >An antenna's gain is what it is and it doesn't change with elevation. > > I am assuming you mean elevation over the surrounding terrain?? > > This is not true. For example, a dipole has an energy distribution > pattern that changes markedly with height above ground. Just try > using a NVIS for DX! And verticals become ineffective at very high > installation points unless special steps are taken to compensate (by > improving the counterpoise). Anyway, that's my opinion and I'm stickin' > to it. Once the antenna is several wavelengths above ground (as it will be with any reasonable height at VHF and above) the pattern is going to be the same no matter how much higher it is raised. The ground will have insignificant effects on the radiation pattern. 73 Gary K4FMX
RE: [Repeater-Builder] Height Gain figure
> -Original Message- > From: Repeater-Builder@yahoogroups.com [mailto:Repeater- > [EMAIL PROTECTED] On Behalf Of Dave Gomberg > Sent: Monday, August 11, 2008 8:37 AM > To: Repeater-Builder@yahoogroups.com > Subject: Re: [Repeater-Builder] Height Gain figure > > At 16:42 8/10/2008, Dick wrote: > >An antenna's gain is what it is and it doesn't change with elevation. > > I am assuming you mean elevation over the surrounding terrain?? > > This is not true. For example, a dipole has an energy distribution > pattern that changes markedly with height above ground. Just try > using a NVIS for DX! And verticals become ineffective at very high > installation points unless special steps are taken to compensate (by > improving the counterpoise). Anyway, that's my opinion and I'm stickin' > to it. Once the antenna is several wavelengths above ground (as it will be with any reasonable height at VHF and above) the pattern is going to be the same no matter how much higher it is raised. The ground will have insignificant effects on the radiation pattern. 73 Gary K4FMX
RE: [Repeater-Builder] Height Gain figure
My reply was strictly tongue in cheek as to the amount of range increase that would be obtained. As the other poster claimed that adding 100 feet to some unknown antenna height would yield an additional 14 miles range. Free space loss is not going to be a factor in a normal repeater system. Unless of course you are starting out with microwatts of power. After all you only loose 6 db every time you double the distance in free space. There are many other factors that will cause attenuation of the signal that will dominate free space loss. 73 Gary K4FMX > -Original Message- > From: Repeater-Builder@yahoogroups.com [mailto:Repeater- > [EMAIL PROTECTED] On Behalf Of Eric Lemmon > Sent: Sunday, August 10, 2008 11:42 PM > To: Repeater-Builder@yahoogroups.com > Subject: RE: [Repeater-Builder] Height Gain figure > > Probably not. The range of any repeater or base station is limited by the > ability to receive a signal from the units in the field, not by the amount > of power at the base or repeater station. At some point, the free-space > losses will prevent the unit in the field from getting a usable signal > into > the base station- even if there is a line-of-sight path. This doesn't > happen very often, due to the curvature of the earth, but it is a physical > barrier that exists. We often assume that a line-of-sight path is a > guarantee of solid communications, but it doesn't work that way. After > all, > you can't use a handie-talkie on the moon to talk through a repeater on > Earth, even though you might have a clear line-of-sight path. > > 73, Eric Lemmon WB6FLY > > > -Original Message- > From: Repeater-Builder@yahoogroups.com > [mailto:[EMAIL PROTECTED] On Behalf Of Gary Schafer > Sent: Sunday, August 10, 2008 9:20 PM > To: Repeater-Builder@yahoogroups.com > Subject: RE: [Repeater-Builder] Height Gain figure > > So if the antenna is already at 1000 feet height and it is moved up > another > 100 feet to 1100 feet, you are going to increase the range by 14 miles?? > > > > 73 > > Gary K4FMX > > > > > > > > From: Repeater-Builder@yahoogroups.com > [mailto:[EMAIL PROTECTED] On Behalf Of > [EMAIL PROTECTED] > Sent: Sunday, August 10, 2008 3:20 AM > To: Repeater-Builder@yahoogroups.com > Subject: Re: [Repeater-Builder] Height Gain figure > > > > It is interesting to see the many responses, none of which I have problems > with, but all seem to skirt your question. If you are moving the site any > distance from the present site, then it is very true that these variables > must be considered. If you are moving only a very short distance from > your > current site, then, I believe what you are looking for is a simple formula > to givr a close guess of what to expect. I think you will find that > should > yout take the square root of the change in height, in this case, the > square > root of 100 which is 10, and mulitply that by the square root of 2, which > is > 1.414, you will come up with an approximattion of 14 or so miles > improvement. Again, as others have pointed out, many variables inter into > the equasion, but then, the bumble bee can not fly either. . . .. > > > > Hope this helps. > > 73 and cheers, > > Gene, W4FWG > > > > -- Original message from Chuck Kimball > <[EMAIL PROTECTED]>: -- > > At one point I had read a number for figuring out the gain you get > by > increasing the height. Of course at the moment I'm unable to locate > that. > > ie: If I move the same antenna (VHF 2m) up a hill and gain 100' of > elevation, but it costs me the line loss (300'), did I really gain > anything. > I'll figure in the line loss, and adjust the hardline to minimize > the > loss, but I'm looking for the number to compare how much gain (in > db) > did I get with the increased height. > > So... Anyone know what number is for gain as a function of height? > or > know a reference I can look up. > > Thanks > Chuck > n0nhj > > > > > > > > > Yahoo! Groups Links > > >
Re: [Repeater-Builder] Height Gain figure
I've seen several instances where doubling the antenna hight typically adds about 20 percent more coverage over normal terrain. Of course this has it's limits since the earth hasn't been flat for many hundreds of years. I once saw a SMR operator spend about 100K to go from 200 feet to 450 feet with his system. He stated he was expecting to double his coverage. In reality it only added about 5 miles to his previous 20 mile coverage. He sure was disappointed. Dex
Re: [Repeater-Builder] Height Gain figure
At 16:42 8/10/2008, Dick wrote: >An antenna's gain is what it is and it doesn't change with elevation. I am assuming you mean elevation over the surrounding terrain?? This is not true. For example, a dipole has an energy distribution pattern that changes markedly with height above ground. Just try using a NVIS for DX! And verticals become ineffective at very high installation points unless special steps are taken to compensate (by improving the counterpoise). Anyway, that's my opinion and I'm stickin' to it. -- Dave Gomberg, San Francisco NE5EE gomberg1 at wcf dot com All addresses, phones, etc. at http://www.wcf.com/ham/info.html -
RE: [Repeater-Builder] Height Gain figure
Not always To: Repeater-Builder@yahoogroups.com From: [EMAIL PROTECTED] Date: Sun, 10 Aug 2008 23:19:52 -0500 Subject: RE: [Repeater-Builder] Height Gain figure So if the antenna is already at 1000 feet height and it is moved up another 100 feet to 1100 feet, you are going to increase the range by 14 miles?? 73 Gary K4FMX From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Sunday, August 10, 2008 3:20 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Height Gain figure It is interesting to see the many responses, none of which I have problems with, but all seem to skirt your question. If you are moving the site any distance from the present site, then it is very true that these variables must be considered. If you are moving only a very short distance from your current site, then, I believe what you are looking for is a simple formula to givr a close guess of what to expect. I think you will find that should yout take the square root of the change in height, in this case, the square root of 100 which is 10, and mulitply that by the square root of 2, which is 1.414, you will come up with an approximattion of 14 or so miles improvement. Again, as others have pointed out, many variables inter into the equasion, but then, the bumble bee can not fly either. . . .. Hope this helps. 73 and cheers, Gene, W4FWG -- Original message from Chuck Kimball <[EMAIL PROTECTED]>: -- At one point I had read a number for figuring out the gain you get by increasing the height. Of course at the moment I'm unable to locate that. ie: If I move the same antenna (VHF 2m) up a hill and gain 100' of elevation, but it costs me the line loss (300'), did I really gain anything. I'll figure in the line loss, and adjust the hardline to minimize the loss, but I'm looking for the number to compare how much gain (in db) did I get with the increased height. So... Anyone know what number is for gain as a function of height? or know a reference I can look up. Thanks Chuck n0nhj _ Meet singles near you. Try ninemsn dating now! http://a.ninemsn.com.au/b.aspx?URL=http%3A%2F%2Fdating%2Eninemsn%2Ecom%2Eau%2Fchannel%2Findex%2Easpx%3Ftrackingid%3D1046247&_t=773166080&_r=WL_TAGLINE&_m=EXT
RE: [Repeater-Builder] Height Gain figure
Probably not. The range of any repeater or base station is limited by the ability to receive a signal from the units in the field, not by the amount of power at the base or repeater station. At some point, the free-space losses will prevent the unit in the field from getting a usable signal into the base station- even if there is a line-of-sight path. This doesn't happen very often, due to the curvature of the earth, but it is a physical barrier that exists. We often assume that a line-of-sight path is a guarantee of solid communications, but it doesn't work that way. After all, you can't use a handie-talkie on the moon to talk through a repeater on Earth, even though you might have a clear line-of-sight path. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Gary Schafer Sent: Sunday, August 10, 2008 9:20 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Height Gain figure So if the antenna is already at 1000 feet height and it is moved up another 100 feet to 1100 feet, you are going to increase the range by 14 miles?? 73 Gary K4FMX From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Sunday, August 10, 2008 3:20 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Height Gain figure It is interesting to see the many responses, none of which I have problems with, but all seem to skirt your question. If you are moving the site any distance from the present site, then it is very true that these variables must be considered. If you are moving only a very short distance from your current site, then, I believe what you are looking for is a simple formula to givr a close guess of what to expect. I think you will find that should yout take the square root of the change in height, in this case, the square root of 100 which is 10, and mulitply that by the square root of 2, which is 1.414, you will come up with an approximattion of 14 or so miles improvement. Again, as others have pointed out, many variables inter into the equasion, but then, the bumble bee can not fly either. . . .. Hope this helps. 73 and cheers, Gene, W4FWG -- Original message from Chuck Kimball <[EMAIL PROTECTED]>: -- At one point I had read a number for figuring out the gain you get by increasing the height. Of course at the moment I'm unable to locate that. ie: If I move the same antenna (VHF 2m) up a hill and gain 100' of elevation, but it costs me the line loss (300'), did I really gain anything. I'll figure in the line loss, and adjust the hardline to minimize the loss, but I'm looking for the number to compare how much gain (in db) did I get with the increased height. So... Anyone know what number is for gain as a function of height? or know a reference I can look up. Thanks Chuck n0nhj
RE: [Repeater-Builder] Height Gain figure
So if the antenna is already at 1000 feet height and it is moved up another 100 feet to 1100 feet, you are going to increase the range by 14 miles?? 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Sunday, August 10, 2008 3:20 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Height Gain figure It is interesting to see the many responses, none of which I have problems with, but all seem to skirt your question. If you are moving the site any distance from the present site, then it is very true that these variables must be considered. If you are moving only a very short distance from your current site, then, I believe what you are looking for is a simple formula to givr a close guess of what to expect. I think you will find that should yout take the square root of the change in height, in this case, the square root of 100 which is 10, and mulitply that by the square root of 2, which is 1.414, you will come up with an approximattion of 14 or so miles improvement. Again, as others have pointed out, many variables inter into the equasion, but then, the bumble bee can not fly either. . . .. Hope this helps. 73 and cheers, Gene, W4FWG -- Original message from Chuck Kimball <[EMAIL PROTECTED]>: -- At one point I had read a number for figuring out the gain you get by increasing the height. Of course at the moment I'm unable to locate that. ie: If I move the same antenna (VHF 2m) up a hill and gain 100' of elevation, but it costs me the line loss (300'), did I really gain anything. I'll figure in the line loss, and adjust the hardline to minimize the loss, but I'm looking for the number to compare how much gain (in db) did I get with the increased height. So... Anyone know what number is for gain as a function of height? or know a reference I can look up. Thanks Chuck n0nhj
Re: [Repeater-Builder] Height Gain figure
An antenna's gain is what it is and it doesn't change with elevation. Increased elevation just lets the antenna "see" farther. In other words, it moves the radio horizon further out...just as yoiu can see farther from the hilltop than you can from the base of the hill. Raising the antenna can also lose some coverage in close under the antenna. The main beam could look over some would-be users, depending on its down angle. Dick - Original Message - From: Chuck Kimball To: Repeater-Builder@yahoogroups.com Sent: 09 August, 2008 09:57 Subject: [Repeater-Builder] Height Gain figure At one point I had read a number for figuring out the gain you get by increasing the height. Of course at the moment I'm unable to locate that. ie: If I move the same antenna (VHF 2m) up a hill and gain 100' of elevation, but it costs me the line loss (300'), did I really gain anything. I'll figure in the line loss, and adjust the hardline to minimize the loss, but I'm looking for the number to compare how much gain (in db) did I get with the increased height. So... Anyone know what number is for gain as a function of height? or know a reference I can look up. Thanks Chuck n0nhj
Re: [Repeater-Builder] Height Gain figure
It is interesting to see the many responses, none of which I have problems with, but all seem to skirt your question. If you are moving the site any distance from the present site, then it is very true that these variables must be considered. If you are moving only a very short distance from your current site, then, I believe what you are looking for is a simple formula to givr a close guess of what to expect. I think you will find that should yout take the square root of the change in height, in this case, the square root of 100 which is 10, and mulitply that by the square root of 2, which is 1.414, you will come up with an approximattion of 14 or so miles improvement. Again, as others have pointed out, many variables inter into the equasion, but then, the bumble bee can not fly either. . . .. Hope this helps. 73 and cheers, Gene, W4FWG -- Original message from Chuck Kimball <[EMAIL PROTECTED]>: -- At one point I had read a number for figuring out the gain you get by increasing the height. Of course at the moment I'm unable to locate that. ie: If I move the same antenna (VHF 2m) up a hill and gain 100' of elevation, but it costs me the line loss (300'), did I really gain anything. I'll figure in the line loss, and adjust the hardline to minimize the loss, but I'm looking for the number to compare how much gain (in db) did I get with the increased height.So... Anyone know what number is for gain as a function of height? or know a reference I can look up.ThanksChuckn0nhj
RE: [Repeater-Builder] Height Gain figure
I think that is the reason they use the first peak going up the tower. That minimizes the difference in time of arrival of the ground reflected signal vs the direct signal. I understood that each channel had several peaks at different heights on the tower, but using a peak up higher would give you a lot more difference in Time of Arrival between the ground reflection and the direct path. Also, I understood that using a higher on the tower peak was not as stable a point as the lowest one. All this is from the tech doing the installation, and of course, he may have known how to set it up without understanding why he was doing it. 73 - Jim W5ZIT --- On Sat, 8/9/08, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: From: [EMAIL PROTECTED] <[EMAIL PROTECTED]> Subject: RE: [Repeater-Builder] Height Gain figure To: Repeater-Builder@yahoogroups.com Date: Saturday, August 9, 2008, 8:36 PM At 8/9/2008 17:58, you wrote: >I watched a cable TV system installation on a 300 ft tower many years >back, and it was interesting to see where the receive antennas were >placed. We had channels 4,5,8,11, and 13. > >The tech took a portable antenna and receiver up the tower and watched the >signal strength for each channel as he climbed, and placed a marker on the >tower for the FIRST peak he found in signal strength. He started on ch 4 >and that antenna position was at about 100 ft. We were about 70 miles >from the TV stations. > >As he worked his way up the channels the ch 13 antenna wound up at about >200 ft. All these points were at the first peak he found going up the >tower. As he climbed above that point, the signal strength would go down >for a given channel, as the ground reflection was starting to cancel out >the direct signal, or was no longer adding to the direct signal, whichever >way you want to look at it. > >I thought this might be interesting to the group - Yes. But what about multipath? Ground reflection "adding" to the direct path can result in severe ghosting. Bob NO6B ._,___
RE: [Repeater-Builder] Height Gain figure
At 8/9/2008 17:58, you wrote: >I watched a cable TV system installation on a 300 ft tower many years >back, and it was interesting to see where the receive antennas were >placed. We had channels 4,5,8,11, and 13. > >The tech took a portable antenna and receiver up the tower and watched the >signal strength for each channel as he climbed, and placed a marker on the >tower for the FIRST peak he found in signal strength. He started on ch 4 >and that antenna position was at about 100 ft. We were about 70 miles >from the TV stations. > >As he worked his way up the channels the ch 13 antenna wound up at about >200 ft. All these points were at the first peak he found going up the >tower. As he climbed above that point, the signal strength would go down >for a given channel, as the ground reflection was starting to cancel out >the direct signal, or was no longer adding to the direct signal, whichever >way you want to look at it. > >I thought this might be interesting to the group - Yes. But what about multipath? Ground reflection "adding" to the direct path can result in severe ghosting. Bob NO6B
RE: [Repeater-Builder] Height Gain figure
I watched a cable TV system installation on a 300 ft tower many years back, and it was interesting to see where the receive antennas were placed. We had channels 4,5,8,11, and 13. The tech took a portable antenna and receiver up the tower and watched the signal strength for each channel as he climbed, and placed a marker on the tower for the FIRST peak he found in signal strength. He started on ch 4 and that antenna position was at about 100 ft. We were about 70 miles from the TV stations. As he worked his way up the channels the ch 13 antenna wound up at about 200 ft. All these points were at the first peak he found going up the tower. As he climbed above that point, the signal strength would go down for a given channel, as the ground reflection was starting to cancel out the direct signal, or was no longer adding to the direct signal, whichever way you want to look at it. I thought this might be interesting to the group - 73 - Jim W5ZIT --- On Sat, 8/9/08, Jeff DePolo <[EMAIL PROTECTED]> wrote: From: Jeff DePolo <[EMAIL PROTECTED]> Subject: RE: [Repeater-Builder] Height Gain figure To: Repeater-Builder@yahoogroups.com Date: Saturday, August 9, 2008, 4:25 PM > Where can you experience a situation where you have > line-of-sight, but poor > fresnel clearance, and have no communications path (assume > VHF and UHF, not > microwave)? Is there ever a case? A couple of simple examples: 1. If you have an exactly-wrong height as far as Fresnel clearance goes, you have complete cancellation. Hard to realize in the real world though, at least not a consistent basis, but you can get close... 2. Ducting and inversions that "bend" the signal, either horizontally or vertically. I have 950 MHz STL paths over water and marshland with full LOS and Fresnel clearance that, when conditions are just right, will go from > 1000 uV to below squelch threshold (about 5 uV), about a 50 dB drop. 3. Multipath. Signals arrive out-of-phase at equal amplitude. 4. Antenna pattern issues, nulls, etc. Probably self-explanatory, and obvious. > We've got a link path that an analysis indicates "absolutely > no way" yet it > works just fine (UHF). The obstructions are numerous and > large, but they are > some distance from either site. Then I've seen other paths > (UHF) where a > somewhat mild obstruction causes grief, but the obstruction > is close-in to > one of the sites. As far as path obstructions go, diffraction is one of the biggest factors. The further from either endpoint the obstruction is, the more of a chance diffraction will work in your favor, "bending" the signal over the obstruction. Think of it as a "shadowing" or "shielding" effect - if you're up close to the obstruction, the shadowing effect is much more pronounced as compared to if you are further away from it. In a bit of a hurry, sorry for the short responses. --- Jeff WN3A __
RE: [Repeater-Builder] Height Gain figure
> Where can you experience a situation where you have > line-of-sight, but poor > fresnel clearance, and have no communications path (assume > VHF and UHF, not > microwave)? Is there ever a case? A couple of simple examples: 1. If you have an exactly-wrong height as far as Fresnel clearance goes, you have complete cancellation. Hard to realize in the real world though, at least not a consistent basis, but you can get close... 2. Ducting and inversions that "bend" the signal, either horizontally or vertically. I have 950 MHz STL paths over water and marshland with full LOS and Fresnel clearance that, when conditions are just right, will go from > 1000 uV to below squelch threshold (about 5 uV), about a 50 dB drop. 3. Multipath. Signals arrive out-of-phase at equal amplitude. 4. Antenna pattern issues, nulls, etc. Probably self-explanatory, and obvious. > We've got a link path that an analysis indicates "absolutely > no way" yet it > works just fine (UHF). The obstructions are numerous and > large, but they are > some distance from either site. Then I've seen other paths > (UHF) where a > somewhat mild obstruction causes grief, but the obstruction > is close-in to > one of the sites. As far as path obstructions go, diffraction is one of the biggest factors. The further from either endpoint the obstruction is, the more of a chance diffraction will work in your favor, "bending" the signal over the obstruction. Think of it as a "shadowing" or "shielding" effect - if you're up close to the obstruction, the shadowing effect is much more pronounced as compared to if you are further away from it. In a bit of a hurry, sorry for the short responses. --- Jeff WN3A
Re: [Repeater-Builder] Height Gain figure
Jeff - Where can you experience a situation where you have line-of-sight, but poor fresnel clearance, and have no communications path (assume VHF and UHF, not microwave)? Is there ever a case? We've got a link path that an analysis indicates "absolutely no way" yet it works just fine (UHF). The obstructions are numerous and large, but they are some distance from either site. Then I've seen other paths (UHF) where a somewhat mild obstruction causes grief, but the obstruction is close-in to one of the sites. Can you shed some light on why this happens? Chuck WB2EDV - Original Message - From: "Jeff DePolo" <[EMAIL PROTECTED]> To: Sent: Saturday, August 09, 2008 4:14 PM Subject: RE: [Repeater-Builder] Height Gain figure > > It's not as simple as that. If the receiver and transmitter are > line-of-sight with full Freslen clearance, going any higher buys you > nothing, you just have more line loss. > > If the transmitter and receiver aren't LOS, going higher may help clear > intervening terrain obstructions, but how much improvement is realized > will > vary depending on the obstruction. If going up an extra 100' helps you > clear a near-by obstruction, the improvement can be significant. > >
RE: [Repeater-Builder] Height Gain figure
> At one point I had read a number for figuring out the gain you get by > increasing the height. Of course at the moment I'm unable to > locate that. > > ie: If I move the same antenna (VHF 2m) up a hill and gain 100' of > elevation, but it costs me the line loss (300'), did I really gain > anything. It's not as simple as that. If the receiver and transmitter are line-of-sight with full Freslen clearance, going any higher buys you nothing, you just have more line loss. If the transmitter and receiver aren't LOS, going higher may help clear intervening terrain obstructions, but how much improvement is realized will vary depending on the obstruction. If going up an extra 100' helps you clear a near-by obstruction, the improvement can be significant. Coverage models that take terrain into an account can give a much better indication as to how much improvement might be realized in raising the antenna height. Field testing is even better, but obviously expensive if you have to install a new antenna to test with. Anything short of those is a guess at best. For those of you that haven't already seen it, there's kind of a neat site that can help give you some idea of what kind of terrain obstructions you're dealing with http://www.heywhatsthat.com . It will do a "panorama" where you give it all of the details for your site (location and elevations) and it will give you a panoramic view of the terrain. It will also do the equivalent of a point-to-point path profile, showing you the terrain along the path. It doesn't do any actual propgation analysis; it's aimed more toward outdoorsmen than engineers. It takes a little time to figure out how to use it - don't get discouraged if it seems confusing at first. To get an idea of what it does, go to the site and pick "K1WHS" (as an example) from the list of previously-saved paranoramas. Click somewhere on the panorama and the path will show up on the topo map. Click on "View Profile" over on the right side, then click again on the panorama and you'll see the point-to-point path profile between your site and the location you clicked. You'll also see there are markers (little triangles) for recognized landmarks, and elevation/lat/lon for those is also displayed. Poke around and you'll find more features. The site runs slow sometimes, so be patient. --- Jeff WN3A
Re: [Repeater-Builder] Height Gain figure
Another reason to consider the terrain is that if you raise it up more, will you be "overshooting" some of the users close in "under" (in the cone) of the antenna (ie: needing downtilt). my $.02 worth, Mike KB5FLX - Original Message - From: Eric Lemmon To: Repeater-Builder@yahoogroups.com Sent: Saturday, August 09, 2008 12:17 PM Subject: RE: [Repeater-Builder] Height Gain figure Chuck, It's just not that simple. If the earth were completely flat, you would get some increase in range- but there are many other factors to consider besides transmission line loss. Most propagation calculation programs consider free-space loss, diffraction loss, and Fresnel loss separately. This is because one must consider the topography for the latter two factors, including the type of ground cover such as trees or shrubs, and if there are buildings in the way. That's one reason why the HAAT (Height Above Average Terrain) is more important than HAGL or HAMSL. Although high-end propagation programs like ComStudy can be a great help in evaluating candidate sites, nothing can replace a drive test with a Coyote or similar signal-survey instrument. Obviously, the higher your antenna is, the further away is the horizon and the greater is the line-of-sight distance. Here's a good reference on this topic: 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Chuck Kimball Sent: Saturday, August 09, 2008 9:58 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Height Gain figure At one point I had read a number for figuring out the gain you get by increasing the height. Of course at the moment I'm unable to locate that. ie: If I move the same antenna (VHF 2m) up a hill and gain 100' of elevation, but it costs me the line loss (300'), did I really gain anything. I'll figure in the line loss, and adjust the hardline to minimize the loss, but I'm looking for the number to compare how much gain (in db) did I get with the increased height. So... Anyone know what number is for gain as a function of height? or know a reference I can look up. Thanks Chuck n0nhj
RE: [Repeater-Builder] Height Gain figure
Chuck, It's just not that simple. If the earth were completely flat, you would get some increase in range- but there are many other factors to consider besides transmission line loss. Most propagation calculation programs consider free-space loss, diffraction loss, and Fresnel loss separately. This is because one must consider the topography for the latter two factors, including the type of ground cover such as trees or shrubs, and if there are buildings in the way. That's one reason why the HAAT (Height Above Average Terrain) is more important than HAGL or HAMSL. Although high-end propagation programs like ComStudy can be a great help in evaluating candidate sites, nothing can replace a drive test with a Coyote or similar signal-survey instrument. Obviously, the higher your antenna is, the further away is the horizon and the greater is the line-of-sight distance. Here's a good reference on this topic: 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Chuck Kimball Sent: Saturday, August 09, 2008 9:58 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Height Gain figure At one point I had read a number for figuring out the gain you get by increasing the height. Of course at the moment I'm unable to locate that. ie: If I move the same antenna (VHF 2m) up a hill and gain 100' of elevation, but it costs me the line loss (300'), did I really gain anything. I'll figure in the line loss, and adjust the hardline to minimize the loss, but I'm looking for the number to compare how much gain (in db) did I get with the increased height. So... Anyone know what number is for gain as a function of height? or know a reference I can look up. Thanks Chuck n0nhj
[Repeater-Builder] Height Gain figure
At one point I had read a number for figuring out the gain you get by increasing the height. Of course at the moment I'm unable to locate that. ie: If I move the same antenna (VHF 2m) up a hill and gain 100' of elevation, but it costs me the line loss (300'), did I really gain anything. I'll figure in the line loss, and adjust the hardline to minimize the loss, but I'm looking for the number to compare how much gain (in db) did I get with the increased height. So... Anyone know what number is for gain as a function of height? or know a reference I can look up. Thanks Chuck n0nhj
