A99 VS. I MAX CHOICE AT IMPROPER HIGHT

[222DBFL]

There are a bunch of factors that need to be taken into account, but like I said, at least 1/2 mile or more between stations. Runna clean setup and don't use a bunch of power. Don't know of any rule of thumb on this but where I am I have 3 locals within 2 miles. The only ones that bleed over on me are the 2 that are within about 1/2-3/4 mile from me. And it's about 2 channels each way at that distance. One guy using a 3 element beam and the other an imax 2000 or A99 I can't remember. But they both bleed enough that I can tell when they are on and can follow to where they are just by the bleedover. The guy with the beam runs a galaxy radio with a power mic, the other a 2995 that does about 150-200 watts I beleive he said. He can turn it down but he leaves it up to talk locally like this. Not sure why but he does. Again both bleed on me. The 200 watt station obviously is easier for me to hear but make no mistake even the tuned up Galaxy makes enough power to bleed over. And this is with several different radios and not just my Icom. Just so happens my Icom has a hot rx and I end up having to run my NB, and ATT. To comprehend what the 200 watt station is sating when he is running at full power. He really over loads my receive. Hope all this helps and makes sense.

 

[222DBFL]

Okay, now that is a bit different. No it should not affect the radiating pattern of the other antenna if they are seperate as at least 50ft or so from each other. As far as obstructions go, keep as far away from power lines as possible at all costs!!! Again hope this helps.

 

[222DBFL]

The way you describe the yards it seems like they are almost like what I have. A small lot with more front to back space between neighbors than side to side. Or am I off base here?? And again I ask are both antennas being used? Or should I say are both stations I use or plan to be in use??

 

[222DBFL]

If one antenna is dead and it's I the next yard 50ft away, don't sweat it. It shouldn't bother another setup as long as the other isn't transmitting as well. Make sense???

 

[worldwidejack]

36ft

 

[Heavy Metal]

If one antenna is dead and it's I the next yard 50ft away, don't sweat it. It shouldn't bother another setup as long as the other isn't transmitting as well. Make sense???

Yes

 

[Heavy Metal]

Now lol, 36' seems be best for local and long distance as a medium it what's best max height and still have same as 36'. Hope asking this in the right way. Was thinking of 45' 54' which besides 36' would still maintain local and good DXing

 

[hotrod]

as rule of thumb ive learned .if 2 antennas both verticle like you asked they should be 36 feet apart . 1 wavelenth. @ 11 meters.
far as antennas being affected by other things id only worry about buildings. for blocking signal.

 

[Heavy Metal]

as rule of thumb ive learned .if 2 antennas both verticle like you asked they should be 36 feet apart . 1 wavelenth. @ 11 meters.
far as antennas being affected by other things id only worry about buildings. for blocking signal.

Take it as far as height and up against home higher the better or least 36' from ground to were one mounts it to it at.

 

[M0GVZ]

Now lol, 36' seems be best for local and long distance as a medium it what's best max height and still have same as 36'. Hope asking this in the right way. Was thinking of 45' 54' which besides 36' would still maintain local and good DXing

For DX it doesn't make a difference with a vertical antenna between any of those heights. The differences are going to be purely for local contacts with higher=better. If 36' is working fine for you locally leave it at 36' - for DX there's nothing to be gained.

With horizontal antennas such as dipoles and beams you can actually end up being too high. If you look at the following chart, a dipole/yagi 2 wavelengths high is at its worst point 25dB down from a dipole/yagi one wavelength high for stations you're going to be receiving within the 1000 to 2000 mile range meaning you're unlikely to hear that much from the USA but it'll go great guns to stations 6000 miles or more away. In both cases both the one wavelength and two wavelength high antennas will suck at sub 1000 miles compared to even a quarter wave vertical - one of the reasons why some of you get better reports with your Imaxes and A99s etc for stations up to 1000 miles than someone with a beam 36' or more off the ground. Their beam is just too high for where they want to work and they'd do a lot better if they lowered it to 18-20ft, up to 20dB better or half a dozen S points on a typical CB signal meter.

The biggest amateur radio stations have stacked beams so they can switch between them and get the best gain for the distance away the station they're trying to contact is. The half wave high dipole/yagi antenna (yellow) is the best compromise.

 

[Heavy Metal]

For DX it doesn't make a difference with a vertical antenna between any of those heights. The differences are going to be purely for local contacts with higher=better. If 36' is working fine for you locally leave it at 36' - for DX there's nothing to be gained.

With horizontal antennas such as dipoles and beams you can actually end up being too high. If you look at the following chart, a dipole/yagi 2 wavelengths high is at its worst point 25dB down from a dipole/yagi one wavelength high for stations you're going to be receiving within the 1000 to 2000 mile range meaning you're unlikely to hear that much from the USA but it'll go great guns to stations 6000 miles or more away. In both cases both the one wavelength and two wavelength high antennas will suck at sub 1000 miles compared to even a quarter wave vertical - one of the reasons why some of you get better reports with your Imaxes and A99s etc for stations up to 1000 miles than someone with a beam 36' or more off the ground. Their beam is just too high for where they want to work and they'd do a lot better if they lowered it to 18-20ft, up to 20dB better or half a dozen S points on a typical CB signal meter.

The biggest amateur radio stations have stacked beams so they can switch between them and get the best gain for the distance away the station they're trying to contact is. The half wave high dipole/yagi antenna (yellow) is the best compromise.

How about for 5/8, .64, 7/8 ect antenna vs height?


Also now say a horizontal 10-32Mhz log periodic were is the yellow happy medium for that?

Just asking/ curious this way others thinking it will know too.

 

[M0GVZ]

How about for 5/8, .64, 7/8 ect antenna vs height?


Also now say a horizontal 10-32Mhz log periodic were is the yellow happy medium for that?

Just asking/ curious this way others thinking it will know too.

That graph applies for all horizontal antennas. In regards to the verticals, the same that I posted earlier in regards to it making little difference for DX and only really being important for local applies no matter the wavelength of the antenna. Below a wavelength high the ground does have an effect on take off angle to some extent but not as much as a horizontal antenna. 36' being a wavelength for 11m band, anything higher than that isn't going to make a difference.

 

[Needle Bender]

I'm sorry, if you were asking how far apart do 2 antennas need to be so they won't screw up the performance of one another;
I had an Imax2K & a P500, 1/2 wave apart on 2 different masts, and there was no noticeable difference in performance of either if the other was up or down.

I also had a P500 & an I10K on the same 2 masts, 1/2 wave apart, and no appreciable interaction noticed.

 

[wavrider]

That graph applies for all horizontal antennas. In regards to the verticals, the same that I posted earlier in regards to it making little difference for DX and only really being important for local applies no matter the wavelength of the antenna. Below a wavelength high the ground does have an effect on take off angle to some extent but not as much as a horizontal antenna. 36' being a wavelength for 11m band, anything higher than that isn't going to make a difference.

Thread is about an IMAX or A99 so when you start posting about other bands it can be confusing.

TOA is TOA whether it is a dipole horizontal or a vertical GP.

To the questions?? Google Take Off Angle and you will have many hits and many different opinions.

ARRL did a study and published it and it pretty much is dead on as I have tried different heights on my tower ( have a hazer so easy to raise and lower)

Anything above 1/2 wl for horizontal you start splitting your transmitted rf in to lobes and nulls.

The AOA also makes a difference on the receive.

the higher the vertical up to 2 WL the lower the TOA and thus the lower the AOA so in a nutshell higher is better for more long distance DX ( not talking Fl to Texas, Long distance is another Continent.

This can also be proven incorrect as how many times have we worked into EU on a stainless steel whip?

So how high do you need to go with your antenna??

As high as you can comfortably accomplish with safety being the key factor.

The average tower is 50 to 90 feet.

I decided a few years ago to keep my towers at around 50'. easy to work with, not hard to guy or dig a foundation for.

 

[M0GVZ]

Thread is about an IMAX or A99 so when you start posting about other bands it can be confusing.

I'm not talking about any bands at all. I mentioned wavelengths, not bands. The same applies no matter what the frequency is. The height just changes with the frequency sa the wavelength gets longer/shorter.

the higher the vertical up to 2 WL the lower the TOA and thus the lower the AOA so in a nutshell higher is better for more long distance DX ( not talking Fl to Texas, Long distance is another Continent.

This can also be proven incorrect as how many times have we worked into EU on a stainless steel whip?

But that is an effect of propogation which is variable and to which we have no control over, rather than anything to do with antenna height. We're discussing things we have a direct control over and antenna height is one thing we have direct control over.