Antenna height

[edfiero]

Is anyone aware of any studies on effect of antenna height on local (<200 miles) receive and transmit?

For example, station A has an antenna 30 ft up. He receives station B, 40 miles away with 4 s-units.

If station A raises his antenna to 40 ft, would there be any change in how well he receives station B? If so, is there a rule of thumb like every 10 ft of antenna height is good for 1 S-unit of signal change? Same question for transmission distance..... any rule of thumb to say that every 10 ft is good for another 20 miles, or something similar?

This kind of information would be useful for someone trying to choose between raising their antenna vs, putting up a bigger antenna, say going from a 3 element beam to a 5 or 6 element.

 

[sp5it]

Do not mount groundplane antennas at heights between 0.25 and 1.25 wavelength. At those levels above ground most of the energy will be radiated at angles of 27° to 45° into the ionosphere. This phenomenon seems to be independent to the number of radials or other counterpoises. Further simulations indicates that this is true for all other variants of vertical antenna systems too.

https://www.qsl.net/df3lp/projects/vertical/index.html

 

[DainBramage]

...

https://www.qsl.net/df3lp/projects/vertical/index.html

Not everyone agrees with that linked info.
it certainly is incorrect as it does not include the I squared R ground losses and efficiency data.
https://r.search.yahoo.com/_ylt=AwrEZ67hi5hfJ3oAUgYPxQt.;_ylu=Y29sbwNiZjEEcG9zAzIEdnRpZAMEc2VjA3Ny/RV=2/RE=1603861602/RO=10/RU=https://www.kkn.net/dayton2004/HF_vertical_ground_system_design_N6LF_Dayton.pdf/RK=2/RS=5G.QNJZkrgvBbS9oJNDP3w3abvE-

not to mention that it doesn't even differentiate between HF and the higher bands.

 

[jessejamesdallas]

There is a difference between having something like a A99 up at 30' vs. the same antenna up at 50'...

Couple of guys I talk to daily both live just two streets apart from each other, and both run about the same amount of power...

One has his A-99 up on a 30' pole, the other is on a 50' tower...

When I'm on the other end of town from them, roughly 30 miles away, the guy with the 50' tower is always twice as loud as the guy with the 30'...

I know some guys that live out in east Texas that are anywhere from 50 miles away, to over 100 miles away that have towers up 60-90' and I have no problem hearing them or getting back...

"Height is Might!"

 

[The DB]

Do not mount groundplane antennas at heights between 0.25 and 1.25 wavelength. At those levels above ground most of the energy will be radiated at angles of 27° to 45° into the ionosphere. This phenomenon seems to be independent to the number of radials or other counterpoises. Further simulations indicates that this is true for all other variants of vertical antenna systems too.

From an experienced modeler, the angle in question is determined by two things, the height of the antenna's current node, and the quality of the earth below. Considering the same antenna at the same height, some ground types will favor the lower angle lobe, while others will favor the higher angle lobe.

However, something else needs to be said about this. The angle of radiation that you see on antenna models like in the above link has absolutely nothing to do with how well an antenna will perform when making local contacts. It is only relevant when referring to DX contacts. That angle isn't generally even measurable at the antenna itself, unless the antenna is ground mounted.

As far as the ops question, there is no definite answer to those questions, I guess the best answer would be "it depends". At minimum it depends not only on the antenna's height, but the terrain, and the quality of the earth in between the two antennas, and there are likely other factors as well, and this isn't even taking into account how flat/hilly said terrain is. Unfortunately, there is no easy answer here. All I can do is repeat the last line in jessejamesdallas' post above...

"Height is Might!"

This is one of the few absolute truths in radio, and when it comes to performance this trumps all other one liners people will throw at you.


The DB

 

[Slowmover]

Had a guy shutting down my Peterbilt at 24-miles.
And, again at 56-miles.

175’ (on a tower).

 

[ForestRunner98]

I recently got a new antenna (Sirio 5k) it sits at little over 6’ on top of my truck and gets out a lot better being in top. Both TX and RX.

 

[TIN_CAN]

From an experienced modeler, the angle in question is determined by two things, the height of the antenna's current node, and the quality of the earth below. Considering the same antenna at the same height, some ground types will favor the lower angle lobe, while others will favor the higher angle lobe.

However, something else needs to be said about this. The angle of radiation that you see on antenna models like in the above link has absolutely nothing to do with how well an antenna will perform when making local contacts. It is only relevant when referring to DX contacts. That angle isn't generally even measurable at the antenna itself, unless the antenna is ground mounted.

As far as the ops question, there is no definite answer to those questions, I guess the best answer would be "it depends". At minimum it depends not only on the antenna's height, but the terrain, and the quality of the earth in between the two antennas, and there are likely other factors as well, and this isn't even taking into account how flat/hilly said terrain is. Unfortunately, there is no easy answer here. All I can do is repeat the last line in jessejamesdallas' post above...



This is one of the few absolute truths in radio, and when it comes to performance this trumps all other one liners people will throw at you.


The DB

Back in 1992 I ran an antron 99 on the roof of a 33 story building in North Toronto, the height seemed to help me out alot, was running a 139xlr and a Elite Line 2250, seemed to have no problem reaching across lake Ontario to western NY even on AM.

 

[FredTx63]

Back in 1992 I ran an antron 99 on the roof of a 33 story building in North Toronto, the height seemed to help me out alot, was running a 139xlr and a Elite Line 2250, seemed to have no problem reaching across lake Ontario to western NY even on AM.

Wow. And I thought my omni @ 100 ft. was mighty...

 

[Marconi]

Tin_Can, when you were that high, could you still communicate with locals in the community close-in and around your location, or was that point much farther away, like several miles?

 

[Slowmover]

Tin_Can, when you were that high, could you still communicate with locals in the community close-in and around your location, or was that point much farther away, like several miles?

That WAS good herb . . . .

.

 

[binrat]

Back in 1992

TC, you are old...
We used to do Port Dover across to Erie PA back in the 70's all the time.

 

[SIX-SHOOTER]

Once it's at at least a full wave length I've always heard that's the most important part.Under that height & you will suffer.That would be slightly over 36 ft on 27 mhz as I recall.

SIX-SHOOTER

 

[TIN_CAN]

Tin_Can, when you were that high, could you still communicate with locals in the community close-in and around your location, or was that point much farther away, like several miles?

The closest local would have been around 8km it was a base station but could always hear mobile units running close around my building.

 

[Tokin]

Once it's at at least a full wave length I've always heard that's the most important part.Under that height & you will suffer.That would be slightly over 36 ft on 27 mhz as I recall.

SIX-SHOOTER