Radiation Patterns vs Power level

[koØm]

I am going to cache this question under the guise of "Antenna Modeling" but, underneath is the relationship to take-off angle, distance and, power levels.

Is it possible to "Over-shoot" (use too many watts) to communicate with a station that is closer than one that is farther away?

Given: of the two mobile stations running the same power (w /identical transmitters) looking for a signal report, the station with the best antenna system (depending upon how far away the receiving station is) would get the better signal report.

Eleven meter "Facts and Fallacies" (they are hard to tell apart): The more watts to the antenna, the better your chance of being heard; counter argument, too many watts for a given distance (close) will be beat by less watts because the higher powered signal is over-shooting the target. Example, recorded audio from two locations one location is 40 miles away while, the other is 2000 miles away. On the long distance recording, the high powered station was heard loudest while, at the 40 mile point the lower powered station was declared the winner according to the audio tape.

The wildcard in this equation is antenna take-off angle and radiation pattern; I have had better luck with Top-Loaded antenna (mobile) than center or base loaded antenna.

Ideas?

BTW: If I can't get any answers here, do you think if I posed this exact same question "over there" in the tech section that I would get facts, figures or, fried first?

.

[NQ6U]

I am not an expert but I believe the answer to this is "no."

As far as 'overshooting' goes, that has more to do with the takeoff angle and, to the best of my knowledge, an antenna is going to radiate with the same pattern regardless of the power applied to it; the only thing that changes is the density of the electromagnetic field.

[PA5COR]

With my inverted L i have a groundwave on 160 reaching out 90 miles ( 77 feet high)
After that there is a "dead"zone where the skywave doesn't reach, after 300 km's the first hop comes down depending on the hight of the reflective layer.

All with 200 watts...
If i use 1000 watts in the same antenna my reports go up in the zone my s=kywave reaches down, the dead zone itsself changes hardly, the higher field might in fringe area's become just clear, but the dead zone doesn't change, further out after morre hops i found that the dead zones become less pronounced using more power here, maybe because the reflection from the skywave scatters more.

I also have the OCF antenna here which with coil and added wire is resonant on 160, and just at 45 feet up is a skywave NVIS antenna for 160.
Totally different pattern, good for Europem bad for DX.
But it fills in the first and 2nd dead zone nicely, so using both antenna,s in Europe i can cover the field without dead zones..

Same goes for more power, i expect from 200 - 1000 watts to see just under 1 S point change for the better, sometimes that is a (lot) more...
Maybe the refraction is better using more power as just keeping in account the extra power.
Sweet spot is about 600 wats power, the difference between 600 or 1000 watts is mostly never rewarded in signal reports.

Using the inverted L with MFJ 998 legal limit autotuner on 80/40/20 i see the same happen as 160, though he bands have their own specific propagation effects.
Also using the OCF or L makes me cover the bands almost without dead zones.
With a homebrew amplified Loop antenna as extraa receiving antenna i'm set for most bands and propagation on my small plot here.
For the bands above 20 i use an Imax 2000 with 15 feet long radials to get ou.

Though the OCF will work on most bands there, the vertical with it's lower angle of radiation mostly wins hands down.

[kb2vxa]

"Eleven meter "Facts and Fallacies" (they are hard to tell apart): The more watts to the antenna, the better your chance of being heard; counter argument, too many watts for a given distance (close) will be beat by less watts because the higher powered signal is over-shooting the target."

CB is laugh city and this is no exception. There is no such thing as too many watts overshooting the target, have you ever heard of a shootout? That's when mobiles gather in a parking lot or field, set up monster antenna arrays on the roofs of their vehicles and two line up to shoot at a target vehicle downrange. The loudest signal wins, that is to say the one who stomps on the other. Of course there are super power amps and heavy duty alternators driven at high RPM by hemi engines, sometimes sparks fly and antennas go into melt down.

I couldn't find the video I was looking for but you might find this interesting. Notice the herringbone pattern caused by the intense RF field:
http://www.youtube.com/watch?v=fEAGHixZHJg

[koØm]

I am not an expert but I believe the answer to this is "no."

As far as 'overshooting' goes, that has more to do with the takeoff angle and, to the best of my knowledge, an antenna is going to radiate with the same pattern regardless of the power applied to it; the only thing that changes is the density of the electromagnetic field.

That's one vote for "Science"




All with 200 watts...
If i use 1000 watts in the same antenna my reports go up in the zone my skywave reaches down, the dead zone itsself changes hardly, the higher field might in fringe area's become just clear, but the dead zone doesn't change, further out after morre hops i found that the dead zones become less pronounced using more power here, maybe because the reflection from the skywave scatters more.

I also have the OCF antenna here which with coil and added wire is resonant on 160, and just at 45 feet up is a skywave NVIS antenna for 160.
Totally different pattern, good for Europem bad for DX.
But it fills in the first and 2nd dead zone nicely, so using both antenna,s in Europe i can cover the field without dead zones..

Same goes for more power, i expect from 200 - 1000 watts to see just under 1 S point change for the better, sometimes that is a (lot) more...
Maybe the refraction is better using more power as just keeping in account the extra power.
Sweet spot is about 600 wats power, the difference between 600 or 1000 watts is mostly never rewarded in signal reports.



That's two votes for "Science", the more "NVIS" properties ("Near Vertical"-higher radiation angle) a so-called Shoot-Out antenna has, the higher the density of signal will bounce back locally (versus an antenna with a lower radiation angle).



CB is laugh city and this is no exception. There is no such thing as too many watts overshooting the target, have you ever heard of a shootout? That's when mobiles gather in a parking lot or field, set up monster antenna arrays on the roofs of their vehicles and two line up to shoot at a target vehicle downrange.

You, are tellin' me? For more times than I can count on both hands and feet in the last 30 years, I've heard the same excuse about "Overshooting" because of watts (usually by the loser) expressed by someone. That's why I brought this subject up, if there was a plausible explanation, it would be in antennas.


The loudest signal wins, that is to say the one who stomps on the other. Of course there are super power amps and heavy duty alternators driven at high RPM by hemi engines, sometimes sparks fly and antennas go into melt down.

11064

You are talking about the "Lex-a-dyne" (Electrodyne) Alternator and the legendary 383 Stroker Engine. I've seen the aftermath of one those alternator fan coming apart; miracle that no one was injured, shrapnel tore a hole through the hood of that truck like a Hand Gernade.


I couldn't find the video I was looking for but you might find this interesting. Notice the herringbone pattern caused by the intense RF field:
http://www.youtube.com/watch?v=fEAGHixZHJg

Like I said, I hang out with the fellows once or twice a year and it's always the same stories and explanations, I've suggested that they do antenna trials and also offered my opinion on the QRO vs QRO showdowns and, of course, I was wasting my breath.

I would have done a better job proselytizing my Prostate Gland as, they had already done a great job of proselytizing their own.

Food for thought: I know that studies say the RF energy below a certain frequency doesn't affect the body but, we all know how unfiltered those devices are; I once heard one of the locals on the TV band as well as around the high end (108 MHz) of the FMBCB. The DC "Sky's-Da-Limit" champ passed last year of Leukemia after many year of RF exposure to scores (as in "Four Score" and seven years) of kilowatts enclosed in the Faraday shield of his van. Go figure, if a warning label on a pack of smokes doesn't deter cigarette smokers, why would an operator stop doing QRO shoot outs even if they know it is dangerous?

.

[kb2vxa]

I'm not surprised that alternators fly apart, the drive ratio is 1:4 so when the engine is pushed to the red line (as always by the sound of it) 7,000rpm the alternators are spinning at 28,000rpm. There comes a point of diminishing returns but you'll never convince a pedal to the metal freak.

Of course the explanation is in the antennas, the average CBer never heard of modeling software so they're clueless when it comes to gain and proper spacing of the elements. A common array is a row of Rod of God sticks spaced too close together and phased who knows how, let the devil take the hindmost. He does in the video I was looking for, they arc and flare like mad and fall off the boom.

"Food for thought: I know that studies say the RF energy below a certain frequency doesn't affect the body..."
Eh, sort of, but check the FCC RF exposure tables and you'll see safe distances based on power level and frequency. Even AM BCB towers can radiate dangerous amounts of energy, as an example when I was at the WOON Woonsocket, RI transmitter site I approached the tower for a closer look at something and the CE warned me not to go inside the fence. I already knew what that was about, judging by it's spacing from the tower base, at 1KW @ 1240KHz the safe distance is >2'. Distance increases with frequency and power level because smaller and smaller body organs resonate and heat up.

"The DC "Sky's-Da-Limit" champ passed last year of Leukemia after many year of RF exposure..."
Why am I not surprised? Considering it's cancer of the bone marrow the longer the bone the lower its resonant frequency. If one's the right fractional wavelength at 27MHz the marrow heats up enough to be damaged and of course the effects are cumulative. FYI there's growing evidence that cell phones cause brain damage, not hard to figure out why. For that reason I hesitate to use an HT in hand, mine stays clipped to my belt and the speaker-mic clipped to my lapel.
"I would have done a better job proselytizing my Prostate Gland..."
I'm sure mine is but is 2M a religion?

"...why would an operator stop doing QRO shoot outs even if they know it is dangerous?"
Because being king of the hill infuses one's ego with a feeling of power and that's what CB is all about... Crazy Band. On the other hand I know a ham with a 10KW transmitter on 160M but I digress.

[W7XF]

I think what you mean by "overshooting" would be better defined by the term "overdriving", as in the front-end receive stages of the nearby station(s), akin to if you're really close to an AM BCB station. I sometimes have that problem myself on 2 metres as i'm <2 miles from a television tower array (KOLD-Channel 13). Normally, their signal poses no problem to me...except when we get a fair amount of rain, have a low cloud ceiling, or a temperature inversion (fun on 2m/70cm).

Of course, YMMV.

[kb2vxa]

I see what you mean, front end overload often results in what appears to be a weaker signal, a lower S reading and sometimes modulation drives it backward. A "shootout" is entirely different, the guy who stomps on the other one wins since they transmit simultaneously.

That reminds me of back in the day when a bunch of local CB old farts went on a rampage against Thunder Base (thanks to a Johnson Valiant) located in a small town here at the shore when The Crusher was on. Half jealousy and half outrage at how the younger set loved his acerbic wit? They tried to track it down with their mobiles to no avail, whenever they came into town their receivers went haywire. In those days every other house had an antenna and ours was high in a tree where they couldn't see it. (;->)

[N5RLR]

...In those days every other house had an antenna and ours was high in a tree where they couldn't see it. (;->)
Ah, yes. Back in the day I'd seen quite a few 11m groundplanes [with full-length radials attached, mind] mounted in trees for stealth. When the Antron 99 and its ilk came along, concealment became that much easier [camo spray paint & zip ties, and you're good to go]. :snicker:

The question I have, is how can these radio reprobates afford all this...junk and the vehicles [read: trucks/SUVs] in which to mount it? I have my suspicions to a degree. It must be nice; some of us have bills to pay.

[kb2vxa]

Once upon a time I put a ground plane in a tree for a friend not for stealth but because trees are natural antenna masts. Some years later for another friend I topped a dead pine, lopped off the branches leaving stubs for foot pegs and put a huge TV antenna and rotor up there. Playing monkey with a chainsaw is just one of the Fearless Fosdick* adventures in my feckless youth I wouldn't even THINK of today.

Yeah, those radio reprobates are amazing, in my travels around the web I've seen photos of those monster mobiles parked in front of hillbilly shacks shown off by toothless Bubbas. It only goes to show their misplaced priorities, they win shootouts while the kids go hungry.

[NQ6U]

How did you attach the rotor to the tree?

[kb2vxa]

I didn't, with the top and branches missing all that's left is a telephone pole with roots. I cut the metal mast in two with the short section between the rotor and antenna, then lashed the long bottom piece to the tree trunk. In the end both rotor and antenna were above the pole that was a tree. The interesting part was this job introduced me to TV open wire ladder line, along with everything else he had one of those thin cardboard spools of it. Since it's a long way from Lake Wall In Po Pack in the the Poke In Nose to Philadelphia and New York a TV store in Hawley sold it.

[K7SGJ]

How did you attach the rotor to the tree?

By the roots, of course.

You've heard of a rotor rooter, right?

[koØm]

The question I have, is how can these radio reprobates operators afford all this...junk equipment and the vehicles [read: trucks/SUVs] in which to mount it? I have my suspicions to a degree. It must be nice; some of us have bills to pay.

Hello Station, be careful when you start slinging that broad brush, your paint might color the wrong people; we're not talking about "Cletus" down in the trailer park. Yes the entry level fee for 11 meters is cheap. Just as, I was a licensed Amateur long before I became able to afford equipment to fully utilize the bands.

All of the QRO trucks locally are owned by retirees from Ford, GM, General Electric, Cincinnati Milacron etc or, guys with their own mechanic shops or businesses; as is the same for a lot of amateur radio operators. People have different priorities, some want boats, vacation homes and expensive radios others want Big CB trucks homes, boats and to travel. I would imagine that the things your are suspicious about apply to all big radio operators.

Remember, "When you point a finger, there are three pointing back at you!"

.

[kb2vxa]

Aw cummon, while you may be right about some, what I saw on the CB message boards and You Tube make Cletus look like a Wall Street executive. Could it be those QRO truck locals have more sense than to video brag on the internet?

[koØm]

Aw cummon, while you may be right about some, what I saw on the CB message boards and You Tube make Cletus look like a Wall Street executive. Could it be those QRO truck locals have more sense than to video brag on the internet?

Wait-wait, don't get me wrong, that other station might just slap some of that paint in my direction, I was pointing out, contrary to his presumptions, that you cannot enter into the QRO Mobile "Class" on a government assistance check / "not having to pay bills" budget. It all about priorities.

Now, don't get me wrong but, if you are messin' around on those CB message boards, you have too much free time.....:chin:

And, about the QRO operators bragging, go to "Pal-Talk", there are a couple of CB chat rooms that operate in real time so, if sky wave conditions exist, they key on each other and talk about it in the chat room.

QRO mobiles (20 KW+) are on the way out, the money isn't there anymore in competitions and the builders are retiring, 10 years from now, there will not be many (if any) 3 Phase HV B+, Steel Toob-with-handles trucks riding around. They will be a few miles behind International Morse Code.

.

[kb2vxa]

I didn't get you wrong, "while you may be right about some" pretty much separates sheep from goats so if that other station splatters paint he's driving his brush modulator too hard. Right, you can't enter the QRO mobile class on government assistance, some have the check but they have all the class of a dummy load.

"Now, don't get me wrong but, if you are messin' around on those CB message boards, you have too much free time."
You got ME wrong, the too much free time is time taken to follow the occasional link here and time wasting entertainment on You Tube. (;->)

I don't know about sky waves and chat rooms, the internet and PCs didn't exist back in my CB daze and the biggest QRO mobiles had 100W amps. If 3 phase big toobz with handles are on the way out I guess we'll have to look to Honey Boo Boo for entertainment, oh well.

Time to pry my tongue out of my cheek, I look like a lopsided hamster.