| Author |
Message |
    
Big_thunder
Junior Member
Username: Big_thunder
Post Number: 15
Registered: 9-2004
| | Posted on Wednesday, September 29, 2004 - 12:16 pm: | 
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I have about 90 feet of tower thinking about putting all of it up. I was talking to along time cber he said the best height is around 40 to 50 feet on a beam for DX your opinion.. |
Tech808
Moderator
Username: Tech808
Post Number: 3709
Registered: 8-2002
| | Posted on Thursday, September 30, 2004 - 12:03 am: |
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Big thunder,
36' ~ 54' ~ 72' ~ 90'
You will be set at 90'
Lon
Tech808 |
Road_warrior
Member
Username: Road_warrior
Post Number: 94
Registered: 7-2004
| | Posted on Thursday, September 30, 2004 - 3:11 pm: |
|
TECH 808,
When you specify a certain distance.
It's measured from the ground to what part of
the beam???
JIM/CENTRAL PA/CEF 375 |
Tech808
Moderator
Username: Tech808
Post Number: 3712
Registered: 8-2002
| | Posted on Thursday, September 30, 2004 - 6:12 pm: |
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Road Warrior,
On an Omni I figure to the bottom of the load / antenna and on Beams I try and get the boom at the 36, 54', 72', and 90' mentioned.
The Boom on our SE White Lightning Quads are at 54' and our IMAX is 36' from the ground to the bottom of the antenna / load.
Lon
Tech808 |
Road_warrior
Member
Username: Road_warrior
Post Number: 95
Registered: 7-2004
| | Posted on Thursday, September 30, 2004 - 8:03 pm: |
|
Ok, thanks Lon!
JIM/CENTRAL PA/CEF 375 |
Airplane1
Intermediate Member
Username: Airplane1
Post Number: 179
Registered: 5-2004
| | Posted on Friday, October 01, 2004 - 12:30 pm: |
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So if i`m reading this right,I should not put up my whole 48' tower for my maco v but instead I should only go with 36' of my tower?
Is this so, I thought the highest I can get it the better.
|
Tech808
Moderator
Username: Tech808
Post Number: 3717
Registered: 8-2002
| | Posted on Friday, October 01, 2004 - 2:24 pm: |
|
Airplane1,
36' = 1
54' = 1-1/2
72' = 2
90' = 2-1/2
108' = 3
If you cannot hit 36' get it as high as you can.
If you can go higher than 36' Great!
48' of tower and 6' or more of Re-inforced mast pipe sticking out of top of tower will get you to the 54' |
Keithinatlanta
Intermediate Member
Username: Keithinatlanta
Post Number: 387
Registered: 3-2003
| | Posted on Friday, October 01, 2004 - 4:07 pm: |
|
Lon, this is another great learning scenario for me as well. So here is my question that may not be any where near theirs. I have a 50 foot push up pole that I want to mount this Antenna Specialists Super Scanner on. At what "height" should I attach it to the pole?
And again, another opportunity to learn. Thanks!!
Keith in Atlanta
CEF 150 |
Tech808
Moderator
Username: Tech808
Post Number: 3718
Registered: 8-2002
| | Posted on Friday, October 01, 2004 - 4:26 pm: |
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At the Top of the pole. |
Bullet
Intermediate Member
Username: Bullet
Post Number: 370
Registered: 7-2003
| | Posted on Monday, October 04, 2004 - 4:47 am: |
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multiples of wave lenghts is cb folklore!
simply put the higher, the farther out your coverage will become.due to a higher line of sight and lowering radiation take off angles.
go as high as you need to clear any objects blocking your signals path.and youll do fine what ever the hight is.
thier is no set MAGIC numbers. sorry!
36 feet my work great at bobs qth and not work worth a darn at my qth. terain has alot to do with it as well.
each site will varry as to its special conditions and landscape,elevation, soil condutivity,ect ect.
73's KC9GCF |
Peddler
Intermediate Member
Username: Peddler
Post Number: 123
Registered: 3-2002
| | Posted on Monday, October 04, 2004 - 7:58 pm: |
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Well I have an M104c at 38ft which is where a local tech told me to put it (anything over 36ft). I was just curious as to why a jump from 36 to 54ft (1 1/2 Wave length). I can understand the 36ft from the ground (being a full wave above ground), it would appear that being in the second wave is all that would be required.
Thanks |
Tech833
Moderator
Username: Tech833
Post Number: 869
Registered: 8-2002
| | Posted on Tuesday, October 05, 2004 - 1:13 am: |
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Please remember that the FCC rules limit omni directional antennas to 60 feet above ground (to the tip of the antenna) OR 20 feet (to tip) above a building they are mounted on (like a skyscraper). Also, the limit for beam antennas is 20 feet above ground.
For ham bands, the limit is 200 feet. Licensed hams- Knock yourself out.
Bullet,
For the flattest (lowest) takeoff angle, Lon is right. |
Gonzo
Junior Member
Username: Gonzo
Post Number: 34
Registered: 9-2004
| | Posted on Thursday, October 07, 2004 - 7:30 pm: |
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Sorry, I am in agreement with Bullet,go as high as you can. The higher the antenna the lower the radiation angle period. Because there is less ground reflection. Your antenna electrically does not know if it is 36' or 45'
If you are below a half wavelenght 18', then there will be significant reflection, and only then will there be a significant measurable difference in performance |
Road_warrior
Intermediate Member
Username: Road_warrior
Post Number: 103
Registered: 7-2004
| | Posted on Thursday, October 07, 2004 - 9:50 pm: |
|
From doing some testing of my own with Omni
Antennas in my area, 36 ft & above is best.
My local & DX talking suffered at lower heights.
As for beams, I do not have much experience.
From what I understand some Beams need to be
installed higher than a Omni to achieve the
same lower angle of radiation. How much higher
I do not have the correct answer.
That's why I like the Quad Beams (white Lightning)
as they can be installed alittle lower & still
achieve a low angle of radiation.
My opinion is any 11 meter Antenna should be at
least 36' and no lower. I have not yet formed
an opinion on any magic numbers.
JIM/road_warrior/ CEF 375
|
Bullet
Intermediate Member
Username: Bullet
Post Number: 371
Registered: 7-2003
| | Posted on Friday, October 08, 2004 - 5:27 am: |
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for the flattest take off angle Lon is right?
no offence Lon, i hope you dont take it as such cause its not ment as such. youve given alot of good advise in the past.
and this is not directed to you as much as it is just put out as an oposing opinon on this subject.
cb folklore is hard to break free of for everyone.
thiers five heights posted above in 1/2 wave increaments. so are we all supost to beleive all 5 are the flattest(lowest take off angle) or just one of them?
the lowest angle of rad is acheived at some 500 feet.. thats the 27.77777778th wave lenghts.
that doent fit in the whole 1/2 wavelenght program.
i can understand cutting your feedline to 1/2 electrical wavelength multiples for reading vswr measurements along the line for a more accurate readings.but antennas
an antenna is much like a light bulb,light is alot like rf. the closer to the floor/ground it is the more light is reflected upword(high angle of radiation) the higher its raised above the floor/ground the lower the angle of radiation becomes.
take a lamp outside on an extension cord. mount it 2 feet above the ground. take a measuring tape and measure the distance it lights up the ground.
now take and mount the lamp 7 feet above the ground (not a mult of 2) and measure the distance the lamp lights up the ground.
as in all thing youll reach a point of diminishing returns with your lamp as is the case with height of an array such as the 500ft.
no where in the middle are thier magic multiples that whisp your rf or light every where the best.
propogate for the intended useage of the system, that is the way to set up your array.
forget about feet above ground. go strictly on whats real and what matters "numbers of db's on receive". that tells the tail.
that antenna dont know how high its supost to be to perform the best all it knows is how far it can see,or how many hops it takes to get thier.
you might even find out that your antennas best elevation above ground is not even a factor of 18 or 36 at all!
the best way to learn is not just to ask others, its to read for yourself,experiment alot jot down your findings and keep records of them. and compare your finding along with others that have tried the same.
other wise you get this..
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Tech833
Moderator
Username: Tech833
Post Number: 871
Registered: 8-2002
| | Posted on Friday, October 08, 2004 - 10:43 am: |
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Bullet,
SW broadcasters have been taking advantage of ground proximity effect since the beginning. 11 meters IS effected by ground proximity effect since the wavelength is still fairly long.
Since the feedpoint is at the base of most omni antennas, we will consider this the current focal point. When the current focal point is placed on a vertical reflector grid (as in a 'dish' antenna), the beamwidth can be adjusted by moving the current point slightly closer or further from the grounded reflector. Playing with the 1/2 wavelength rule changes the main lobe quite a lot.
Now, fast forward to a SW antenna system. The skywave attack angle is adjusted primarily through antenna height above ground when the antenna is built. Secondarily, the takeoff angle is adjusted with phasing of elements as a 'fine tune'. It is well known that RF acts differently over different ground, and the scope of that science was not discussed above, as it is too technical and could take a whole book to get the point across fully.
Now, back to the subject at hand. True that the 'higher the better' is a good rule of thumb. However, to 'fine tune' a flat (lower) takeoff angle, a multiple of a 1/2 wavelength could be used.
Before anyone hyperventilates, I am NOT saying that a full wave (36 foot) mounting height will have a lower taleoff angle than 50 feet. Heck, 72 feet will have a lower takeoff angle than both 36 OR 50. What I AM saying is that 36 feet will have a lower takeoff angle than 40 feet. 72 feet will have a lower takeoff angle than 80 feet.
So, the 'higher the better' is certainly true, but for those who wish to squeeze out that last degree of angle, stick to the half wave multiple rule.
I am not supposed to place links, so do a web search for Decibel antenna company's website and find their polar plots for tower spacing by wavelength. The math is exactl;y the same horizontally or vertically and this will allow you to 'see' how wavelength and spacing effects pattern. In your case, your takeoff angle. 1/2 wave multiples spread signal perpendicular to the elements. 1/4 wave multiples spread signal the opposite.
I will bow out and just continue monitoring this thread as an observer. The longer I participate here in the Copper forum, the more I am learning that NO amount of knowledge or experience or education can overturn firmly rooted CB folklore. |
Road_warrior
Intermediate Member
Username: Road_warrior
Post Number: 104
Registered: 7-2004
| | Posted on Friday, October 08, 2004 - 11:55 am: |
|
Thanks Tech 833,
That helps me understand more about this subject.
My Imax 2000 right now is just a hair above 36ft
from ground to feedpoint. That height does
great for me with skip talking. |
Tech808
Moderator
Username: Tech808
Post Number: 3769
Registered: 8-2002
| | Posted on Friday, October 08, 2004 - 12:05 pm: |
|
Tech833,
That is why we are Very Lucky to have you on board as a Copper Tech as antennas are your profession and your daily job.
They are not just a part of a hobby like it is to most of us.
Your daily work as well as your many years of hands on professional experience in designing antennas and having the most up to date equipment for testing antennas in every condition and height imaginable is worth it’s weight in Gold to the Copper Forum Members.
Your daily hands on experience and many years of knowledge you have gained have been a great help to many of the Copper Forum Members, over the last couple of years.
And your information has always been 100% accurate and dead on target.
This is what makes you the #1 man in your field and why your articles have been published all over the world and on many different (Commercial & Private) Radio related sites.
Yes, there are many ways to do things when installing Antennas and with the use of Coax but it is always nice for the Copper Forum Members to have the Correct Procedure to do it right the first time and dispel a lot of the myths and rumors flying around in radio land.
We All Greatly Appreciate your time and experience and first hand knowledge that you are willing to share with us and your Reviews on the IMAX and A-99 as well as GP Kits that you have done for the Copper Forum Members and your new Short Wave Area you have started.
The radio hobby is a learning experience and I as well as othe Copper Forum Members are always willing to learn the correct way to do things.
Please do not become discouraged, as we need the professionals like you to help dispel the myths and folklore that continues to run rampant around the radio world.
And since I as well as many other Copper Forum Members are always willing to learn more about all aspects of the radio hobby, and the Correct way to do things PLEASE KEEP POSTING! 
Thank You,
Lon / N9OSN
|
Gonzo
Junior Member
Username: Gonzo
Post Number: 38
Registered: 9-2004
| | Posted on Friday, October 08, 2004 - 2:29 pm: |
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Everyone here is very knowledgeable I have learned. The various effects of propagation over different types of ground is called the Pseudo-Brewster angle, this complicated formula says different types of ground (salt water vs rocks) reflect different amounts of RF. This can affect the ground radiationpatterns. Aside for that: These knowledgable guys say....
The ARRL:"height gain between 10-30 feet is assumed to be zero, anything above that gives consistent but small increasing gains"
They also say"Ground reflection is a factor in propagation patterns up to 2 wavelenghts in height"
The ARRL does NOT say: place your antenna at 1/2 wavelenght multiples.
I don't know, all I know is the higher the antenna the better. Would you get better gain with your antenna at 36' versus 45/42feet? I personally don't think so. |
Tech833
Moderator
Username: Tech833
Post Number: 873
Registered: 8-2002
| | Posted on Saturday, October 09, 2004 - 1:11 am: |
|
Lon,
Don't worry! I am not discouraged at all. More like amused. The CB folklore is pretty firmly rooted. I do not intend to pull the weeds by the roots, but I will trim them when I can.
People just need to remember- Hams don't know it all. Most hams are just CBers who passed a test. Having a ham license does not make you smart. That is like saying having a driver's license makes you a better driver. Only driving classes or other education can make you a better driver, not a card. Same with a ham ticket. Some of the most psycologically incapacitated people I have ever met are hams. Curiously, lack of knowledge does not inhibit one from writing about subjects beyond their knowledge if they are a ham.
Gonzo,
I am beginning to think your post may be bait. This fish will not bite. Sorry. |
Gonzo
Junior Member
Username: Gonzo
Post Number: 39
Registered: 9-2004
| | Posted on Saturday, October 09, 2004 - 12:56 pm: |
|
No bait here Tech883, I am just repeating what the ARRL says in the ARRL antenna handbook. If you don't want to believe it, thats up to you. I didn't write the book, just repeating what other knowledgeable Hams have written.
Not debating anyone, it just seems that the higher the antenna the better...that makes sense to me...and apparently others as well. |
Bullet
Intermediate Member
Username: Bullet
Post Number: 373
Registered: 7-2003
| | Posted on Saturday, October 30, 2004 - 5:37 am: |
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gonzo,
its obvious that the ARRL,Carr,Cebik,Orr,Haviland and West have much they could learn here!
|
Peddler
Intermediate Member
Username: Peddler
Post Number: 130
Registered: 3-2002
| | Posted on Saturday, October 30, 2004 - 9:17 am: |
|
I myself appreciate the responses. Some is way to technical for me and looses me very quickly. I really prefer a more simple direction as do a lot of users. Maybe that is why CB folklore is so popular. I also agree with Tech 833's statement " Hams don't know it all. Most hams are just CBers who passed a test. Having a ham license does not make you smart ". It seems that holding a licence automatically makes one an expert. LOL.
Thanks for all the answers (even if I can't understand some of them). |
Mikefromms
Intermediate Member
Username: Mikefromms
Post Number: 256
Registered: 6-2003
| | Posted on Saturday, October 30, 2004 - 11:28 am: |
|
For local talking get that antenna up as high as you can. For DX you can talk it at any height but under different conditions a flatside beam at 18' at the boom may walk the dog over a groundplane at 72' in DX. The same is true for a simple dipole. I have a dipole at about 20' and it ourperforms my Thunder 8xb in dx under certain conditions.
If I understand right, the Imax being .64 wave will outperform the 1/2 wave groundplane in dx over 1500 miles. Height, ground reflexion, the wave factor of the groundplane, conditions, sunspots, etc., are all factors. I guess we must combine the factors which will help performance be its best more constantly. Few things are constant with signals.
mikefromms |
Gonzo
Member
Username: Gonzo
Post Number: 91
Registered: 9-2004
| | Posted on Thursday, November 04, 2004 - 6:24 pm: |
|
No Hams don't know it all.
However being a Ham, means you probably have experience on frequencys other than CB, and have much more experience than the average Cb'er putting up all types of antennas including wire antennas. As a Ham you probably have pretty good experience with antenna heights and towers.
The average CB'er puts a A-99 20 feet above his roof once.
Should you blatently disregard 50 years of Ham operator antenna research, just because you are not a Ham? Would that be smart?? Or maybe something could be learned?? Hmmm.
----------------------------------
Picking up on Mikefromms EXCELLENT response:
for local as Mike said...high as you can.
DX: different heights of different antennas will create different angles of ground reflection, which may actually HELP in DX.
--------------------------------
In other words if you talk regularly to DX at 750-1000 miles away....and you raise your antenna higher 60 feet or more then before... there is a possibility you will now NOT be able to reach stations within those distances as easily as before, but will be able to speak with stations much farther then before... 1500 miles +
-------------------------------
This has been proven over and over before by Ham operators......Of course you can choose to ignore this ridiculous nonsense. |
Road_warrior
Intermediate Member
Username: Road_warrior
Post Number: 170
Registered: 7-2004
| | Posted on Friday, November 05, 2004 - 12:24 pm: |
|
Gonzo,
Tech 833 said, 'The higher the better' is certainly true. But, for those who wish to
squeeze out the last degree of angle to stick
with half wave multiple rule.
He's not saying anybody is wrong by not
using half wave muliples.
JIM/CENTRAL PA/CEF 375 |
Tech833
Moderator
Username: Tech833
Post Number: 882
Registered: 8-2002
| | Posted on Friday, November 05, 2004 - 3:37 pm: |
|
If being a ham gives you slightly more experience with antennas than a CBer, what does being a 20 year broadcast engineering veteran give you? What about designing and building many AM BCB directional arrays and designing/building SW arrays do for you? I suppose the hams may have more experince than the broadcast engineers since a professional broadcast array is installed only once and proofed only once per year whereas, a ham is constantly fiddling with their amateur antennas.
In this case, I must agree, hams have more experince. I will step back and learn from all the amazing ham knowledge. I have been so blind to not recognize all the combined experince that suddenly is downloaded into a man's mind when they open the envelope from the FCC containing an amateur radio license. I would hope that all the experinced hams could somehow forgive me for doubting the pool of knowledge shared amongst the community of those who purchase antennas designed by others of limited professional knowledge, or build antennas from environmentally sensitive/recyclable materials like plastic pipe, duct tape, and broom handles. |
Mike0228
Junior Member
Username: Mike0228
Post Number: 11
Registered: 6-2004
| | Posted on Saturday, November 06, 2004 - 11:04 am: |
|
Depends on what you want to do. If your main interest is to talk to locals then the higher the better. Why? Simply because your antenna can "see" further to the horizon. For DX work, well that depends on propagation and where the DX is. Generally the further you want to work DX the higher you want your antenna. Why? Fewer hops/lower angle usually means stronger signal at the other end. Now you may be able to work New Zealand but the Caribbean may now be weak. Take a hint from successful Amateur contest stations. They will use stacked yagis with an arrangement to have them phased or use the higher antenna or the lower antenna alone. Most of us don't have the cash for that. So what do you do? I would say get the boom of the antenna up at least 1 wavelength which is doable for most of us for 10/11M. At lower frequencies hams shoot for at least 1/2 wavelength. Half wavelength height on the 40M band is about 67ft. Most of us can't do that so common wisdom is go as high as you can. I hope I haven't muddied the waters more because the real answer is there is no ideal height. What's ideal today may not be ideal tomorrow. That's the fun of experimenting with antennas. Don't know if he's been mentioned here before but do a search for L.B. Cebik W4RNL. He has a great antenna info site.
BTW verticals is a whole other subject. DX can be worked very successfully with a ground mounted vertical over a good ground screen but not worth much locally. Put a vertical on the ground about a half wavelenght from salt water and you will outperform a yagi that is too low.
Mike |
Dindin
Intermediate Member
Username: Dindin
Post Number: 429
Registered: 2-2004
| | Posted on Saturday, November 06, 2004 - 1:30 pm: |
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today I'm in the process of finishing up second tower here.it will have 11 meter 4 ele horz yagi at 45',a 6 meter 6 ele horz yagi at 55' and a 6 meter 5/8 vert at60' to the mount,should suite me ok.
|
Applejack
Intermediate Member
Username: Applejack
Post Number: 227
Registered: 8-2003
| | Posted on Sunday, November 07, 2004 - 1:45 am: |
|
a picture dindin? |
Unit199
Member
Username: Unit199
Post Number: 50
Registered: 8-2003
| | Posted on Sunday, November 07, 2004 - 10:05 am: |
|
I hope this post doesn't offend anyone, but I'm known for being outspoken. So here goes. The really only intelligent things I have read on this thread were by Tech808 and Tech 833. You guys keep talking about ham operators and although I am a ham, I didn't notice becoming any smarter after I passed exams.
I have been in radio for over 40 yrs. Long before I became a ham, and have been involved in television and AM/FM broadcast antennas. I have designed antennas for the military and NASA. I don't claim to know everything, because I would hope I never get so smart that I can't learn something new. 833 could teach you a lot, if you would just listen to him, instead of thinking that hams are the only ones that know anything. Like he said most hams are putting up antennas that are already in print and everything is there to tell you step by step how to build it. you want to read about antennas, read Lew McCoy. He is more knowledgable than the others that were mentioned in this thread. I will end this post by saying, keep an open mind and you may find out that you can learn from some of the people that does or has done work in this field.
Semper Fi!!!
Harve-Unit199 |
Gonzo
Member
Username: Gonzo
Post Number: 96
Registered: 9-2004
| | Posted on Sunday, November 07, 2004 - 11:00 am: |
|
Sorry if I offended anyone. Lets be clear:
I never said Ham's know it all
I never said just being a Ham makes you smart.
I did say being a Ham, means you probably have more experience than the avg CB'er with antennas and towers. I believe this to be true.
I did repeat what the ARRL says in their handbook about antenna heights. This is echo'd by William Orr a terrific CB /Ham antenna handbook writer if anyone cares to notice.
I did say that maybe people could learn from the multitude of books and research done by thousands of Ham radio operators during the past 50 years. This appears to make sense to me. I like to learn from anyone who has more experience than me. You can disregard this knowledge obviously and make your own conclusions of course. Its America.
I did compliment several people and their excellent responses to this thread.
------------------------------------
HOWEVER
Its getting kinda silly now, and the subject is hardly that crucial to a good sounding station (whether 36 feet or 42 feet high is more important). So Big Thunder I hope your set-up works out great, best of luck to you. |
Gonzo
Member
Username: Gonzo
Post Number: 97
Registered: 9-2004
| | Posted on Monday, November 08, 2004 - 3:39 am: |
|
Unit199.... I appreciate your response.
BTW--FYI....I am glad you have learned something from Lew Mc Coy..yes he is a knowledgeable antenna book writer. Unfortunately you must immediately ERASE anything you might have learned from Lew's books, and better yet please BURN any copies you may have.......WHY???
Well it seems that Lew is just some CB'er who passed a test!! |
Tech833
Moderator
Username: Tech833
Post Number: 885
Registered: 8-2002
| | Posted on Monday, November 08, 2004 - 8:49 am: |
|
Gonzo,
I do not believe you offended anyone. We all just want to make sure all the information here is accurate. Nothing personal at all. Yes, I used sarcasm because I wanted to make a point, but also lighten the moment.
Lew McCoy had other qualifications besides the ham license, so his work may be accepted as a slightly higher 'authority' then the average ham down the street.
Experimentation is a wonderful thing. Unfortunately, without the professional science community to perform checks and balances, hams occasionally are biased when it comes to their findings regarding performance of a project in which they have some emotional attachment or time investment. Very few hams have an antenna test range or the equipment or ability to provide true unskewed results or comparisons. 'Worked 10 countries on the first day' appears to be a glowing endorsement for a ham antenna, regardless of true performance. Case in point- My inverted L antenna yasterday was heard by so many CEF members on a test transmission, you would have thought it superior to an I2K. I can tell you that on former weekends I could go all weekend without a single contact on the Imax. However, yesterday, dozens of stations caught my test witht the inv L. Does that mean it works better than an Imax? Not a chance. Just conditions and chance.
This type of observation is why I always caution the statements of hams here in this forum. CBers have for so long been made to feel inferior by the hams that a mindset has been imbedded in the CB community. I am here to break that. I have fact and proven science on my side. The hams' years of CBer oppression is falling apart. I wouldlike to think I had a small part of it.
BTW, I am a ham licensee myself. I just do not believe I am superior to anyone. |
Unit199
Member
Username: Unit199
Post Number: 51
Registered: 8-2003
| | Posted on Monday, November 08, 2004 - 11:02 am: |
|
Gonzo,
I will first start by saying Lew McCoy is more than a cb'er with a license. Maybe you should check it out. Most hams were cb'ers before they were hams. They have just forgot where they come from. My experience with quite a few hams has not been what you would call pleasant. BUT that is another story. I started on CB and am very proud of still being a member of the CB community and most of the time being a ham.
I was experimenting with antennas for CB about 30 yrs before I became a ham. I am not saying hams are not knowledgable and at the same time cb'ers are also knowledgable.
I think that we can learn from each. I just don't like it when someone says hams are a bunch of snobs and whose fault is that? You will find that there are very knowledgable antenna people that are cb'ers. Maybe I came on A little strong, but as I said, I am a very outspoken person.
Semper Fi!!!
Unit199-Harve |
Jp1116
Member
Username: Jp1116
Post Number: 75
Registered: 5-2002
| | Posted on Monday, November 08, 2004 - 12:57 pm: |
|
I kinda figured if you can model an antenna with computer software then most all there is to know about antennas has been discovered and is available to anyone. About all we can do is tweak it to fit our application and our particular variables. I see it like amplifiers builders, everybody has invented a better mousetrap but in reality RF is going to act like RF. While you might tweak a circuit to best work with your situation and goals, what is left to discover?
Just so I can learn something out of all of this discussion, What kind of gain difference are we talking about by using the 1/2 wave multiples over a random height. I'm not worried about comparing a beam to an omni direction or taking into account that the antenna can "see" over an obstruction when a few feet higher but comparing say a PDL II at the same location at 36 feet to one at say, 30 feet. I'm not talking about an antenna at 72 feet or something like that but one that is just 6 feet lower off the half-wave multiple, just how much more will that show me on my s-meter. I have never seen a difference myself when just trying to hit a multiple and not just gain a height advantage. I've cranked my pole up and down and don't see any difference in my situation. Just wondered if this was like a guy worrying if his amp is putting out 600 against 750 watts when nobody can really tell the difference when all things are equal or should I move the antenna again to find that magical spot.
O.K. now you guys have made my brain hurt trying to figure out what everyone has said and I have to stand up and get off it.
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Tech833
Moderator
Username: Tech833
Post Number: 888
Registered: 8-2002
| | Posted on Tuesday, November 09, 2004 - 2:36 am: |
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JP,
There is no gain difference, only a takeoff angle difference. For the flattest (lowest) takeoff angle, use the 1/2 wave multiple rule. It has been pointed oiut ad nauseum, that the 1/2 wave rule will not make or break an antenna installation, it is just for those looking to squeak every last once of DX performance out of their installations. |
Gonzo
Member
Username: Gonzo
Post Number: 98
Registered: 9-2004
| | Posted on Tuesday, November 09, 2004 - 7:22 am: |
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Unit199.."Lew McCoy is more than a cb'er with a license." Yes I know, I was being sarcastic, I was commenting on Tech883's prior comments.
Jp1116..."I have never seen a difference myself when just trying to hit a multiple and not just gain a height advantage.".........
~~~~~~BINGO~~~~~~~ We have a winner....I agree
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I would hope Tech883 and I would both agree, (sarcasim aside) this is a little silly now.
I can only hope that no one asks, whether cutting your coax into 1/2 wave multiples gives you any gains as well. |
Wayne
Junior Member
Username: Wayne
Post Number: 33
Registered: 12-2001
| | Posted on Monday, May 30, 2005 - 9:59 am: |
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Tec. 833 I read what you said about FCC rules about hight of antennas. and if they wanted to crack down and pass pink slips it would be a lot of antennas that would be comming down. , |
Crackerjack
Advanced Member
Username: Crackerjack
Post Number: 568
Registered: 7-2004
| | Posted on Monday, May 30, 2005 - 11:28 am: |
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Wayne:
Plain fact is that one issue where the Government does crack down, is antenna height.
I think because there so many people involved with an axe to grind. From the FAA, to neighbors, to building code onspectors, to safety people. They have roo many reasonable arguments against you. The FCC really doesn't care.
The only defense is to be inside the FCC and local building code regulations, so that there are no glaring errors.
Face it, if your antenna looks like it might fall on my house, and I see it swaying in a high wind -It is easier to call tghe County Code Inspector than it is to knock your door. And I will do it -if your antenna looks like it might fall on my house.
And if I am under 60 feet and have not violated any building/safety codes -all you can do is talk behind my back. |
Bruce
Senior Member
Username: Bruce
Post Number: 2750
Registered: 9-2003
| | Posted on Monday, May 30, 2005 - 11:49 am: |
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We dont have a tower problem here .......
You can't have one. |
Crackerjack
Advanced Member
Username: Crackerjack
Post Number: 571
Registered: 7-2004
| | Posted on Monday, May 30, 2005 - 2:00 pm: |
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Bruce:
Shame, isn't it. I do what I can to stay "under the radar" here.
I am getting ready to mount a long sloper in the back yard, and the beauty of that is that I have complete privacy back there from everything but the road that the County Inspector rides. So far, he hasn't been a problem -so I am reviewing the local ordinated before I select the spot, etc.
A local State Police Officer put a tower on his property, he is in the boonies in a huge open area next to a cattle ranch -and the County came back and made him pull it down until he recieved a varience for a strobe lighted tower, (tower and guy wires are now marked with bright orange balls, too)and the FAA had to issue a Morse Code for the light to emit before, he could re-errect it.
While it didn't make sense to me at the time, I later watched a crop dusters operating over there, spraying the pastures.
Bingo -so my tax dollars are not always wasted.
My complaint is this, why can't I call the county before I errect the antenna and get a straight and helpful answer
Why? Because the antenna doesn't need a varience unlless it "violates the code"?
"Catch 22" |
Bruce
Senior Member
Username: Bruce
Post Number: 2755
Registered: 9-2003
| | Posted on Monday, May 30, 2005 - 2:46 pm: |
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Here you have to have a engineer design and install your tower. It must also pass faa and fcc rules. The engineer must sign off on 125 mph winds including the antenna.
Cost? 1000+ tower |
Crackerjack
Advanced Member
Username: Crackerjack
Post Number: 574
Registered: 7-2004
| | Posted on Monday, May 30, 2005 - 3:18 pm: |
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Well, if it would insure that God couldn't blow it down, it might be worth it.
I don't see why they worry about antenna towers, corrogated roofing materials are FAR more dangerous -flying around at 100mph.
You can buy that at Home Depot, and nail it to anything you want, without a permit in many cases. |
Crackerjack
Advanced Member
Username: Crackerjack
Post Number: 575
Registered: 7-2004
| | Posted on Monday, May 30, 2005 - 3:19 pm: |
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So bruce, how does one mount an IMAX 2000 down there in Disney Land?
What is legal and still popular?
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Bruce
Senior Member
Username: Bruce
Post Number: 2757
Registered: 9-2003
| | Posted on Monday, May 30, 2005 - 3:42 pm: |
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a pole ( under 2 in dia ) mounted antenna under 35 foot is exsempt the tv antenna installers got that passed. |
Yankee
Advanced Member
Username: Yankee
Post Number: 620
Registered: 7-2003
| | Posted on Tuesday, May 31, 2005 - 10:40 am: |
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My contacts for Sunday last should speak for my antenna highth. Where I live here in Oklahoma we at times get flat winds of 85 MPH and better. My beam installation is not much but it has stayed up. From the ground up, this is what I have, 17 foot 8 inches of heavy gauge inch and a half OD galvanized steel chain link fence pipe, the rotor, 6 foot of 2 inch mast to the boom of the PDL-ll and well guyed. My location is at the south end of the city on a hill out in the open and I don't dare go any higher with my beam, I like many others have to much of an investment to have mother nature take it down. I can't have a tower as I'm very close to the landing path of our small local airport for small aircraft, I can see the south end of the runway from my front porch,less than a mile away. |
