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Hawk1
Junior Member
Username: Hawk1
Post Number: 29
Registered: 11-2003
| | Posted on Saturday, March 13, 2004 - 11:23 am: | 
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anyone ever compare these two? was reading where some people say glass antennas are bleeder sticks..the wolf is all metal as opposed to the imax,,they are both .64 wave tho the imax is a little taller..the wolf is 22 feet tall..i belive the wolf sells for 145.00,,also the wolf comes with 4 ,,9 foot ground planes as the imax gpk is alot shorter..the wolf also has a top hat for static disapation..would realy like to see a comparison test between these two..hk |
Bigbob
Senior Member
Username: Bigbob
Post Number: 1743
Registered: 12-2001
| | Posted on Saturday, March 13, 2004 - 1:35 pm: |
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A top hat is usually for tuning if the antenna presents too much inductive reactance then they add a top-hat to cancel it out. |
Yankee
Junior Member
Username: Yankee
Post Number: 44
Registered: 7-2003
| | Posted on Saturday, March 13, 2004 - 5:37 pm: |
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I kinda think it's which one you like, it's hard to judge antennas. Because no 2 antennas will act the same and location is a huge factor, after 41 years on 11 meters I've found the glass to be best. the connections on metal antennas over the years get dirty, you have to pull them down and clean them up, screws on the metal go bad. So antennas are a matter of choice, my station sports an I MAX-2000 5 years old and still as good as new. Yankee |
Bigbob
Senior Member
Username: Bigbob
Post Number: 1744
Registered: 12-2001
| | Posted on Saturday, March 13, 2004 - 8:34 pm: |
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One thing though seen a fiberglass and a metal antenna after a direct lightningstrike,the heat generated by the lightning super pressurises the air or other gasses in the fiberglass and causes it to shatter,thousands of pieces,the metal one just showed some loss of metal at tip but otherwise was undisturbed,as far as performance the glass one has a copper radiator,and the metalones usually use aluminum,some use stainless steel,if corrosion is a bad problem,take assembled antenna to a good welding shop and have them mig weld the sections then you will have a solid seamless radiator free from loosening and corrosion and superior in fending off lightning,it would be interesting to sub out the fiberglass and replace with aluminum adjusting for velocity factor but retaining the stub with the tuning rings,a hybrid so to speak,the fiberglass is there just to keep us stupid people from killing ourselves on power lines. |
Creator
Member
Username: Creator
Post Number: 54
Registered: 1-2004
| | Posted on Sunday, March 14, 2004 - 2:27 am: |
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Hawk1.. What do you mean "bleeder sticks", and can you provide links to what you read..
Sounds like a great comparison, is it true aluminum gets out better? |
Yankee
Junior Member
Username: Yankee
Post Number: 45
Registered: 7-2003
| | Posted on Sunday, March 14, 2004 - 11:04 am: |
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Bigbob,
I'll wager that the aluminum antenna was fried, and the coax cooked and if there was a radio hooked up some damage there also. several years ago the same thing happened to me fried the coil in the base of a CLR2, came down the coax RG8 opened that up for about 2 feet melted the center conductor about a foot went to ground on the base of a floor lamp, cooked the almost new sideband mobile that was hooked up. You can bet i'm a believer even when there is a hint of a thunder storm, I unhook and unplug every thing in the shack, when I'm away from home I do the same.
Yankee |
Bigbob
Senior Member
Username: Bigbob
Post Number: 1752
Registered: 12-2001
| | Posted on Sunday, March 14, 2004 - 6:56 pm: |
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Actually it was a star duster,no coil in it,ground wire was melted,coax was disconnected and in mason jar,but unharmed,radio is still working after that(20 years),well pump was fried,some house wiring had to be replaced,I have the antenna in my barn with replaced tip 2" was burned off top,but was still usable swr was 2 to 1 on ch19,but he used it on 27.615 all the time and swr was improved.Antron99 was in pine tree, tree was burned to ground, antron was all over yard,coax was burned to a crisp,coax end was in mason jar,entire radio room was gutted with fire,house became unlivable due to water and fire dammage.Copper sells a lightning arrester called Polyphazer that allows you to keep the radio connected and recieve a direct hit and suffer no damage to house or radio,but I assume everything above it may suffer damage,Tech833 is the one to talk to concerning this. |
Creator
Member
Username: Creator
Post Number: 55
Registered: 1-2004
| | Posted on Sunday, March 14, 2004 - 9:31 pm: |
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I was reading, the only real thing you can say about an aluminum antenna is the SWR can change during wet or icey weather...BUT.....what if you sprayed clear enamel all over the antenna, insulating it from wetness... Would'nt your SWR's remain unchanged.... I highly doubt a thin coat of dry clear enamel will have any negative effect on the antenna, on a fiberglass antenna the signal has to go through fiberglas first before it travels out. I'm sure a thin coat of enamel would be like it was never there..
Any thoughts? |
Bigbob
Senior Member
Username: Bigbob
Post Number: 1753
Registered: 12-2001
| | Posted on Monday, March 15, 2004 - 12:05 am: |
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well,try it if it works for you then you,ve uncovered somthing,if it works for others then we have gained knowledge
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Bigbob
Senior Member
Username: Bigbob
Post Number: 1754
Registered: 12-2001
| | Posted on Monday, March 15, 2004 - 12:21 am: |
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moisture changes the radiation resistance of the radiator,rf uses the skin effect to travel on a conductor if the conductor is wet then the water is the suface of the conductor no longer the metal,paint and fiberglass is invisible to rf,because of the proximity of the fiber glass water on it is also invisible,thus you see it is unessessary to chop down all the trees in the antennas field it does not "see" them. |
Creator
Member
Username: Creator
Post Number: 56
Registered: 1-2004
| | Posted on Monday, March 15, 2004 - 12:53 am: |
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Enamel is what they coat the wire thats spun into a transformer also electro-magnets, I bet it would be invisible on a aluminum antenna also.. |
Creator
Member
Username: Creator
Post Number: 57
Registered: 1-2004
| | Posted on Monday, March 15, 2004 - 5:39 pm: |
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RE: rf uses the skin effect to travel on a conductor
An aluminum antenna has much more surface area than the wire inside of a fiberglass antenna. I wonder since rf travels on the surface, if the extra surface area on the aluminum makes for better gain on the transmit signal, hence what people say about it getting out better...
I would like to see a comparison betwen the two..
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Bigbob
Senior Member
Username: Bigbob
Post Number: 1757
Registered: 12-2001
| | Posted on Monday, March 15, 2004 - 6:00 pm: |
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It has to do with l/d ratio,length/diameter,the larger diameter radiator is slightly shorter,physically for the same electrical length,hence the capacity hat,if it is the same length as i-max then it has inductive reactance that must be canceled out with capacitance,it is easier to make the antenna a little long and add a capacity hat. |
Tech833
Moderator
Username: Tech833
Post Number: 591
Registered: 8-2002
| | Posted on Tuesday, March 16, 2004 - 1:39 pm: |
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Answers-
Bigbob
"moisture changes the radiation resistance of the radiator,rf uses the skin effect to travel on a conductor if the conductor is wet then the water is the suface of the conductor no longer the metal,paint and fiberglass is invisible to rf,because of the proximity of the fiber glass water on it is also invisible,thus you see it is unessessary to chop down all the trees in the antennas field it does not "see" them. "
*** Moisture does not change much on the aluminum antenna, except perhaps lowering the velocity factor slightly. Paint and fiberglass is not invisible to RF. RF slows down when traveling through these materials. That effectively lowers the velocity factor. In far field conditions, it has the effect of changing the pahse. When signal out of phase meets signal still in phase with the transmitter (other side of the tree) the two fields will cancel each other to some extent. Trees do not 'absorb' your RF, they slow it down.
Creator
"Enamel is what they coat the wire thats spun into a transformer also electro-magnets, I bet it would be invisible on a aluminum antenna also.. "
*** No. See above.
Creator
"RE: rf uses the skin effect to travel on a conductor
An aluminum antenna has much more surface area than the wire inside of a fiberglass antenna. I wonder since rf travels on the surface, if the extra surface area on the aluminum makes for better gain on the transmit signal, hence what people say about it getting out better... "
*** No. Aluminum antennas being of larger diameter elements will lower the Q and thusly improve the bandwidth and power handling characteristics.
Bigbob
"It has to do with l/d ratio,length/diameter,the larger diameter radiator is slightly shorter,physically for the same electrical length,hence the capacity hat,if it is the same length as i-max then it has inductive reactance that must be canceled out with capacitance,it is easier to make the antenna a little long and add a capacity hat. "
*** Perfect! |
Hawk1
Junior Member
Username: Hawk1
Post Number: 30
Registered: 11-2003
| | Posted on Tuesday, March 16, 2004 - 2:24 pm: |
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creator,,by bleeder stick i mean alot of people say glass sticks cause alot of tvi..why a glass one would do this more than a metal one,i cant say but would like to know if anyone out there knows.... |
Highlander
Intermediate Member
Username: Highlander
Post Number: 460
Registered: 12-2001
| | Posted on Tuesday, March 16, 2004 - 3:11 pm: |
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It's a myth. Tech833 can explain better than me, though. |
Bigbob
Senior Member
Username: Bigbob
Post Number: 1764
Registered: 12-2001
| | Posted on Tuesday, March 16, 2004 - 6:46 pm: |
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God I'm glad you came in there Tech833,I knew I was getting awful close to "out of my league",I'm so glad you came and shedd the light of truth on this according to antenna theory,I was going by what I remembered,but you work with this everyday,so I knew I may have accidently made a falsehood,but was not sure as I remembered it that way,thank you ,thank you. |
Tech833
Moderator
Username: Tech833
Post Number: 595
Registered: 8-2002
| | Posted on Tuesday, March 16, 2004 - 8:54 pm: |
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Bigbob,
You are one of the good ones. You do not spread false information. In my experience, if you do not know for sure, you usually state such. For that, I thank you. |
Creator
Member
Username: Creator
Post Number: 59
Registered: 1-2004
| | Posted on Tuesday, March 16, 2004 - 9:13 pm: |
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So, what slows down the velocity more, a thick coat of fiberglass mixed with resins possibly epoxy, or a micro thin coat of enamel. I know I have a radio shack antenna next to me that is a wire coated in fiberglass, then was dipped in black plastic.
I was just listening to some of the locals on 35 complain about their SWR's tonight (it's snowing and raining all day) and I know they have aluminum antennas. I still think a quick coat of enamel would do the trick. |
Tech833
Moderator
Username: Tech833
Post Number: 600
Registered: 8-2002
| | Posted on Friday, March 19, 2004 - 1:30 am: |
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Enamel has a lower VF than a thick layer of fiberglass. What was the point? |
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