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Author Topic: want to build 11 Meter homebrew antenna  (Read 8129 times)
113MB159
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Posts: 2




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« on: September 26, 2005, 12:22:07 PM »

Actually i want to build some antenna for 11 meter
(27.238 mhz) but i do not know what the first think to do.. I hope somebody can help me..

My idea to build antenna simple because my home base very-very limited area..

TQ
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WB6BYU
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Posts: 13479




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« Reply #1 on: September 26, 2005, 02:56:48 PM »

Cut three pieces of wire each 2.6m long.

Connect one piece to the center conductor of the coax cable
to your radio.  Hang the top end from a tree or wooden
pole as tall as you can make it.

Connect the other two pieces of wire to the shield (outside
metal braid) of the coax cable.  Run the two wires in
opposite directions: they can be horizontal, or they can
angle down towards the ground.

Connect the other end of the cable to your radio.

You can use any type of wire that you can find.
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WA9SVD
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Posts: 2198




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« Reply #2 on: September 27, 2005, 04:48:31 PM »

Well, this is not exactly the best (or most friendly) place to ask about "CB"  anything.
    But if you wish information on designing and/or building an antenna, (for whatever band/frequency) there are VERY GOOD resources available, including the ARRL (American Radio Relay League) Handbook, and the ARRL Antenna Book.  They will give plenty of ideas, plus information on scaling designs for any other frequency under the sun.  And some may be available at your local library.
    And DO consider the Field of Amatuer Radio.  It has much more to offer than the limitations of the CB Service, and there will be many here willing to help you along the way.
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N5EAT
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Posts: 175




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« Reply #3 on: September 27, 2005, 08:48:13 PM »

Do what WB6BYU said.  You can mount the ends so they
are vertical or horizontal.  You can arrange them so they form an "L" shape.  

Just make sure that the inner coax conductor does not touch the braid. This will produce a short and blow your rig (probably).  

You will find that this type of antenna will outperform most of the commercial non-beam antennas you can buy.  

If you want to know how to calculate the length of the legs of your antenna, divide 468 by the Frequency in Megahertz.  If you want to make an antenna for 27.3megahertz, divide 468 by 27.3.  That will give you a length of about 17.14 feet.  Cut a wire 17.14 feet in length.  Now, cut that in half.  Each leg of your antenna will be 8.47 feet.  (the math was done on a web based calculater and could be wrong..).

Just make sure that your coax does not run parallel to either of the legs  and you'll do fine.  If you have an swr meter, cut the wire about a foot longer than you calculated.  Then, after you've got your legs soldered to your coax, measure your swr.  If it's too high, cut an inch off each leg.  The swr should go down.  Cut another inch or two.  If it still doesn't go down, try the antenna on different channels.  If it never gets better, start over or re-arrange your antenna.  If you do this right however, using the formula should result in an swr of < 3 to 1 or better
even if you don't have an optimum place to put your antenna.  Large metal objects can really mess up your swr, so avoid proximity to them at all costs.  Using plastic coated speaker wire can really help keep your antenna from contacting other metal objects such as nails, etc.  
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WA4PTZ
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Posts: 528




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« Reply #4 on: September 29, 2005, 05:26:12 AM »

I still can't understand why some folks feel that
their manhood is being attacked when folks ask
questions about CB. I ,and thousands of others,
got our first taste of radio with CB, which led
us to seek more information and then a HAM license.
Your manhood is safe.
Now, CB antennas can be calculated and constructed
just like HAM antennas. You just have to use the
correct frequency for your calculations. Center of
the band would be good. I built a 2 element quad
for my father-in-law way back when so he ,as a CB'er,
could talk to his friends in the community. His
friends were very impressed and some became HAMS.
Good luck 73,
Tim
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WB6BYU
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Posts: 13479




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« Reply #5 on: September 29, 2005, 01:42:17 PM »

Actually, Tim, I thought this time we did a pretty good
job of being helpful with relatively little flaming or
bellyaching.

Just because there have been other threads more deserving of
your comments, of course, doesn't mean that it isn't good
advice for all of us.
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WA9SVD
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Posts: 2198




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« Reply #6 on: September 29, 2005, 10:18:11 PM »

Tim,
    I believe you are overreacting.  Nobody made disparaging remarks or value judgements about the person who asked the question, or about CB.
    A valid question was asked, and the person stated that he "didn't know where to start."  Some of the best places to start ARE the ARRL books (among others) and understanding construction techniques from a book (with pictures) is infinitely better than getting instructions on this forum.  And the books gives enough theory to allow scaling an antenna to any practical frequency.
    And if the person is at the level of wanting to construct antennas, perhaps he would be interested in pursuing Amateur Radio, as well.  If not, that's his choice.  Just wanted to make the offer.
    I'll be more than willing to help anyone who has a legitimate question, regardless of License Class, lack thereof, or from a different Radio Service.  As long as it doesn't involve anything that is illegal, (or immoral, or fattening...) I think we all should be helpful to anyone and everyone.  Who knows, they just MIGHT become Amateurs if they find we are all helpful.
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113MB159
Member

Posts: 2




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« Reply #7 on: October 21, 2005, 09:34:58 AM »

Thank you my friend to reply my question..I get some idea and try to built one..

TQ
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N4ZYV
Member

Posts: 90




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« Reply #8 on: November 04, 2005, 04:26:22 PM »

TQ, it may take some expirimentation to get it to match (transmitting antennas MUST be properly tuned to the frequency or channel they are going to be used on). I have to ask: do you have an SWR meter? This meter is absolutely neccessary to properly set the antenna for your transmitter. Without it, you are chancing wrecking your radio.

Learning and expirimenting with different antennas can be great fun. There are many simple designs that can be easily and cheaply constructed. Leave the more complicated antennas for when you have some experience and a good book or two.

Also, don't be afraid to look into getting a ham license and really opening up your radio world!
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KC9SZU
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Posts: 0




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« Reply #9 on: December 10, 2005, 04:43:09 PM »

from a fellow cb'er, you ham's in here are a good crowd. here's my idea that brewed amongst my cranium one day.

i had bought some 50' roll of 5/16" copper tubing, had some left over fence top rail, a 7'3" 1 1/4" piece of square tubing, and a '75 celica axle left over and my idea came together.

the driven element would be 212" with a gamma match that was 1/4" and 27" long with 24"length and a 90* bend with 3". the 3" section was screwed in at a location where the end of the gamma arm hovered above the center of the dipole. the gamma match was finalized by inserting a tight fitting wire of roughly 10 ga. into it until the swr is a match. the gamma arm i'm not sure if it should face up or out but i place mine in relation to where i think the beam's going, so, outward. the reflector i made of 223" up to 226" of 5/16" copper tubing that will be spaced behind the driven element by 7'2"+/- 2-3".

it just so happens that i had a perfect boom for a 2 element cb antenna. 7'2" of 1 1/4" thin sqare steel tubing, that seemed to had already had the holes drilled where they needed to be. kinda like it was meant for it!

gots lots of toprail fence pole, and a coupler. measured out 18ft and what i intended to drive into the ground and drove it next to my window. put my top rail coupler in about 4' off the ground and now i have no need for some expensive antenna rotator!! ofcourse, i mounted it to the side of my home! but how was i gonna get a boom on top of my fence pole? easy, i had an extra '75 celica axle leftover from a repair. 1 half shaft did the trick fitting extremely tight into the fence pole. with a little digging i found some make shift brackets. mounted it between the lug studs and fits good.

if you've ever bought one of those lousy tent-like carports with those 3' section tube poles that hold it up, well, 3 make the support for 1 element and 3 for another. with the right manipulation, i cut a hole on top, drilled a hole through the bottom bolted it to my new found boom, same for the other end, and set my elements in place atop,(insulated from) my homebuilt junk pole and platform, whalah! it seems to work very well, with appropriate tuning as mentioned above with gamma match. though i would recommend going above 1/2 wavelength high or roughly 18ft and above. before i realized that i had this leftover carport tubing i had constructed it with 2x4's supporting the elements, so i am very sure of my constuction techniques/practices are by far, well beyond sufficient, though when hurricane rita decided to blow by us in houston, it was too close to call to wonder if it would have stood, lol! and i willingly and furiosly raced to take it apart.

i've had cb'ers come by my house thinking i couldn't do that or this... if you have the patience, the will to do it, and a thought in your head, you can do it, just try to imagine the junk above. if you really wanted you could get a good ham antenna tuner, and i dont mean the swr box either. a antenna tuner and a fence can make an antenna, but may suffer some efficiency loss, i'd suspect. best easy reference is the arrl's handbook for the radio amateur. i think it's the best! good luck

73's from houston, tx
couch potatoe ch.19 27.185mHz
1600 ch.38 lsb 27.385mHz
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K7MBL
Member

Posts: 5




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« Reply #10 on: March 03, 2007, 04:35:25 PM »

Yep! As per a previous post, this is the place if you want to get flamed, ridiculed, questioned or if you're just looking to lose interest in amateur radio in general or if you would like to engage in an argument regarding damned near anything.

If you're looking for an outstanding CB (11m) antenna, I would highly recommend the copy of the Starduster M-400.  Yea, you can build a dipole, convert a mobile or erect a vertical monster, but the Starduster is inexpensive, easy to tune and not too big of an eye sore.  And it's fairly broad-banded to boot.  And the best thing is that it is easily tuned to 10m should you decide to earn your Tech ticket (if you haven't already).

Don't get discouraged senor.  There's a bunch of holier-than-thou fellas in the Ham hobby who aren't very skilled at encouraging new operators, but it's a great hobby nevertheless.  Good luck with your CB endeavors!!
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