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[Photos] Home Built Antenna

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K9GTJ

Member
Joined
May 20, 2006
Messages
612
Location
Kokomo, IN
I finally took an hour on Saturday and built the "off-center dipole" from the wiki -
http://wiki.radioreference.com/index.php/Homebrewed_Off-Center_Fed_Dipole

It was a pretty easy project that almost anyone could do for fun.

I started by picking up the supplies a few weeks ago.


I decided to use copper caps rather than plastic.


I cut the 2 elements to length after the end caps were attached.


A tubing cutter is much easier to use than a hack saw.


It makes for nice clean ends.


I clamped it down and drilled for the stainless steel screws. A light touch is best on the brittle plastic T. (As cheap as they are, you might just get 2 while you are at the store.)


The finished up T connection.


I made up about 25' of RG6U myself. I had picked up an F to BNC adapter at RS when I got the balun.


A quick test and it works!


I just used an old mailbox post for a quick mount. It works pretty well for being low to the ground. Maybe another day I will get it roof mounted.
 

K9GTJ

Member
Joined
May 20, 2006
Messages
612
Location
Kokomo, IN
scanner231 said:
what freq. range does this dipole work the best for? looks great
This is seems to be a copy of the Grove Omni-II VHF-UHF Receiving Antenna which has a 25-1300 MHz range - http://www.grove-ent.com/ANT5.html

I am not sure how it works in the 800 MHz range as that is my primary listening range and I can pick that up on both scanners without any antenna.

It did pick up some public safety about 70 miles away tonight in the 154 MHz range and I can get decent improvements in 2 meter reception from the local repeater and other nearby counties.
 
N

N_Jay

Guest
Hey, your driveway needs a new seal-coat!:lol:

Nice job, also!

BTW, you may want to paint the PVC to add some UV protection.

I have been told that a good coat of black primer covered with white gloss is best, but then the guy who told me that could have just been making it up. (well it sounded logical)
 
Last edited:

tneff

Member
Joined
Jun 23, 2004
Messages
144
Location
Rosenberg, Texas
I cant open the referenced link to the wiki , so please excuse the possible goofy question. What would be the difference in using emt instead of copper pipe ? Thanks
 

user786

Member
Joined
Jun 17, 2006
Messages
9
Can anyone clarify for all of us what size copper tubing was used ? I didn't see it mentioned anywhere in this thread or in the wiki.
I have some 1/4" hollow aluminum tubing sitting outside.

Could I use that instead of going out to buy copper pipe ?

Would my measurements be the same 48" and 18" or do I need a different measurement based on the diameter and type of metal using my aluminum tubing being different ?

Thanks
 

tonsoffun

Senior Moderator
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Messages
1,499
Location
Central Ontario
user786 said:
Can anyone clarify for all of us what size copper tubing was used ? I didn't see it mentioned anywhere in this thread or in the wiki.
I have some 1/4" hollow aluminum tubing sitting outside.

Could I use that instead of going out to buy copper pipe ?

Would my measurements be the same 48" and 18" or do I need a different measurement based on the diameter and type of metal using my aluminum tubing being different ?

Thanks
Hey Kokomo1,
Great job on the antenna. I think you should seal the connection points with some RTV sealant to keep the weather out.
Other then that you did a great job, and thanks for putting the pics up! Is that 1/2" Tubing?
Take care
 

K9GTJ

Member
Joined
May 20, 2006
Messages
612
Location
Kokomo, IN
I used 1/2" tubing. I plan to seal it before it goes up higher.

N_Jay - when will you be over to sealcoat? (Hey you brought it up!) Actually, is was done last year and is in good shape. I plan to upgrade to concrete in a couple of years anyway.

Thanks again for the compliments.
 

K9GTJ

Member
Joined
May 20, 2006
Messages
612
Location
Kokomo, IN
GrayWolfSA58 said:
nice work...how bout a beam
I really don't need a beam for anything unless I want to DX some 800 MHz trunked systems. The problem is I don't have a good location for the antenna that isn't a considerable distance from listening post. The loss for 800 MHz seems to be quite high so I am not thinking I will even try to tackle that.

But who knows if I had a beam antenna plan. ;)
 

Scar

Member
Joined
Jan 22, 2006
Messages
25
Is there really any difference between aluminum, copper or stainless steel?

I want to try to build a few different antennas for 800mhz and 150mhz and would like to know the pro/cons of each material.

Thanks
 

ka3jjz

Wiki Admin Emeritus
Joined
Jul 22, 2002
Messages
21,881
Location
Bowie, Md.
user786 said:
Can anyone clarify for all of us what size copper tubing was used ? I didn't see it mentioned anywhere in this thread or in the wiki.
I have some 1/4" hollow aluminum tubing sitting outside.

Could I use that instead of going out to buy copper pipe ?
I seem to recall from the original discussion that the antenna becomes more broadbanded using the larger diameter elements. If true, it seems you would sacrifice some bandwidth going with the narrower diameter tubing.

Seems like a useful homebrew project, to be honest. Sure wish I had the skill to build one of these. 73s Mike
 

K9GTJ

Member
Joined
May 20, 2006
Messages
612
Location
Kokomo, IN
JeffTurner said:
Why copper?
Other than the obvious conductive properties of copper, my guess would be it is (relativly) cheap and easy to come by plus is easy to work with.
 

sony

Member
Joined
Mar 31, 2006
Messages
203
kokomo1 said:
I finally took an hour on Saturday and built the "off-center dipole" from the wiki -
http://wiki.radioreference.com/index.php/Homebrewed_Off-Center_Fed_Dipole

It was a pretty easy project that almost anyone could do for fun.

I started by picking up the supplies a few weeks ago.


I decided to use copper caps rather than plastic.


I cut the 2 elements to length after the end caps were attached.


A tubing cutter is much easier to use than a hack saw.


It makes for nice clean ends.


I clamped it down and drilled for the stainless steel screws. A light touch is best on the brittle plastic T. (As cheap as they are, you might just get 2 while you are at the store.)


The finished up T connection.


I made up about 25' of RG6U myself. I had picked up an F to BNC adapter at RS when I got the balun.


A quick test and it works!


I just used an old mailbox post for a quick mount. It works pretty well for being low to the ground. Maybe another day I will get it roof mounted.
Looks like the Channel Master Antenna or Scant-Antenna
 

PeterGV

K1PGV, ScannerCast author
Joined
Jul 10, 2006
Messages
753
Location
Mont Vernon, NH
Nice project, and great pictures. Thanks for sharing kokomo1.

Now this looks like a hardware project that even *I* could build. But I'm confused by the antenna's dimensions. I hope somebody's measured this antenna and/or can clarify my understanding:

If this is a (rather conventional) half-wave OCF dipole, it's resonant frequency would be very close to F=90MHz (and 2F, 4F, 8F). Also, I'd expect the short-end to be 33% the overall length... but it's 27% of the overall length.

I'm (certainly) not arguing that this antenna doesn't "work"... I'm merely wondering what its actual characteristics are.

Anybody able to offer any help? Happen to build one of these and toss an antenna analyzer on it?

P
 
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