| Author |
Message |
    
Racer X (Unregistered Guest)
Unregistered guest
| | Posted on Friday, January 28, 2005 - 5:48 pm: | 
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Has anyone stacked two Imax 2000s - one up and one down? How did you feed them? Is there a noticeable gain advantage? |
Tech808
Moderator
Username: Tech808
Post Number: 4667
Registered: 8-2002
| | Posted on Friday, January 28, 2005 - 6:15 pm: |
|
Racer_X,
Yes I have seen them stacked but never one under the other.
They Probably used the:
A65-00074 PHASE 2 (A99) MATCHING HARNESS
$ 29.99
http://www.copperelectronics.com/cgi-bin/checkitout/checkitout.cgi?catalogSTORE:CKIE:prodA65-00074+
Lon
Tech808
CEF808
N9OSN |
Boxcar
Intermediate Member
Username: Boxcar
Post Number: 335
Registered: 4-2002
| | Posted on Friday, January 28, 2005 - 10:00 pm: |
|
What should the best distance be in between cophasing these antenna's? |
Road_warrior
Intermediate Member
Username: Road_warrior
Post Number: 270
Registered: 7-2004
| | Posted on Saturday, January 29, 2005 - 10:02 am: |
|
Your better off buying a small beam rather
than cophasing 2 Imax 2000's./ But, it is fun
and a learning experence playing with the idea./
JIM/CENTRAL PA/ CEF 375 |
Boxcar
Intermediate Member
Username: Boxcar
Post Number: 336
Registered: 4-2002
| | Posted on Saturday, January 29, 2005 - 2:00 pm: |
|
What's the main issue when cophasing these antenna's anyway? Better reception? Power multiplication? |
Road_warrior
Intermediate Member
Username: Road_warrior
Post Number: 272
Registered: 7-2004
| | Posted on Saturday, January 29, 2005 - 7:53 pm: |
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We had a guy around here that cophased two
A-99 together & turned them with a rotor./
I noticed it was alittle stronger on transmit and
he said, it recieved better than just 1 A-99./
I have plans on how to do it, gotta dig them
out of the attic...//
JIM/CENTRAL PA/CEF 375 |
Racer X (Unregistered Guest)
Unregistered guest
| | Posted on Saturday, January 29, 2005 - 9:35 pm: |
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Phasing omnidirectional antennas can make them directional. You generally want about a full wavlength of distance between the antennas to get the best directivity.
When you feed them in phase the gain is perpendicular to the plane of the antennas, and when you feed one antenna 180 degrees out of phase you get directivity in the plane of the antennas. It's a cheap and easy way to get directional performance without using a rotor.
By stacking one omnidirectional antenna on top of the other and feeding them in phase you should realize a fair amount of omnidirectional gain over using just one antenna. It's very common for VHF and UHF antennas to be made this way.
It occurred to me that I've never heard of anyone doing this with CB antennas so I thought I'd ask if anyone else has. |
Rick330man
New member
Username: Rick330man
Post Number: 1
Registered: 9-2005
| | Posted on Sunday, September 18, 2005 - 12:32 am: |
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My base set up consists of two 102" whips co-phased. I've got a 27' run of RG-8X from the room to outside. The second leg is an 18' run of RG-8. The latter connects to the 21' cophasing runs of RG-59. The two whips are set deliberately set up just a hair over 36' apart (one full wave length). With all of these coaxial runs and with the SWR headaches people often get trying set up a co-phased array, my SWRs run from 1.4 on channel 40 to 1.6 on channel 1. The cophased set up beats the unity gain I'd get with just one antenna, and it was a fun project too. |
