| Author |
Message |
    
Birddog01
Junior Member
Username: Birddog01
Post Number: 17
Registered: 11-2009
| | Posted on Tuesday, December 29, 2009 - 8:28 pm: | 
|
What is the proper way to co phase wilson fiberglass wipes 4 footers on a f-350 behind cab 5.6 feet apart |
Tech808
Moderator
Username: Tech808
Post Number: 17341
Registered: 8-2002
| | Posted on Tuesday, December 29, 2009 - 11:08 pm: |
|
CLICK HERE >>> C80-00017 9' Co-Phasing Harness
$9.99 W/PL-259 Ends.
Hope this help's,
Lon~Tech808
N9CEF
CEF#808~CVC#002
Radio Enthusiast!
|
Tech237
Moderator
Username: Tech237
Post Number: 1277
Registered: 4-2004
| | Posted on Wednesday, December 30, 2009 - 12:27 pm: |
|
At 5.6ft you'll not see much advantage. To be properly co-phased they need to be 1/4 wave apart or around 9ft.
At best, they'll look good.
Tech237
N7AUS
Chipmonks roasting on an open fire
Hot sauce dripping from their toes.
|
Slugo4449
Intermediate Member
Username: Slugo4449
Post Number: 190
Registered: 7-2004
| | Posted on Friday, January 01, 2010 - 12:23 am: |
|
I agree with Tech 237, it should be at least 1/4 wavelength apart, but even at 5.6 ft you will notice one thing. The lobes of your signal will be to the front and the rear of the vehicle. You WILL BE directional. |
Tech833
Moderator
Username: Tech833
Post Number: 1803
Registered: 8-2002
| | Posted on Friday, January 01, 2010 - 10:41 pm: |
|
SLIGHTLY directional. At only 5.6 feet spacing, that is about 56 degrees electrical.
Ideal separation for nulls to the sides of the vehicle is 180 degrees (about 18 feet), but 9 feet is a good compromise with minimas to the sides and about 70% of the major lobe going fore, aft, and to a lesser degree, up.
With 56 degrees of separation, you would have about 62% of your signal favoring the fore and aft with about 46% of your signal favoring the sides. However, as the antennas get closer than 90 degrees apart, you begin to incur some losses in the system. So factor in (estimate) 18% losses (vector difference between ideal and actual, squared plus cable and inverse phase losses) and you end up with about 44% of your signal going fore and aft and 28% of your signal going to the sides. 28% of your signal is lost in heat and dielectric and traveling wave cancellation in the cables.
In short, you would actually be better off using just a single antenna than co-phasing at such close spacing, unless you really want to minimize signal to the sides of the vehicle for some reason.
Your radio 'Mythbuster' since 1998
|
Sitm
Intermediate Member
Username: Sitm
Post Number: 330
Registered: 1-2004
| | Posted on Wednesday, January 27, 2010 - 10:46 am: |
|
Question for the techs on this issue. Not on a vehicle, but what would the optimal distance be if two antenna, (say two 102 inch whips) were seperated in a base situation. Of course with a ground plane on both. |
Tech237
Moderator
Username: Tech237
Post Number: 1286
Registered: 4-2004
| | Posted on Wednesday, January 27, 2010 - 3:02 pm: |
|
depends on where you want the signal to go. At some distances it will be at 90 degrees to the plane of the two antennas, and at others inline with the antennas.
Tech237
N7AUS
Chipmonks roasting on an open fire
Hot sauce dripping from their toes.
|
Tech833
Intermediate Member
Username: Tech833
Post Number: 133
Registered: 12-2001
| | Posted on Friday, January 29, 2010 - 9:13 pm: |
|
If you want maximum nulls when co-phased, 180 degrees (18 feet) is what you want. If phasing inline (antennas phased 180 degrees electrically), you want them 90 degrees (9 feet) apart.
Your radio 'Mythbuster' since 1998
|
