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Message |
    
Uillean
New member
Username: Uillean
Post Number: 8
Registered: 12-2006
| | Posted on Thursday, December 14, 2006 - 10:40 am: | 
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This isn't a question for the Tech, but this is where most of the antenna discussion is happening, so:
How many here are using quad antennas? Did you settle on vertical or horizontal, and why?
I recently built a 2 element quad, have been happy with it so far, VSWR is less than 1.2:1 across the 40 channels-- with no tuning, using a 1/4 wave matching section.
What are your general impressions of your quad?
thanks,
Uillean |
Revpo
Intermediate Member
Username: Revpo
Post Number: 106
Registered: 7-2006
| | Posted on Thursday, December 14, 2006 - 10:48 pm: |
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Where did you get the info on building the quad..materials etc..
revpo
CEF 795/doctor |
Bruce
Senior Member
Username: Bruce
Post Number: 4233
Registered: 9-2003
| | Posted on Friday, December 15, 2006 - 10:04 am: |
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Quads are good antennas and have about 2 db more gain than a beam. The quad was invented by the enginers at HCJB RADIO and is widely used by hams today |
Uillean
Junior Member
Username: Uillean
Post Number: 10
Registered: 12-2006
| | Posted on Friday, December 15, 2006 - 10:28 am: |
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Revpo,
I'd been kicking this idea around for years, but the Cubical Quad book by William Orr and Stuart Cowan is probably the best source-- and I bought it used off Ebay for about 7 bucks. They don't have dimensions specifically for 11m, but all the standard formulas are there, so calculating them is no big deal.
I got all the materials (except for the wire) from Lowes-- used 3/4" x 3/4" angle aluminum for the hubs, ripped straight-grained 1x4s into 3/4" square strips for the spreaders. Used 2x2s for the boom and mast into the rotor. Ended up having to order the wire-- the days of walking into Radio Shack and getting actual radio stuff are over, I'm afraid.
The wood ends up being only slighty heavier than a similar antenna I built years ago using sch 40 PVC for the spreaders, but is much more rigid. I settled on a 5' 6" boom to give a good match to the 1/4 wave 75 ohm matching section, but you could space the elements around 3 1/2 feet and have a good match to 50 ohms if you wanted.
You could also make a wire gamma match and use a short length of coax as a gamma capacitor, but the matching section doesn't require any adjustments, so I went that route.
There are several good sources on the web, W4RNL's site may be overload, but it's good stuff. I've seen Signal Engineering's website mentioned on this board- very well done, but has some inaccuirate info (gain figures are wrong, f/b ratios, etc.).
But I have maybe $40 total in this antenna, including the flat black paint. May write an article about it for the Copper Forum if there's any interest. |
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