Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: A Sterba Curtain with Extended Double Zepp Length Elements  (Read 904 times)
WA2TPU
Member

Posts: 210




Ignore
« on: March 05, 2013, 09:51:00 AM »

Hi to All.
Last November's flood damage here on my land on Wilkins Brook has been finally clearly. After looking over the area I now have to use I'm thinking about putting-up another Sterba Curtain for possibly 20  or maybe 15 meters. I have the room to build a 8 element array.

I was wondering IF...IF anyone out there has ever built a Sterba Curtain using 5/8 wavelength elements(43 feet on 20 meters) instead of the 34 feet long half wavelength elements.

IF so, what was their impressions were...Huh? the radiation patterns might be...???and most of all is it worth it to go to the 5/8 wavelength over the half wavelength typical configurations for a regular Sterba Curtain...Huh

Any and All thoughts would be greatly appreciated.
Thank you.
Best regards and many 72/73.
Don sr. --WA2TPU --
Logged
WA2TPU
Member

Posts: 210




Ignore
« Reply #1 on: March 05, 2013, 10:19:46 AM »

Hi to All.
Last November's flood damage here on my land on Wilkins Brook has been finally cleared away. After looking over the area I now have to use..... I'm considering  putting-up another Sterba Curtain for possibly 20  or maybe 15 meters. I have the room to build a 8 element array on 20....maybe a 12 element on 15 meters.

I was wondering IF...IF anyone out there has ever built a Sterba Curtain using 5/8 wavelength elements(43 feet on 20 meters) instead of the 34 feet long half wavelength elements.

IF so, what was their impressions were...Huh what the radiation patterns might be...Huh the gain Huh And most importantly of all....... Is it worth it to go to the 5/8 wavelength over the half wavelength typical configurations for a regular Sterba Curtain...Huh??

Any and All thoughts would be greatly appreciated.
Thank you.
Best regards and many 72/73.
Don sr. --WA2TPU --
Logged
WB6BYU
Member

Posts: 13342




Ignore
« Reply #2 on: March 05, 2013, 11:11:20 AM »

Technically, of course, 5/8 wave is NOT the length of an Extended Double
Zepp - that should be 5/4 wavelengths.

In order to get the phasing correct, to use 5/8 wave elements you would have
to shorten the vertical spacing.  (Basically, the total perimeter of each bay
is 2 wavelengths, and that has to remain constant for proper phasing. You can
make it longer only if you reduce the height.)

At some point the top and bottom elements are so close together that they
don't provide significant broadside gain, and you might as well use a straight
collinear (which, if installed at the same height as the top of the Sterba
curtain, would have a higher average height above ground.)  The more gain
you get from the collinear elements rather than broadside will narrow your
azimuth pattern

But if your limitation is the overall length, going to 5/8 wavelength elements
won't help:  yes, you can cover the total length in fewer bays, but the gain
per half wavelength of antenna stays about the same.  In that case actually
making the sections a bit taller and not so wide would increase the broadside
gain without changing the collinear gain (which is determined by the overall
length), as long as you had sufficient height above ground to work with.


There are some possible combinations of elements if, for example, you wanted
to use a longer center section, basically a pair of EDZ broadside elements
with Sterba bays on the ends, but you may want to feed it with equal line
lengths to each radiator rather than a half wave phasing line between the
feedpoints.  But again, for the same overall antenna length, those are minor
details that really don't affect the gain.
Logged
WA2TPU
Member

Posts: 210




Ignore
« Reply #3 on: March 05, 2013, 11:28:45 AM »

WB6BYU....Thanks Dale. I'll just have my son help me make a standard Sterba Curtain. I also thought about a Bruce Array on 15 meters but not sure IF the gain will be as much as a Sterba Curtain for the same length....

Again, Thanks so much Dale.
Best regards and many 72/73.
Don sr. --WA2TPU --
Logged
K4SAV
Member

Posts: 1847




Ignore
« Reply #4 on: March 05, 2013, 11:32:33 AM »

I assume you aren't going to rotate a 209 ft long antenna, so you need an accurate method of aiming it.  The beamwidth of an 8 element Sterba is about 17 degrees.  If you aim it out into nowhere, you may not have anyone to talk to.

Everything you want to know about Sterba and similar antennas:
http://www.w8ji.com/curtain%20sterba%20USIA%20array.htm

Jerry, K4SAV
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!