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: Cubical Quad for Sat Work  (Read 10319 times)
KO1D
Member

Posts: 383




Ignore
« on: November 26, 2012, 07:46:35 AM »

I am finally doing it. Whatever it is. Smiley

I am going to be heading out to get the bits for a 2m/70cm quad with 7 ele each band. Currently I have a max of 50w out of an FT 847, no preamps, but plenty of hardline. (Cable TV left overs and some 1/2" stuff). So the antennas will have N connectors on them. I run HRD so I will be working to integrate an AZ/EL rotor I came into either computer interface into the system if possible for full automatic control.

What I am curious about is antenna spacing.

I'd like to put my 4 ele 6m beam up on one side of the AZ/EL rotor with the interlaced quad on the other. I have heard you need to space the uplink and downlink antennas about 6 ft but I have also seen very active sat folks successfully using antennas that interlace 2m and 70cm.

Also, I understand the Doppler effect and changes in polarization on signals, so is there any benefit to using a quad in a horizontal polarization versus a diamond configuration. This system will also be for terrestrial weak signal work.

Any feedback and ideas are appreciated related to this approach.

Thanks!
Logged
WB6BYU
Member

Posts: 12979




Ignore
« Reply #1 on: November 26, 2012, 06:12:07 PM »

Quote from: KO1D

I am going to be heading out to get the bits for a 2m/70cm quad with 7 ele each band...



It would be worthwhile modeling that antenna first to see how much interaction there
is between the bands - the 2m elements will have resonances near 435 MHz, so the
70cm pattern might not be as clean when they are built on the same boom.



Quote

I'd like to put my 4 ele 6m beam up on one side of the AZ/EL rotor with the interlaced quad on the other. I have heard you need to space the uplink and downlink antennas about 6 ft but I have also seen very active sat folks successfully using antennas that interlace 2m and 70cm.



Presuming your receiver is adequately protected from your transmitter signal, the
issue becomes one of interaction among the elements (and with the mast and/or
boom, depending on the relative polarization of the antennas.)

If the antenna is vertically polarized, it needs to be far enough out from the mast
(which is also vertical) to avoid pattern distortion.  With horizontal polarization the
cross-boom (which is also horizontal) becomes more important if it is made of
conductive material.

In some cases you may also want to vary the spacing to balance the weight of
the antennas at the rotator - this may mean putting the lighter antenna further
out from the mast.  (But you also want to try to keep the wind forces equal on
each side of the rotator.)


Quote

... is there any benefit to using a quad in a horizontal polarization versus a diamond configuration.



A quad can be in the diamond configuration and STILL be horizontally polarized.  Or
vertically.  Same with square elements.

A quad is horizontally polarized if it is fed at the center top or bottom of the driven element,
regardless of whether the element is square, diamond, rectangular, septagonal, or round.  It
is vertically polarized when fed at the center of one vertical side of the element.
Logged
N6JSX
Member

Posts: 216




Ignore
« Reply #2 on: December 11, 2012, 11:28:36 AM »

But what about a loop element Quad?.... Yes, there would be some amount of feedpoint polarization but over all it would  take on CP characteristics. Hwever, I've not seen any commerically sold loop-quad/yagi for 2m or 70cm but there are a few DYI designs floating around.
Logged

K1FPV
Member

Posts: 30




Ignore
« Reply #3 on: February 27, 2013, 02:22:34 PM »

But what about a loop element Quad?.... Yes, there would be some amount of feedpoint polarization but over all it would  take on CP characteristics. Hwever, I've not seen any commerically sold loop-quad/yagi for 2m or 70cm but there are a few DYI designs floating around.


Well, when I lived in an area with a Home Owners Assn., I couldn't use outdoor antennas, so I built a pair of 4 element quads pointed up permanently at about 45 degrees. One quad was for 2 meters and the second for 432 MHz. They were made out of PVC plumbing and stranded antenna wire. These were mounted with a TV rotator in my attic and even through the roof, I was able to work many satellites. I was using an Icom IC-910H.

Try it, it works!

73,
Bill/K1FPV
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!