| Author |
Message |
    
Radioreddz
Member
Username: Radioreddz
Post Number: 77
Registered: 9-2006
| | Posted on Sunday, May 18, 2008 - 6:38 pm: | 
|
how much would i gain by stacking 5 element beams on the flatside. wanted to use 2, 5 element Macos on a 40' tower and put one 8'too 10' above the other. would i get the same results as if they were staked vertical side x side, but just being horizontalaly polorized. also would this give me better band width and performance then a 8 element beam. would this be a killer DX set up. |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 4241
Registered: 7-2004
| | Posted on Sunday, May 18, 2008 - 7:51 pm: |
|
would this be a killer DX set up-and then some! for 27 mhz, you are going to have 1 heckuva time keeping stacked 5's up in the air do to tremendous size and weight! overall though, you will see roughly the same forward gain because you'll get near 12 dbd from one 5 element, stacking a 2nd will give you another 3 dbd for a total of near 15 dbd. a single 8 element should be around 14 dbd or so. rejection should still be better on the 8 element. the big difference however will be in beamwidth. for better or worse-depending on how YOU see it-the single 8 element will have a tighter pattern then the stacked 5's. meaning if you're looking for a weak signal, you won't have to be so 'dead-on' to find it with the stack. as i said the big problem will be keeping it up & turning it. what rotator WON'T break??? i couldn't even guess-check what the big ham guys use to turn their multi-, oversized stacks. it would have to be mounted inside the tower, but heavy winds will still wreak havoc on the break....and i mean by snapping it. the added torque of a 2nd 35 lb antenna 10' above the 1st, plus the weight of a mast that won't bend, will probably get you in the neighborhood of 100 lbs total, if not more. vertically stacked, side by side will be easier overall, and maybe even a bit less windload. as for performance, vertical vs horizontal....locally you need to be polarized the same, no more base to mobile, but on DX, you won't know because every signal could get flipped differently. in all honesty, an 8 element like a laser 500 pretty much covers all your bases-gain, rejection, performance & both polarities..... |
Mrclean
Member
Username: Mrclean
Post Number: 96
Registered: 12-2003
| | Posted on Saturday, June 21, 2008 - 12:39 pm: |
|
I have a friend who runs stacked 7s flat and has a 7 on another tower vertical. He talks where he wants most of the time. Like pat says a single antenna is much easier. I am in the process of putting a Maco dual polarity HV 105 up right now. I have a 48 ft Delhi freestanding tower, the five element and a yeasu SA 800 rotator.Still need a carbon steel mast and coax and I will be ready to get it in the air. I figured for my first beam this would be plenty big and after five elements the patern just tightens up and dont get much more gain like pat stated. Good luck whatever you do! |
Tech237
Moderator
Username: Tech237
Post Number: 1016
Registered: 4-2004
| | Posted on Sunday, June 22, 2008 - 12:17 pm: |
|
Stack them a quarter wave apart and feed them through a properly measured and constructed coax harness. if you dont you'll loose more than you gain.. 10db is 10x times power multiplication, 13db is 20x, so 15db is approx 22x and that works on both transmit and receive..
To protect the rotor from high winds you rig a deadman type break that drives a heavy pin into a hole in the mast. This pin takes the strain of the rotator brake.
Simon
Tech237
N7AUS
|
Captian_radio
Intermediate Member
Username: Captian_radio
Post Number: 408
Registered: 9-2004
| | Posted on Monday, June 23, 2008 - 8:11 pm: |
|
Another nice thing about stacking antennas is that if done properly you should be able to switch between the top one and the bottom with some surprising results.
Bob CEF451/VE1CZ
Robert L. Spicer The days of radio are just beginning!
|
Marconi
Advanced Member
Username: Marconi
Post Number: 771
Registered: 11-2001
| | Posted on Tuesday, June 24, 2008 - 12:21 am: |
|
Hey Captian radio, I sure would like a little more explaination of how that co-phase setup would look, allowing one to properly switch.
Just curious as to what kind of suprising results would you be expecting also. |
Captian_radio
Intermediate Member
Username: Captian_radio
Post Number: 409
Registered: 9-2004
| | Posted on Tuesday, June 24, 2008 - 7:56 am: |
|
Marconi, I have never tried this but on old friend of mine who is a long time big dxer on 6 meters did it years ago with 2 homebrew 6 ele yagis,it worked like a charm and he was able to switch between the 2 .I was there during a 6 meter E skip opening and was amazed by the fact that he could hear different signals on one antenna or the other just by switching.He made a phasing harness so he could make the switch between the 2 or use them both.If I ever see him again {lost touch over the years}I will ask him how it was done.I think it had something to do with feeding them 180 degrees out of phase with a delay that would make one fire before the other,can't remember the theory now but I will do some reading to find out what I can, it was quite an interesting thing to see when he was working stuff on 6 meters.
Bob CEF451/VE1CZ
Robert L. Spicer The days of radio are just beginning!
|
Drzuo
Junior Member
Username: Drzuo
Post Number: 19
Registered: 1-2006
| | Posted on Sunday, July 06, 2008 - 9:02 pm: |
|
Grab an antenna analyzer, an experienced ham or two that are cb friendly, and some nice steaks.
a) it will be a pain in the a.. b) if done right it can be very worth it.
stacking one above the other(if vertically polarized) yields a flatter lower angle signal, while stacking side by side yields a narrower beam width.
everything has to be exact, and things may get unpredictable- it will take time. If you get everything spot on your first time, go directly and buy a lotto ticket.
My friend did this with 4x m12's for 2 meters(That's 4 12 element beams=48 elements)
He lives 36 miles from me (by air) and can hear me on my ht, in my basement with 250mw at an s7)
He frequently checks in on nets in Wisconsin and Michigan, he is in Pennsylvania. It always gets suprising comments. We usually monitor the nets on echo link so we can hear both sides of the conversation, its a blast. We calculated his gain to be between 19 and 21 dbi, he can also put 500 watts FM to the antennas.
Hope this inspires you. You'll be the talk of the town if you get it right (and the next town, and the next town) Just be careful it starts to get addictive (stack two 7 element beams stack 4, stack 4 10 element etc...)
remember if the antenna stays up, it's too small
--73 |
Marconi
Advanced Member
Username: Marconi
Post Number: 779
Registered: 11-2001
| | Posted on Monday, July 07, 2008 - 11:40 am: |
|
Thanks CR, that makes more sense then, I was thinking more about the typical way it is done in 11 meter work where the antennas are just co-phased. |
|
