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] 2 Next   Go Down
  Print  
Author Topic: The Higher the Better??  (Read 4959 times)
KA3HIE
Member

Posts: 9




Ignore
« on: February 25, 2011, 01:31:41 PM »

I posted my quandry last week in
TowerTalk but got no responses, partly because I think it was too confusing.

Situation:   A four element 6 meter beam at 30' next to the house.

I can likely add another ten feet of elevation to this setup.

However, was thinking of taking my newfound 40' setup up my steep grade in the backyard.   This would add another 15' to the horizon.
Literally, 40' plus 15' uphill makes the beam at 55' higher than it sits now.
The new setup puts it at least equal to the treetops.

Problems:  #1.  might have to do some chainsaw pruning.
                #2.  this idea means at least a 120 run of feedline(likely lmr 400)
                 #3.  the current Armstrong method of rotation would
                        yield a longer, steeper walk to rotate(no real plans
                        for a rotator).
The plan is ambitious, but is it worthwhile primarily for 6m ES/(dx), or would all the work/expense be near futile?
 
Logged
WB6BYU
Member

Posts: 13339




Ignore
« Reply #1 on: February 25, 2011, 02:14:30 PM »

It gets complicated once you start working with slopes, as it isn't simply the height
above ground at the antenna but also the relative shape of the ground for many wavelengths
in all directions.

It is possible to get an antenna too high over sloping ground - a friend put his 20m yagi
at 140' and it was awful - turns out that 55' is about optimum for his ground slope (where
the ground reflection adds in phase right at the horizon.)  But this varies with the wavelength,
antenna height, angle of slope, and how far above and below the antenna the slope is
maintained.

So while getting the antenna up over the tops of the trees generally is a good thing, we
don't really have enough information to say for sure which will work better.
Logged
W5LZ
Member

Posts: 477




Ignore
« Reply #2 on: March 01, 2011, 12:05:33 AM »

That higher is better thing is a fact.  But it means the height above the average terrain (HAAT, or AGL if you're a pilot?) around/under that antenna.  Typically, higher is good till the losses from the feed line length get to be too great so there's no 'improvement' anymore.  That's when you quit trying for more height.  The higher you get the further you can see.  Same for that antenna.
 - 'Doc
Logged
KM3F
Member

Posts: 509




Ignore
« Reply #3 on: March 01, 2011, 03:19:41 PM »

I have done a similar change while building my antenna systems/ station.
Began with building beams and testing at 20' located on the side of a mountion location.
Went to a tower plus another 15' in elevation for a total height gain of about 45 feet.
Feedline is very low in loss being Heliax 7/8" at about 200 feet.
The observed gains are about 6 db in receive from the relocation and use of low loss feedline and antenna gains.
The difference in Tropo contacts are quite striking for distance.
My grid square is FN20 and can make contacts into Canada (FN 35 etc) with 150 watts.
It should make a good difference in your case but you need to work the system long enough to assess the difference overall.
Always aim for the best and lowest loss highest gain assembly you can afford to get the most out of the effort you have to live with.
Logged
WB2WIK
Member

Posts: 20611




Ignore
« Reply #4 on: March 01, 2011, 03:41:51 PM »

I wouldn't want an antenna far away and up a hill if I had to rotate it by hand.

I turn my 6m beam fifty times an hour when the band's active, like in a contest or during major sporadic-E sessions.  No way I'd do that by hand.
Logged
W3HKK
Member

Posts: 596




Ignore
« Reply #5 on: March 03, 2011, 02:48:50 PM »

Talking strictly Es,  the 55 ft on 20m ht analogy is less than 1 wavelength.  1 wavelength on 6m is 20 ft or so.  and that should do a very nice job.

As an example, my 5 el yagi  6 ft off the ground and beaming THRU the house works  all up and down the west coast during Es season.  Made c. 200 qsos in 40 or so states and 7 countries including Portugal last season.  Id LOVE to be up at 25 ft.
Logged
WB2WIK
Member

Posts: 20611




Ignore
« Reply #6 on: March 03, 2011, 03:52:14 PM »

The problem with such situations is you can't possibly know what you're missing, because you won't hear it.

I've made many thousands of contacts on 6m over many years, from dozens of different locations, and "propagation" does most of the work for a lot of them.  Good timing and operating skills help a great deal, too.  Understanding how to track the propagation and even anticipate when it will peak is something that just comes with experience.

However, I can't recall a single case ever where a low antenna worked as well as a high one, for any kind of 6m propagation -- and I've often had multiple beams for comparison.

I use mostly telescoping towers both at home and in the field so we can change their elevation above ground in just a minute or so.  At home now, with my 6m beam at 67 feet (tower "up") I can normally hear five beacons all the time, irrespective of propagation -- it's all normal tropo.  If I crank the tower down so the same beam is at 30 feet (tower "down"), I lose three of those beacons and can still copy the other two.  I've done that test repeatedly over days, weeks, months, years.  It's always the same.

When signals are screaming in at S9+ via sporadic-E, I can leave the tower down and for most paths it hardly matters; but for the longer-haul F2 stuff which we were commonly working in 2001-2002 time frame (peak of Cy. 23), it made a huge difference.  I had the tower nested when the band popped open the morning of November 17, 2001 (still have all logs and notes) and I "heard" stations in CA working into eastern EU, but I wasn't hearing the EU stuff at all.  I ran outside to elevate the tower, ran back inside, and stations in Poland were S4 that were not there at all just 60 seconds earlier.  Ditto for stations in north AF, and some in Scandanavia...all copyable, and ultimately workable, with the beam "high," and simply nonexistent with the same beam "low."

I have a single story home, as are all in the neighborhood, and there aren't any very tall trees to obstruct -- the height advantage was purely from the takeoff angle change.  When the tower is "up," my beams are the highest thing in the neighborhood by about 40 feet.

We had similar experience even operating from the summit of Mt. Pinos, CA (8831' asl) in the June VHF contest as N6CA/6 (highest VHF contest score ever made from the west coast), where I was primary 6m operator.  We had my 4-stack of 5 element beams (16' booms) in an H-frame on an LM-470 that was trailer mounted.  We could set the center of the stack from about 30' above ground to about 80' above ground just by pushing a button and letting the motor elevate the tower.  Now, this is already over a mountain nearly 9000' high and by far the highest point in every direction for several miles, with a very low horizon.

Height above ground still made a big difference.  With the beams "high," we could catch meteor scatter (pre-WSJT days, it was all SSB) from 1200-1300 miles away easily, and quite consistently.  With the beams "down," half of that consistently went away -- so we decided to just keep them "up."  This was the judgment of every 6m op there, about six of us, and we all came to the same conclusion.





Logged
WY3X
Member

Posts: 768




Ignore
« Reply #7 on: March 08, 2011, 08:34:38 PM »

In nearly 10 years of operation on 6M, I never once heard Europeans with an antenna height of 40 feet. No slope here, I'm a flatlander on the coast of South Carolina. We moved to a new home and I bought a new (used) tower, and boosted my height up to about 85 feet. Somewhere a few years ago I read that 85 feet is a "magical" height for 6M. Since setting up the new tower (same antenna), I've been slaying the European stations whenever the band is open in that direction. Your mileage may vary with this suggestion, but it worked for me!
Logged
WB2WIK
Member

Posts: 20611




Ignore
« Reply #8 on: March 09, 2011, 01:43:02 PM »

In nearly 10 years of operation on 6M, I never once heard Europeans with an antenna height of 40 feet. No slope here, I'm a flatlander on the coast of South Carolina. We moved to a new home and I bought a new (used) tower, and boosted my height up to about 85 feet. Somewhere a few years ago I read that 85 feet is a "magical" height for 6M. Since setting up the new tower (same antenna), I've been slaying the European stations whenever the band is open in that direction. Your mileage may vary with this suggestion, but it worked for me!

An example of "you can't possibly know what you're missing if you don't hear it."

The old expression "I can work everything I can hear!" is silly.  Everybody can.  But you can't work what you can't hear, and if your antenna's not high enough, there's all sorts of stuff you can't hear.
Logged
W0BTU
Member

Posts: 1718


WWW

Ignore
« Reply #9 on: March 09, 2011, 09:04:42 PM »

I use mostly telescoping towers ...

Steve, could you please recommend some good telescoping towers? :-)
Logged

WB2WIK
Member

Posts: 20611




Ignore
« Reply #10 on: March 10, 2011, 10:12:55 AM »

I use mostly telescoping towers ...

Steve, could you please recommend some good telescoping towers? :-)

There used to be more than there are today.

I stick with Tri-Ex/Tashjian and U.S. Tower.  American made, galvanized steel.

There are some aluminum telescoping towers made, they scare me.

Luso makes some fantastic telescoping towers, but they're very pricey and not for the feint of heart.  If I hit the Lottery, I'd get a 100' Luso. Smiley
Logged
W0BTU
Member

Posts: 1718


WWW

Ignore
« Reply #11 on: March 11, 2011, 06:33:23 AM »

I stick with Tri-Ex/Tashjian and U.S. Tower.  American made, galvanized steel.

Thanks. I just did some Google searches for Tri-Ex and U.S. Tower. Strangely, no relevant links appeared on the first page of results. I guess I'll look in QST.
Logged

WB2WIK
Member

Posts: 20611




Ignore
« Reply #12 on: March 11, 2011, 09:22:37 AM »

I stick with Tri-Ex/Tashjian and U.S. Tower.  American made, galvanized steel.

Thanks. I just did some Google searches for Tri-Ex and U.S. Tower. Strangely, no relevant links appeared on the first page of results. I guess I'll look in QST.

Tri-Ex is http://www.tashtowers.com

U.S. Tower is http://www.ustower.com

Logged
N3OX
Member

Posts: 8847


WWW

Ignore
« Reply #13 on: March 11, 2011, 11:57:58 AM »

An example of "you can't possibly know what you're missing if you don't hear it."

You can if you're listening on 6m while logged into ON4KST's 6m chat with K3TKJ and his 235 foot rotating stack.

Logged

73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
W0BTU
Member

Posts: 1718


WWW

Ignore
« Reply #14 on: March 11, 2011, 04:54:36 PM »


Thank you! It gives me something to think about and plan for. If we ever get another big job, maybe I'll come up with the money.

I haven't had a tower since 2000, and I haven't had a GOOD tower since 1989. All I've had here since we moved here in 2004 is an inverted-L and a couple of Beverage antennas. I guess I shouldn't complain, but I would like to operate something other than 160, and ESPECIALLY put up a decent array for 2 meter SSB again on a tall tower.

The way those tower prices increase exponentially as you get above 50 feet is just crazy. 50 feet will just not cut the mustard, for what I want to do. I can buy Rohn 25 and pay tower climbers (IF I can find any!) for a lot of hours, and not get anywhere near that kind of money.
Logged

Pages: [1] 2 Next   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!