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: 80m loop over the shack..  (Read 2279 times)
W4MRH
Member

Posts: 26




Ignore
« on: September 11, 2010, 08:57:13 PM »

First off, I read every single thread eham's search brought up on 80m loop antennas before I did anything. That's a Lot of good info. Only took 3hrs, lol. However, I found no mention of this particular issue.

I have a 1acre lot that is about half wooded with 70+ foot trees. I would like to use an 80m fullwave loop, which I believe I can achieve an average height of 50ft. With the way the property is laid out and the location of the house/shack, most or at least part of the loop would be directly above the house no matter what I do. The antenna would be approximately 35ft above the roof. What kind of issues, if any, should I expect here?

Thanks in advance,
Sean-W4MRH 
Logged
W5LZ
Member

Posts: 477




Ignore
« Reply #1 on: September 11, 2010, 09:55:53 PM »

Sean,
   There's no sure way of predicting how much interference you will have.  I think it's a very safe bet that there will be enough RF that there will be -some- problems with it though.  I ran a loop around a house once and it did produce some problems.  It was quite a bit closer than your proposed antenna so that had much to do with it.  With all the 'variables' in that, about the only way to find out for sure is to try it.
Paul
Logged
W4MRH
Member

Posts: 26




Ignore
« Reply #2 on: September 12, 2010, 12:30:06 AM »

Paul,

  Glad to hear from someone who actually had this problem. To clarify, the best I can achieve is that one side of the square would hang over the house. I'll simply see what happens. I intend to feed it with 450ohm ladder line, with a good 1:1 choke at the shack wall(too much metal to bring ladder into the shack), so if it's only "minor" rfi, I may just run with it. I don't have a whole lot of electronics in the house, and the computer can be shut off while transmitting if necessary. All this providing I don't start glowing in the dark, LOL.

Thanks,
Sean
Logged
NE5C
Member

Posts: 320


WWW

Ignore
« Reply #3 on: September 12, 2010, 02:55:48 AM »

You've almost described exactly what I utilize here at home with my 80 meter loop. I do have my loop configured in an elongated Delta or triangle pattern and I used a path which allowed me to get more to the back side of my property and away from the house (1-side passes within 25ft) #12 Gauge THHN Wire, using a good 4:1 Current Balun fed in the corner. On some occasions the wife tells me she can faintly hear me in her PC speakers, and I'm not heard in our TVs, which is on Dish Network. I do love the Loop antennas, Go for it, Good luck, and God Bless you. 73 Jerry
Logged
K8AC
Member

Posts: 1475




Ignore
« Reply #4 on: September 12, 2010, 04:56:06 AM »

It depends on how much power you'll be running.  If using an amplifier, you'll discover that you have a lot more electronics in the home that you think!  Ground fault circuit breakers have electronics inside and you may find them tripping unexpectedly.
Logged
K3AN
Member

Posts: 787




Ignore
« Reply #5 on: September 12, 2010, 10:19:47 AM »

On 80, most of the RF goes upward and downward, so you may encounter some problems. On 40 and up, more of the RF goes toward the horizon (especially on 20 and up) so I wouldn't expect any more problems than if you hung a dipole 35 feet above the roof of the house. At these frequencies the loop (compared to a dipole) might even produce a lower field strength inside the house.
Logged
WB8UHZ
Member

Posts: 125




Ignore
« Reply #6 on: September 12, 2010, 05:31:23 PM »



  I really don't think you will have many issues. Now with some of the consumer electronics today you may hear from those devices( noise in the ham bands from switching supplies etc.) and or you may effect those devices. However in most cases you will not have a problem. When you think of it most ham antennas are close to the house due to the feed-point being near the shack. I have four acres here and have a dipole on 80 30 feet from the shack and a full wave loop on 80 50 to 150 feet from the shack. Oh make certain you have a good ground system for you ham station.

Put it up and have fun.

73 tim
wb8uhz
Logged
W4MRH
Member

Posts: 26




Ignore
« Reply #7 on: September 12, 2010, 07:04:50 PM »

Thank you gentlemen.

I currently have no issues from my inverted vee 30ft from the shack(feedpoint 35ft high), I simply didn't know what having that large a radiator would do Directly over the roof. As most have stated, there's only one way to find out.

Once again, thanks
Sean-W4MRH
« Last Edit: September 12, 2010, 07:06:39 PM by Sean Hazelwood » Logged
AI7RR
Member

Posts: 164




Ignore
« Reply #8 on: September 13, 2010, 09:45:43 AM »

The long side of my 5 sided horizontal loop (?) fed with LMR 400 runs directly over the length of my house and only about 10' above the peak of the roof. I have not observed any ill affects to things in the house with or without the amp. I'm sure the pattern is distorted, but, you gotta do what ya gotta do with the space you have. My loop still outperforms any other 80m antenna I've tried at this QTH.

73,,Roger
Logged
KE7FD
Member

Posts: 169


WWW

Ignore
« Reply #9 on: September 13, 2010, 10:06:10 AM »

In practical terms, there's always some kind of oddity for every antenna.  I've used a full-sized 80m loop for years with part of the wire hovering just feet above the roof.  While any antenna in free space is the ideal, in my case this antenna was the best one I've ever used and after nearly 40 years of operating, I've tried quite a few.  Perhaps it would work better  configured differently but I am of the opinion (no hard science here) is the irregularies have probably contributed to the better perforance that I would have expeccted if the loop was built to ideal specifications.  I've been able to work stations from Europe to South America, up and down the bands as condtions permitted.  The loop was also not as "staticy" as dipoles I've used in the past.

Bottom line: Build it and they (the QSO's) will come.

Glen - KE7FD
Logged
K4LJP
Member

Posts: 38




Ignore
« Reply #10 on: September 14, 2010, 07:07:48 AM »

I have an 80 meter loop, 268 ft. of #14 THHN wire, not exactly square, above and surrounding my house.  The four corner corners vary in height  between 25 and 35ft. I have no issues at all. Antenna loads up fine, 6 thru 80 meters, plays great, especially at night. Look up Loop Skywire in the ARRL Antenna Book, all versions, back to 1994 for how to info.
de Lee
K4LJP
73
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!