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: Prev 1 [2]   Go Down
  Print  
Author Topic: 160M Antennas in Limited Spaces  (Read 10240 times)
W8JI
Member

Posts: 9296


WWW

Ignore
« Reply #15 on: September 24, 2012, 08:47:09 AM »

If 15' to 20' radials is all that is needed I may be able to pull that off.

How many ground rods do you think it would take to maximize radiation efficiency?

TIA



Do NOT let anyone dissuade you about trying 160 just because you cannot have a large antenna or a prefect system.

I have worked Europe on 160 SSB many times with my mobile, and it has a ~8 foot tall antenna with 12 feet of tip height above ground, and only a truck body as a small ground. I have also worked VK6 and Japan on 160 mobile several times.

You would be far better off, as a general rule, with 20 short radials than several ground rods. I would not expect a ground rod, no matter how deeply driven, to have less than ~50 ohms on 160 meters. More likely it would be higher. 

Also, as you parallel rods, they do not parallel in a linear resistance reduction. Two rods are NOT half the resistance of one rod, because the rods "elevate" the soil potential around them. That may be difficult to follow, but the largest change is the first "bite" on the soil in an area. There is a diminishing return and doubling the rod number does not ever halve the resistance unless the rods are a very large distance apart.

Still, just do the best you can.
Logged
W5WSS
Member

Posts: 1772




Ignore
« Reply #16 on: September 24, 2012, 04:23:46 PM »

I built a closed loop rectangle, the dimensions were 8ft vertical ends and 25ft top and bottom 50+16= 66ft of #14 stranded copper wire. The loop was indoors installed along the baseboard up each opposite corner and along the crease of the interior ceiling.

I used a wide range tuner t-match and integral 1:1 current balun at the antenna feedpoint easily done since the antenna was indoors.I

I broke open the vertical 8ft end and fed at the center 4ft point using a table top to set the tuner on. There was no coaxial cable used or any open wire line the tuner received the antenna wire directly at it's terminals.

I made many contacts with 20 watts pep.

I am not recommending an antenna just wanting to relay that I would not have made any contacts having not tried.
Logged
N4NYY
Member

Posts: 4816




Ignore
« Reply #17 on: September 24, 2012, 04:46:09 PM »

I have been dying to get on 160M. I have a trap dipole inverted V for 20-40-80 at 35 feet. For 160, I need 40 or more feet of wire on each leg. I just do not have the room. Being at 35' high, I am assuming loading the end with a coil is out.
Logged
W5WSS
Member

Posts: 1772




Ignore
« Reply #18 on: September 24, 2012, 08:10:26 PM »

Hello I am thinking about your question Traps would need to be designed and can be an excellent solution but if not, what if you add equal lengths of wire to either leg onward downward towards the ground but not on it then outward to plastic tent stakes for the final dead ending,and see if you can tune it by length adjustment on 160 then throw the extra out of line via remote switches capable of rf use when using the other bands within the antenna design? Crude but worthy of consideration.
Logged
AE5JU
Member

Posts: 231




Ignore
« Reply #19 on: September 27, 2012, 01:54:40 PM »

I found this sketch somewhere, might have been here on eHam, a few years ago. 

http://i15.photobucket.com/albums/a384/PaulCoats/160m40mAntenna-1.jpg

This 160/40 meter antenna is the same overall length as an 80 meter dipole.  This was the inspiration for the 75/20 segments of my Field Day Antenna.  I needed to be able to do 75, 40, and 20 meters at a minimum.  So the thought occurred to me, make this half size, tune it for 75 and 20 meters.  Then with legs for 40, that will triple and work 15 meters... ahah!  4 bands!  And the tuner lets me force 17 meters out of it.  I don't konw if 17 m is working off the 40 m or the 20 meter segments, but it works.

http://www.hamuniverse.com/ae5jufielddayantenna.html

And here's yet another for 160 meters.

http://i15.photobucket.com/albums/a384/PaulCoats/80m160mInvVee.jpg

73,
Paul - AE5JU
Logged
WX7G
Member

Posts: 6194




Ignore
« Reply #20 on: September 27, 2012, 02:05:25 PM »

I have been dying to get on 160M. I have a trap dipole inverted V for 20-40-80 at 35 feet. For 160, I need 40 or more feet of wire on each leg. I just do not have the room. Being at 35' high, I am assuming loading the end with a coil is out.

A common way to get on 160 meters is to drive the feedline of an inverted-vee as a vertical working against ground. I've done is using a homebrewed coil and with an MFJ antenna tuner.
Logged
VA3MW
Member

Posts: 13




Ignore
« Reply #21 on: October 04, 2012, 09:16:44 AM »

Have a look at this:

http://www.iw5edi.com/ham-radio/files/160Half-Slooper-Antenna.pdf

Mike va3mw
Logged
VE3FMC
Member

Posts: 1000


WWW

Ignore
« Reply #22 on: October 04, 2012, 05:12:31 PM »

I know a ham who makes Screwdriver antennas, and they work great. Google VE3EDY.

Now he has told me that I could get on 160 with limited space by using a screwdriver antenna, and a ground radial system which is in a loop formation.

Check his website out, http://www.ve3edy.com/
Logged
ND6P
Member

Posts: 98




Ignore
« Reply #23 on: October 05, 2012, 05:39:04 PM »

If the antenna don't fit, you gotta quit!

Sorry, just had to throw that in.  I've tried a number of compromise 160 meters antenna here on my small city lot over the years.  None of them worked that well, and that was without XYL restrictions.  I could be heard up to about 1000 miles. Anything longer was rough going.
Logged
Pages: Prev 1 [2]   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!