The AM Forum
March 28, 2024, 05:33:36 AM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: zig zag +dipole antenna  (Read 5403 times)
0 Members and 1 Guest are viewing this topic.
Opcom
Patrick J. / KD5OEI
Contributing
Member
*
Offline Offline

Posts: 8308



WWW
« on: September 20, 2008, 04:37:00 AM »

I have a 4-leg dipole, intended to be used as a 'fan' type antenna. It's 100Ft long. (top image, a side view)

I can only string two of its legs out though since a pole has to go behind the shack, and one in front of the house. This leaves me with two legs something needs to be done with.

Does it make sense to fold them as shown in the bottom drawing (top view)?

The antenna is all made of 2" ladder line including the legs, very nicely. I don't really want to cut it up. I figure anythings better than what I have now. Maybe it will give me a more omnidirectional pattern rather than just north-south.


* untitled.jpg (39.54 KB, 512x768 - viewed 1123 times.)
Logged

Radio Candelstein - Flagship Station of the NRK Radio Network.
AF9J
Guest
« Reply #1 on: September 20, 2008, 10:30:32 AM »

Hi Patrick,

I've done similar things in a pinch with portable dipoles,  It shouldn't screw up your efficiency too much.  Yes, it will make it a little more omnidirectional.  But, remember that the highest field stergth in a dipole, is in the middle of each leg.  The further you go towards the ends, the less field strength you have.  So, your dipole will still be biased for then main (straight) section of the antenna patternwise.  Oh yeah, and of course the impedance will change a little bit from the standard flattop dipole impedance (just as it does for an Inverted V vs flattop dipole).

73,
Ellen - AF9J
Logged
flintstone mop
Contributing
Member
*
Offline Offline

Posts: 5055


« Reply #2 on: September 20, 2008, 09:00:39 PM »

I don't think a typical dipole 30 or 40 feet high for 160 or 80M is going to show any directional pattern. It will be basically a NVIS antenna. (Near Vertical Incident Scattering) A high angle radiator. Now at 40M things start to happen around 40 feet high.
Basically a local or 300-500 mi range.
Get the amount of wire needed to achieve resonance out there, even if it means zig-zagging the wire around your property. Drooping the ends downward also works.
Fred
Logged

Fred KC4MOP
Pages: [1]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone © 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.049 seconds with 18 queries.