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Title: 80 M VERTICALS SPACING Post by: KB5MD on August 29, 2012, 03:35:55 PM What is the best spacing for two 80m verticals? I have mine spaced at 1/2 wave or approx 125'. I have heard 1/4 wave, 3/4 wave and 1/2 wave for the spacing between the verticals.
Mine work okay but I wonder if they are at the proper spacing for greatest performance. Some of you antenna guru's, I would like to settle this once an for all. I sure don't want to move one unless there is something to be gained. Title: Re: 80 M VERTICALS SPACING Post by: W4NEQ on August 29, 2012, 03:42:29 PM It all depends upon the pattern you are trying to achieve. Your spacing is ideal for a figure 8. At 1/4 wave spacing, when fed with 90 degree phase shift, a cardioid pattern will result.
Chris Title: Re: 80 M VERTICALS SPACING Post by: K3YA on August 29, 2012, 04:49:57 PM I've worked with 80M verticals for more then 20 years now chasing DX. There is no one right answer to your question, like Chris said it depends on the desired pattern. For a 2 element array I like a switchable cardioid patten. 1/4 wavelength spacing. I use about 120 degrees of phase difference obtained with an L network between the elements.
1/2 wave spacing provides a bidirectional pattern. However I prefer the "front to back" of a unidirectional pattern. Elements in a wide spaced arrays have a higher feedpoint impedance and I feel that gives greater efficiency if used with a less then ideal ground system. If you have the room, a "4 square" is a lot better then any 2 element array in my experience. Title: Re: 80 M VERTICALS SPACING Post by: KM1H on August 30, 2012, 09:23:31 PM With 1/4 wave you can get a cardioid pattern in 2 directions endfire and a figure 8 broadside with simple coax phasing lines. I ran that way for decades on 80 and 160 and worked lots of DX....over 300 DXCC on 80 and first 5BWAZ in New England.
If the verticals are short then its possible to use 1/8 wave spacing but in all cases I suggest you get ON4UN's Low Band DXing book, 5th Edition on line or at ham stores. Carl Title: Re: 80 M VERTICALS SPACING Post by: Steve - K4HX on August 31, 2012, 06:40:36 AM Couldn't agree more. Excellent coverage in this book, plus recent editions include a ton of software that will help you design the system, especially the phasing lines or phasing networks. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
As with any vertical system, the radial field will make or break the performance. Quote If the verticals are short then its possible to use 1/8 wave spacing but in all cases I suggest you get ON4UN's Low Band DXing book, 5th Edition on line or at ham stores. |