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Title: LAZY-H ANTENNA ARRAY For AM/RTTY Post by: aa5wg on July 15, 2012, 09:34:40 PM Hi to all:
When making a wire Lazy-H antenna for AM and RTTTY legal limit power what size wire would you use to have no worries? When at W8JI's Curtain Antenna web site http://www.w8ji.com/curtain%20sterba%20USIA%20array.htm He list formulas to find approximate maximim colinear length of the single doublet element. How do you find the actual optimum length of the single doublet element which is shorter than above maximum colinear length? He mentioned optimum length is shorter than maximum length. (1) When using a reflector element with a single driven element what is the formula for: (a) best front t back ratio, (b) best forward gain and (c) best compromise between front to back ratio and forward gain? This data would be for a multiband Lazy-H made for 10-20 meters and 20-40 meters. (2) Has anyone modeled the Lazy-H with a driven director? (3) Has anyone modeled the Lazy-H with a driven reflector? (4) Has anyone modeled the Lazy-H with a driven director and a driven reflector? (5) Has anyone modeled the Lazy-H with four driven elements? Below attachment shows a dual driven Lazy-H antenna I saw on the web. Would some one be willing to model any one of these four different configurations for me? Than your consideration. Chuck Title: Re: LAZY-H ANTENNA ARRAY For AM/RTTY Post by: W4AAB on July 16, 2012, 07:33:47 PM As far as wire size, #12 stranded should be OK for maximum legal power. The other questions I will leave to the experts who have undoubtedly built such antennas.
Joe W4AAB Title: Re: LAZY-H ANTENNA ARRAY For AM/RTTY Post by: aa5wg on July 16, 2012, 08:25:50 PM Thanks Joe.
Chuck Title: Re: LAZY-H ANTENNA ARRAY For AM/RTTY Post by: Bill, KD0HG on July 17, 2012, 10:03:33 AM Chuck..My own experience with the Lazy H is that they don't work as theorized unless the lower set of elements is at least 1/4 wavelength above the ground. Bear that in mind.
Bill Title: Re: LAZY-H ANTENNA ARRAY For AM/RTTY Post by: aa5wg on July 17, 2012, 10:11:49 AM Thank you Bill.
I'll make sure what ever we come up with is at least 1/4 wave above the ground/grass for the lower element. It is a lot of work but I think it would be worth it to put several of these antennas in the air. I would like to have some input also on the extra driven elements to see how these would work out. Again, thank you. Chuck Title: Re: LAZY-H ANTENNA ARRAY For AM/RTTY Post by: aa5wg on July 26, 2012, 09:55:46 AM Any other comments? AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
Chuck |