I have something here that I believe is new. If it isn't then that's ok ,I don't use EZNEC or read antenna articles much. I like to innovate. This antenna is an innovation. . ( I have read about a sloping two band Delta loop but it used two feed lines-- mine uses one). It is called the 40/30 pyramid.
This antenna is predicated on what I will call ZO's law. That is, If rf can find resonance in an antenna, it will. I learned that on my fan verticals ( see my article on the fan vertical) . The same principal gave birth to the PYRAMID
It is a two band delta loops. One for 30 and one for 40 meters using the same wire for the top slopers on both 30 and 40 meters ( yes, they are connected at the base line corner points of the 30 meter base and they have same feed point, 75 ohm feed line and no balun. It is on a single 35' support . I use weed eater line ( I buy it by the spools) to tie the corners of the 30 meter Delta back to ground posts. and then extend the 40 meter sloping sides down the guy line and tie it off. My 30 meter base wire is about 11 feet off the ground and the 40 is about 8' off the ground. This is the greatest wire antenna for the height you can have with a single wire except for the EDZ. The problem with the EDZ is its angle of radiation at 30 feet is 35 degrees vs 25 degrees with the Pyramid.
I don't need to tell you about loops The standard formula is 1005/Freq. I found 1039 better with no balun at 72 ohms. I use insulated multi -strand wire any size wire work but effects the velocity factor . These antennas can be trapezoidal if need be. Equal length is a bunch of crap .They can be 4 sided, 3 sided , 12 sided. They match 50 ohm coax or in my case 75 ohm low loss RG6 ( cheap) coax. (RG6 has fantastic line loss superiority that you can see on page 44 of the February 2015 issue of QST magazine. It it remarkable . It compares with LMR !) .
This antenna works!! I am resonant ( 1.2:1 on 30 and 1.3:1 on 40) on both bands with outstanding results on Reverse Beacon Network. depending on propagation I light up 20 beacons up to 40 db s/n with 100 watts. If you don't know about Reverse Beacon Network for antenna testing, read my article on that easy way to measure your antennas output performance.
Notice that the location on the feed point must be on the sloping side ( either one) of the highest frequency loop ( which you build and test first) . Let's notice why. The RF will not circuit properly flow if you put it anywhere else. The feed point RF sees the resonant loops on both bands. If you feed the base of the lowest frequency loop what does the RF see the other band? Right? ? It may see the outside loop and then it may see just the lower extension area. Feed the sloping side of the highest frequency and then it will work on the lower frequency . This antennas has great potential for example on 10/15/17 . Feed the 10 loop sloping side. That also gives you vertical polarization and the lowest angle of radiation ( about 20-25 degrees) for DX.
Like all antennas, the resonance is trimmed and tuned by using an analyzer or you rig swr with 1 watt out. ( I know you do that too). All formulas are effected by soil conditions , height , velocity factors , temperature, etc. YOU HAVE TO TRIM THEM OR EXTEND THEM .( I have to trim when weather temperatures change because of expansion and contraction on these bigger loops ) These loops take patience and some math. Let's say you are showing best SWR at 7.450 MhZ. When we divide that into 1005--/ 7.450 , that shows that the antenna is operating as if it is 134.9 feet in the full wave loop. But you say "that is not right!! It is physically something else-- let's say 140' . Who cares ? The antenna is seeing resonant as if it was 134.9 feet ( even though its not right on the Formula!!!) . That is what you want to assume. " BUT I don't want it on resonant on 7.450!!" and " I want it to resonate on 7.025 !!! " What do I do? What does the formula tell us the loop length should be at 7.025 mhz? 1005/ 7.025.
It should be 143 feet. Now here is the trick. Forget what it is and deal with what it thinks it is ( based on soil etc.) because of all the factors I mentioned . It "Thinks" it is 134.9 feet. It needs to be increase to 141 feet , so simply add the difference of 8.1 feet and you will now see resonance. Yes, you have 148.1 feet of loop but it thinks it is 141 feet in circumference. What do you care? .
I want to add a way to splice wire on a loop. ( on even a dipole ). Soldering is nice but the wind will break that soldering point. This gets important on big antennas where you need to add or subtract wire length to resonate. Stress will eventually break the wire unless you do something to give it strength. I do that with a square knot . Yep. Tie a square knot with the two ends you are joining , then cinch it down tight as you can, then twist the two wire ends and solder if you want ( I don't) . That wire may break but not there!! That knot makes no difference in the swr, continuity or the performance of that antenna.( only the net length) All you need is the correct total length of that loop or dipole.
Just add or subtract the length necessary to find that resonance!! 8.1 feet ( above anywhere and adjust the pull lines to balance the two sides. It makes ZERO difference if it is not exactly equal lateral sides . It can be way out of balance. It matters not. Maximum efficiency is to strive to the largest inside area. The perfect Circle is optimum but very costly indeed to construct.( hi!) The difference is not worth it in DBd gain . ( maybe ,outside, .07 DBd) . These Deltas are estimated at anywhere from 1.5 DBd to 2.9 DBd against dipole at same heights ,depending on ground loss . (I reduce ground loss with a reflective radial system on the ground but that is another subject). But all we have for our Pyramid is ONE mast or tower 30 to 50 feet high ,like most hams and a pulley system to pull the center top up so we do a Pyramid configuration. You tie off to a tree or a fence post or anything that gets your sloping sides and base pulled straight. I have used tee posts. I will repeat ,I love weed eater line (.090 or larger) to insulate and tie off antennas, but use anything but rope that holds moisture. Remember . If the base has to be longer than the sloping sides-- THAT'S OK!! I promise. This "optimum" theology is a myth .
This concept will work on any two bands-- 17/20 would work well. Try 3 bands-- 10/12//15.
This was a fun and exciting project. First tested January 23 ,2016. Yes, I have duplicated it twice on 17/20 also. . w5zo@arrl.net
.
This antenna is predicated on what I will call ZO's law. That is, If rf can find resonance in an antenna, it will. I learned that on my fan verticals ( see my article on the fan vertical) . The same principal gave birth to the PYRAMID
It is a two band delta loops. One for 30 and one for 40 meters using the same wire for the top slopers on both 30 and 40 meters ( yes, they are connected at the base line corner points of the 30 meter base and they have same feed point, 75 ohm feed line and no balun. It is on a single 35' support . I use weed eater line ( I buy it by the spools) to tie the corners of the 30 meter Delta back to ground posts. and then extend the 40 meter sloping sides down the guy line and tie it off. My 30 meter base wire is about 11 feet off the ground and the 40 is about 8' off the ground. This is the greatest wire antenna for the height you can have with a single wire except for the EDZ. The problem with the EDZ is its angle of radiation at 30 feet is 35 degrees vs 25 degrees with the Pyramid.
I don't need to tell you about loops The standard formula is 1005/Freq. I found 1039 better with no balun at 72 ohms. I use insulated multi -strand wire any size wire work but effects the velocity factor . These antennas can be trapezoidal if need be. Equal length is a bunch of crap .They can be 4 sided, 3 sided , 12 sided. They match 50 ohm coax or in my case 75 ohm low loss RG6 ( cheap) coax. (RG6 has fantastic line loss superiority that you can see on page 44 of the February 2015 issue of QST magazine. It it remarkable . It compares with LMR !) .
This antenna works!! I am resonant ( 1.2:1 on 30 and 1.3:1 on 40) on both bands with outstanding results on Reverse Beacon Network. depending on propagation I light up 20 beacons up to 40 db s/n with 100 watts. If you don't know about Reverse Beacon Network for antenna testing, read my article on that easy way to measure your antennas output performance.Notice that the location on the feed point must be on the sloping side ( either one) of the highest frequency loop ( which you build and test first) . Let's notice why. The RF will not circuit properly flow if you put it anywhere else. The feed point RF sees the resonant loops on both bands. If you feed the base of the lowest frequency loop what does the RF see the other band? Right? ? It may see the outside loop and then it may see just the lower extension area. Feed the sloping side of the highest frequency and then it will work on the lower frequency . This antennas has great potential for example on 10/15/17 . Feed the 10 loop sloping side. That also gives you vertical polarization and the lowest angle of radiation ( about 20-25 degrees) for DX.
Like all antennas, the resonance is trimmed and tuned by using an analyzer or you rig swr with 1 watt out. ( I know you do that too). All formulas are effected by soil conditions , height , velocity factors , temperature, etc. YOU HAVE TO TRIM THEM OR EXTEND THEM .( I have to trim when weather temperatures change because of expansion and contraction on these bigger loops ) These loops take patience and some math. Let's say you are showing best SWR at 7.450 MhZ. When we divide that into 1005--/ 7.450 , that shows that the antenna is operating as if it is 134.9 feet in the full wave loop. But you say "that is not right!! It is physically something else-- let's say 140' . Who cares ? The antenna is seeing resonant as if it was 134.9 feet ( even though its not right on the Formula!!!) . That is what you want to assume. " BUT I don't want it on resonant on 7.450!!" and " I want it to resonate on 7.025 !!! " What do I do? What does the formula tell us the loop length should be at 7.025 mhz? 1005/ 7.025.
It should be 143 feet. Now here is the trick. Forget what it is and deal with what it thinks it is ( based on soil etc.) because of all the factors I mentioned . It "Thinks" it is 134.9 feet. It needs to be increase to 141 feet , so simply add the difference of 8.1 feet and you will now see resonance. Yes, you have 148.1 feet of loop but it thinks it is 141 feet in circumference. What do you care? .
I want to add a way to splice wire on a loop. ( on even a dipole ). Soldering is nice but the wind will break that soldering point. This gets important on big antennas where you need to add or subtract wire length to resonate. Stress will eventually break the wire unless you do something to give it strength. I do that with a square knot . Yep. Tie a square knot with the two ends you are joining , then cinch it down tight as you can, then twist the two wire ends and solder if you want ( I don't) . That wire may break but not there!! That knot makes no difference in the swr, continuity or the performance of that antenna.( only the net length) All you need is the correct total length of that loop or dipole.
Just add or subtract the length necessary to find that resonance!! 8.1 feet ( above anywhere and adjust the pull lines to balance the two sides. It makes ZERO difference if it is not exactly equal lateral sides . It can be way out of balance. It matters not. Maximum efficiency is to strive to the largest inside area. The perfect Circle is optimum but very costly indeed to construct.( hi!) The difference is not worth it in DBd gain . ( maybe ,outside, .07 DBd) . These Deltas are estimated at anywhere from 1.5 DBd to 2.9 DBd against dipole at same heights ,depending on ground loss . (I reduce ground loss with a reflective radial system on the ground but that is another subject). But all we have for our Pyramid is ONE mast or tower 30 to 50 feet high ,like most hams and a pulley system to pull the center top up so we do a Pyramid configuration. You tie off to a tree or a fence post or anything that gets your sloping sides and base pulled straight. I have used tee posts. I will repeat ,I love weed eater line (.090 or larger) to insulate and tie off antennas, but use anything but rope that holds moisture. Remember . If the base has to be longer than the sloping sides-- THAT'S OK!! I promise. This "optimum" theology is a myth .
This concept will work on any two bands-- 17/20 would work well. Try 3 bands-- 10/12//15.
This was a fun and exciting project. First tested January 23 ,2016. Yes, I have duplicated it twice on 17/20 also. . w5zo@arrl.net
.
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