Here is my disclaimer, I am not an antenna RF engineer. Having said that I was looking for something that would give me a bit of gain and some good F/B on 40 meters. I have always liked loops and thought I would give a set of 40 meter loops a try. I recently put up a 90′ tower and just had to suspend something from it. I built a boom out of military green camo netting fiber glass poles that I got on ebay for $20 a bag of 48′ worth. If you have not seen the boom post, here is a link to it 40 Meter Phased Delta Loop Boom.

So I did the standard calculation for a loop 1005/Freq=Length in feet and it came out to about 140 ‘ at 7.175khz.  So my XYL (KD5ZPD) helped me cut the wire. I began to string the wire, what a nightmare if there is loose rope or wire laying around it will find a way to turn into a spider web. Not to mention the Cedar and Oak trees that I had an epic battle with. I had to go midevil on the trees and get out the chain and pole saw, so 9 hours later I had both loops up in the air and somewhat symetrical.

Doing the calculations and modeling on EzNec I decided that my best combination would be 75 ohm RG-11 type coax at 30′ for the feed lines and 100 ° phasing with  LMR 400 type 50 Ohm Coax. According to the EzNec program this would give me approximately 18 db F/B and 5.23 gain. I used a budwig

Budwig center insulator

center insulator in the corners of the loops, it is best to feed the loops approximately 1/3 of the way up the vertical legs but that makes it difficult to support the feed point and the coax, these things are great for wire antenna projects.  I settled for the corners which only makes a few tenths of a DB difference. MAKE sure that when connecting the coax to the loops the hot side is on a vertical leg of the loop. I use loops for vertical polarization. So far the numbers reflect the results of the modeling. I get anywhere from 12 to 24 db F/B on my FT1000MP meter and I was in QSO with Geroge EI6S in Ireland on 40 during terrible conditions and got a 59+15 report. Wade W5ERX about 2 miles from me with a inverted V Dipole also running 1500 watts got a signal report of 58. His dipole is oriented N/E so this shows a gain of 4 SA Units based on 6 DB per S unit so approximately 24DB WOW, if I can hear you I can work you. Not very scientific but I am very happy with the results of this antenna system. If you have any questions feel free to contact me I look forward to hearing from you.

To calculate phasing I used the formula and explanation found on Va7st web site.

To figure out 84 degrees:

• Figure out 360 degrees (1 wavelength) in feet
  (3.550 mhz = 277.06 ft).
  I use an online wavelength calculator to get the 1-wave length
• Divide this by 360 degrees (to get the length of 1 degree)
  277/360 = 0.77 feet per degree
• Multiply this by 84 degrees
  84 x 0.77 = 64.63 feet for 84 degrees
• Multiply this by your coax’s velocity factor
  64.63 feet x 0.66 vf (RG58) = cut the coax at 42.66 feet (42’8″)
  

To figure out 71 degrees:

• Multiply 0.77 feet per degree x 71 degrees = 54.67 feet
• Multiply this by 0.66 vf = 36.08 feet (the length to cut the coax)

I made a simple switch (Phase Box) for the loops using a simple DPDT relay for details of the switch box you can follow this link Phase BOX. This allows me to easily switch directions of the loops to N/E 45° and S/W 225°.

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