Details on the N2CKH/NNN0WWL 2Mhz Delta Loop Antenna

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1 Details on the N2CKH/NNN0WWL 2Mhz Delta Loop Antenna Updated 11 November 2009 Started 23 August 2008 This paper presents my design approach for a Delta Loop antenna which is resonant at 2Mhz which has become my main antenna for all my HAM/MARS/SHARES MF/HF NVIS and Skywave antenna as it meets all my needs. I can t offer much in the way of anything new regarding the electrical design of an HF Delta Loop antenna other than my approach to building one, where my goal was an all band full legal power limit antenna that was an all weather conditions simple, yet sturdy design that was easy to install and maintain. I choose a Delta Loop configuration as only three points are required to support the antenna, in my approach one is the feed point and that consists of a very sturdy Ladder Loc ladder line to antenna coupler which is the only stationary part of the antenna as the other to support points allow the wire to free float. The placement of the loop is seen below in the overhead view of my property where the antenna is depicted in red. The antenna is installed over the eastern part of my property away from the main house at about 30 feet above ground depending on the grade below it, which varies by about 1 to 6 feet in places.

2 I say 2Mhz Delta Loop as it uses a standard 500 foot roll of 12ga. electrical wire in its construction and it resonates just about at 2Mhz, which is my main interest being as my lowest MARS frequency for ALE is just above 2Mhz. To achieve resonance within the 160m band an additional 20 feet or so of wire is all that is required depending on the point of resonance desired. This loop antenna, as expected, is very quiet compared to all other wire antennas I have used in the past and have here currently for A/B comparison at this location. The antenna being all insulated has proven to be impervious to changes in characteristics when wet or iced, unlike the Cobra Ultralite which I also have installed. In addition, with most wire antennas, you really need to look closely to see them, even with the 500 foot loop this is true. Also, the loop is easily tuned on all frequencies 160m through 6m using my LDG Z11PRO or AT200PC auto tuners and obviously with my HF roller inductor antenna tuner. However the antenna does present a challenge to most automatic antenna tuners from radio manufacturers that have the typical ohm tuning range. As with most wire antennas, you really need to look closely to see them, even with 500 feet of 12ga. wire for a 2Mhz Delta loop that is the case as can be seen looking over the photo below, where is that loop?

3 The Ladder-Loc ( used at the feed point is suspended over the NE side of my 32x32 foot garage that contains my radio station. From the Ladder-Loc one leg of the loop runs North to South for some 167 feet past the front of my 10x15 foot building housing my repeater stations to a support that is in a large pine tree past the bend in the drive way near the SE corner of the property. The loop then heads West to another support in a pine tree on the South side of the drive way that across from the main house. The loop then runs NE over the driveway and east lawn back to the Ladder-Loc feed point. As can be seen in photos below in detail, the insulated wire runs through one end of modified Alpha Delta-CIN insulators where the wire is free floating in the two far end supports, its only held in place at the Ladder-Loc. The Ladder-Loc in the picture above as seen from the ground with camera zoom appears have all the insulation on the wire elements and the ladder line, however I used that to outdoor flexible paint on tape in the color black to weather proof the connections so that the entire antenna is WX proof. There is a lot of tension on that Ladder-Loc what with 500 feet of wire handing off both ends that is free floating through the other two supports, but is has with stood an awful lot of winter wind and ice loading on the wire and a tree limb coming down on the wire during a winter ice storm that snapped the wire and made the antenna into a 200/300 OCF dipole for a few weeks until the WX was good enough to repair it. The tree branches here in NC are very prone to breaking, unlike what was used to in NJ, KC2CNB discovered this upon his initial climbing of my trees here. There is about a third of my loop under tree branches which could pose a falling branch threat and the use of common electrical wire which only has about a 400lb breaking point is obviously not good enough. So its either trim back more branches or use stronger and much more expensive wire, such as insulated copper clad steal wire with a 1900lb. breaking point as we have lots of winter ice storms in NC.

4 A 9:1 CWS ByteMark ( BAL-450 W2FMI balun mounted on the eve on the East side of the garage that feeds 40 feet of 450 ohm ladder line to the antenna where there is 30 feet of RG-214 coax that runs in the antic and drops down into the radio station in the two bay garage on the rear side closest to the house. The balun is grounded with a heavy ground braid lead to a UL rated ½ inch copper clad 8 Foot ground rod with 7 /12 feet into the ground, which was no easy task here in NC as a sledge hammer was needed to get that far into the ground.i bought a few more CWS ByteMark 9:1 baluns recently after using all the units I had on hand for the antennas I now have installed at the new QTH and I was surprised by the new packaging as seen below as its not advertised on their web site. The new CWS ByteMark 9:1 balum now has the wire attaching to the top, rather than the sides of the unit. This new housing is some what smaller than the previous one I used for years, but after testing it I have found it performs exactly the same. However I do feel that more care is needed in where to mount the unit to protect against icing even if insulated with coax seal of the like as the feed point connections are so much closer together and coax seal and the like can weather, dry and crack over time if not maintained.

5 Heavy 5/8 dacron rope was used with modified Alpha Delta CIN end insulators where one end was opened to accept the rope and is held in place using heavy wire ties and stainless steel hardware on the rope, yet allowed to swivel on the rope with the wire free floating through the other end of the CIN insulator. The rope is guided through 3/8 stainless steel eyebolts installed up in the supporting trees by my friend KC2CNB where the bottom end of the rope is secured to cleats near the bottom of the trees. To cut the Dacron rope for a clean and hot sealing cut, a professional Weller Butane soldering torch with hot knife tip was needed that I borrowed from my friend N4GLT.

6 The image below is of the far South West end support where the wire run goes from East to West and then heads back North East to the Ladder-Loc over the garage.

7 Parts List One Ladder-Loc One CWS ByteMark 9:1 balun, BAL-450 W2FMI now in new Military packaging. 450 ohm Ladder Line Coax Cable PL-259 Connector Two modified Alpha Delta CIN end insulators 5/8 dacron rope 500 Feet 12Ga. Insulated Wire Stainless steel U bolt hardware 3/8 stainless steel eyebolts Black [size] Nylon Ties Black Liquid Tape 3M Electrical Tape Coax Seal 8 Ft. 5/8 inch UL Copper Clad Ground Rod 5/8 inch Ground Rod Clamp Ground cable Solder Tools Weller Butane soldering torch with hot knife tip Wire Cutter/ Stripper Exacto Knife Claw Hammer Adjustable Wrench 60w or better Soldering Iron and Resin Core Solder