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Entire Article Copyright by Hamuniverse.com and or KL7JR
An 80/160 Meter "Inverted L" for Arctic Use

by Yukon John, KL7JR/VY1RST
See additional updates for more bands and operating from hotter climates like
 Puerto Plata Dominican Republic at bottom of article

It was time for me to get on 160 meters.
Living in the North (Alaska), provides me a wonderful opportunity to do just that on my portable operations. I also wanted 80 and 40 meter coverage with the same antenna, and I wanted to try something other than a loop this time.

For my low band portable winter operations from the Yukon, I needed an antenna that was not only suited for both 80 and 160 meters but it had to be easy to install, require minimal supporting and it couldn't take up a lot of space. My motor home would be one support and for the other support I'll have to "wing-it" in the field.
 
Thanks to 2E0BAX for his inspiration (see "Limited Space HF Antenna For 160, 80 and 40 Meters" at Hamuniverse.com), I've designed my version around my portable operating position (motor home).

I decided a full wavelength on 80 meters (254 feet) which yields a half-wave on 160 meters would be enough wire for me to get tangled up in, or trip over several times, while erecting, hi hi! Oh, did I mention it will probably be 40 below zero with howling winds as well? But this is just half of the fun.....the ground system will have to be elaborate if I'm to achieve success with this antenna. I'll use a mesh screen and all the scrap wire I can muster up for the ground system.

I'll also use a "long coil" (see "A 28 MHz through 7 MHz Vertical Portable Dipole" by yours truely, at Hamuniverse.com) that I've had good luck with in the past to "shorten" the antenna length.

I decided not to use more than 30% of the entire antenna length in the coil (ie-254 feet x 30% is 76 feet. Subtracting 76 from 254 gives me the real antenna length of 178 feet minus the mast height of 25 feet equates to 153 feet for the sloper part.

I changed the design and used #10 stranded wire for the sloper part to give the added strength I'd need on the long span. For the rest of the antenna #14 wire was used.

The vertical radiator terminates to the PVC coupling and the coax center conductor is tied to that. The coax shield connects directly to the ground lug on the 1" pipe flange. The plumbers tape (metal ribbon) bonds the pipe flange to the metal screen.

So, I'm all set, and when winter rolls around I'll give this beauty a try! I plan to be on for ARRL phone contests (SS, 160 Meter and 10 Meter from "up here") and perhaps some PSK-31 activity as well.

160/80 meter sloper antenna diagram
Diagram of 160/80 meter Inverted L

Optional method

Instead of using the mast as the "vertical radiator", set the coil about 2 feet out and away from the mast at the top and use wire as the vertical radiator instead of the mast and then drop and terminate the vertical radiator wire in the PVC coupling where it is terminated with the coax center. (remember to add more wire if wire is used rather than the mast).  The wire can be pulled out and away at an angle from the mast.  This is probably the approach I'll use depending on available space.  I'll also use my drive on mast base support ......
(this is where my motor home aids as a support!). 


Coax Termination base point. Notice white PVC insulator!

 
The "Launch Pad" showing the ground radial screen and plumbers tape attached.

Update - March 2011
Operating with it in the Dominican Republic with some modifications for coverage from 40 meters to 10 meters.

I'm amazed at what I'm doing with a piece of wire!  With some simple modifications while operating from the Dominican Republic, this is now a tried and proven winner for me.
As it is now at 75 ft long with a 15 ft coil near the top end, it's 10-40m rated with 20, 15 and 17 being "hot"! 
Only made one contact on 10m but it does not allow full power output, so I'd say it's a compromise on 10....maybe "too long" or not long enough".  HI3/KL7JR

Updated contacts and performance of antenna March 17, 2011

HI3/KL7JR First 3 weeks of operating: 75 foot long "Inverted L" at 30 feet high in coconut trees sloping to 20 feet w/15 ft coil on end facing north/south of ocean. (From Costambar, Dom. Republic) See aerial image from Google Earth below.

12M...XE2, DF2, EA5 and 8, VE1 and 3, HK3 and PZ5

15M...OM3, OK1, I7, IK0, OZ7, OH6, EA1, 2, 3, 4, 5, 7 and 8, UX6, DL3, UR3, ON4, OM3, HB9, ZF1, SP3, S58, YB0, EC4, VE5 and 6, RV4, HI3, PZ1, F5, CT2, 9Z4 and PA3

17M...HI3, PZ1, F5, EA1, 3, 4, 5, 7 and 8, CT2, 9Z4, PA3, EC7, PT7, VE1, 2 and 3, GI3, G1 and 4, HK3, XE1 and 2, SM2, OZ7, OH2, HR1, CU7, ON7, UA4, PZ1, YV8, OE6, IZ2 and 5, F1, 5 and 8, S57, EK6, IF9, VY2, EI9, UT1, CO2, YV8 and 8P6

20M...EI9, VE3, HP1, EA 3, 4 and 8, FG4, FM5, IK8, VA2, YV3, SM7, EI6, VP2, 8R1, HI3, 9Z4, PY2, ZL1, 9Y4, 8P6, YS1, VP9 and TO1

40M...8P6, 8R1, EA6, YV5 and OM7

80M...KG4

Google Earth Image of General location of QTH
Google Earth Image of general area of QTH about 100 feet inland from the beach!

(I'm only lacking 3 or 4 states for WAS on 20 and 17m and about 12 on 40m in the first 3 weeks of operating)



73, de Yukon John, KL7JR

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