[HCARC] super antenna

Sat Feb 28 01:02:45 EST 2015

Loop Skywire Link and variations:  n1su.com/loop.html

Gary J
N5BAA

-----Original Message----- 
From: Dale Gaudier
Sent: Friday, February 27, 2015 12:51 PM
To: 'Hill Country Amateur Radio Club'
Subject: Re: [HCARC] super antenna

All:

I've run the model in EZNEC 5.0 and the results are in. See below for my 
summary report. Anyone who is interested in seeing the SWR sweeps and 
elevation/azimuth plots for the HF bands (160m through 10m) can email me 
direct at k4dg at arrl.net and I will send you a pdf file of the graphs.

One side note: this antenna is very similar to the well-known "Loop Sky 
Wire" described by Dr. Dave Fischer, W0MHS, in QST, Nov. 1985 pp. 20-22. 
ARRL members can access this article via the www.arrl.org website. I have a 
copy of this article if you are interested. I knew Dr. Dave - he and I were 
members of the Atlanta Radio Club. His antenna had a good reputation among 
those who had built it.

73,

Dale - K4DG
===========================================

Summary Report on Full Wave Horizontal Loop Antenna

Antenna parameters used in model:

• Square loop made of #13 AWG insulated wire, 282 ft. per side
• I used a dielectric constant, κ, of 2.25 per original design described 
below [Wireman #531 Toughcoat 'Silky' 13 AWG, 19 strand 40⁰ copper-clad 
steel (OD 0.0795") with high density, low-gloss polyethylene (nominal OD, 
0.120"including 0.020" jacket].
• 104 feet high
• Fed at corner with 440 ohm ladder line
• Modeled over real/high accuracy ground
• All SWR curves are referenced to Z0 = 440 Ω
• Modeled using EZNEC 5.0

Summary of results:

Antenna performs relatively well.  Four lobed pattern on lower HF bands; 
more complex cloverleaf patterns on the upper bands.

Band       Max. Gain Takeoff Angle

160m          7.57 dBi       55⁰
80m         11.59 dBi       32⁰
40m         11.59 dBi        14⁰
30m          9.83 dBi       45⁰
20m         11.64 dBi        28⁰
17m         14.20 dBi        7⁰
15m         11.19 dBi       33⁰
12m         11.05 dBi       17⁰
10m         13.63 dBi        5⁰

Maximum Gain and Takeoff Angle figures are in reference to the main lobe of 
radiation.

Notes:

1. Antenna was modeled using 282 feet of #13 AWG insulated wire for each 
side. However, a better match for 440 ohm input impedance would be to use 
258 feet of wire for each side.
2. Model assumes wire is horizontal between the elevated supports; however, 
there will be some sag in a wire that is 282 feet long. The impact of sag on 
SWR and elevation/azimuth patterns is unknown.
3. Main lobes on the lower HF bands are oriented in line with the corners, 
i.e. in line with the diagonals to the square.
4. Impedance match varies from band to band; SWR is below 2:1 only for small 
part of 15m band; otherwise it is often much higher than 3:1 on most bands. 
This antenna will require a matching network (tuner) and open wire feeder to 
minimize losses.

=============================================================================================

In a message dated 2/26/2015 3:35:18 P.M. Central Standard Time, 
w5lew at reagan.com writes:

A friend in Mississippi sent me some info about a super loop antenna.
Thought you might like to dream of having such and antenna.  Enjoy!

A ham's dream antenna, which I saw when visiting Bob W0JEE in Smiley, TX SE 
of San Anrtonio.

Elvin JA3CZY from Osaka came to TX for a visit. He has a 3 element 80M yagi 
at 220 ft atop a building and said that W0JEE on 75M SSB was the loudest 
signal he ever hears form the USA, beating even the west coast high power 
and big antenna guys. So I took Elvin to see Bob in Smiley.

Here's what Bob told me about it.
He has experimented with long wires, vees, rhombics and other designs.
Then enlisted ham friends help to design the best single antenna for all 
bands.
There was no literature on the design they eventually came up with.
it is a square loop 282 feet per side square loop at 104 feet over good 
ground.
Wire is from http://thewireman.com/antennap.html
#531 Toughcoat 'Silky' 13 AWG, 19 strand 40% copper-clad steel (OD 0.0795") 
with tough, high density, low-gloss polyethylene (Nominal OD, 
0.120"including 0.020" jacket. Designed for through-the-trees, sea coast, 
acid rain or other inclement atmospheric conditions. Our most rugged, 
longest-lived, stranded antenna wire for any purpose. Jacket has minimal 
effect on performance - less than that of a year's accumulation of oxidation 
product on bare wire, with less noise. Break strength 400lbs Sag is 3 feet 
between steel used oil well drill pipe at corners: 3/4" wall 5" dia 42 feet, 
4" dia 42 feet, 3" dia 42 feet nested/welded 7 ft inside each other with 7 
feet in concrete in ground.
Pipe guyed in 3 directions at 120 degrees with 3/8 galv. steel cable at 35 
and 70 feet up, 40 feet out from pipe on drill pipe posts 10 feet above 
ground and 5 feet below in cement.

Fed at the SE corner with 265 feet of Ladder line 
http://thewireman.com/antennap.html#balanced Wireman # 554
440 ohm, 14 AWG, 19 strand copper-clad steel, same as 552 but designed for 
maximum legal power. VF .91

Bob says he got design help from Bud W5RPU in Allen, TX who figured out with 
modeling software what would be the best performing single antenna for all 
bands. This one performed best of all:

160M 6.6 db max gain at 49 deg elevation / 80M 11.1 db at 29 deg

40M 12.4 db at 15 deg / 30M 13.5 db at 12 deg

20M 14.5 db at 9 deg / 17M 14.1 db at 8 deg

15M 14.6 db at 6 deg / 12M 15.1 db at 5 deg

10M 15.0 db at 4 deg / 6M 15.3 db at 3 deg

Now that's some fantastic DX antenna! Bob said he spent about $4000 on 
materials and labor with volunteers helping. 73, Skip W5GAI

______________________________________________________________
HCARC mailing list
Home: http://mailman.qth.net/mailman/listinfo/hcarc
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:HCARC at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2015.0.5751 / Virus Database: 4299/9191 - Release Date: 02/27/15 