SIGMA-40 Vertical
"This is not your Daddy's vertical!"
This is a brand new, high performance vertical for the 40 meter band. Consuming over 4 years of elapsed time for several designs and long term testing, the SIGMA-40 will open your eyes on 40 meters. If we knew how to make it better, we would do it! The only thing to enhance the SIGMA-40 is to place it adjacent to salt water.
The need for efficient vertical antennas has been evident for many years and, as a result of customer requests, the Force 12 ZR-3 was developed several years ago. This small, 6' tall antenna is an effective 20-15-10 meter vertical dipole and needs no radials. Many requests were subsequently received for a 40 meter version of this design. "Team Vertical", operating from Jamaica and Venezuela (6Y2A, 4M7X) used 40 meter ZR's to set records; however, these were lightweight units and could not be used as a production product. Force 12 built some 40 meter ZR's for customers, but they were large and expensive. Performance was as expected: excellent. How to provide a 40 meter vertical with the same performance as these ZR's, but at a reasonable price and simple to install has spanned the last four (4) years. We said we would do it and we have.
The name for this new vertical is "Sigma." This is the Greek mathematical symbol meaning "the sum of" and the Sigma series is truly the sum of years of experience, designs and testing. Not all ideas were successful, but that is the manner of research.
SIGMA-40 40 METER VERTICAL DIPOLE |
|||||
 |
SIGMA 40 24' tall, plus base 90 mph, free standing 38 pounds 2:1 VSWR >300 kHz 5KW rating |
||||
| SIGMA-40 tilt base. The square tube is cemented in the ground. The lower bolt (1/2") is removed and the upper bolt is the hinge bolt. Base insulator is 2.5" pultruded solid fiberglass. Antenna uses 2.5" thick wall bottom section, then 2.25" thick wall to center insulator. Upper sections are 2", tapering wall. |  |
 |
|||
The Sigma verticals are all vertical dipoles. This means they do not need radials, so the real estate needed is minimal. The first one being released is for 40 meters - as promised. The name is "SIGMA-40" and the antenna is 24' tall, plus a base mounting post. It is more than 96% efficient, with an operating bandwidth to please everyone. The design is a combination of several techniques to achieve high efficiency and small size. One of the real life tests is working Europeans barefoot from California, both direct and on the long path. The SIGMA-40 has also been compared with the new 140N 85% full size rotatable dipole (at an effective height to the east of 160') as an additional test. It is right on the mark.
The SIGMA-40 is free standing with a tilt base, rated for 90 mph and 5KW. The SIGMA-40 is bolted together and the loading technique is a combination of T-bars at the top and bottom of the antenna, plus 4" diameter, high-Q coils (3/8" diameter tubing) at the center. The coils are non-adjustable and tuning is very simple -> adjust the length of the T-bars. The SIGMA 40 comes with compression clamps to make initial or temporary adjustments on the T-bars, plus rivets to complete a permanent installation.
DXpeditons and portable might prefer the smaller, lighter SIGMA-40XP. This comes in 4' sections for easy transport and is only 16' tall for faster installation. It comes complete with guy ears welded to a collar for simple one-set of guying. Bandwidth is about 200 kHz and tunable to anywhere in the band. Same power handling.
Price of the high performance SIGMA 40 only is $489.
Price of the DXpedition, 16' tall, 4' section SIGMA 40-XP is only $449.