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Reviews Categories | Antennas: HF: Verticals; Wire; Loop | Force 12 Sigma 40 Vertical Dipole Help

Reviews Summary for Force 12 Sigma 40 Vertical Dipole
Force 12 Sigma 40 Vertical Dipole Reviews: 5 Average rating: 4.8/5 MSRP: $$489
Description: A shortened, coax-fed vertical dipole for the 40 meter
band, to be used as a single radiator or as part of a
phased array
Product is in production.
More info: http://
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You can write your own review of the Force 12 Sigma 40 Vertical Dipole.

W7WZ Rating: 5/5 Mar 16, 2009 19:42 Send this review to a friend
Works Well  Time owned: more than 12 months
We have two Sigma40 vertical dipoles spaced 49 feet apart and phased with a Comtek box. They work as advertised. SWR is under 2:1 across the band. Running 1kw is no problem. One S-unit gain on transmitt and 10-20db front to back on receive. Spray painted brown, they work fine and offer a very low aesthetic impact in the yard. Good performance for limited space and no cob web of radials! Solid construction and easy to set up.
NI0C Rating: 5/5 Jul 6, 2007 05:58 Send this review to a friend
Great no radial DX antenna  Time owned: 0 to 3 months
If I had to choose one HF band to operate, it would definitely be 40 meters. Due to backyard constraints, I can only deploy radials during the late Fall to early Spring months.

My solution for a year round dependable 40 meter DX antenna is this Sigma 40 vertical dipole. I also own the Sigma GT-5 for 20-10 meters, and have previous experience with the Sigma 40XK.

This is one very heavy duty well-constructed antenna that's going to stay put for a long time. The tilt-base works very well, and if my backyard were clear, I could have erected the antenna with little or no help. However, because of trees and wires in the vicinity of the antenna, I needed several helpers to rotate the antenna to clear obstacles, as it was being raised.

The balun support is a stiff fiberglass rod that gets "tapped" into a hole drilled in the center fiberglass insulator. I found I had to sand the end of the rod slightly to get it to fit without using too much force. Some judicious placement of ty-wraps is necessary to prevent the weight of the coax cable from stressing the balun leads.

Rather than bury part of the tilt-mount in concrete, I chose to slide it over a 2.5 inch galvanized steel pipe concreted into the ground. I used some stove pipe to shim the fit. This mounting method allows the lower T-bars to be at shoulder height, which helps reduce interaction with metal patio furniture in my backyard.

The antenna really gets out. It works at least as well as my HF-2V (full-size quarter-wave, with 60 or more radials).
KK6AW Rating: 4/5 Jan 1, 2003 17:38 Send this review to a friend
Very Good Vertical  Time owned: 6 to 12 months
I won't bore you with repeated remarks, I agree with the favorable remarks of the other reviewers. If it wasn't for this antenna I would not have my WAS on both SSB and CW. I also have a Carolina Windom on 40m this antenna is extremly noisy and I would not have accomplished my goals.
my reason for the 4 rating is that there is alway room for improvement. I am thinking about the sigma 80 as I need an antenna to finish off my 5bwas the last band I need.
AB0SI Rating: 5/5 Dec 12, 2002 17:33 Send this review to a friend
works & well built  Time owned: 0 to 3 months
It is not magic, but it is a fine antenna.

This is a true vertical dipole, hence no radials. Since it is a dipole, it is center fed and the coax needs to be run for several feet at something approaching 90 degrees from the antenna.

It comes with a fold-over mounting mast for easy futzing (remove one bolt and fold it over; futz; move it bck to vertical, replace bolt -- very easy).

It covers almost all of 40m at less than 2:1 without a tuner and handles the 1200 watts I throw at it without a problem.

The Sigma 40 is EXTREMELY well built and very easy to put together and tune.

Rather expensive at $489 plus balun plus shipping, but worth it if you need/want a 40m vertical that works well and is well constructed.
W9AC Rating: 5/5 Jul 22, 2001 17:25 Send this review to a friend
Excellent 40-meter Antenna!  Time owned: 3 to 6 months
When I recently moved from one deed-restricetd community to another, I took another look at the available options for a high-performance 40-meter antenna that could be reasonably concealed in my back yard.

I had used the GAP Voyager at my previous QTH since 1993. The GAP offered excellent performance on 40, good performance on 80, and enbarassing performance on both 160 and 20. At seven years of age, it was time to replace the GAP as it did not disassemble weel after many years oceanside abuse! Given the GAP's mediocre to poor performance on bands other than 40, I never missed this "feature.

The Sigma-40 is not a magical antenna by any means: it is simply a shortened vertical dipole with great physical attributes which appealed to me over the alternative of dropping a vertical dipole from a tree limb. The Sigma-40 vertical dipole does an extremely good job of penetraing any pile-up, even at 100-watts. At 1500 watts from my oceanside location, one call is all it ever takes. Although the GAP's performance was excellent on 40, I would have to rate the Sigma as a better performer. Part of the GAP's problem is that it is much too broadbanded. The 2:1 VSWR points extended well beyond the limits of the 40-meter ham band. While many will consider this a good thing, it is not. The GAP's extended bandwidth is coming at the expense of efficiency. The Sigma's 2:1 SWR points are approximately 200 kHz, much more in line with the predicted bandwidth versus efficiency of a shortened vertical dipole.

Construction quality is superb and with one hand, I can tilt the Sigma down to the ground for maintenance when that time comes. It simply involves removing one bolt at the base to tilt over. In fact, when I was optimizing the feed point, I did this work alone and had the antenna up and down several times and did not encounter any difficulty.

If you want a highly-effective stealth look, I recommend painting all aluminum sections with Rust-Oleum's flat-black charcoal grill paint. Only one coat is required and it dries almost instantly. I am very satisfied with my Force12 Sigma-40. In fact, I plan on purchasing their Sigma-5 which is a similar antenna but operates from 20-10 meters.


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