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Reviews Categories | Antennas: HF: Vertical, Wire, Loop | Force 12 Sigma-5 vertical dipole Help

Reviews Summary for Force 12 Sigma-5 vertical dipole
Force 12 Sigma-5 vertical dipole Reviews: 19 Average rating: 3.8/5 MSRP: $369.99
Description: 5 band HF vertical antenna. 9 ft. tall
Product is in production.
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K4RT Rating: 5/5 Jun 23, 2015 06:46 Send this review to a friend
Sturdy Construction, Performs Well  Time owned: more than 12 months
I bought my Sigma-5 new in 2002 and it has been in regular use since then.

What It Is:

The Sigma-5 is not a Yagi. It is a broad-band shortened dipole with loading coils designed for optimum use at ground level. Considering its limitations, I believe the performance of my Sigma-5 has been quite good.


Following the instructions in the manual, assembly was straightforward. The antenna elements are made from sturdy aluminum. All screw holes were aligned. I installed the antenna at ground level, with the coax and control cable oriented at 45 degrees as the manual specifies.

Installation & Performance:

At about 10 feet in height when installed at ground level, the Sigma-5 was an excellent choice for our former home, which was located in a neighborhood with antenna restrictions. I painted my Sigma-5 with black non-metallic spray paint, which greatly reduced its noticeability. I briefly hung a house flag from the top bar to help disguise the antenna, but the flag seemed to make the antenna more obvious, so I removed it. In the 10 years we lived at that location, not one neighbor asked about the antenna.

The rotary switch Force 12 provided with the Sigma-5 was mounted to a small plastic panel similar in design to an acrylic picture frame. For me, this left something to be desired, so I eventually moved the switch assembly to a sturdier enclosure.

I have never had to use a tuner with the Sigma-5. I have worked quite a bit of DX using this antenna, including New Zealand and South Africa. I have also used it for several portable operations. Transporting the antenna in my vehicle requires removal of the top section. A 5-gallon bucket containing bricks has proved sufficient as a base for the antenna. I have also tied three nylon cords to the mast and anchored the cords to tent stakes.


Every few years, I disassemble the antenna, remove the weather cover entirely, and use a soft brush to remove cobwebs and dead bugs from the circuit board that supports the coils & relays, followed by using compressed air to blow out dust and debris. Water and a stiff-bristle brush have worked well to clean the cover and end-caps. I have been surprised by the small amount of dirt and debris found inside considering that the weather cover has a narrow opening on one side to accommodate the coax and control cable. The amount of dirt that accumulates inside the cover probably varies with location, however. Before re-assembly, I make a close inspection of the circuit board and components for damage. To date, I have not had any component failures or problems with the antenna elements or hardware.

From my point of view, the Sigma-5 is well built and has performed well for many years.
ON4ANN Rating: 1/5 Nov 28, 2010 08:06 Send this review to a friend
Not worth it  Time owned: 3 to 6 months
holes where not drilled correctly and SWR is bad on several bands, send an email and receive info about how to do it, but had many problems to the coils and hope it's better- to the correct frequency. Waste of money..bought better a SteppIr
KB3HJK Rating: 0/5 Jan 5, 2010 19:58 Send this review to a friend
It's also deaf  Time owned: more than 12 months
An addendum to my review - this thing is deaf. I had an Isotron (!) that heard 10 times the signals that this does.

There are stations on 20M within a mile or two of me. They are big guns, and work pileups. I never hear the calling stations. May that statement serve to elucidate what "compromise" really means. With antennas like these, you are not really hearing the ham bands. So, effectively, I have never really heard what’s out there.
VE3XB Rating: 0/5 Dec 1, 2009 18:28 Send this review to a friend
Don't expect customer support  Time owned: more than 12 months
Works as a shortened vertical dipole should - no miracles. The biggest problem is Force 12 customer support. Sent e-mail to request replacement part - no reply after 2 weeks. Just another unhappy customer.
KK7SS Rating: 4/5 Oct 4, 2007 11:00 Send this review to a friend
8 yrs on and still going strong  Time owned: more than 12 months
It's been in my NW back yard for 8+ years in all weathers. I've removed wasp nests, spiders, etc. from the coil unit and it's still going strong.
My only complaint is that the fiberglass insulator is fraying..
Haven't asked for a new one yet...
K6GMA Rating: 3/5 Oct 3, 2007 19:14 Send this review to a friend
Returned it the next day.  Time owned: 0 to 3 months
I opened the Sigma 5 package and I was just not totally pleased with the antenna. I actually didn't even finish unwrapping it. To the credit of Force 12, it was fairly easy return the antenna and recieve a full refund.
K9YNF Rating: 5/5 May 28, 2005 13:53 Send this review to a friend
An IOTA DXpedition Dream  Time owned: more than 12 months
I have owned this wonderful DXpedition antenna for over two years.In that time I have taken it to NA-057 Roatan Island, Honduras and NA-014 Deer Island New Brunswick, Canada.On both trips it was mounted on a wooden deck jutting out over saltwater. This antenna ROCKS over saltwater!

I run a TS-50S and RG-8X into it and have worked in excess of 50 DXCC entities on all continents without a problem. Packing it into a rolling duffel with a zipper-bottom "antenna compartment" is simple, given the fact that the antenna knocks down into 2-foot sections.It stands 9 feet tall on the deck floor and is easily lashed with two bungee cords. I had mine specially tuned at the factory for the 20 meter SSB IOTA frequency (14.260). It performs superbly there without any tuner and equally well on the 17, 15, 12 and 10 meter bands as well.I also purchased the optional X-base for use at the home QTH.

If you are looking for a radial-free, DXpedition powerhouse antenna that can be packed in your suitcase, this is the one for you!
N9QGU Rating: 3/5 Oct 3, 2004 17:43 Send this review to a friend
It works  Time owned: 3 to 6 months
I was looking for a portable antenna for Caribbean vacations. I like to play ocean side radio from either Jamaica or the Bahamas. Finding an effective antenna that is easy to pack and deploy has been a challenge. I have tried wire dipoles. They are easy to pack. But there is not always a convenient structure to hang them from. So I read through the eham reviews and found a number of candidates. First I considered the Cushcraft MAV. The price was right. But it just wouldn't pack down small enough. I briefly considered the Buddi-Pole. But I wasn't sure I could get it up high enough and by the time I added in all of the bells and whistles it was close to $400. This was a little steep for an antenna I would only use once or twice a year. The rest appeared to be extreme compromises. Then I hit upon the Force12 Sigma-5.

The Sigma-5 appeared to be robust enough for permanent installation yet light enough for easy packing when I went portable. I read through the reviews and was struck by the fact that users were, with a few exceptions, very pleased with the product and its performance. However, when users were dissatisfied it was generally due to Force-12's factory and technical support. Recognizing that you can't please everyone, I decided to pursue it a little further.
I was pleased to see that Force-12 would be at the Dayton hamfest. I stopped by the booth, spoke to Tom, and had a closer look at the antenna. He was very helpful and answered all of my questions. Unfortunately, he did not have a control unit for me to look at. I ordered a Sigma 5 and the x-base on the spot. Tom promised me it would be shipped out upon his return to the office and I should have it in about 2 weeks. “Great” I thought, I will have it in plenty of time for field day. I returned home and eagerly awaited my antenna.

Three weeks later, the antenna still had not arrived. I called Force 12 and spoke to a very nice lady. She told me that Tom should have never promised two week delivery as they were way behind in production and most likely I would not receive it for another 3 weeks. Three weeks later, the antenna arrived.
So on a bright shining Saturday morning in later June I opened the box and started to put it together. The pieces were numbered with a black marker and arrows were drawn to show where the pieces connect together. This is generally a good idea. However, I noticed that the marks were rubbing off rather quickly. So I used colored electrical tape to show which pieces went to together (i.e. blue to blue, red to red, yellow to yellow, and white to white). The antenna sections are held together with short machine screws and wing nuts. Although the screw holes were clean there were several not properly indexed, aligned, and definitely not drilled through the center of the tubing sections. Thus, I often had to rotate a section 175 degrees to get the holes to line up. The antenna sections join together male to female. When I got to the point where the bottom section of the antenna joins to the base I ran into a problem. Both pieces were male. They weren't going together. I read back through the manual and found a reference to an "insulator". But there was no additional information. Hoping to find further clarification I called Force 12. But unfortunately they are not open on weekends. So I sent an email to Tom and searched the Force12 website. The pictures showed something that I could not clearly identify between the bottom of the antenna and the base. According to a sticker on the base, the antenna was assembled by "Jason". It appears that he left a piece out. Disappointed, I dissembled the antenna and put it back in the box.

On Monday, afternoon I called Force12 and spoke to Tom. He acknowledged receiving my email. However, he didn't explain why he hadn't replied. He explained about the missing piece and promised to send it to me. It would take 7-9 days to arrive. Apparently, it was being sent by mule train. We also discussed using 6 inches of 1 inch PVC as a sleeve in the interim (The missing piece was an insert). The PVC worked ok, but it was a little too wobbly for my comfort.

Time passed and the piece didn't arrive. So I called back and spoke to a young woman. The piece had not been sent. But she would send me one right away. But it wouldn't arrive for 7 to 9 days. I called the next day to make sure it had been sent. It hadn't, but she promised to send it out that day. I called back the next day. She gave me a fed-ex tracking number. It took about 9 days to arrive. The piece was so small that if it had been sent in a padded envelope via US Mail, I would have had it in three days.

The insert did not come with any instructions or hardware. And, it was not drilled out to accept the connecting bolts. So I drilled it to match the holes in the antenna and the base.

Now to connect the controller:
The controller is a rotary switch mounted to a “L” shaped piece of plastic. The back of the switch is exposed. This might be just fine for desktop use at home. But, it is completely unacceptable for portable use, and certainly a very poor choice in any harsh environment such as found in most DX-peditions. The five controller wires and two 12 volt DC power wires have to be terminated at the back of the control switch ‘console’ on a long and unmarked screw clamp terminal strip. I don't know why they did not use a quick connect plug or at least mark the terminal strip with some simple color code or band position information. It would have made the set up process a lot easier. The entire controller is built open-chassis style and uses one color of solid hookup wire for the connections from the switch to the terminal strip. This is another potential failure point. Stranded wire is far more vibration resistant for a portable antenna. In addition, I discovered that one of the wires leading from the terminal strip to the switch was not soldered on the control switch end. This would have come loose with minimum use. None of the wires were properly mechanically terminated on the rotary switch lugs – they were simply stripped, shoved through the switch lug holes, and soldered. All of the solder joints and wire work was extremely poorly done --- lots of bare wire sticking out both sides of the switch lugs and every solder joint appeared dark and dull indicating that they were probably cold joints. Excessive solder everywhere!

My DX-Pedition partner built a very compact replacement “sealed” control unit with plug in connectors. This “one off version” cost less than $5.00 to construct. In quantity, they would be no more expensive to construct than the controller that was supplied.

The guts of the antenna (coils and relays) are mounted on a circuit board inside the center box (A fat piece of PVC). This section is not moisture resistent. There are openings at the top and bottom to accommodate the antenna and a large slit in the side of the tube for the controller arm. These openings are not sealed. However, the relays themselves appear to be sealed. Whether this "open" design becomes an issue in the future due to water, ice, snow, bugs, and general dirt intrusion is still an item of concern. The soldering job on this board was extremely sloppy. There are places where the solder has been allowed to drip on the circuit board and many cold joints. For whatever reason, someone also ran beads of solder on the traces of the circuit board building up ridges. Maybe this is part of the tuning process? Maybe it increases the current handling capabilities of the PC board assembly? In any case, this is extremely shabby construction technique and another point of concern for longevity and reliability.

In addition, there is a slit in the PVC coil/relay enclosure tube to accommodate the control cable and the coax. The slit was far from neat and had jagged edges that had cut through the insulation on the control cable during shipping or possibly before it ever left the factory. That had to be repaired immediately before I could even use the antenna. I used a file to remove the rough edges. It is unfortunate that Jason did not take the time to do this when he initially assembled the antenna. The smoothing process took less than 30 seconds.

I assembled the antenna and tested it using an MFJ antenna analyzer, Daiwa SWR Meter, and the SWR meter in the rig (Icom 706 MKII G). They all showed the same result. The antenna was resonant at 13.5 MHz when set for 20 meters. The SWR reading was 5:1 at 14.250 MHz. However, I was able to remove the cover and adjust it with out too much difficulty. Be aware of 2 things. First, the cover affects the SWR. The SWR measured lower in the USB portion of the band without the cover in place. Second, it is easy to accidentally bump and compress the 20 meter coils when re-assembling the PVC cover enclosure. This adjustment did not appear to affect the rest of the bands.

Now on to the Bahamas for field testing:
The antenna was set up about 20 feet from a saltwater estuary. We extended the control cable to about 75 feet. I fed the antenna with a 100 foot length of standard RG8X coax. The results were quite spectacular. I made approximately 300 contacts over a 3 day period. 17 meters had some very good openings and the bulk of my contacts were on that band. My total radio time was around four hours. At several points we were averaging close to 100 contacts per hour. If you have never been on the receiving end of a huge pileup, it is truly an adrenalin rush and a whale of a lot of fun! We could have made many more contacts, but we were on vacation with the XYLs and they refused to be radio widows. We were able to work many of the Canadian Provinces from Newfoundland to British Columbia. The bulk of our contacts were with the US and Canada. But we were also able to work much of Europe, Diego Garcia (12 meters), Australia, and Japan. The band conditions and close proximity to saltwater undoubtedly played a significant role in our success.

In summary, the Force12 Sigma-5 antenna works and breaks down small enough to fit in standard checked luggage. That’s the end of the list of good comments. But I doubt the antenna as originally delivered would have stood the tests of time. The control box is inadequate for portable use and as delivered would have failed after minimal use. The electrical/mechanical design of the coil and relay assembly is of questionable longevity. The construction techniques used are extremely poor and totally unprofessional throughout. Quality control is non-existent. The factory support is worse than poor and their promises are not credible. Force 12 could easily compete with MFJ for “Worst Amateur Radio Equipment Manufacturer of the Decade”. If you don’t mind paying a very high price for very poor design and workmanship, don’t mind tinkering and rebuilding something you paid over $300 for then this antenna is for you. Maybe I should have gotten the Buddi-pole after all.
VA2VYZ Rating: 5/5 Aug 9, 2004 23:45 Send this review to a friend
Great antenna !!!  Time owned: 0 to 3 months
Just installed today. I put it on my chimney because I don't have enough space around the house, and too many things... BBQ, trees, electric wires, etc...

I checked all bands with my MFJ-259B, and exept for the 17M, all other bands are below 2.1 : 1 on all bandwidth !!!

I got nearly 1.4 : 1 on the lowest point on all bands.

I'm very satisfied for now.. exept that the cost is a little expensive.... but really worth it !!!


KE6VG Rating: 5/5 Aug 13, 2003 23:24 Send this review to a friend
Lotta bang for the size  Time owned: 0 to 3 months
I gotta say it's amazing for the size. Quality materials, beautiful welds. I tried it in several locations. On the roof with the base at 17' was not as good at my location as in a cement filled bucket on my 6' block wall behind the house. SWR 2:1 bandwidth was right where they said it would be. I did tune the coils using my MFJ-259b. Unlike others, it took less than 3 minutes to set all bands right where I wanted them. Easily field tunable with the analyzer. Being able to stand next to the antenna on the ground made things way easiter than tuning a dipole and running around trimming ends. You just need to understand how the antenna works. Start with the highest frequency and work your way to 20 meters. On 20 meters the signal travels through all the coils combined. Now the performance. For its size, fantastic. It was very quiet. I put up a reference parallel inverted vee dipole at 30'. The inverted vee outperformed it on almost all instances. This included long path, short path, you name it. Europe, Asia, Pacific, East coast, South America, Africa. However, being only 1 s-unit below the inverted vee most of the time, makes this a great portable, or restricted CC&R antenna. Sometimes signals would be almost equal and sometimes signals would be 2-3 s-units stronger on really long paths broadside the inverted vee. I did always have less noise on the Sigma5 (man made or natural) which made hearing some stations easier on the Sigma than the inverted vee. So, if you can't get a dipole up at least 30' or put up a beam, this might be an antenna for you. I gave it a 5 because as verticals go, this little guy had some kick, and you could easily hide it in your backyard.
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