Does your neighborhood forbid antennas but allow flagpoles? Is tearing up your lawn to lay 64 radials not an option? Or maybe you just want a high-performance, easy to install all-band HF antenna?
NEW UPGRADED DESIGN FOR 2016!
Our Flagpole Antennas have been long-time best sellers known both for their outstanding performance and for their stealthy demeanor. They look like real flagpoles (and they are indeed real flagpoles!) and radiate RF as well as patriotic pride. Historically, their only drawback was that their ground plane vertical design required radial ground systems to work properly. And, if you know ground plane verticals, you know that you need a lot of copper on the ground to achieve an efficient ground system (16 quarter wave radials at lowest operating frequency, at least, many purists recommend 64). So, we went back to the drawing board...
We challenged antenna designer, QST author, and inhabitant of a neighborhood where towers and Yagis would not go down well, John Portune, W6NBC, to come up with a compact vertical dipole with its feedline hidden inside the lower tubing sections and which would be ATU "friendly" delivering good-to-excellent VSWR matches on all bands 80m through 10m with popular autotuners, in particular the new breed of outdoor rated units. John delivered, in spades. John opted for an OCF (Off Center Fed) design which makes it easier in most cases for ATUs to find a good match across a wide range of frequencies. 20 foot, by the way, is a common upper limit in many neighborhood flagpole height CC&R regs.
Since we're Force 12, we didn't cut any corners. Tubing is our usual aircraft grade 6063-T832 aluminum, 2-inch OD top to bottom, thick fiberglass insulators at the feed and base, stainless hardware, Davis RF Buryflex coax and genuine Amphenol PL-259 connector for the pigtail, plus six Mix 31 Fair-Rite ferrite beads from for the common mode choke. We even have an optional golden eagle to crown your flagpole! Let Old Glory flap in the wind while you work DX, what could be better?
We have tested the new FPA-20F-OCF with several ATUs include multiple LDG models and also the MFJ-998RT and MFJ-993BRT. All worked excellent on all bands 80m through 10m. We urge the use of the Flagpole antenna with an outdoor ATU located near the antenna to keep feedline losses to a minimum, however, this antenna will work with indoor ATUs (call us to discuss whether your model will work) and even some rig ATUs (we have tested with the Flex-6700 ATU, contact us for info) but we can't guarantee performance across all bands when the FPA is used with indoor ATUs as the coax feedline between the ATU in the shack and the antenna is an impedance transformer itself which could cause very high mismatch on one or more bands plus many built-in rig ATUs have limited adjustment range.
The video below shows a LDG AT-200ProII autotuner (rated for 6 to 1,000 Ohm loads) at the end of 82 feet of Bury Flex 9914F coax (including the 5 foot coax 'pigtail' that comes with the antenna) to simulate a typical installation worked excellent in our tests on all bands 80 through 10 including 80m, 60m, 40m, 30m, 20m, 17m, 15m, 12m, and 10m in the CW, data and phone band segments. 6m matched to about 2.2:1 VSWR which will work fine with many transceivers with the output power dialed back. (Think of 6m as a bonus on this antenna, the radiation angle on 6m is higher than the other bands, please note.)
Placing the ATU near the antenna will maximize performance, and we recommend you do so if you can. There are many outstanding outdoor-rated ATUs from LDG, MFJ, and other manufacturers that can be powered over coax. Force 12 loves LDG ATUs in particular and we've arranged to offer specially priced packages of our FPA-20F-OCF with the LDG RT-600 (600 W - order bundle here) and RT-100 (100 W - order bundle here) outdoor rated remote autotuners.
Considering a 43 foot vertical? Here's the downside of that option: FPA-20F-OCF is less than half that height, doesn't need radials, and has lower angle of radiation - more DX! - on many bands. Bigger is not necessarily better!
We use six Mix 31 ferrite beads in the common mode choke (which we think are preferable to Mix 43 ferrite for all-band HF applications). We recommend you keep your transmit power to 200 W ICAS or less and also be cognizant of Federal radiation exposure regulations if your Flagpole Antenna is near your residence or where people may gather. You can run higher power. There is an optional Balun Designs balun for installations running > 200 W ICAS.
Installation couldn't be easier. Three feet of PVC tubing (supplied) buried in compacted soil will be enough in most locations to support the antenna, just "drop it in." Of course, you're welcome to install in concrete, on your rooftop or deck or other locations. If you have any concerns about installation, call or email us and we also recommend consulting a PE.
FPA-20F-OCF has been engineered to withstand 90 MPH wind gusts with the flag removed, according to “Guide Specifications for Design of Metal Flagpoles,” ANSI/NAAMM FP 1001-07. This was used rather than ANSI/TIA-222-G (regulating antennas and towers) as this standard will be the one needed by building committees for flagpole structural analysis (you are telling your building committee that you're installing a flagpole, not an antenna, right?). In any event, you will want to remove your flag when very high winds are forecast to prevent damage to your flag itself.
We can powder coat paint your Flagpole Antenna any of dozens of different colors, contact us for pricing and other info. As this a great portable, quick-deploy, emcomm, DXpedition, IOTA, Field Day, et al, antenna, we will soon have a wide variety of application-specific options. If you're interested taking your FPA-20F-OCF far from home, get in touch with us about the possibilities.
John W6NBC, designer of the new Flagpole antenna has calculated antenna efficiency < 90% if a remote ATU is used near the feed. Here is an animated GIF with the radiation angles for each band, note no significant pattern breakup until 6m - you can't say that about a 43 foot vertical!
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