by William Eric McFadden

44' Doublet supported by a 20' Black Widow
(click image to enlarge)

My main field rigs, an Elecraft K2 and an Elecraft KX3, are all-band MF/HF rigs, covering 160m through 10m. (The KX3 also covers 6m.) It is my goal to find an easy-to-deploy yet effective 80-10m antenna for use during my field operations.

Because I began this quest to find an easy-to-deploy yet effective 80-10m field antenna while I was using an Index Labs QRP Plus, in places this page may still refer to my QRP Station in a Bag.

The following descriptions are not necessarily presented in chronological order because my experiments antennas tend to overlap in time.

Quick Jump:  

Resonant Dipoles
(return to top)

Originally, I carried single-band dipoles for 20 and 40 meters. These dipoles were built with plexiglass center insulators and button end insulators, and each dipole has an integral thirty-foot RG-174 feedline. While these dipoles don't require the use of a tuner, the pair only cover the two bands, and both antennas have to be hung to operate on the two bands. (photos: 1 | 2)

These dipoles were originally built for use with my first Heathkit HW-8.

The W3EDP and End-Fed Wires
(return to top)

In my quest to find an easy-to-deploy all-band antenna, I have experimented extensively with the W3EDP wire antenna. The W3EDP, a variation of a true Zepp, is an interesting antenna and was described in Practical Wire Antennas by John D. Heys, G3BDQ; additional information on the W3EDP can be found in my Archives and Articles; in the article The FFD Antenna: A Field-Friendly Doublet, with Notes on Related Designs by Charlie Lofgren, W6JJZ; and in the article W3EDP Antenna by Nick Toparcean, AE5VV.

The W3EDP consists of an 85' wire and a 17' wire that's sometimes called a "counterpoise". The counterpoise isn't connected for 80m or for 10m, but is connected for 15m, 20m, and 40m. The W3EDP is very easy to deploy; it can be hung with only one elevated support, doesn't need a separate feedline, and packs up really small.

My initial trials of the W3EDP were using an MFJ-901B antenna tuner and Heathkit HM-9 SWR bridge. I was able to successfully use the the W3EDP on 20m and 40m over the year that I experimented with it, on several operating events as well as on two trips away from home. Following the recommendations (article) of Charlie Lofgren, W6JJZ, I tried configuring my W3EDP such that the 17' wire was half of a parallel feedline, using 0.75" x 1.5" sheet styrene pieces as separators. However, when I tried this arrangement as an Inverted-L (using a sliding "button" insulator on the radiating element) from a cabin on Presque Isle, Michigan, I had trouble getting a good match on 20 and 80 meters. On subsequent trials with the 17' counterpoise lying on the ground it tuned easily on 20 and 40 meters, but I couldn't get a match on 80 meters. Clearly, the W3EDP/MFJ-901B antenna system was not the ideal all-band antenna system.

The arrival of the LDG Z-11 QRP autotuner changed everything. The Z-11 easily tunes the W3EDP on 10, 15, 20, 40, and 80m through a homebrew 4:1 balun. I used this antenna from my billet at Rickenbacker Air National Guard Base (KLCK) during the month of June, 2003, suspending the 85' portion of the antenna between my third-floor window and the outside staircase of the neighboring building, allowing the 17' component to hang out the window. The tuner with balun easily tuned the antenna on all bands tried and QSOs were successfully made on 40m. I have also used the W3EDP/Z-11/balun combination in the field. I operated the 2003 E-PA QRP "TAC" Contest with the W3EDP/Z-11 antenna system, this time with the 85' portion extended in an inverted-L arrangement between two trees and the 17' component lying on the ground beneath the radiator. Again, the tuner easily tuned the antenna on all the bands tested and QSOs were successfully made on 20m and 40m despite poor band conditions. The W3EDP/Z-11 antenna system is a viable all-band antenna system. It's easy to deploy, tunes easily, and covers all the bands of interest.

The W3EDP spool -- click to enlarge My current version of the W3EDP has the 85' end-fed wire wound onto an inexpensive plastic camping-style clothesline reel (photo).

Following Charlie Lofgren's recommendation to keep the 17' wire off the ground to improve efficiency, I plan to make plexiglass feedline-insulators to enable me to easily configure the 17' wire as half of a parallel-feedline.

UPDATE 1: I've retired the LDG Z11 QRP Autotuner in my K2 Travel Kit in favor of the K2's internal autotuner (KAT2). At the 2012 QRP ARCI Fall QSO Party at Mount Gilead State Park I verified that the KAT2 will match the W3EDP on all bands, 10m through 80m, inclusive; for 40m, the KAT2's "ALT" mode was required to achieve a match on 40m.

UPDATE 2: I used the W3EDP with the Elecraft KX3 and its built-in KXAT3 automatic tuner for the 2014 Arizona ScQRPions "Freeze Your B___ Off" contest. I verified the KXAT3 easily and quickly tunes the W3EDP with the 4:1 balun on all bands 10m through 80m, inclusive; the 17' counterpoise wire was left connected for all bands.

I have 100' of teflon-coated wire wound on a second spool. My plan with this 100' wire antenna is to spool out as much as the available supports allow and operate it against a portion of the 85' W3EDP wire as a counterpoise. I have not yet tried this antenna in the field.

I would like to experiment with End-Fed Half-Wave Antennas (EFHWA) as described by Joe Everhart, N2CX (End-Fed Half-Wave Antennas) and Diana Eng, KC2UHB (Portable 17-40m EFHWA).

The Extended Double Zepp and Non-Resonant Doublets
(return to top)

After reading the article Antennas and the QRP Operator by Jim Thompson, W4THU, in Low Power Communications, Volume 2 (edited by Rich Arland, K7YHA), I built a 20m Extended Double Zepp. This is an 86' foot doublet and is fed with balanced line. W4THU claims the 20m EDZ will provide 4dB gain over a 1/2-wave dipole on 20m, performance similar to a dipole cut for 40m and 80m on those bands, and useful gain over a dipole on 10m and 15m. I built my first version with lightweight hookup wire for the elements, using military buttons for the center and end insulators, and fed it with Radio Shack "Ultra Low Loss" 300Ω TV twinlead. During the 1998 QRP ARCI Fall QSO Party this antenna worked very well on 15, 20, and 40m, and also tuned easily on 10m and 80m. After the event, I "ruggedized" the EDZ with a 35mm film-canister center insulator.

After using both the portable 20m EDZ and another installed permanently at home, I decided the 20m EDZ provides nodes that are too narrow for general use and that the QRP Station in a Bag needs an antenna with more omni-directional coverage. Towards that end, in preparation for the 1999 Arizona ScQRPions "Freeze Your B___ Off", I changed the 20m EDZ (now fed with 300Ω windowline) into a 70' doublet. I chose the 70' length based on the chart of "lengths to avoid" in Practical Wire Antennas. Unfortunately, at FYBO, I found that the antenna could be tuned only on 40m with the MFJ-901B, so I cut about three feet off of both ends which allowed the antenna to tune well on 15, 40, and 80m, but it still wouldn't tune on 20m. (It is quite possible I misinterpreted the "lengths to avoid" chart.)

Ron Wiesen, WD8PNL, described a field-portable doublet antenna in this email to me. His doublet is made with clear-insulation speaker wire which his tests have shown to have very low loss when used as a feedline. Ron has reported good results with this flexible and inexpensive antenna.

Doug Hendricks, KI6DS, and Howard Zehr, N9AHQ, describe similar field-portable 44' doublets that are light enough to be supported by a 20-foot "Black Widow" fishing pole. Their designs use computer ribbon-cable and are described in these articles:

NorCal Doublet by Doug Hendricks, KI6DS, at NorCal
Crappie Portable Antenna by Howard Zehr, N9AHQ, at AmQRP
Crappie Portable Antenna by Howard Zehr, N9AHQ, at NorCal

In an email to me, KI6DS wrote that the first 150 QSOs with his doublet at 20' included forty-four states and six DX countries. Tests conducted to determine the loss-qualities of ribbon-cable when used as feedline showed that it is, in his words, "lossy, but not too". His doublet was rugged enough to stay up at his home QTH for a couple of years before falling down. (For a different view on zip cord feedline, here is an article by KK6MC/5 describing zip cord feedline losses.)

The Dipole Fixture -- click to enlarge I had intended to build a doublet this type, using either ribbon-cable or zip-cord as the feedline and elements, but upon looking through my wire-box, I found that I didn't have a enough of either material on hand. I did find, however, a marvelous military-surplus "Dipole Fixture" (#1540368) which included 30' of excellent low-loss 72Ω military twinlead, so I built a doublet using this 72Ω twinlead as the feedline, 22' pieces of ribbon-cable as the legs, a film canister for the center-insulator, a fishing-swivel to hang the thing, and military "BDU" buttons as end-insulators. The "Dipole Fixture" itself was designed to serve as a center-insulator, center support, strain-relief, and wire reel for a doublet/dipole but is far too heavy to hang from a "Black Widow" 20' fiberglass fishing pole. However, it serves beautifully as a tangle-free spool for transport of the doublet elements and feedline.

Here are photos of the completed 44' doublet:

The "Dipole Fixture", with elements and feedline wrapped on it
The factory-insulated plugs on the radio-end of the feedline
The film-canister center-insulator
The button end-insulators

I've erected this antenna, supporting it in the center with the Black Widow, and verified that the Z-11 will tune it on all the MF/HF bands. (I don't expect this 44' antenna to radiate well on 160m, but it seems the rig will be happy to pump RF into it!) I used this antenna during the 2005 Freeze Your B___ Off contest. It worked very well on 20m and 40m. No activity was heard on 80m during this daytime contest, so I don't know yet how the doublet works on 80m.

The Black Widow supports the doublet as an inverted-vee without problem, but there is significant bowing at the top of the pole. I am curious as to whether a NorCal Doublet (built with one continuous length of computer ribbon-cable and no center-insulator) would cause less bowing of the Black Widow. I also remain curious about the feedline-loss of antennas made of ribbon-cable. Eventually, I hope to run some tests on ribbon cable as a feedline and possibly make a NorCal Doublet to test. In the meantime, the doublet, as constructed, remains a viable field-portable antenna.

In the summer of 2009 I acquired an MFJ-1910 33' telescoping fiberglass mast (link) that I hope will be useful in field operations. This mast is very much like a larger version of the 20' Black Widow I have been using. Reviews of this mast (link) indicate that it is fragile so I will use it to support only very lightweight wire antennas and will support these antennas at the second-from-the-top section to reduce mast bowing. I used this mast to support a an 88' doublet (see below) during the 2010 2010 Arizona ScQRPions "Freeze Your B___ Off" event and the mast did a yeoman job of supporting this antenna with only insignificant bowing (photo). To support this mast, I have re-engineered a retired roof-top TV antenna tripod. (Note: replacement elements for the MFJ-1910 mast are available from MFJ at a cost of $5 each.)

In order to use the 44' doublet with the 33' MFJ mast, I made a 30' feedline-extension from a second piece military 72Ω twinlead. (Alas—I have lost this feedline-extension; any ideas where I might find more of this nice twinlead?)

For improved performance on 80m, I made a lightweight 88' doublet to be supported by the 33' MFJ-1910 mast; it is constructed of 24AWG speaker wire and light-duty 300Ω TV-type twinlead, a film-canister center-insulator, and military "BDU" button end-insulators.

According to L.B. Cebik, W4RNL (SK), who called both the 44' and the 88' antennas "Broadside Doublets", both antennas should provide a broad directional pattern on the bands they're designed for. My original 44' doublet should work well on 10, 12, 15, 17, 20, 30, and 40m. The 88' doublet should work well on 20, 30, 40, 60, and 80m. (Read L.B.'s article, "My Top 5 Backyard Multiband Wire Antennas", in the Fall, 2009 "QRP Quarterly". The article is available online here in PDF format.)

I tested my 88' doublet during the 2010 Arizona ScQRPions "Freeze Your B___ Off" event and found that the LDG Z-11 matched the 88' doublet easily on 20 and 40m but the best the Z-11 could do on 80m was about 2.5:1. This antenna worked well during the 2010 ARCI Fall QSO Party, and it even allowed me to make a two-way QRP QSO with Hawaii on 15m, a band it's not supposed to work well on. As during the previous event, the best match I could achieve on 80m was about 2.5:1. It's likely a slightly different feedline length would allow a better match on 80m.

UPDATE 1: After using the 88' doublet suspended as an inverted-vee on the 33' mast for the 2011 Arizona ScQRPions "Freeze Your B___ Off" event I have begun to re-think this antenna's usefulness. Propogation was very poor the day of this event and very few stations were heard on 20m. In fact, I heard only three FYBO stations on 20m, and all were located in Florida. I later learned that K8RAT, just 150 miles or so north of me, heard many stations on 20m with his 98' doublet suspended horizontally at 40' and worked FYBO stations all over the country on 20m. I have verified that the 88' doublet is neither open nor shorted at the center insulator, the feedline and legs aren't open, and the balun is properly constructed and performing as it should. I am left with the conclusion that either the doublet is too directive on 20m--it's effectively an Extended Double Zepp on 20m--or that it was close enough to the ground when supported as inverted-vee from the 33' mast that the take-off angle was high enough I simply wasn't able to hear most of the stations on the band. The problem may be, in fact, a combination of both of these.

UPDATE 2: I used the 88' doublet suspended as an inverted-vee on the 33' mast the week of July 11, 2011 while in Lexington, Kentucky. The primary goal was to make daily contacts with K8RAT in north-central Ohio on 80m and, as such, the low height of this antenna would be expected to provide good NVIS performance, and it did. However, even with an unmeasured length of 300Ω twinlead added to the feedline to reach the operating position the LDG Z-11 could not achieve a match of better than about 2:1. Despite the high SWR, daily contacts were made with K8RAT although 9-watts was the most the K2 would generate without complaining. The Z-11 easily matched this antenna on 15, 20, and 40m although no operating occurred on these bands.

UPDATE 3: I tested the 88' doublet again during the 2011 Adventure Radio Society "Flight of the Bumblebees". Even though 80m isn't used for this event, I took the opportunity to find a feedline-length that would allow the LDG Z-11 to tune this antenna on 80m. I removed all but two feet of the random length of twinlead I had added in Lexington and the Z-11 tuned this antenna/feedline combination easily. The antenna also tuned easily on 20m and 40m. (Unfortunately, I didn't think to check tuning on the other bands.)

UPDATE 4: I've retired the LDG Z11 QRP Autotuner in my K2 Travel Kit in favor of the K2's internal autotuner (KAT2). At the 2012 QRP ARCI Fall QSO Party at Mount Gilead State Park I verified that the KAT2 can match the 44' doublet with 60' of 72Ω feedline on all bands 10m through 80m, inclusive.

Field Verticals
(return to top)

I built the 80-10m version of the W6MMA Vertical using a 20' Black Widow telescoping fiberglass crappy pole from Cabelas and Vern Wright's nicely-machined 80m coil kit (photo). I had very high hopes for this 80-10m no-tuner-needed self-supporting vertical antenna. The W6MMA has proven to be very easy to deploy, and requires no supporting mast or tree. I successfully used this antenna in the 1999 E-PA "TAC", the 2000 FYBO, and the 2000 ARRL Field Day.

Initially I used radials made from computer ribbon cable. These ribbon cables store very well and are relatively tangle-free but are fragile. I've since replaced these with radials made from split #18 zip cord--white for easy visibility--and have found these to be flexible enough that tangling hasn't (yet) been a problem.

The only real problem with this antenna is that adjusting it after band changes seems to require two people--one to key the rig and read the SWR bridge, and one to adjust the sliding tap. If I owned an antenna analyzer this wouldn't be so much of a problem.

UPDATE: I acquired an MFJ-249 Antenna Analyzer from the estate of WA8DYD at the Athens Hamfest (April 28, 2013); I plan to start using the W6MMA more often now.

Immediately upon learning of it, I was very intrigued by the MFJ-2286 "Big Stick" (~ $100, link) 40m-6m 17' stainless-steel telescoping portable vertical. This vertical would provide all of the utility of the W6MMA Vertical except for coverage of 80m but would be much lighter and would pack into a much smaller package. The MFJ-2286 would be much easier to carry than the W6MMA Vertical on human-powered-transport field operations with my KX3 Travel Kit.

Instead of purchasing an MFJ-2286, I've built my own 80m-6m field vertical using my existing W6MMA 80m coil and base/feedpoint assembly, an MFJ-1979 17' stainless-steel telescoping whip (~ $60; link), four pairs of #18 radials, and two 25' RG-58 feedline lengths with BNC connectors. I have engineered and implemented all required changes to the 80m coil and base/feedpoint assembly and am awaiting an opportunity to begin testing the antenna. (Photos: 1 | 2 | 3 | 4 | 5 | 6 | 7)

How to Get Wire into Trees?
(return to top)

I have had a really difficult time getting string and wire into trees. I've tried using small lead weights and weighted tennis balls, but I've been most successful with half-full disposable water bottles.

I would like to try to build a slingshot system such those described by Bill Jones, KD7S, and Russ Carpenter, AA7QU, in the following articles:

The HyLaunch, Build a Compact, Integrated Antenna Launching System
Antenna Launching for Serious Practitioners (and correct URL for the reel)

The Throw Bag/Slick Line technique as described by John Kalotai, N1OLO, is also worthy of consideration:

In the Bag: Throwing Antenna Woes to the Wind

Doc, W5TB, sent me an email regarding his version of the N1OLO Throw Bag:

W5TB Throw-Rope

Tom, W4UUC, sent me an email describing his use of a fishing rod and reel to throw a line over a tree. He is able to throw an appropriately-weighted fishing line over trees taller than 70', and uses the fishing line to pull paracord over the tree to support his antenna. In his opinion, a rod-and-reel is much better than a slingshot.