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Showing posts with the label Twin-lead

Simple Ham Antennas: The Novice 40 meter delta loop. Post #271

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During that brief period between getting my novice amateur radio license and moving on to the technician and general class license (1977-1983), I built several dipoles, inverted vees, and verticals.  All of these antennas worked very well, considering the lack of space I had at the time.  When my xyl and I moved from Honokaa to Laupahoehoe , we occupied a larger home and had more backyard space to place antennas. Just before I passed the Advanced Amateur License exam, I built what I considered my best and "most forgiving" antenna--a full-wavelength 40-meter loop.  The loop displayed some gain over a dipole at the same height, needed only one tall support, and didn't require a ground radial system to operate efficiently.  Using balanced feed line , a 4:1 current balun, and a Drake MN-4 transmatch, I could cover 40, 20, 15, and 10 meters with one antenna.  Later on, when 30 meters became available to amateur radio operators, I used a MFJ-941-E Versa Tuner II and my sp

Simple Ham Radio Antennas: An 80-10 meter inverted vee dipole. Post #263

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A few days ago I read a fascinating antenna article by Cecil Moore (W5DXP) on the http://www.eham.net website.  Cecil described what he called a " Multi-Band 33-ft dipole" that works on 20, 17, 15, and 10 meters without an antenna "tuner" (i.e. transmatch ).  The secret to this outstanding antenna was the use of 450 ohm ladder line in conjunction with a series of switches and relays that selected the proper length of ladder line used to feed the antenna.  Depending on the band of use, Cecil could insert and remove sections of ladder line with his relay/switch system so that swr across his chosen band remained low.  By carefully selecting which section of feed line to add or subtract, he got a decent performing antenna without having to resort to a transmatch or "tuner." Cecil's idea got me thinking of ways to improve the dipoles I'm using at my new home site.  Although his idea has a lot of merit, I felt the need to build something a bit simpl

Simple Ham Radio Antennas: The W3EDP antenna revisited. Post #261

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The "classic" W3EDP antenna has been around since March 1936 when Yardley Beers (W3AWH/W0JF) described a multiband antenna built by his friend H.G. Siegel (W3EDP).  Siegel used the traditional method of "cut and try" to arrive at an antenna length that would work satisfactorily on 160, 80, 40, 20, and 10 meters. Beers remembered that "A length of 84 feet (25.60 meters) seemed to stand out as being the best of all the combinations tried."  A similar "test and tune" method was used to determine a satisfactory counterpoise length of 17 feet (5.18 meters), "as the one working best in combination with the antenna." Since that time, several variations of this true "Zepp" antenna have been developed to facilitate portable, emergency, and even home use.  Many QRP enthusiasts use some kind of W3EDP-derived antenna for their operations.  The W3EDP antenna is a simple, cheap, and field deployable.  The antenna requires a 1:1 or 4:1

Simple Ham Radio Antennas: A Low HF Band Triangle. Post #259

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Over the past few years, I've built a variety of HF antennas for my amateur radio station.  All of my verticals, inverted vees, dipoles, and loops have been a learning experience, especially when I've been faced with limited resources and space.  Operating from an apartment or a home governed by CC&Rs and HOAs has been a challenge. Now that I'm slowly moving into a full acre of space in the rural Puna District of Hawaii Island, my space restrictions are gone and there are no committees to oversee my antenna activities.  I count this as a definite blessing.  For the first time in many years, I can build full sized dipoles, verticals with a decent ground system, and large full-wave loop antennas without interference.  Since my new property is surrounded by tall trees approaching 50 feet/15.24 meters, my antennas are well shielded from prying eyes.  When I operate out of my rental home in Laupahoehoe, I'm still hemmed in by utility poles and neighbors.  My antenna

Simple Ham Radio Antennas: Antennas without tuners, part 4. Post #257

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So far, the "tunerless" antennas I've built have worked very well.  They have been made with locally available materials from my "junk" box, neighborhood garage sales, and the nearby Ace Hardware Store.  These antennas have consisted of individual dipoles/inverted vees for my bands of preference (40, 20, 15, 10 meters), telescoping fiberglass masts (33-ft/10.06 meters tall), a single RG -8X coaxial feed line , and supporting wooden stakes or tree branches. Dipoles for each band were built on the ground and were later hoisted into position via a halyard and pulley system.  A "choke balun" made from part of the RG-8X feed line was attached to the mast just below the center connector at the top of the mast. In my first multiband antenna system, I changed bands by lowering and raising the appropriate antenna into place.  I couldn't change bands by staying in the shack. My second system was a modified "fan dipole/inverted vee" using mul