[Antennas] Antenna Suggestions

2002年5月28日 12:55:21 -0500

Let me be the first to second Duncan's recommendation of the Extended
Double Zepp antenna. I use two of them - designed for 20 meters - mounted
at right angles for essentially full coverage. Makes a very effective
"rotary" arrangement. The key is to make the feedlines the same length so
that the same tuner settings work for either antenna. Then changing
direction is just a matter of flipping the tuner selector switch.
I have used the EDZ on other bands and generally found that the actual
lengths of either the flattop or the feedline are not at all critical.
Anything within a foot or so of the design length will work fine. Since the
antenna itself is non-resonant in any band, the length is just not
critical. 
Presently, my 20 meter EDZ's are about 88 feet long, and they tune up very
easily from 80 through 10 meters. I intend to put up a 44 foot version
designed for 10 meters and use it primarily for 17,12 and 10 meters.
Another antenna that I just put up a few weeks ago is proving to be a real
champ on 20 meters. It is an "almost" full-wave loop on 80 meters in the
form of a tilted triangle with the apex at 40 feet and the base of the
triangle at 10 feet. It is fed in the center of the base with ladderline
for horizontal polarization. 
The radiation patterns from EZNEC are very encouraging for 20-10 with some
good low-angle lobes on the higher bands. Of course, on 80 and 40, the
antenna is so low that it is essentially non-directional. On 20 it shows
some directivity but not enough to pose a lobing problem. Gain is that of a
dipole or better on 20 and above. Interesting antenna . . .
73/72/oo, George W5YR - the Yellow Rose of Texas 
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe 
Amateur Radio W5YR, in the 56th year and it just keeps getting better!
QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771 I-LINK 11735
Icom IC-756PRO #02121 Kachina 505 DSP #91900556 Icom IC-765 #02437
Duncan Cameron wrote:
>> Michael-
> Something I have used and can highly recommend, is the Extended Double Zepp.
> (Just a long dipole fed with ladder line) Here are some dimensions that I
> have used. Just feed it in the center with either 450 ohm or 300 ladder line
> to your tuner, or you can terminate the ladder line just outside the shack
> with a 4:1 current balun and go into the tuner with coax.
> Here are the dimensions-
> 30 meters=59 feet 5 inches each leg
> 20 meters= 42 feet 4 inches each leg
> 15 meters=33 feet each leg
> For 80 meters it gets a little long=83 feet 10 inches each leg.
> Please be aware that you get very good gain with these antennas, but the
> tradeoff is a narrowing of the radiation pattern. It becomes extremely
> important to figure out where your signal will go when you transmit. At the
> band/frequency of design you will have two lobes at right angles (broadside)
> to the wire. On bands above the design band, the lobes will split and move
> more toward the plane of the wire. (you can also operate this antenna at
> lower bands with pretty good results) I would suggest that you check the
> internet with a search for "EDZ antenna". You will find quite a bit of
> information. This antenna works great, and provides some real gain, but you
> may loose out if you orient your antenna in the wrong direction.
> Good Luck!