Nov. / Dec. 1941 Radio-Craft
People old and young enjoy waxing nostalgic about and learning some of the history of early electronics.
Radio-Craft was published from 1929 through 1953. All copyrights are hereby acknowledged. See all articles
Any mention of a 'Zeppelin' conjures up thoughts of disaster in
the form of the famous
Hindenburg incident at Lakehurst, New Jersey, back in 1937.
Fortunately, not all things 'Zepp' are bad news. The end-fed Zepp
(short for Zeppelin) antenna is as
popular today as it was when the Germans developed it for use in
the Zeppelin airships. One of the major advantages to an end-fed
Zepp is that it is, as the name suggests, fed from the end rather
than in the center like a dipole. The configuration makes installation
simpler than a dipole. Being so simple in construction, the Zepp
handily functions as a multi-band harmonic antenna so it is useful
on, for instance, the 160, 80, 40, 20, and 10 meter Ham bands. Many
sell Zepp antennas as well as the modified Zepp known as a J-pole
antenna. This article will help you make your own system, including
a matching network.
End-Fed Zepp for Receiving
R. H. Newkirk, W9BRD
Many valuable pointers are given by the author in this interesting
article, describing the use of a simple antenna which will markedly
improve your reception. Details of the proper tuning unit to use
are also given.
The illustration at the above shows the simple method
of erecting and connecting the end-fed Zepp aerial for receiving
purposes. How to tune it is explained in the accompanying
In an earlier article I sought to point out the advantages possessed
by Zeppelin-type antennas for reception as compared to doublets
or random-length wires. This dealt with an antenna combination for
top performance in the larger short-wave broadcast bands and the
ten and twenty meter amateur radiophone bands.
As pointed out, the chief advantages of the Zepp, especially
the type fed in the center (also called "tuned doublet"), is its
ability to resonate efficiently over a considerably wider band of
frequencies than the doublet, and to operate on harmonics of the
fundamental frequency (the frequency for which it is cut).
Center-feed was chosen for the purpose of resonating in the short
wave broadcast bands because, as these bands do not occur in harmonic
relation, its property of a more balanced resonance than the end-fed
Zepp at frequencies slightly lower or higher than the frequency
for which it is cut, or its harmonic frequencies, made it to be
A Zepp antenna for coverage of the amateur bands is a different
proposition. The bands lie in quite good harmonic relation, and
so one end-fed Zepp approximately 69 feet long (flat-top only) will
operate efficiently on the 40, 20 and 10 meter ham bands. By use
of feeders about 66 feet in length it is also possible to use the
antenna as a Hertz on 80 and a Marconi on 160, resonating it in
each band for best signal-to-noise ratio. (The 160 meter case is
subject to exception as will be pointed out.)
Also, those interested in BCB DX can, with a little experimentation,
get the antenna to resonate in the broadcast band as a Marconi with
a consequent improvement in reception.
Now, a few words on present amateur band DX listening may not
be out of order. Recently ham DX has been much curtailed; in fact,
English-speaking foreign stations in the ham bands are rare indeed.
One still has our Pacific islands and other possessions to hunt
for, but these are none too plentiful either.
S.W.L.'s Learn Spanish!
South American 'phone hams are still pounding through on the
20 and 40 meter bands, however, and the short wave listeners who
have acquainted themselves with the Castilian alphabet and numerals
are still adding to their DX logs. I know of many who never knew
a word of Spanish before and who are growing quite proficient at
the language, through their DX listening. Along this point also,
it might be pointed out that our government has urged Americans
in general to become more familiar with the Spanish tongue, in line
with promoting closer Latin-American relations.
Of course, to learn a language fluently requires an able instructor.
But a short wave receiver and a textbook can do a pretty fair job.
Anyway, not to digress further, there are still many DX stations
in the ham bands to be logged by those who specialize in this branch
of listening. Then, too, there is the embryo ham, who is just getting
acquainted with the amateur frequencies and is learning his code
by daily amateur band sessions.
The antenna described here will be recognized by hams, as an
ordinary Zepp. This type of "skywire" is perhaps the most widely
used antenna on the 20 and 40 meter bands for amateur transmitting-and
it makes just as good a receiving system as transmitting. It is
used here at W9BRD for both purpose and, as is shown in Fig. 2F,
G, H and I, it can also be used to advantage in the short wave broadcast
bands for reception,. As has been said before, a Zepp meant only
for receiving can be much less elaborate than one for transmitting.
The insulation problem is minimized and wire size is unimportant.
The feed-line should be close to 66 feet in length, if tuning
is to conform with that given in this article. Other lengths will
require considerable cut-and-try experimentation in the tuning unit,
in order to obtain resonance. Bending the feed-line when necessary
should not cause complications if not carried to excess. Wooden
spreaders or others of insulation material should space the feeders
approximately four inches apart, from the end or the flat-top to
the tuning unit. Other pointers on construction of Zepp feeders
can be found in the article on the "Center-fed Zepp for Receiving."
(See June issue of this magazine.)
Now for the tuning unit. It is diagrammed in Fig. 3 and pictured
in Fig, 4. The coil, L, is wound of No. 12 enameled . wire, self-supporting.
Its diameter is approximately 2 inches. The clips extending from
each end of the coil are used to "short out" the necessary turns
when a smaller coil is desired. Three values of L are used; 35,
15 and 5 turns. Hence, L consists of 35 turns, close-wound, with
provision made for shorting out portions of the coil. The enamel
should be scraped clean from a section of the wire 10 turns from
each end, and also 15 turns from each end. At these points the winding
should be spaced a bit to enable the clips to grip. In the center
of the coil should be a space just wide enough to admit the link
coil, L2. The link coil could be wound around L but the
spacing permits variation of coupling between the unit and the receiver
by simply pulling L2 in and out.
The link coil connects to the doublet input of the receiver,
and consists of three turns of insulated wire of any size, about
1 3/4 inches in diameter. The smaller the wire the better, since
less spacing will be necessary in the center of L.
The condenser, C, may be any variable receiving type condenser
with a capacity of at least 200 mmf. If you use one with side trimmers,
open these as far as possible, so that a low minimum capacity can
be obtained. The single-pole single-throw switch, SW, is used to
detach the reflecting, or "dummy" feeder, when it is desired to
resonate the antenna for reception in the 80, 25 and 31 meter bands.
The feeders connect to the tuning unit at the points marked X.
Normally, on 160 meters, one would tune 135 feet or so of wire
against ground as a Marconi. But this antenna can be tuned to this
band in the same manner as a Zepp, using a coil of approximately
35 turns. This provides good reception in the 1.7 mc. band but the
antenna is not operating as an orthodox Zepp. Whether or not it
operates as well as a Marconi would is not certain, but it is much
simpler to adjust in this case. Those interested in 160 meter reception
can determine this for themselves.
Tuning and adjusting a Zepp for reception was discussed in the
article previously mentioned. The procedure is simple and for those
who missed it I will go through it again.
We will take, for instance, the twenty meter band. With the receiver
tuned to an amateur phone signal (be sure it isn't a broadcast image)
and the tuning unit condenser at a random setting, insert the link,
L2, into the center of L as shown in Fig. 4. The receiver
signal should be very weak. Now rotate C until there is a noticeable
increase in signal strength. The point at which the signal is loudest
is the point of resonance for the Zepp. Now decrease the coupling
by pulling the link gradually out of L until optimum coupling is
reached. This is the minimum amount of coupling possible with maximum
Too much or tight coupling at this point will cause the resonance
point on the condenser to become broad and will decrease the signal-to-noise
ratio. Too little coupling will cause the signal strength of received
signals to drop. This variation of coupling gives you an effective
R.F. gain control if your receiver is not already equipped with
Once the knack of making this adjustment is learned you will
be able to switch the antenna from one band to another in a jiffy.
This antenna makes a very good transmitting wire for work on
all bands from 160 to 10 meters in restricted locations, where longer
wires are not possible. Efficiency is highest on 40, 20 and 10 meters
where it operates as a Zepp, but all states have been worked on
80 meters, using less than 100 watts. On 160 meters both coasts
have been contacted on CW with 15 watts input, the 135 feet of wire
tuned against a radiator ground as a Marconi.
Posted January 8, 2015