Left Border Content - RF Cafe
Copyright: 1996 - 2024
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while typing up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
All trademarks, copyrights, patents, and other rights of ownership to images
and text used on the RF Cafe website are hereby acknowledged.
My Hobby Website:
Sub-Header - RF Cafe
The Swiss Quad Antenna at ZS6PP
September 1967 QST
design for a "Swiss Quad" antenna appeared in the September 1967
edition of QST magazine. One of its touted strong points is not
needing spreaders or a boom. I am not an antenna design guy, so
I can't comment on its usefulness. No gain measurement was provided
by the author. The article states that the antenna had not yet enjoyed
widespread adaptation in the U.S. at the time of the writing. A
Google search for Swiss Quad antennas turns up a handful of modern
LU7MGP. I could not locate an example of a computer-generated
gain plot (radiation pattern) for the Swiss Quad, so if you know
where one exists, please let me know so I can post a hyperlink.
Maybe you own a copy of
EZNEC and can
model it? BTW, the drawings are very well done a la patent artwork.
September 1967 QST
Wax nostalgic about and learn from the history of early electronics. See articles
QST, published December 1915 - present (visit ARRL
for info). All copyrights hereby acknowledged.
The Swiss Quad Antenna at ZS6PP
Rotatable Antenna with Phased Elements
By E.P. Towers, ZS6PP
This antenna, designed originally by HB9CV, has not yet received
widespread attention in the Western Hemisphere. Measurements made
by the designer indicate that its performance is superior to the
conventional two-element quad, while the structure is much simpler
In a worldwide survey of 60 DX-minded hams,1 the majority
rated the quad as the "Number One" antenna. However, as we all know,
this antenna is more difficult to construct and erect than a conventional
Yagi beam. It is for this reason, presumably, that it is not in
such general use as its reputation would lead us to expect.
After conducting extensive experiments, HB9CV was so successful
in simplifying the construction and design of the quad that he filed
a patent application in 1960 for an entirely new concept of this
antenna, and named it the "Swiss Quad."2 Since then,
the design of this antenna has been treated in additional articles
by others.3 Reference to this previous material is recommended
for full information.
In constructing a Swiss Quad for 20
meters, the author found that he had to modify and adapt details
suggested by these articles. In response to requests from other
hams around the world for information on his design, these notes
from his own experience and that of others who have constructed
similar antennas are presented. Due acknowledgment is made here
to the inventor and to the authors of earlier articles.
to the sketch of Fig. 1 for a general idea of what the Swiss Quad
looks like. It differs from the conventional quad electrically in
that both elements are driven - with a phase difference of 180 degrees.
Construction is simplified by making the horizontal members of aluminum
tubing sufficiently rigid to support the weight of the vertical
members, which are made of wire, thereby eliminating the customary
spreaders. Additionally, the horizontal members are bent in such
a manner as to provide the desired element spacing without the need
for a boom.
The author's antenna is fed with coax line and
gamma match, as shown in Fig. 2.
vertical members are 230 inches long for 14,250 kc. Thus the supporting
mast must be about 20 feet long, plus sufficient length at the bottom
for mounting in a rotator socket or tower bearing. It may also be
desirable to add rigidity to the antenna by extending the mast 2
or 3 feet above the top horizontal members so that the outer ends
of these members can be guyed to the mast with nylon cord. In any
event, it will usually be necessary to splice sections of tubing
together to obtain the necessary mast length. A method of splicing
that the author found satisfactory is illustrated in the sketch
of Fig. 3. Sections of 2-inch 10-gauge dural tubing were used for
the mast. Further strength can be added by applying a self-guying
or truss system to the mast. However, the author did not consider
The horizontal members
are fastened to the mast at the cross-over points by means of two
brackets (one for the top set, and one for the bottom set). The
brackets are made up of three pieces of aluminum or steel angle,
as shown in Fig. 4. An alternative that would avoid welding would
be to use wider angle stock which would provide space for attaching
the element-supporting angles individually to the mast with U bolts
and serrated yokes. If this method is used, care must be taken to
make sure that the two angle pieces are oriented at exact right
angles to each other. (The welded arrangement assures this automatically.)
The antenna elements must be insulated from the brackets. To
accomplish this, the author cut sections of flexible 1-inch polyethylene
pipe to lengths slightly longer than the bracket. The pipe was then
slit lengthwise so that it could be spread and forced over the 7/8-inch
aluminum tubing of the elements. The angles should be notched as
shown to allow the clamps (gear-type, stainless steel) to secure
the elements firmly. The top bracket can be mounted permanently
on the mast before assembling the antenna. Mounting of the bottom
bracket should be postponed until later.
The sketch of Fig. 5 shows the dimensions of the horizontal antenna
members used by the author for 14,250 kc. All four members are made
identical. Forty-five degree bends are made at equal distances from
the centers of a 16-foot length of 7/8-inch 18-gauge aluminum tubing
which forms the center section. (Borrow a conduit bender from your
local electrician, or have him do the job; otherwise, the tubing
is sure to kink when the bends are made.) The ends are slit to take
extensions of 3/4-inch 16-gauge tubing. The junctions are secured
with stainless-steel gear-type hose clamps. The ends of the extensions
should be flattened and drilled for screws that will be used to
fasten the horizontal members and the vertical wire members together.
The extensions are not added until final assembly.
The assembly can be started by laying the mast, with upper bracket
attached, across the tops of a pair of stepladders at least 5 ft.
high. Clamp the top pair of horizontal members not too tightly in
the bracket while their positions are adjusted so that the members
cross each other at their exact centers. Then twist the members
in the bracket, if necessary, so that they lie in the same plane,
at right angles to the mast. Clamp the members firmly in this position
while hole centers are marked at the exact centers, and in the mast
bracket, as shown in Fig. 4. Drill the holes for sheet-metal screws,
attach soldering lugs, line up the members accurately again, and
tighten the clamps. Wire the three lugs together with the shortest
possible leads. Do not allow the leads to touch the bracket at any
point. The author found this precaution necessary to obtain a satisfactory
The end extensions can now be added,
and the telescoping adjusted to give the widths shown in Fig. 1.
The two extensions in each element should be maintained at equal
length, of course. Give all four ends of the horizontal sections
a slight upward bend to help compensate for the weight of the vertical
The vertical wires can be made of No. 14 copper
wire, or stranded wire of equivalent cross section. No. 8 aluminum
TV ground wire is also suitable. If solid wire is used, stretch
the kinks out, and try to avoid reintroducing them during the assembly.
Measure off the vertical lengths shown in Fig. 1. Mark the wires
plainly at the measured length, then add several inches for adjustment.
Attach the top ends of the wires securely to the ends of the top
set of horizontal members. Then spray all connections with acrylic,
or apply other suitable protection against corrosion, or loosening
of the securing bolts.
At the center of the clearest available
space, drive a section of pipe whose inside diameter is slightly
larger than the outside diameter of the mast into the ground. Swing
the mast vertically and insert the bottom end into the pipe. If
an extension can be added temporarily to the mast to bring the lower
horizontal members at step ladder height above ground, so much the
better. (It may be necessary to guy the mast temporarily with rope.)
Temporarily clamp the bottom mounting bracket to the mast, while
the mounting and adjusting procedure described previously for the
upper set of horizontal members is repeated for the bottom set.
Be sure that the longer extensions are on the same side of the mast
as those of the upper set, and that the sets are lined up as accurately
as possible in the same plane. At the conclusion, give the ends
a slight downward bend.
Attach the vertical wires temporarily to the bottom horizontal set
at the measured points. Then slide the bottom bracket down on the
mast until the vertical wires are reasonably taut, and reclamp the
The author made the matching section
of 3-conductor plastic-insulated electrician's house wire, conductors
in parallel. The wire was spaced about 1/200 wavelength (about 4
inches for 14 Mc.) from the elements by means of a series of aluminum
clamps spaced at intervals, as shown in Fig. 6. (In some other instances,
it has been necessary to use either wider or closer spacing to obtain
a match.) The insulation was removed from the wire only at the ends
for connection to the adjustable clamps, and at the center for connection
to the feed line. Notice that the matching taps must be made at
equal distances from the cross-over point. The distances from the
taps to the ends of the horizontal members will not be equal because
of the difference in lengths of the reflector and director members.
The matching taps were set initially about halfway between the
bends and the ends of the horizontal members. A short length of
line terminated in a loop of 2 or 3 turns of wire was connected
to the feed point. Resonance was then checked by coupling a grid-dip
oscillator to the loop. All four lengths of the vertical wires were
then adjusted equally until the g.d.o. showed resonance at the desired
center frequency. The bottom bracket was then repositioned to bring
the vertical wires taut, and the bracket was fastened permanently
The line was then connected and the matching taps
adjusted for minimum s.w.r., keeping the taps at equal distances
from the cross-over point. The author found that there was no change
in the s.w.r. when the antenna was elevated to full height.
Those with tilt-over towers should have no difficulty in mounting
the antenna. Those with fixed towers will probably have to feed
the mast up through the tower, fasten on the top horizontal members,
raise the mast, and then attach the bottom set of horizontal members.
No attempts were made to establish the gain of
the antenna in respect to a dipole. On receiving, signals can be
heard that just aren't there on a dipole. With the bottom of the
antenna 35 ft. above ground, and an input of 150 watts, performance
on transmitting has been excellent to all points on the globe. Judging
from S-meter readings, the front-to-back ratio appears to be better
than 20 db.
1 Ross, "How
DX Kings Rate Antennas," QST, January, 1964.
"The Swiss Quad Beam Aerial," R.S.G.B. Bulletin (England), June,
3 DL-QTC (Germany), October, 1964. Amateur Radio
Bulletin (Australia), April, 1965. Radio ZS (Republic of South Africa),
Posted December 1, 2013
Footer - RF Cafe
Right Border Content - RF Cafe