Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Thi~ invention relates to improved electrical circuit
components and more part~cularly to antennas including such
components.
Antennas for use in conjunction with various types of
radio frequency transmitters and receivers are well known. The
variety of shapes and electrical configurations of antennas is
almost limitless. These range from end-fed antennas, which are
substantially linear conductive rods of various lengths having
specific relationships to the wavelengths of the frequency of
the signa]s transmitted from or received by such antennas, to
complex arrays of components. Helical antennas, as well as
composite antennas involving combinations of various antenna
shapes and configurations, e.g., complex lens antennas, multi-
p~ tuned antennas, dipoles and the like are well known. The
partlcular configuration which is employed for any specific
purpose is selected in order to function properly with respect
to -the frequencies which are involved and the radiation patterns
desired.
Irrespective of the type of antenna or antenna con-
figuration which is employed~ all antennas, both transmitting
and receiving antennas or those used for both functions, are
subject to limitations in the power gain of any given antenna
due to what is known as "skin effect". This phenomenon is one
of non-uniform current distribution over the cross section of
an alternating current conductor. At high frequencies, the
current for a conductor is carried only by a thin surface layer
of the conductor~ the thickness of the layer decreasing with
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~nc~easin~ fre~uency. The re~ult of this phenomenon is a self-
induced counter-electro~ot~ve force ~n the conductor which re-
sults in considerable cancellation of the received energy and
increased effective resistence.
Thus, the gain or power of the antenna~ whether it is
a transmitting antenna or a receiving antenna, is reduced from
the theoretical ideal which it could exhibit if "skin effect"
was not present. This means, for a receiving antenna, the cap-
acity of the antenna to respond to weak signals is substantial-
ly impaired. The signal to noise ratio is lowered; and for any
given receiver, i-t is necessary to employ subs-tantially greater
gain in the RF stages than would otherwise be necessary for the
same reception capabilities if the undersirable effects of
"skin effect" were not present. Similar disadvantages result
with respect to transmitting antennas, the power of which is
substantially impaired by the increased effective resistance
produced by skin effect. Thus, for any given transmitted power,
the power of the output amplifying sta~es mus-t be considèrably
higher -than would otherwise be required if "skin effect" phen-
omenon was not present. As stated above, as the frequency of
the carrier signal increases, the deleterious effects of skin
effect increase proportionately.
As is well known, communications systems in a wide
variety of different forms, e.g., AM radio, FM radio~ tele-
vision, two-way FM communications, e.g., used in citizens' band
(CB) radios, police and fire communications networks and the
like are in widespread-use throughout the world. These
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communica-tions s~stems utilize the tran$mission and reception
of electromagnetic radio frequency waves which are radiated
through space from a transm~tting antenna at the origina-ting
source or station to a receiving antenna at the point of utili-
zation. The radio frequency waves extend in frequency from a
relatively low 10 kilohertz up into frequencies of hundreds of
megahertz. Different portions of this spec-trum are divided
into different frequency bands allocated to various systems of
transmission. The moving electromagnetic radio frequency waves
which are radiated through space are created at the transmi-tting
s-tation by coupling the transmitter output to an antenna which
has a configuration particularly adapted to the frequency of
the transmissionand the use or application of the signal in the
particular system with which the transmitter and antenna is em-
ployed. At -the receiving end, a receiver which is used in con-
junction with the transmitted signal to receive and convert it
to a usable form, such as audio or visual, has an antenna which
in-tercepts the moving electromagne-tic waves and converts them
to electrical signals which are processed by the receiver.
In conventional antennas, both transmitting and re-
ceiving, the antenna itself is what may be termed a "passive"
component in the system. At the transmitting end, the alter-
nating current signal creates electromagnetic radiation when it
is applied to the antenna. At the receiver, the moving elec-tro-
magnetic wave is intercepted bythe conductive antenna and re-
sul-ts in the generation of a corresponding alternating current
electrical signal in the conductor which then is applied to the
RF amplifier and processing stages of the receiver. These
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conventional antennas are electrical de~ices only~ The trans-
mitter generates an electri~cally polari`zed electromagnetic wave
and the receiver responds to the electrical components and re-
sonates with the corresponding electrical polarization of the
electromagnetic wave. Because of the 'tskin effect" mentioned
above, a-t higher frequencies -the thickness of the layer of the
conductor in the antenna which actually carries the current be-
comes increasingly thinner and results in an increasing counter
electromotive force. This, in turn, results in increased ef-
la fective resistance in the antenna and correspondingly greater
self-cancellation. Thus, at higher frequencies, the power of
an antenna, either a transmitting antenna or a receiving an-
tenna, is substantially lessened by "skin effect".
In order to provide sufficient power, either for
transmission or reception, for conventional antennas in any
given situation, it often is necessary to have extremely large
antenna structures or antenna towers to attain the desired
operating characteristics of the transmitter or receiver. Such
structures are costly to build; and because of the substantial
space they require or the substantial height to which they must
reach, result in expensive, cumbersome and unattractive in-
stallations. For example, bulky rooftop television receiver
antennas are commonly employed in order to provide some measure
of reasonable reception for television receivers used in homes.
Similarly, two-way radio antennas 7 e.g., used for ham radio
operators, CB radio base stations, and the like require large
unsightly installations if any reasonable range is to be at-
tained from the radio system using the antenna. In addition,
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mob~le antennas used by polIce cars and CB installations in
automc~les and trucks, Por max~mum e~ectiveness over a
reasonable range,requ~re a relatively long t'whipt' antenna
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It is desirable to provide transmitting and/or receiving
antennas in a variety of configurations which have relatively high power
capabilities, minimum size, and which minimize the "skin-effect" self-
cancellation phenomenon ordinarily encountered in antenna structures.
Accordingly, it is an object of a broad aspect of this
invention to provide an improved electrical circuit component.
It i's an object of another aspect of this invention to provide
an improved antenna structure including such component.
It is an object of an additional aspect of this invention to pro-
vide an improved magnetic antenna.
It is an object of yet another aspect of this invention to pro-
vide an improved magnetic antenna structure utilizing a permanently magnetized
dielectric material.
By one broad aspect of this invention, an electrical circuit
component is provided including in combination, an electrical conductor encased
inside a permanently magnetized, magnetically hard, dielectric ~aterial, wherebyskin effect is minimized.
By a variant thereof, the permanently magnetized ma~erial comprise~s
a solid suspension of ferrite powder in a dielectric resin.
By a variation thereof, the ferrite powder is selected from the
class of magnetically hard materials comprising isotropic and anisotropic
barrium ferrites and cobalt ferrites.
By another variant of this inYention, the electric circuit com-
ponent is an antenna and the conductor is an elongated electrical conductor
embedded in permanently magnetized magnetically hard dielectric material.
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By a variant thereof, the dielectric material comprises
a dielectric resin having a colloidal dispersion of powdered ferrite therein
and the elongated electrical conductor is embedded in the dielectric material.
~ By a variation thereof, the dielectric material comprises
glass fibres impregnated with a resin binder mixed with a magnetic ferrite in a
ratio of from 5 percent to 90 percent ferrite to resin.
By another variant, the elongated electrical conductor is
potted in the permanently magnetized dielectric material and the dielectric
material comprises an intimiate mixture of a resin binder and Eerrite powder.
By a variation thereof, the ferrite powder is selected from
a class comprising barium ferrite and cobalt ferrite.
By another variant, the elongated electrical conductor comprises
a helical coil embedded in a glass fibre dielectric impregnated with a resin
binder having a colloidal suspension of powdered magnetic ferrites in it.
By a variation thereof, the ratio of the powdered ferrite
to resin ranges from 1:20 to 9:10.
By another aspect of this invention, a composite antenna is
provided including in combination a spiral electrical conductor having a first
end and a second end embedded in a permanently magnetized dielectric material;
a second elongated electrical conductor having a first end and a second end,
embedded in a permanently magnetized dielectric material and extending substan-
tially perpendicularly from the spiral; and utilization circuit means coupled
with the first ends of said spiral conductor and said second conductor.
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Consequelltly 9 in accord?~nce with a preferred eml~odiment of
this invention, an electrical circuit component comprises an electrical
conductor embedded inside a permanent magnet made of dielectric material.
More specifically, a magnet antenna exhibiting substantially improved
operating characteristics is fabricated by embedding a conductive wire
for the antenna in a dielectric material formed of a resin with a
colloidal suspension of magnetic ferrite particles in it and which is
permanently magnetized.
In the accompanying drawings,
Figure 1 is a perspective view of a preferred embodiment of one
aspect of the invention;
Figure 2 is a cross-sectional view of the embodiment shown in
Figure l;
Figure 3 is a perspective view of another embodiment of another
aspect of the invention;
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Figure 4 is a cross-sectional view of the embodiment of
Figure 3;
Figures 5 and 6 illusttate another embodiment of a further
aspect of the invention 5
Figure 7 shows still another embodiment of another aspect of
the invention;
Figure 8 illustrates another embodiment of yet another aspect
of the invention formed by a combination of the structures shown in
Figures 3, 4 and 7;
Figures 9 through 12 illustrate various radiation patterns
for the antenna of Figure 8;
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Figs~ 13A throu~h 15 i,llustrate other forms o~
antenna structure;
Fig. 16 ~s a partially cut~away view of an antenna
structure us~ng a base member structure as illustrated in Figs.
13C, 14 and 15;
Figs. 17 and 18 show radiation patterns of the
antenna of Fig. 16; and
Fig. l9 is a graph showing standing wave ratios use-
ful in explaining the operation of the antenna structure shown
in Fig. 8.
In Figs~ 1 and 2, there is illustrated a new approach
to electrical components, par-ticularly conductive elements used
either as transmitting or receiving antennas. As shown in Figs.
1 and 2~ a helical conductive coi:l 20 is embedded or potted in
a conventional dielectric potting compound, e.g., a resin bin-
der (epoxy or thermosetting) to form what appears to be a con-
ventional potted electrical component 21. The resin binder for
the potted component 21~ however, when it is in its liquid
state, has a quantity of iron powder or ferrite powder mixed in
it to form a uniform colloidal suspension of ferrite particles
in the liquid epoxy. The amount of ferrite may be varied from
an amount approximately five percent by weight of the mixture
to ninety percent by weight, depending upon the characteristics
desired in the components produced~
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When the epoxy~ferrite for the component mixture 21
cures and becomes hard, ~-t then is subjected to a magnetizing
field to impart a permanent magnet~zation to it as indicated
by the "N'J and l'S" letters placed on the top and bottom, re-
spec-tively, of the component shown in Figs. 1 and 2. When this
is done, the use of the component shown in Figs. 1 and 2 as an
an-tenna, either in a transmitting antenna or a receiving
antenna, results in an antenna component which is an active
generator or amplifier rather than the conventional passive
lQ component normally used.
When the component is used as a part of a receiving
antenna, the moving radio frequency electromagnetic energy
passing over it is amplified through a principle believed by
the inventor to be caused by changes in the magnetic field of
the Rf wave interacting with the permanen-t magnet of -the mag-
netic dielectric material 21 which then is coupled to the con-
ductive coil 20 in the manner of a transformer. It further is
believed that by using the changing magnetic energy of the RF
filed instead of the changing electrical energy, the deleter-
ious skin effects normally associated with antenna components
are either eliminated or substantially minimized. In any
event, an antenna constructed in accordance with the structure
shown in Figs. 1 and 2 generates energy at the same frequency
and modulation as the passing RF energy but with much greater
amplitude than is possible with the same conductive portion or
coil 2a used alone without embedding it in a pelmanent magnet.
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~t also should ~e noted that -the co~l or conductor
20 is Ins~de t~e ma~net ~hICh i~ in colltrast to winding the
co~l around magnet;c material, This is in direct contrast to
winding the co;l around magne-tic material. This is in direct
contrast to the construction o~ known ferrite antennas where
the coil is wound around an unmagnetized ferrite core.
The material 21 may be formed of a large number of
various types of thermosetting or epoxy resins, and the iron
1~ particles or ~owder also may be in a number of different forms.
~ermanent magnets made of such materials are conventional and
are made in a number of di~ferent shapes for various appli-
cations~ Use of magnets of this type, however, as an active
circuit par-t of an antenna is not known to the inventor.
Pig~ 3 and 4 illust~a-te another antenna configur-
ation utilizing the same principles shown in the structùre of
Figs. l and 3. In the antenna structure of Figs. 3 and 4, the
active conductive component of the antenna comprises a flat
2Q spiral antenna element 25 terminating in a pair of terminals 26
and 28, connected respectively -to the outer and inner ends of
the spiral 25. The conductive spiral component of the antenna
is potted or embedded in an epoxy/ferrite-powder mixture of the
type described above in conjunction with Figs. l and 2. As in
Figs. l and 2, the flat disk 27 resulting from the structure
after it cures or hardens is subjected to a uniform magnetizing
field to permanently magnetize it across its thickness, as
shown in ~ig. 3.
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An antenna as shown in ,Figs,~ 3 and 4 may be used as
an AM radio receiving antenna~ Without placing the coil 25 in
the center of a permanent magnet, the power output of the an-
tenna is quite low. The same coil, potted in a suitable epoxy
or thermosetting resin having suspended ferrites in it and then
permanently magnetized, however, produces a substantial in-
crease in the signal power from the antenna. An active gener-
ator or amplifier i5 obtained with the structure of Figs. 3 and
4 which combines a permanent magnet with the embedded coil 25.
Various ratios of ferrite powder, preferably barium
ferrite or cobalt ferrite, have been used to construct the an-
tenna of Figs. 3 and 4. The ratio of barium or cobalt ferrite
powder to the resin used in actual antenna structures has been
varied from a ra-tio of approximately twenty percent of the fer-
rite powder by weigh-t to ninety percent. Throughou-t this en-
tire range, substantially increased power output was obtained
as opposed to conventional antennas which do not use the di-
electric magnet principle illustrated in Figs. 1 through 4.
The optimum percentages for a given antenna structure
have not yet been determined, but the antenna structures which
have been built clearly show that the combination of the di-
electric permanent magnet and the antenna coil generates energy
at the same frequency and modulation as a comparable antenna
coil without the permanent magnet, but at a substantially
greater amplitude than the conventional antenna~ As stated
previously, it is believed that this is caused by the inter-
action of electromagnetic waves with the permanent magnet in a
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manner similar -to a -trans~ormer coupling, resulting in a sig-
nificant measured ~ncrease in the power of the antenna.
An antenna ~or the ~M ~requency band was bui~-t in
accordance with the structure shown in ~igs~ 3 and 4 by winding
approximately 30 feet of wire 25 into a very loose coil of 7
a
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approximately 12 inches diameter. A mixture of 40~ barium
ferrite powder to 60~ resin was used to fill a mold approximatqly
1 inch thick. The wire coil or spiral 25 was then placed in the
center of the mold, which placea the coil 25 in the center of the
magnetic material after it hardened. Following hardening of the
material, it W2S permanently magnetized, as shown in Figure 3.
The gain of this antenna was measure to be 500% to 700% of the
gain of a standard ferrite antenna used as a built-in antenna in
a ~uality FM tuner. With the built-in ferrite antenna, the tuner
was capable of receiving only 5 stations in full stereo (antenna
voltage over 10 microvolts). With no change in the location of
the receiver, but using the antenna described above, the receiver
received 14 stations in full stereo. The antenna of Figs 3 and 4
produced a gain which is nearly as good as large conventional
roof-mounted antennas.
Referring now to Figs. 5 and 6, there is illustrated a
modification of a standard whip antenna 30, the power of which
is increased by applying the principles of this invention to it.
The antenna 30 may be any conventional whip antenna of the type
ordinarily used in mobile communications. Sometimes the conductive
rod of such an antenna is coveredwith fiberglass to reduce the
effects of corrosion and the like In most cases, however, the
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metal antenna rod 30 is compeltely exposed. As shown in Figs. 5
and 6, the antenna rod 30 may be covered with a conventional
FIBERGLAS gauze ttrade mark for glass fibres impregnated with a
resin of Owens Corning Fiberglas Corporation) or cloth 31 which
then is impregnated with a conventional bi~der to which is added a
colloidal suspension of a ferrite powder (preferably barium ferrite
or cobalt ferrite). When this resin/ferrite mixture is applied to
the FIBERGLAS cloth 31, it hardens to impregnate the cloth 31 with
a layer of ferromagnetic resin 32 indicated in Fig. 5.
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The manner of application of the resin/ferrite mixture
may be in accordance with conventional techniques, e.g., by
spraying, dipping, potting or the like. If desired, as shown
in Fig. 6, more than one layer may be placed around the antenna
30. In Fig. 6, an additional FIBERGLAS cloth layer 33 and an
outer or additional resin/ferrite layer 34 is illustrated. When
this is done to an otherwise conventional antenna; and the
resultant structure is permanently magnetized across the axis of
the conductive whip 30, as illustrated in Fig. 6, the power of
the antenna, both for transmission and for reception, is signif-
icantly increased several dbs. This is true even where the
amount of ferrite powder in the resin binder 32 is as low as five
percent of the total weight of the resin/ferrite mixture.
When an antenna structure of this type is made, the length
of the whip 30 must be reduced from that which is used in the
conventional antenna. In an actual modification of a standard
base loaded quarter-wave mobile whip antenna (41.75 inches long)
it became necessary to shorten the length of the antenna by 3 1/2
inches when a single layer of fiberglass impregnated with a mag-
netic resin (comprised of 20~ barium ferrite powder~ was used.The resultant structure, appears to add effective length to the
antenna (inductive reactance) caused by the permanent magnet mat-
erial. Thus, it is necessary to shorten the overall length of the
antenna when it is modified as shown in Figs. 5 and 6. A modified
antenna of this type exhibited substantially incresed power ( 5 db
to 6 db improvement on receive) when it was used with a standard
CB radio, over that exhibited by the same a~tenna prior to its
modification. The results for the antenna used as a receiving
antenna are even greater tllan when it is used as a transmitting
antenna.
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Because of the nature of this structure, however, it no
longer is necessary to employ a relatively heavy duty rod 30
for the conductive portion of the antenna. A whip antenna may
be fabricated by using a thin copper wire embedded within a
FIBERGLAS structure formed either by wrapping multiple layers of
FIBERGLAS or by potting. The FIBERGL~S structure, however, uses
a resin/ferrite mixture as described above and is permanently
magnetized to form the resultant antenna. In this manner, a true
FIBERGLAS antenna is obtained, because the FIBERGLAS becomes an
active part of the circuit. Apparently, the undesirable skin
effects are substantially eliminated from the antennas of Figs.
5 and 6. The power of these antennas is substantially higher than
standard whip antennas. In addition, the signal-to-noise ratio
is much improved.
Referring now to Fig. 7, there is illustrated a helical
antenna which is particularly adapted to two-way mobile commun-
ications such as used in Citizen's Band (CB) radios. This
antenna comprises a helical coil 37 which is wound with relatively
open turns for the lower two-thirds cf its length with closely wound
turns. The ~iire 37 may be wound about any suitable dielectric
hollow cylinder or rod, which is then potted in an epoxy/ferrite
misture of the type described previously, or formed as part of
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a ~'IBERGLAS enclosure 38 in the manner described in conjunction
with Figs. 5 and 6. Whatever construction is used for the mag-
netic dielectric covering 38 over the coil 37, it is magnetized
across the axis of the coil (or radially outward from the
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axis~ to form a permanent magnet dielectric wi-th the coil 37
emhedded in it. The di'electric/magnetic covering 38 completely
encases the coil 37~ The operating characteristics of this
antenna, either used as a transmitting antenna or a receiving
antenna, are significantly improved over a comparable antenna
which does not use the permanent magnet dielectric.
~ variation of the structure of Fig. 7 is effected by
winding the helix coil 37 as a standard tapered linear coil.
la The antenna dielectric then also is constructed as a tapered
linear magne-tic structure. By way of example, this may be ac-
complished for a 36 inch antenna by dividing it into 6 inch seg
ments. The epoxy/ferrite mixture for -the lower six inches is
5% ferrite to 95% epoxy. Each of the successively higher six
inch sections then has the ferrite portion increased by 5~ over
the adjacent lower section except for the top section. To max-
imize the top loading of the struct:ure, the top six inches has
a ferrite/epoxy mixture which is 80% barium ferri-te and ~0%
epoxy. The tapered coil/tapered magne-tic field antenna which
results after the structure is permanently magnetized is ~ sig-
nificantly improved top loaded antenna.
Referring now to Fig. 8, there is shown a composite
antenna made of a spiral antenna structure, such as shown in
Figs. 3 and 4, fonming the base, and a vertical helical antenna,
such as shown in Fig. 7, attached -to and extending upwardly from
the spiral antenna base. The input feed is to the center of the
spiral 25 and the lower end of the base of the vertical helix
37. The outer end of the spiral and the upper end of the helix
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are open~ so that the resultant antenna is. o~ the Hertz type~
An antenna of th.is type .has been constructed to pro-
vide a 7¦8 wave antenna, with the base sp~ral wound in the form
o~ a 12 inch coil~ The spiral was formed with 540 inches of
number 14 wire as follows:
4 turns at 12 inches ~ 144 inches
3 turns at 11 inches - 99 inches
2 turns at 10 inches - 60 inches
2 -turns at 9 inches - 54 inches
2 turns at 8 inches - 48 inches
2 -turns at 7 inches - 42 inches
2 turns at 6 inches - 32 inches
2 turns at 5 i.nches - 30 inches
2 turns at 4 inches - 24 inches
2 turns at 3 inches - 18 inches
The helical vertical portion of the antenna was formed with 31
turns of number 14 wire close-wound at the top (18 inches) with
46 turns loosely wound at 1/4 inch spacing below this. The
total height of the vertical helical portion of the antenna was
14 inches~ The upper turn terminated in a vertical 6 inch stub
53~
A transmitter 40 is coupled with the upper or "hot"
lead 41 connected to the bottom of the helical conductor 37 of
the antenna, and the ground lead 42 is connected to the center
end of -the spiral base spiral conductor 25~ Magne-tization o~
the base portion 27 is verti:cally through its thickness, as
shown in Figs~ 4 and 5; and magnetization of the dielectric/
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ferrite material 38 in w~hich the hel~cal conductor 37 of the
antenna is embedded is across its ax~s, as shown in Fig. 7.
Figs;. ~, 10, 11 and 12 illustrate the current standing
ding wave patterns contributed by~the different parts of the
composite antenna of Fig. 8. Fig. 9 shows the current standing
wave pat.ern contributed by the flat spiral base portion 27.
Fig. 10 shows the current standing wave pattern contributed by
-the vertical helix portion 37, 38, and Figs. 11 and 12 show the
lQ composite current standing wave pattern which results from
phase differences (in phase and 180~ out of phase) between the
pat-terns contributed by the antenna parts. All of these pat-
-terns result from the antenna being located on a metal ground
plane.
Antenna structures other than those described pre-
viously also are possible using the principles of this inven-
-tion. For example, base configurations such as shown in Figs.
13A, 13B and 13C may be employed~ These base configurations
for winding spiralor helical conductive wires to form the inner
imbedded conductive member of the antenna may be used either
alone or in a number of configurations. The bases or at least
the portions of the base forms in which the conductive wire of
the antenna is embedded are made of resin/ferrite mixtures of
the type described previously in conjunction with the other
embodiments of the invention. Af-ter the antenna structures are
formed, they are permanently magnetized, for example, as illus-
trated in Fig. 13C and Figs~ 14 and 15 for the four-sided pyra-
mid base shape illustrated in those Figures~
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Referring now to Pig. 16~ there is shown a composite
an-tenna which is formed on a py~amid base 50 o~ the type illus-
trated in ~igs~ 13C, 14 and 15 to which is added a flat base 57
with a s~uare spiral winding 58 wh~ch are similar to the member
27 and winding 25 of Figs. 3 and 4. The base 57, however, is
only magnetized in the region lying outside the edges of the
pyramid 50. The base 50 is formed of a suitable dielectric
material, preferably which is impregnated with a ferrite powder
in the proportions described pre~iously, that is, from 5% to
la 90% by weight of
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ferrite to resin. On -the form 50, a spiral coil 52 is wound in
a pattern to match the square spiral 58 shown in Fig. 17. At the
apex of the pyramid, a vertical helical antenna component 37, 38
of the type shown in Fig. 7 is placed, much'in the same manner as
in the composite antenna of Fig. 8, previously described. The
lead 41 of the transmitter 40 then is connected to the lower end
of the helix 37 and the lead 42 is connected to the outer end of
the flat spiral S8. The inner end of the spiral 58 is connected
to the lower end of the winding 50, the other'end of which is
open. Tuning of the antenna may be effected by use of the trim-
mer capacitor 43.
After the windings 37 and 52 are in place, a fiberglass
gauze or winding 55 is wound over the exterior of the pyramid
base and over -the helical antenna winding 37. The FIBERGLAS
gauze 55 then is impregnated with a resin/ferrite mixture 56,
which is allowed to harden. Finally, the base is magnetized to
form a permanent magnet with the poles as shown in Figs. 14 and
15. The vertical portion of the antenna is constructed as shown
in Fig.'7, and is magnetized across its axis. The resultant
antenna exhibits a radiation pattern of the type as shown in
Figs. 17 and 18.
An actual antenna built in accordance with the structure
shown in Figs. 16 through 19 used a pyramiaal base formed of
four equilateral triangles. The height of the base cone was 7
inches, and the height of the vertical helical antenna portion
extending upwardly from the base of the cone was 23 inches. A
6 inch stub ~3 completed the antenna which operaied as a 3/4
wave antenna. The standing wave ratio of this antenna over the
full band of CB frequencies for CB channels 1 through 23 was
measured to be nearly flat 1:1 to 1:1.2 across the full band, as
illustrated in Curve C of Fig. 19. Tilis is in contrast to a con-
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ventional whip antenna Eor the same band, the standing wave
ratio of which is shown in Curve A of Fig. 19. Curve B of
Fig. 19 illustrates a conventional whip antenna which is
modified in accordance with the structure shown in Figs. S and
6.
Even starting with a conventional antenna which is then
potted or wrapped with FIBERGLAS impregnated with a resin/
ferrite material, as described previously, the resultant perm-
anent magnet/ antenna structure greatly increases the gain of
the antenna. Gain improvements of several db have been measured.
Of the various types of ferrite materials which may be employed,
it appears the barium ferrite or cobalt ferrite are the best.
This probably is-because of the high coercive forces which ex-
ist in these materials in their powdered form, which permit them
to make good permanent magnets.
It should be noted that the lower the frequency of oper-
ation of the antenna, the higher the ratio of the ferrite powder
to resin must be. The optimum ratios for given fre~uencies have
not yet been determined, but even without a determination of
optimum ratios, antennas which have been constructed in accordance
with the foregoing examples clearly exhibit improved operating
characteristics over converltional antennas. While the ampere
turns of magnetizing force used to create the permanent magnet
characteristics of the various antenna configurations descri'bed
may vary, the various ~amples which were made and which have been
described above used 2~,000 ampere turns per cubic inch for per-
manently magnetizing'materials. The magn~tization preferably was
effected perpendicular to the surfaces of the various antenna
where possille since it appears that this is the most effective
- 18 -
~3~ Q~
direc-tion of polarization of the~ perm.anent magne-t in which the
conductive wire for the antennas is embedde.d. The theory which
results in the improved operation of these dielectric/magnetic
antenna structures is not fully understood, but the many dif-
ferent models of antennas which have been built, both by modi-
fying standard antennas and by antenna structures such as shown
in Figs. 8 and 16 clearly exhibit improved power or gain and
significantly improved signal-to-noise ratios over their con-
ventional counterparts. The antennas operate with a relatively
1~ large ground plane for best res.ults, but this is common with
many radio frequency antennas~ Merely placing the antenna
s-tructure of the various types shown in the drawings and des~
cribed above on a large metal surface, such as the roof of a
car or directly on the ground, results in the excellen-t oper-
a-ting characteristics which have been described.
The antennas of Figs~ 8 and 16 operate best from a
balanced input which eliminates line radiation and causes
essentially all radiation to occur from the antenna only. This
2a causes the standing wave ratio (S~R) and impedance, once balan-
ced to be more independent of ground effect and environment
since the antennas of these Figures are ungrounded antennas.
-- 19 --
