U.S. patent number 3,605,102 [Application Number 05/018,209] was granted by the patent office on 1971-09-14 for directable multiband antenna.
Invention is credited to Talmadge F. Frye.
United States Patent |
3,605,102 |
Frye |
September 14, 1971 |
DIRECTABLE MULTIBAND ANTENNA
Abstract
An electrically directable antenna having a plurality of
radially extending dipole rods which may be selectively
interconnected to provide various directivity patterns. In
addition, various pairs of dipole rods within each directivity
pattern may be selected such that optimum reception is obtained in
each of a plurality of widely separated broadcast bands.
Inventors: |
Frye; Talmadge F. (Asheboro,
NC) |
Family
ID: |
21786798 |
Appl.
No.: |
05/018,209 |
Filed: |
March 10, 1970 |
Current U.S.
Class: |
343/797; 343/802;
343/876 |
Current CPC
Class: |
H01Q
3/24 (20130101); H01Q 1/084 (20130101); H01Q
9/44 (20130101) |
Current International
Class: |
H01Q
1/08 (20060101); H01Q 3/24 (20060101); H01Q
9/04 (20060101); H01Q 9/44 (20060101); H01q
003/24 (); H01q 021/26 () |
Field of
Search: |
;343/876,796-798,793-794,795,802 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Saalbach; H. K.
Assistant Examiner: Nussbaum; Marvin
Claims
I claim:
1. An electrically directable signal-receiving antenna system
having provision to obtain optimum reception from a plurality of
widely separated broadcast bands and comprising,
a plurality of radially arranged signal-receiving elements defining
a plurality of directivity patterns with a plurality of pairs of
said signal-receiving elements within each directivity pattern,
each of said pairs of signal-receiving elements defining an
included angle which is substantially bisected by a line
representing the directivity pattern of the antenna and with each
of said pairs having a substantially different included angle from
those of the remaining pairs,
first switch means for operatively selecting and individual
directivity pattern, and
second switch means for operatively connecting an individual pair
of signal-receiving elements within the selected directivity
pattern to hereby permit variation of the angular relationship of
the operatively connected pair of signal-receiving elements.
2. The antenna system as defined in claim 1 wherein there are at
least twelve signal-receiving elements which are evenly disposed in
the radial arrangement, and wherein there are three pairs of
signal-receiving elements within each directivity pattern.
3. An electrically directable signal-receiving antenna system
comprising,
an antenna array comprising a central hub and a plurality of
signal-receiving elements radially emanating therefrom in an evenly
spaced configuration to define a plurality of directivity patterns
for the antenna, the radially inner ends of said signal-receiving
elements extending into said hub with each end being electrically
insulated from the remaining ends,
switch means for operatively interconnecting selected pairs of said
signal-receiving elements to permit selection of an individual
directivity pattern, and
electrically conductive baffle means positioned within the hub and
having radial spokes extending between and spaced from the inner
ends of adjacent signal-receiving elements for proximately
connecting oppositely directed signal-receiving elements whereby
the same serve as signal reflectors for the operatively
interconnected pair of signal-receiving elements.
4. The antenna system as defined in claim 3 wherein said radial
spokes of the baffle means are electrically connected to the
adjacent inner ends of the signal-receiving elements across a
lightning arrester, and wherein said baffle means is grounded.
5. An electrically directable signal-receiving antenna system
having a plurality of individually selectable directivity patterns
and provisions for receiving signals from three distinct and widely
separated broadcast bands in each of the directivity patterns and
comprising,
an antenna array comprising a central hub and a plurality of dipole
rods radially emanating therefrom in an evenly spaced
configuration,
a control box having a plurality of consecutively aligned contacts
corresponding in number to the number of dipole rods, and a pair of
outlet terminals adapted to be connected to the lead-in line of a
television receiver,
means for electrically interconnecting each dipole rod with one of
said contacts such that consecutive dipole rods are connected to
consecutive contacts,
first switch means for orienting the directivity pattern of the
antenna and comprising six terminals for engaging size of the
contacts, said terminals being arranged such that the six engaged
contacts will be connected to three pairs of dipole rods with all
three pairs having an included angle bisected by a common line
representing the directivity of the antenna, and
second switch means for operatively connecting one of said three
pairs to said control box outlet terminals.
6. The antenna system as defined in claim 5 wherein the central hub
comprises a tubular wall having a plurality of radially directed,
evenly spaced holes therethrough, said dipole rods including a
terminal portion extending through respective ones of said holes
and being secured to said tubular wall.
7. The antenna system as defined in claim 6 wherein said central
hub further includes baffle means having radial spokes extending
between he terminal portions of the dipole rods for proximately
connecting radially opposed dipole rods to thereby serve as a
signal reflector for the operatively connected pair of dipole
rods.
8. The antenna system as defined in claim 6 wherein said electrical
connecting means includes a transmission cable having a plurality
of individual conductors therein corresponding in number to the
number of dipole rods, one end of each conductor being electrically
connected to one of said dipole rod terminal portions and the other
end of each conductor being electrically connected to one of the
contacts in said control box.
9. The antenna system as defined in claim 8 wherein said first
switch means comprises a panel mounting said contacts in a circular
arrangement, a control shaft and knob rotatably mounted to said
panel, along the vertical axis of the circular arrangement, a
radially directed dielectric arm fixedly mounted to said shaft
immediately above the panel, and six spring terminals mounted to
said dielectric arm for engaging six of the contacts.
10. The antenna system as defined in claim 9 wherein said second
switch means comprises a first set of three contacts and a second
set of three contacts, each of the contacts in the first and second
sets being electrically connected to a different one of the six
spring terminals, a rotatable drive shaft and knob, a first arm
fixedly mounted to said drive shaft and adapted to rotate with said
drive shaft for selective engagement with one of the contacts in
said first set, and a second arm fixedly mounted to said drive
shaft and adapted to rotate with said drive shaft for selective
engagement with one of said contacts in said second set, said first
and second arms being electrically connected to said pair of outlet
terminals.
11. The antenna system as defined in claim 10 further including a
pair of diverging elements adjustably secured adjacent the inner
end of each dipole rod, said elements lying substantially in the
plane of said dipole rods and extending radially outwardly on
opposite sides of the associated dipole rod.
12. The antenna system as defined in claim 11 further including a
V-shaped wire whisker attached at the outer extremity of each
diverging element, each whisker extending in a tangential direction
and lying a plane substantially perpendicular to the associated
diverging element.
13. The antenna system as defined in claim 12 wherein each dipole
rod includes a pivotal joint immediately adjacent the hub such that
the dipole rods may be folded into a generally parallel arrangement
for easy handling and storage.
Description
The present invention relates to a television signal-receiving
antenna having a plurality of directivity patterns which are
individually selected by means of a switch unit located near the
television receiver. In addition, the invention relates to an
antenna wherein for each given directivity pattern, the operative
elements of the antenna may be selected from among a plurality of
pairs of dipole rods to thereby permit variation of the angular
relationship of the operatively connected rods.
At the present time, conventional television signals are broadcast
in one of three distinct and widely separated frequency bands,
namely the low frequency VHF band (74-80 mc., Channels 2-6), the
high frequency VHF band (174-216 mc., Channels 7-13), and the UHF
band (470-890mc., Channels 14-83). Since a single antenna will not
normally render equally satisfactory signal reception in all three
bands, it is common practice to employ more than one antenna with
separate feeder systems to the receiver for each band.
Alternatively, a single antenna may include three separate elements
with each of the elements being specifically designed to receive
one of the bands.
It is also well known by those skilled in the art that the
reception of television signals is greatly affected by the
orientation of the receiving antenna with respect to the broadcast
station. In the past, the desired orientation has usually been
accomplished by mounting a motor on the mast to rotate the antenna
in azimuth. Such arrangements, however, are expensive in that they
require a weatherproof motor mounted on the mast, and also a
relatively complex electrical control at the receiver.
In order to obtain directional orientation of an antenna without
physical rotation thereof, a so-called electrically directable
antenna has been proposed. Such an antenna comprises a plurality of
fixed, variously directed dipole elements which are selectable by a
selector switch located at the receiver to obtain directivity of
reception. The directional switching devices of known design
however are not capable of satisfactorily receiving all of the
broadcast bands, and thus separate antennas are required in order
to obtain proper reception in all three bands.
It is accordingly an object of the present invention to provide an
electrically directable antenna adapted to receive at least three
widely separated broadcast bands. More particularly, it is an
object to provide a television antenna which can be adjusted for
directional sensitivity without physical rotation thereof and which
for each selected direction has a plurality of individually
selectable pairs of signal receiving elements, each of which is
specifically adapted to receive a predetermined broadcast band.
It is a further object of the present invention to provide an
electrically directable antenna having a plurality of radially
disposed dipole rods, and wherein various pairs may be operatively
connected to the input terminals of the television receiver, with
the nonselected or parasitic dipole rods serving as a signal
reflector for the operatively connected or driven rods.
It is another object of this invention to provide an electrically
directable antenna of the above type which is relatively simple in
design, is collapsible for easy storage and handling, and wherein
all the electrical connections are protected from the weather.
These and other objects and advantages of the present invention are
achieved in the embodiment illustrated herein by the provision of
an electrically directable antenna system having a plurality of
individually selectable directivity patterns, as well as provision
for receiving a plurality of widely separated broadcast bands in
each of its selected directions. The system includes an antenna
array comprising a plurality of dipole rods radially emanating from
a central hub to define a plurality of directivity patterns. A
plurality of pairs of the dipole rods are provided within each
directivity pattern, with each pair defining an included angle
which is substantially bisected by a line representing the
directivity pattern of the antenna, and with each pair having a
substantially different included angle from those of the remaining
pairs. A control box, which is preferably positioned adjacent the
television receiver, includes a first switch means for operatively
selecting an individual directivity pattern, and a second switch
means for operatively connecting an individual pair of dipole rods
within the selected directivity pattern. Thus operation of the
second switch permits variation of the angular relationship of the
operatively connected pair of dipole rods within the preselected
directivity pattern.
Some of the objects and advantages of the invention having been
stated, others will appear as the description proceeds, when taken
in connection with the accompanying drawings, in which:
FIG. 1 is a perspective view of the antenna array of the present
invention;
FIG. 2 is a horizontal sectional view of the central hub of the
antenna array;
FIG. 3 is a plan view of the hub as shown in FIG. 2 with the metal
cover removed therefrom;
FIG. 4 is an exploded perspective view illustrating the terminal
portion of one of the dipole rods and the manner of its assembly to
the wall of the central hub;
FIG. 5 is a perspective view of the control box of the present
invention;
FIG. 6 is a vertical sectional view of the control box taken
substantially along the line 6--6 of FIG. 5;
FIG. 7 is a horizontal sectional view taken substantially along the
line 7--7 of FIG. 6;
FIG. 8 is a horizontal sectional view taken substantially along the
line 8--8 of FIG. 6;
FIG. 9 is a schematic representation of the control box contacts
and the manner in which they are connected to the dipole rods of
the antenna array and the television receiver lead-in line.
Referring to the drawings, an antenna array embodying the features
of the present invention is illustrated generally at 10 in FIG. 1.
The array is shown mounted on a mast 12, which in turn is secured
to the roof top 14 in a conventional manner. The array comprises a
central hub 16 and twelve radially emanating tubular
signal-receiving elements in the form of dipole rods 18 which are
seen to be evenly spaced about the circumference of the hub. The
dipole rods are fabricated from conventional material such as 1/2
-inch aluminum tubing.
In the embodiment illustrated, each dipole rod carries a pair of
diverging elements 20 fabricated from a material similar to that
used in forming the dipole rods. The elements 20 lie generally in
the plane of the dipole rods and are adjustably secured adjacent
the inner end of the dipole rods by suitable clamps 22 such that
the elements 20 extend radially outwardly on opposite sides of the
associated dipole rods in a diverging manner. By releasing the
clamps 22 and moving the elements 20 along the dipole rods 18, the
maximum diameter of the array can be adjusted.
Each element 20 in turn carries a V-shaped wire whisker 24 at its
remote end. The whiskers preferably each comprise a single length
of aluminum wire which is looped in the middle to form the
configuration shown, nd which is joined to its associated element
by a suitable bolt (not shown). The two arms of each whisker 24
extend in a generally tangential direction and within a plane
perpendicular to the element 20.
The various dimensions and other parameters for the various
components of the array as shown will be determined by the desired
operating characteristics, such as broadcast frequency and
impedance, in a manner well known to those skilled in the art.
However, the following specific dimensions have been found to be
generally satisfactory for most operating conditions: length of
each dipole rod--45 inches; length of each element--36 inches;
length of whisker arms--9 inches. In addition, while twelve dipole
rods are shown in the illustrated embodiment, it will be
appreciated as the description proceeds that a somewhat greater or
lesser number could be employed.
The hub 16 includes a cylindrical or tubular sidewall 26
constructed from a suitable dielectric material such as plastic, an
upper cover 28 which may be metallic, nd a lower metallic bottom
plate 29. One of the components of the hub may include a compass
direction indicium to aid in properly orienting the array, such as
the arrow N (for North) seen in FIG. 3 on the wall 26. The central
portion of the bottom plate 29 includes an aperture 30, and a
coaxial pipe flange 32 is welded or otherwise secured to the under
surface of the plate 29. The pipe flange 32 is internally threaded
and serves to secure the hub to the mast 12.
As best seen in FIG. 4, the sidewall 26 of the hub includes a
plurality of key shaped apertures 34 which are adapted to receive
and lock the radially inner or terminal portion of each dipole rod.
The terminal portion includes a plug 36 having one end 37
frictionally or otherwise secured in the bore of the tubular dipole
rod 18, and a flattened opposite end 38. The flattened end 38 of
the plug is adapted to be received in the slot 39 of the stud 40
and is pivotally connected therein by a pin 41. A sleeve 42 is
slidably mounted over the rod 18 and plug 36, and is designed to
overlie the stud 40 such that the stud and rod are maintained in
coaxial alignment. A setscrew 43 is provided in the sleeve to
maintain its position. By this arrangement, each dipole rod 18 of
the array may be pivoted in relation to the hub 16 as shown at the
left side of FIG. 2, such that the entire array may be collapsed
for easy handling and storage.
The inner end of the stud 40 includes a threaded portion 44 which
is slotted at 45 to receive the transverse extension 46 of the key
48. When assembled, the stud 40 extends through the aperture 34 and
is joined to the hub wall 26 by the nut 49 and washer 50 which are
positioned outside the wall, and the nut 51 and washer 52 which are
positioned on the inside of the wall. By design, the transverse
extension 46 of the key 48 extends into the radial extensions of
the opening 34 such that rotational movement of the key, and thus
the stud 40 and dipole rod 18, is precluded.
The inner end of each key 48 mounts a first terminal connector 54
connected to one of the conductors 56 in the transmission cable 58,
as well as a second terminal connector 60 for the purposes set
forth below. It will be understood that the conductors comprise
flexible insulated wires which are twisted together in forming the
cable 58. If required, an impedance-matching transformer of
conventional design (not shown) may be employed. The cable 58 is
fed through the hollow mast 12, exits from the base thereof, and
continues to a control box 62 which is preferably positioned
adjacent the television receiver.
The interior of the hub 16 further includes a baffle means 63 which
includes a plurality of radial spokes 64 (FIGS. 2 and 3) extending
between but spaced from each of the terminal portions of the dipole
rods. The outer ends of the radial spokes are secured to the hub
wall by a suitable rivet or the like, and the inner ends are
secured together by a central bolt 66. In the illustrated
embodiment, the radial spokes 64 are flat metallic members which
are electrically conductive, and they are connected via a
conventional lightning arrester 68 and the terminal connector 60 to
each of the keys 48. A ground wire 70 leads from the central bolt
68 to the metal plate 29. Since the mast 12 is suitably grounded, a
lightning discharge path is thereby provided from the dipole rods
of the antenna array to the ground.
The control box of the subject invention is illustrated generally
at 62 in FIGS. 5-8. The box comprises a molded plastic cabinet 72
forming the top and sides of the box, and a metal bottom wall 73.
The outer top surface of the cabinet may have various indicia 74,
75 imprinted thereon. Preferably, the indicia 74 represent the
compass directions, and the indicia 75 represent the three
broadcast bands, L for low-frequency VHF, H for high-frequency VHF,
and U for UHF.
A dielectric panel 76 of plastic, Plexiglas, or other similar
material, is fixedly secured within the cabinet and mounts twelve
contacts 78 positioned in a circular arrangement. In the embodiment
illustrated, each of the contacts comprises a flat-headed rivet
secured in suitable apertures in the panel, and each is
electrically connected to one of the conductors 56 in the
transmission cable 58 as schematically illustrated in FIG. 9.
A control shaft 80 is rotatably mounted through the panel 76 along
the vertical axis of the circular arrangement and extends upwardly
through an aperture in the cabinet 72. A radially extending arm 82
of a similar dielectric material is secured to the shaft
immediately above the panel, and a knob 84 is mounted at the upper
end of the shaft on the outside of the cabinet. The outer periphery
of the arm 82 is arcuate and generally conforms to the arc of the
circle formed by the contacts 78. Six spring terminals 86 are
attached to the arcuate periphery of the arm 82 and are adapted to
engage six consecutive contacts. Thus by rotating the knob 84,
various sequences of six consecutive contacts 78 will be engaged by
the terminals 86. To prevent excessive rotation of the shaft in
either direction, suitable stops (not shown) may be provided.
A second switch is provided in the control box and includes a drive
shaft 88 which is also rotatably mounted in the panel 76. The drive
shaft 88 carries an arm 90 which in turn mounts a first flexible
terminal 92 for engaging one of a first set of three contacts 94,
nd a second flexible terminal 96 for engaging one of a second set
of three contacts 98. The terminals 92 and 96 are connected via
lead lines 100 and 102 to the output terminals 104 of the cabinet.
A knob 106 is mounted at the upper end of shaft 88. Here again,
suitable stops (not shown) may be provided on the panel 76 to limit
the rotation of shaft 88.
Viewing FIG. 9, it will be seen that the contacts 78 on the panel
76 are connected to correspondingly positioned dipole rods 18.
Also, the six spring terminals 86 of the arm 82 are connected via
suitable lead lines to the six contacts in the sets 94 and 98 in
the manner shown. By design, the six consecutive contacts 78
engaged by the terminals 86 will define three pairs of dipole rods,
each of which has an included angle which is substantially bisected
by a common line representing the directivity of the antenna. Thus
as shown, the antenna is directed for reception of a station
located to the north, and a first pair of dipole rods A--A (FIG. 9)
has an included angle of approximately 150.degree. which is
bisected by a line from the north. A second pair of dipole rods
B--B has an included angle of approximately 90.degree. which is
bisected by a line from the north, and a third pair of dipole rods
C--C with an included angle of about 30.degree. is similarly
bisected by a line from the north. Thus upon rotation of the knob
84 to any of its 12 positions, there will always be three pairs of
dipole rods which have an included angle substantially bisected by
a line representing the operatively connected directivity pattern
of the antenna.
The second switch, represented by knob 106, is effective to select
the particular pair of dipole rods to be operatively connected to
the television receiver. In particular, rotation of the knob 106
translates the terminals 92 and 96 in unison across the contacts 94
and 98. At the position shown, the pair A--A of dipole rods are
connected. At the mid position of the terminals 92 and 96, the pair
B--B will be connected, and at the right end position the pair C--C
will be connected.
In operation, the first switch (i.e., knob 84) is rotated to direct
the operative dipole rods toward the desired broadcasting station.
The second switch (i.e., knob 106) is then positioned at the
particular broadcast band being received such that a single pair of
dipole rods will be operatively connected to the receiver.
It has been found that when the knob 106 is positioned as shown
(i.e., directed at L) such that the dipole rods A--A are
operatively connected to the receiver, improved reception in the
frequency VHF band is obtained. When the knob 106 is rotated to its
midposition (to H) such that the dipole rods B--B are operatively
connected, improved reception in the high frequency VHF band is
obtained, and finally, when the knob 106 is positioned toward the
right (at U) such that the dipole rods C--C are operatively
connected, improved reception in the UHF band is obtained. It is
believed that these surprising results are achieved by reason of
the fact that the three pairs of dipole rods present differing
effective dipole dimensions in the direction of the broadcasting
station. Thus the extended pair A--A is more effective for lower
broadcast frequencies having longer wave lengths, the intermediate
pair B--B is more effective for the intermediate frequencies having
somewhat shorter wave lengths, and similarly, the contiguous pair
C--C is more effective for the higher frequencies. However, the
operability and advantages of the antenna described herein are not
predicated upon any particular theoretical explanation of
operation, but rather are based on the actual operation of the
antenna combination.
As a further aspect of the present invention, it has been found
that the radial spokes 64 of the baffle means 62 act to proximately
connect the oppositely directed dipole rods to permit the effective
transmission of the broadcast signals therebetween. Thus the pair
of dipole rods immediately behind the operatively connected or
driven pair will serve as reflectors to increase the gain of the
driven pair. For example, if the pair B--B is connected, the pair
A--A serve as a reflector.
In the drawings and specification, there has been set forth a
preferred embodiment of the invention, and although specific terms
are employed, they are used in a generic and description sense only
and not for purposes of limitation.
* * * * *