Note: Descriptions are shown in the official language in which they were submitted.
2153~4 1
METHOD AND APPARATVS FOR MULTI-POSITION ANTENNA
Field of the Invention
The present invention pertains to antennas for communication
apparatus.
Background of the Invention
Radio communication devices include a transmitter and/or
receiver coupled to an antenna which emits and/or detects radio
frequency signals. The device may include a microphone for inputting
audio signals to a transmitter or a speaker for outputting signals
received by a receiver. Examples of such radio communication devices
include one way radios, two way radios, radio telephones, personal
communication devices, and a variety of other equipment. These
communication devices typically have a standby configuration,
wherein the device is collapsed for storage, and an active
communication configuration, wherein the antennae is extended for
optimum performance.
For radio telephones and two-way radios, it is typically desirable
that these devices have a small size during a standby mode to facilitate
storage and transport thereof. For example, users prefer that the radio
telephones are small enough in the standby mode to permit storage in
a shirt or jacket pocket. In the active communication state, it is
desirable for the device to be sufficiently long to position the speaker
adjacent to the user's ear, the microphone near the user's mouth, and
the antenna away from the user's body. To meet these requirements,
the radio telephone housing is reconfigurable to have smaller
dimensions in the standby mode than they have in the active
communication mode.
A difficulty encountered with prior art reconfigurable
3 5 communication devices, such as radio telephones which must receive
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a call alerting signal in the standby mode, is providing a high
performance antenna system in both the standby mode and the active
communication mode. Although the extended antenna position
allows for optimum antenna performance, the retracted position of
S the antenna in the standby mode which minimizes the dimensions of
the communication device results in a decrease in antenna
performance.
An example of a radio communication device including a multi-
10 position antenna is a radio telephone including a body and flap,wherein the flap includes an antenna mounted thereon. When closed,
the flap covers the radio telephone key pad and provides a compact
housing. When the flap is opened, the flap antenna is spaced from the
telephone body which the user holds. Although the flap antenna
15 performs very well when the flap is open, the flap antenna is not
ideally positioned to receive an alerting signal in the standby mode.
Accordingly, it is desirable to provide an antenna system having
high performance characteristics when the communication device is
20 extended in an active communication mode and when the
communication device is collapsed in a standby mode of operation.
Brief Description of the Drawings
FIG. 1 is a front perspective view illustrating an extended radio
telephone including an antenna system according to the invention;
FIG. 2 is a front perspective view illustrating a collapsed radio
telephone according to FIG. 1 which is in the standby configuration;
FIG. 3 is a fragmentary view illustrating the inside of the radio
telephone housing according to FIG. 1 including a transceiver;
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FIG. 4 is a plan view of a flap of the radio telephone according to
FIG. 1 with the front housing section removed and illustrating a first
antenna;
S FIG. 5 is a fragmentary perspective view of a portion of the
inside of a front housing section of the radio telephone body according
to FIG. 1 illustrating a portion of a parasitic radiator;
FIG. 6 is top plan view illustrating the parasitic radiator
10 according to FIG. 5;
FIG. 7 is a top plan view illustrating an alternate embodiment of
the parasiffc radiator according to FIG. 6; and
l S FIG. 8 is a top plan view illustrating another alternate
embodiment of the parasitic radiator antenna according to FIG. 6.
Detailed Description of the r~fer~ed Embo~liment~
The present invention is embodied in a multi-position antenna
system for a device including a housing having first and second
housing portions which move between a first extended position and a
second collapsed position. Circuitry is positioned in the housing to
transmit or receive signals. A first antenna is supported on the first
housing portion and is connected to the circuitry. A parasitic radiator
is supported on the second housing section. The first antenna and the
parasitic radiator coupled when the housing is in the collapsed posiffon
and are not coupled when the housing is in the extended position. The
antenna system has high performance characteristics when the
housing is extended during acffve communication and when the first
antenna and the parasiffc radiator are coupled while the housing is
collapsed.
Iniffally it is noted that those components shown in more than
3 5 one drawing figure have the same last two digits in all the drawing
215354~
figures. However, the first digit identifies the drawing figure being
rere~ ced, such that components in FIG. 1 have the first digit 1,
components in FIG. 2 have the first digit 2, etc. It is also noted that the
antenna system according to the invention is illustrated in a radio
telephone including a flap 103 (FIG. 1), wherein the immediate
invention is particularly advantageous. However, the invention may
also be advantageously employed in other devices, such as one way and
two way radios, or any other communication device employing an
antenna. Accordingly, "device" and "equipment" as used herein refer
to all such devices and their equivalents.
A radio telephone 100 incorporating the invention is illustrated
in FIG. 1. The radio telephone includes a housing 102 including a first
housing portion 101 and a second housing portion 103. In the
l S illustrated embodiment, the first housing portion 101 is a radio
telephone body and the second housing portion is a flap pivotably
connected to the body. The flap 103 moves between an extended
position illustrated in FIG. 1 during an active communication mode
and a collapsed, or closed position, illustrated in FIG. 2, in a standby
2 0 mode.
The radio telephone body 101 includes a back body housing
section 104 and a front body housing section 105 which are
interconnected to define an interior volume housing electronic
2 S circuitry (not shown). A key pad 106 is positioned in body 101 such that
keys 109 (only some of which are numbered) associated with the
keypad are accessible for manual actuation by the user. The illustrated
flap 103 at least partially covers key pad 106 when closed. The flap may
be larger to cover all the keys. The flap prevents actuation of the
covered keys 109 when the flap is closed. Additionally, the flap may
place the telephone in a standby mode when closed.
The flap 103 includes a first antenna 107, which is referred to
herein as a flap antenna. The flap antenna is positioned between a
front flap housing 111 and a back flap housing section 112, and thus is
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illustrated in phantom in FIG. 1. The front flap and back flap housing
sections 111 and 112 are generally planar members, which may be
manufactured of a suitable polymer. The flap antenna is sandwiched
between these members. The flap antenna 107 is in an extended
S position when the flap 103 is open. The flap antenna is in a collapsed,
or retracted, position when flap 203 (FIG. 2) is closed.
Body 101 includes a parasitic radiator, or second antenna 108.
The parasitic radiator 108 is affixed to the inside of the front housing
1 0 section 105, and is thus illustrated in phantom in FIG. 1.
Transceiver circuitry 315 is generally represented in FIG. 3. The
transceiver may be implemented using any suitable conventional
transceiver. The transceiver circuitry 315 is positioned in first housing
1 S portion 301 by conventional means, such as by mounting on a printed
circuit board which is assembled between the front and back body
housing sections 104, 105. The transceiver circuitry 315 is coupled to a
microphone (not shown) and receiver (not shown) positioned in
housing portion 301. The transceiver circuitry is also connected to an
20 elastomeric connector 316 or other means, which connects to a flex
conductor 317. The flex conductor 317 extends into a hinge assembly
318 including a knuckle 319. As illustrated in FIG. 4, the hinge
assembly 418 also includes a knuckle 420 on flap 403 to engage knuckle
319. The flex conductor 417 is also connected to the first antenna 407
25 through the hinge assembly 418. The hinge assembly providing the
connection between the flap antenna 407 and the transceiver 315 may
have any suitable construction
Flap antenna 407 (FIG. 4) includes two conductors 423 and 424
mounted on a board 425 such that the antenna is generally E-shaped in
configuration. The flap antenna is manufactured of two thin strips of a
3 S suitable conductor, such as copper. The flap antenna 407 includes a
~'
21535'11
joinder segment 422 electrically coupling middle finger segments 426
of conductors 423 and 424 with the flex conductor 417. The middle
finger segments 426 include a transmission line transformer 427
providing impedance matching between antenna 407 and the
S transceiver circuitry 315 (FIG. 3). A cross member 428 of conductor 423
connects middle finger segment 426 to outer finger 429. The outer
finger 429 extends generally orthogonally from one end of cross
member 428. Conductor 424 similarly includes a middle finger
segment 426 coupled to a cross member 430. Cross member 430
1 0 connects the middle finger segment of conductor 424 to an outer finger431, which extends generally orthogonally to cross member 430.
Elements 432 (only some of which are numbered) extend generally
orthogonally from outer fingers 429 and 431 to provide a capacitive
loading permitting shortening of antenna 407 to facilitate mounting of
1 S the antenna on the flap. A opening 433 which is cut out of each outer
finger 429, 431 is provided to receive respective magnets (not shown).
The magnets actuate read switches (not shown~ in the radio telephone
housing 101. The read switches and magnets are not described in
greater detail herein since they do not form a part of the immediate
2 0 invention.
The flap antenna 407 is thus a dipole antenna which is thin,
such that it is sandwiched between front housing section 111 and back
housing section 112, to construct a thin flap. The antenna is a half-
wavelength antenna having high performance characteristics when
the flap is open, as illustrated in FIG. 1. The cross members 428 and 430
of conductors 423 and 424 are high current sections of the flap antenna.
A parasitic radiator 508 is illustrated in FIG. 5. The parasitic
3 0 radiator is not directly coupled to the feed line 317(FIG. 3), 417 (FIG. 4)
of the flap antenna 407. The parasitic radiator 508 (FIG. 5) is generally
U-shaped in configuration, including arms 534 and 536 extending
generally orthogonally to a shoulder 535. An elbow 537 extends at an
angle of approximately 45~ with respect to arm 534 and shoulder 535 to
3 5 join these members. An elbow 538 extends at an angle of
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approximately 45~ with respect to arm 536 and shoulder 535 to join
these members. This parasitic radiator is manufactured from any
suitable electrical conductor, such as a thin, flexible copper strip having
an adhesive on one side thereof.
The parasitic radiator is dimensioned according to the
transceiver signal frequency. More particularly, the longitudinal axis of
arm 534 has a length A, the longitudinal axis of elbow 537 has a length
B, the longitudinal axis of shoulder 535 has a length C, the
1 0 longitudinal axis of elbow 538 has a length D, and the longitudinal axis
of arm 536 has a length E. Lengths A, B, C, D, and E are such that their
sum is equal to approximately one-half the wavelength of the
transceiver signal frequency.
1 5 The parasitic radiator 608 (FIG. 6) according to pre~,led
embodiment is connected to an inside surface 640 of front housing
section 605. The front housing section includes a planar front 642 and a
sidewall 643. An opposite sidewall 144, which is not shown in FIG. 6
but can be seen in FIG. 1, extends in parallel to sidewall 643. The
parasitic radiator 608 is assembled to inside surface 640 of the front
housing section 605 using a suitable adhesive. The parasitic radiator is
flexible such that it conforms to the surface 640 of the front housing
section when attached thereto. More particularly, the shoulder 635 of
parasitic radiator 608 is affixed to the inside surface 640 between two
2 5 rows of apertures 660, through which keys 109 (FIG. 1 ) of keypad 106
project. The shoulder of parasitic radiator 608 is narrow such that it fits
snugly between the rows of apertures without extending into these
apertures to avoid inlerfer~lce with the operation of keys 109. Elbow
637 is attached to surface 640 such that it curves from the front wall 642
3 0 to the side wall 643. Arm 634 is attached to wall 643 using an adhesive
such that it extends along this side wall. Most ~re~elably wall 643 is flat
such that the arm 634 extends in a single plane. Arm 536 and elbow 538
are similarly connected to side wall 144. In this manner, the thin
flexible strip is attached to the inside of the front housing section with
'-- 2153$41
predeterrnined locations of the cross members 428, 430 are such that
these cross members are positioned over the surface of front wall 642
which is between the two rows of apertures 660 and to which the
shoulder 535 of the parasitic radiator is connected when the flap 403 is
closed. Thus, when the flap is closed, the cross members 428, 430 and
the shoulder 535 are aligned and positioned proximate one another, as
represented by the arrow in FIG. 1. The cross members 428, 430 and the
shoulder 535 are spaced by the thickness of the front housing section of
the flap 103 and the front housing section of the body 101.
1 0 Additionally, the shoulder 535 of the parasitic radiator is inductivelycoupled to the cross members 428, 430, which are the high current
portion of the flap antenna. Because shoulder 535 is coupled to cross
members 430 and 428 when the flap is closed, the arms 534 and 536
form a second dipole antenna which is parasitically coupled to dipole
1 5 antenna 407. This coupling is an inductive coupling.
In operation, when the flap is open, flap antenna 107 (FIG. 1) is
positioned away from the parasitic radiator 108 and body 101 such that
the antenna has high performance characteristics without interference
20 from the user, circuitry in the body housing 101, or the body housing
101. In this position, the high current sections (cross members 428, 430)
of the flap antenna 107 are remote from shoulder 635 of parasitic
radiator 108, such that the parasitic radiator is not coupled to antenna
107, and is not coupled to the transceiver circuit 315. When the flap is
2 5 closed, as illustrated in FIG. 2, the flap antenna is moved to a position
proximate the body and the circuitry in housing 101. This causes
decrease in the performance of antenna 107 because body portion 102 is
in the near field volume of the flap antenna. However, the high
current sections 428, 430 of the flap antenna 407 are positioned
3 0 proximate to shoulder 635, such that the two antennas are parasitically
coupled. The antenna system performance characteristics are thus
affected by both the parasitic radiator 108 and the flap antenna 107 while
the flap is closed. The parasitic radiator is tuned to the communication
signal wavelength of the transceiver circuit 315 when the body is in the
35 near field volume, whereas the flap antenna 107 is tuned to the
21~3541
communication wavelength of transceiver circuitry 315 when the flap
is open. One of the antennas is thus tuned to the communication
signal frequency of the transceiver when the flap is open and the other
one is tuned to the transceiver circuitry when the flap is closed. This
coupling of the antenna 107 and the parasitic radiator 108 significantly
improves the characteristics of the antenna system when the flap is
closed, such that there is no significant degradation of the antenna
performance caused by collapsing the radio telephone for storage.
Consequently, the flap antenna does not impair the radio telephone's
1 0 ability to receive an incoming call alerting signal, a paging signal or an
E-mail signal.
According to an àlternate embodiment of the parasitic radiator
708, the elbow 738 and elbow 737 joining arms 734 and arms 736 to base
1 5 735, respectively, are ninety degree corners having curved outer edges.
The sum of length F of arm 734, length G of base 735, and length H of
arm 736 is approximately one half the wavelength of the transceiver
operating frequency. The embodiment of FIG. 5 is ~Lefelled because the
tips 555, 556 of arms 534, 536 are further from shoulder 535 than the tips
755, 756 of the arms 734, 736, if the total length of the antennas are the
same (i.e., if both antennae embodiments are quarter wavelength
antennas).
Another alternate embodiment of the parasitic radiator 808 is
2 S illustrated in FIG. 8. Parasitic radiator 808 includes notches 858 in arms
834 and 836. The notches 858 in the arms are provided for positioning
the arms around outwardly extending protrusions (not shown) of front
housing section 605. This is particularly desirable if the inside surface
of the front housing section has a large number of protrusions. It is
3 0 desirable that the arms 834, 836 extend in a single plane for optimum
antenna performance. This is particularly important since positioning
of the parasitic radiator 508 adjacent the circuitry inside housing 101
will detrimentally affect performance of the antenna system. However,
a disadvantage of the embodiment of FIG. 8 is the distance from tips
-
2 1 ~
855, 856 to shoulder 835 is further shortened by the addition of the
notches.
Accordingly it can be seen that an improved antenna system is
S disclosed for a communication device having movable body sections.
The antenna system provides high performance characteristics when
the antenna is opened and when the device is collapsed for ease of
storage.
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