HK1033868A - Switchable matching circuits using three-dimensional circuit carriers - Google Patents

Description

Field of invention of switchable matching circuit using three-dimensional circuit carrier

The present invention relates to radiotelephones, and in particular to matching circuits for retractable antennas for radiotelephones.

Background of the invention

Many radiotelephones use retractable antennas, i.e., antennas that can be extended and retracted from the radiotelephone housing. The retractable antenna is electrically connected to a transceiver operatively associated with an information processing circuit positioned on an internally disposed printed circuit board. In order to achieve maximum power transfer between the antenna and the transceiver, the transceiver and the antenna are preferably interconnected so that the respective impedances are substantially "matched", i.e., electrically tuned to filter out or compensate for undesired antenna impedance components, providing a 50 ohm impedance value at the circuit feed point. Unfortunately, what plagues such a matching system is that the retractable antenna, by its very nature, has a dynamic component, i.e., a component that moves or translates relative to the housing and printed circuit board, as such there is generally no single impedance value. In contrast, retractable antennas generally produce widely differing impedance values when returned from an extended position to a retracted position. It is therefore preferred that the impedance matching system changes the impedance of the antenna so that the impedance of both the antenna and the transceiver can be properly matched when the antenna is extended and retracted.

The miniaturization of radiotelephones and built-in printed circuit boards further complicates the physical structure of the matching network. Many of the more popular handheld wireless telephones are being miniaturized. Indeed, many modern popular styles are only 11-12 centimeters long. Because the printed circuit board is placed inside the wireless telephone, the size of the printed circuit board is also shrinking in correspondence with the miniaturization of the portable wireless telephone. Unfortunately, as the size of printed circuit boards decreases, the amount of space available to support desired operational and performance parameters generally decreases accordingly. It is therefore desirable to effectively and efficiently utilize the limited space within a radiotelephone and on a printed circuit board.

This miniaturization can also result in complex mechanical and electrical connections to other components, such as an outwardly extending retractable antenna, which generally must be interconnected with the housing for mechanical support and, as discussed above, connected to an impedance matching system operatively associated with the printed circuit board so that signals can be processed.

Reference is now made to fig. 1A and 1B, which illustrate the desired equivalent circuits 10, 10' in the extended and retracted antenna positions, respectively. As shown, in fig. 1B, the antenna rod 12 operates with a half-wave (λ/2) load in the extended position. In this case the impedance of the output of the antenna feed is up to 600 ohms. In contrast, in the retracted position, as shown in fig. 1A, the antenna rod 12 operates with a quarter-wave (λ/4) load, with an impedance typically close to 50 ohms. Thus, an L-C matching circuit may be required when the antenna is in the extended position.

In the past, conventional portable radiotelephones have employed a variety of antenna connections to match the impedance of the antenna to the impedance of the housing and printed circuit board. For example, U.S. patent No. 5374937 to Tsunekawa et al suggests the use of downwardly spaced contacts or terminals on a printed circuit board within the radiotelephone housing which function to connect or short the associated matching network. Unfortunately and disadvantageously, this type of transfer connection uses a series of discrete transfer components, such as wiping contacts, and in addition uses an undesirable amount of space on the printed circuit board. In addition, such a configuration may limit the operating bandwidth of the radiotelephone.

An alternative is described in a co-pending patent application entitled "radiotelephone with antenna matching switching system architecture" (8194-73) filed 5/20 1997 by Gerard j. This system uses laterally spaced circuit and antenna contacts to reduce the amount of space on the printed circuit board required to operate the matching system. However, this system uses a series of discrete components in the switch over device and in the interconnection of the antenna to the circuit board of the device.

Others have also attempted to incorporate discrete printed circuit boards with circuit components at the base of the antenna. Unfortunately, printed circuit boards are generally fragile and therefore lack the durability that is desirable in re-use applications. Furthermore, because the RF (radio frequency) and fundamental frequency traces must be isolated from each other, the interconnection of certain circuit components and the required manufacturing tolerances exacerbate the disadvantages of these designs.

Objects and summary of the invention

It is therefore an object of the present invention to provide a matching system that reduces the number of transfer contacts and discrete components used to create a retractable antenna matching system.

It is another object of the present invention to use an integral matching system to switch and match the relative impedances of the antenna in a manner that combines the mechanical and electrical interfaces of the antenna assembly.

It is a further object of the present invention to reduce the number of wiping contacts and individual switches and to reduce the amount of printed circuit board space necessary to operate a retractable antenna matching system.

It is a further object of the present invention to provide an antenna base with an integrated circuit that can be used with existing models of radiotelephones.

It is a further object of this invention to provide an antenna matching circuit that is reliable, durable, and economical.

These objects and others are met by a three-dimensional circuit positioned on an antenna assembly that integrates a matching circuit and separate RF and ground circuits. A first aspect of the invention comprises an antenna assembly configured to define and excite a matching circuit when the antenna is extended. The antenna assembly includes a circuit carrier antenna base unit. The base unit includes a predetermined conductive and non-conductive configuration on the exterior surface. The conductive portions of the outer surface and the channels define separate signal and ground paths. The antenna assembly also includes a retractable antenna having opposite first and second ends, a central axis defined through a center of the retractable antenna. First and second conductive portions are included on the first and second ends, respectively. The antenna is slidably retractable through a passage about a central axis between a first extended position and a second retracted position. When the antenna is extended, the first conductive part is electrically connected with the antenna base. In a preferred embodiment, the circuit carrier antenna base unit includes a matching circuit disposed thereon such that when the antenna is extended, the matching circuit is energized and energized in the signal path. Preferably, the signal path comprises a single RF feed point.

The circuit carrier antenna base unit may also include a disconnect switch positioned at the upper end of the base. The disconnect switch should be configured to contact a conductive portion of the antenna to de-energize the matching circuit when the antenna is in the retracted position, thereby causing the matching circuit to exit the signal path when the antenna is retracted. Preferably this disconnects the reactive components of the matching circuit, thereby allowing a wider radiotelephone operating frequency.

In a preferred embodiment, the antenna base member includes a cylindrical body having an outer surface and a channel having an inner surface. The antenna base includes a circuit carrier that is mounted on selected portions of the inner and outer surfaces so that a first radio signal path and a separate second ground signal path can be defined. The channel is configured to receive a portion of the retractable antenna therein. Preferably, the outer surface includes a non-conductive threaded portion having a recessed area that helps separate the RF and ground traces. In one embodiment, the upper portion of the threaded portion is electrically conductive and is configured to engage a ground plug in the radiotelephone housing. The recessed area prevents shorting to a ground plug when installed in the radiotelephone.

Another aspect of the invention includes a method of forming a carrier circuit for defining a signal path and a separate ground path. Preferably, the bracket circuit is used with a switchable matching system in a retractable antenna base assembly for a radiotelephone. This method comprises the steps of: molding a portion of the base member, i.e., a first layer comprised of a first material; a second layer is formed of a second material over selected areas of the first layer. The surface of a predetermined portion of the first layer of the base member is kept exposed to the outside. The exposed surface of the first layer is coated with a conductive coating to form three-dimensional conductive signal and ground circuits on a base member. Preferably the second layer is formed of a non-catalytic material and the first layer is formed of a catalytic material such that the first layer is formed of a material which is able to accept the metallic coating and the second layer is not able to accept the metallic coating.

Alternatively, a selected portion may be exposed for photoimaging to form a portion of the circuit carrier.

In operation, when the antenna is extended, the antenna base of the antenna forms an integral inductive and capacitive matching element. Preferably, this three-dimensional circuit surrounds the supporting structure, so that the matching system does not require a separate wiping contact, since the mechanical support for the antenna is integrated in the electrical transition corresponding to the retraction and extension of the antenna in the antenna base.

The above objects, other objects, and various aspects of the present invention will be described in detail in the following specification.

Brief Description of Drawings

Fig. 1A is a schematic diagram of an equivalent circuit of a conventional retractable antenna, here shown here in analog form as a stub of 1/4 wavelengths.

Fig. 1B is a schematic diagram of the equivalent circuit of a conventional 1/2 wavelength extended antenna and associated L-C matching circuit.

Fig. 2 is a schematic diagram of a matching circuit from which the L-C components exit when the antenna is retracted, in accordance with one embodiment of the present invention.

Fig. 3 is an enlarged perspective view of a circuit carrier antenna base unit in accordance with the present invention.

Fig. 4 is a perspective view of the circuit carrier antenna base unit of fig. 3 showing the other side and bottom of this unit in accordance with the present invention.

Fig. 5A is a perspective view of the molding process at a first stage showing predetermined raised surfaces on a sub-assembly carrier circuit according to the first aspect of the invention, the raised surfaces being conductive in the finish portion shown in fig. 5C.

Fig. 5B is a perspective view of a second stage of the molding process showing the molded portion of fig. 5A molded over the first sub-assembly with additional material.

Fig. 5C is a cross-sectional view of the portion shown in fig. 5B after metallization according to an embodiment of the invention.

Fig. 6A is an enlarged perspective view of a bracket circuit assembly in accordance with one embodiment of the present invention.

Fig. 6B is another side of the bracket circuit assembly of fig. 6A.

Fig. 7 is an exploded view of a radiotelephone and antenna having a cradle circuit in accordance with an additional embodiment of the present invention.

Figure 8A is a side view of one embodiment of an antenna assembly in accordance with the present invention.

Fig. 8B is a cross-sectional view of the antenna assembly of fig. 8A.

Figure 9A is a top perspective view of an additional embodiment of a cradle circuit according to the present invention.

Fig. 9B is a top perspective view of the opposite side of the bracket circuit shown in fig. 9A.

Fig. 10 is a top perspective view of the cradle circuit shown in fig. 9A.

Fig. 11 is a side view of an antenna assembled within the bracket circuit shown in fig. 9A.

Description of the preferred embodiments

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Like numbers refer to like elements throughout the specification. In the drawings, certain thicknesses have been exaggerated for clarity.

Generally, as shown in fig. 3, 4, 6A, and 6B, the present invention relates to a three-dimensional circuit bracket positioned as an antenna base unit 15. As shown in fig. 7, the circuit carrier base 15 is preferably used with a radiotelephone 30 having a retractable antenna 35. Also preferably, as shown schematically in fig. 1A and 1B, the retractable antenna 35 employs an upper load 36, with the antenna rod 35 operating in a half-wave mode in the extended position and a short line (helix) of 1/4 wavelengths in the retracted position. Of course, the present invention is not limited to this antenna load or antenna configuration, and other alternative antenna configurations may be used in the present invention. For example, the antenna may also include an antenna load that is an integer multiple of a half-wavelength, or a disk-shaped or other type of antenna load element. Preferably, the present invention isolates the RF (signal) and ground traces or paths from each other and allows them to be switched with a variety of mating components without the need for multiple components, such as wiping contact switches, printed circuit boards, located at the base or the like.

As shown in fig. 3, 4, 6A, 6B, the antenna base unit circuit bracket 15 is preferably a cylindrical body where a matching circuit 40 is formed. As shown in fig. 3 and 4, the circuit carrier base unit 15 includes a predetermined conductive and non-conductive pattern on its outer surface 21. The non-conductive portion 23 is shown as a single color of material, while the conductive portion 22 is shown as a stippled material. The base member has opposite upper and lower ends 16, 17 with a longitudinal channel 18 extending through the upper and lower ends 16, 17. As shown in fig. 4, this passage has an exposed inner diameter, and the passage 18 is preferably formed by means of a conductive surface 22 a. Although the channel 18 is electrically conductive along its entire length and periphery, the channel 18 may alternatively have only a predetermined conductive portion (not shown) so that it can carry an electrical signal from the upper portion of the base unit to the lower portion of the base unit when excited by the corresponding antenna conductive portion. The channel 18 is sized and configured to receive a retractable antenna therein. Preferably, as shown in fig. 7 and 8, the channel 18 is sized so that the antenna 35 slidably telescopes with respect to the channel 18. Preferably, the channel 18 is sized and configured such that the lower (or first) conductive portion 75 of the antenna stub 37 makes electrical and mechanical contact with the inner diameter of the channel 18 when the antenna 35 is extended.

Preferably, the outer surface conductive and non-conductive portions 22, 23 of the antenna base member 15, together with the channel 18, define separate signal and ground paths 26, 28 between the antenna 35 and the radiotelephone 30. As shown in fig. 3 and 4, signal path 26 is indicated by the diagonal hatching marks on the right; similarly, an electrically isolated ground path is indicated by a left-diagonal hatched marker. Fig. 3 and 4 show different side perspective views of an embodiment of the invention. These two views show a pattern of a conductive material surface 22 (speckled surface) with a non-conductive surface 20 (non-speckled and solid) interposed therein. This configuration allows the ground and signal paths 28, 26 to be electrically isolated from each other even in a small (i.e., 8-13 mm diameter) base unit body 15. The base member preferably includes a single signal (or RF) feed point 103 along the signal path 26. As shown in fig. 3 and 4, the signal feeding point 103 extends in a circumferential direction around the lower portion of the base unit 15.

As shown in fig. 3, 6A and 6B, the base unit 15 preferably further includes two spaced-apart cavities or gaps 60, 61, the cavities 60, 61 being positioned on the upper surface 16 of the base unit 15 and between the signal and ground portions for mounting discrete circuit components therein. Of course, as known to those skilled in the art, depending on the desired antenna type (e.g., single band or dual band, etc.), the tracks may include: there is only one gap, more than two gaps, or no gap, so that only the inductor is included as part of the circuit track. This latter case may eliminate the need for discrete components.

More preferably, this base unit 15 includes upwardly extending electrical contact protrusions 70, 71, the protrusions 70, 71 being located on opposite sides of the cavity or gap 60, 61 to facilitate proper positioning of the mating component 40, such as discrete inductor or capacitor elements 92, 93 (fig. 6A). Referring now to fig. 4, the ground path 28 in the base unit 15 is configured so that it makes electrical contact with the ground in the radiotelephone at a location intermediate the upper and lower portions 16, 17 of the base unit 15 (ground contact surface 100).

As shown in fig. 4, the signal path 26 extends from the upper portion 17 of the base unit 15 along an external signal track 29c, the external signal track 29c being positioned along the outer length of the base member 15 and being separated from the intermediate ground contact surface 100 by a recessed area 29, the sides of the recessed area 29 being contiguous with the non-conductive portions 29a, 29b adjacent the ground contact surface 100. Similarly, as shown in fig. 3, the ground path 28 raises the ground path 28 to the upper portion 16 of the base unit 15 by a rail 129, the rail 129 being separated from the signal path 26 by non-conductive portions 129a, 129 b. Alternative ways of implementing the circuit tracks may also be used. For example, pathway guidance and connection rails may be used. A via can be generally considered to be a coated hole that electrically connects two layers (not shown). Of course, combinations of vias (not shown) may also be employed for use with the circuit tracks described above. For example, a via may replace a rail surrounding a corner, such as a rail from the upper portion of the base unit to the lower side of the base unit, effectively shortening the electrical power path, thereby possibly improving the electrical characteristics of the channel (not shown).

In a preferred embodiment, as shown in fig. 7, when assembled, the antenna base unit 15 is threaded into a hole in the housing 53 such that portions of the threads 25 (fig. 3) on the base member 15 engage a ground plug 52 positioned over the hole 53 in the radiotelephone 30, thereby electrically connecting the antenna base unit 15.

Referring now to fig. 8A, the antenna base unit circuit carrier 15 is sized and configured to engage the retractable antenna 35 and is preferably configured to switch in the signal path depending on the position of the antenna 35 within the carrier base unit 15 and to electrically include one or more matching circuit components. Specifically, the antenna base unit 15 is configured to automatically engage a matching adapter system 40 (fig. 6A) in response to the extension of the antenna. Thus, matching system 40 has different circuit paths and associated impedances corresponding to predetermined positions of movable antenna 35, i.e., corresponding to retracted or extended positions of antenna 35 relative to antenna assembly 38 located within radiotelephone housing 30.

Obviously, when the antenna 35 is extended, most of the antenna body is outside the radiotelephone housing 30; in contrast, when the antenna is retracted, most of the antenna body is inside the radiotelephone housing 30. In operation, the antenna 35 enters and exits the housing passage 53 (fig. 7) along the central axis 50 and engages the base unit 15 (mounted to the housing 30) to define and energize different signal paths within the antenna base unit 15 by the position of the antenna 35 relative to the retraction and extension of the antenna, as described in greater detail below. The radiotelephone also includes a printed circuit board (not shown) disposed within the housing proximate the antenna 35 to electrically connect the signal or RF feed point 103 from the base 15 to the radiotelephone 30. It will be readily apparent to those skilled in the art that the printed circuit board should be constructed to receive (and transmit) electrical signals from the antenna 35 and the base unit 15.

Referring now to fig. 7, the antenna 35 includes first and second conductive portions 75, 85 that engage the antenna base unit 15 to energize respective signal paths, i.e., extended or retracted signal paths, in response to extension or retraction of the antenna 35 relative to the antenna base unit 15. Preferably, the retracted or extended signal path operates with a 50 ohm impedance into a signal feed point associated with the printed circuit board in the radiotelephone 30. The extended signal path includes a matching system 40 (fig. 6A), the matching system 40 matching the increased impedance due to the extended position of the antenna 35.

As mentioned above, the matching configuration of the passage 18 and the antenna 35 is such that the excitation of the matching circuit 40 occurs with the actual extension and retraction of the antenna 35. This configuration has the advantage of reducing the amount of space on the printed circuit board that is required or dedicated for energizing the corresponding matching circuit components.

Referring again to fig. 7, in operation, the antenna 35 enters and exits the base unit passage 18 along the central axis 50. The base unit 18 is configured to fit to the housing through the housing opening 53 (fig. 7). It is preferred that the electrical length of the antenna 35 (typically determined by the length of the upper load element 36 and the linear rod 37) be predetermined. More preferably, the electrical length of the antenna 35 should be determined so as to provide a half wavelength or an integer multiple of a half wavelength, such that the antenna 35 resonates at the operating frequency. As shown in fig. 7, the antenna 35 includes opposite first and second ends 90, 95 and defines a central axis 50 through the center thereof. The first end 90 extends beyond the housing 30 and includes an upper load element 36, such as an upper load monopole. As mentioned above, the antenna 35 also includes a second conductive portion 85 that is located below the antenna element 36.

Fig. 11 shows the antenna 35 in an extended position and fig. 8A and 8B show the antenna 35 in a retracted position. As shown in fig. 8A and 8B, the second conductive portion may be an electrically conductive contact ring 85 that is electrically connected to the upper load antenna element 36. As also shown in fig. 8A and 8B, the length of the conductive contact ring 85 exposed on the outer diameter of the antenna 35 is large enough to engage one or more contact point(s) or contact surface(s) 110 on the base unit 15.

Referring now to fig. 7, the second end 95 of the antenna includes a first conductive portion 75, the first conductive portion 75 being electrically connected to and formed on (at least a portion of) the lower linear beam element 37 and being spaced from the second conductive portion 85. The first conductive portion 75 is structured to be electrically connected to the upper portion of the inner surface of the rod 37 and the channel 18 when the antenna is extended, so as to transmit and receive signals therebetween. The lower antenna end 95 is preferably maintained within the antenna base unit 15 independent of the extension of the antenna 35. The antenna end 95 or the contact portion 75 may include an integral spring member or structure (not shown) to facilitate contact with the upper portion 18a (fig. 6A) of the inner surface of the channel 18 when the antenna 35 is extended. As shown in fig. 11, the antenna 35 may have an anchor portion 199 to anchor or grip the end within the antenna base to prevent accidental withdrawal of the antenna rod from the housing 30. In any event, as shown in fig. 7 and 11, the antenna is preferably configured such that the upper load element 36, the second conductive portion 85, and the first conductive portion 75 of the antenna are all in electrical communication.

As shown in fig. 6A and 6B, the base unit 15 and antenna 35 should be configured to engage the matching system 40 when the antenna is extended, the matching system 40 preferably including an inductor 92 and a capacitor 93. In the preferred embodiment, the inductor 92 and capacitor 93 are discrete components positioned on the upper surface 16 of the base unit 15 so that they are in the signal path 26 when the antenna is extended. The capacitor is preferably sized to provide a capacitance of about 1/2-1 picofarads. For the embodiment shown, a footprint of a component having typical dimensions will be referred to by those of ordinary skill in the art as "0603". More preferably, as shown in fig. 6A and 6B, the matching circuit 40 includes both an inductor and a capacitor, but the present invention is not limited thereto. Indeed, the matching circuit 40 may be constructed in another manner so as to be selectively matched to the impedance of the inductive portion or the impedance of the capacitive portion of the signal. It is also possible to add a resistive component, either externally to the capacitive and the salt component or integrally with the capacitive and the inductive component.

A typical antenna structure is shown in fig. 11. As shown, the antenna rod 37 includes a conductive core 35a and a non-conductive overmold 35 b. It will thus be apparent that in the preferred embodiment shown in figure 7, when the antenna 35 is extended, radiotelephone signals are transmitted (and received) from the antenna 35 via the signal path defined by the upper load element 36, the extended rod 37 (core), and the first conductive contact 75 of the antenna. The first conductive portion 75 of the extended pull rod 37 engages the inner surface of the upper portion 18a of the channel 18 (fig. 6A) and energizes the matching circuit 40, which is located on the upper surface of the base unit 15 and includes inductive devices and capacitors. This signal is directed by the matching circuit 40 down through the outer track 29c (fig. 4) to the signal or RF feed point 103 and into the radiotelephone 30. This signal feed point 103 is electrically connected to a printed circuit board or other substrate (not shown) in the radiotelephone that handles radio signals.

Referring to fig. 7, the second conductive portion 85 of the antenna is electrically connected to the helical element 36 (e.g., 1/4 wavelength helix) located on the upper portion of the antenna 35. Thus, when retracted, the antenna second conductive portion 85 connects to and electrically contacts the upper surface 16 of the base member 15 (fig. 6A, 6B). This engagement causes the signal to travel down the outer track 29c without electrically connecting the matching circuit 40 (e.g., by shorting out these circuit components outside the signal path), thereby creating a signal path upon retraction. This retracted signal path preferably operates with a 50 ohm impedance. Thus, as shown in fig. 8A and 8B, the retracted signal path is defined by the helical element 36 of the antenna, the second conductive portion 85 of the antenna, the upper contacts 135a, 135B of the base unit (which are electrically connected to the base contact surface 110 (fig. 3)), the base unit outer track 29c, and the signal feed point 103.

Of course, there are various other ways of connecting to the short circuit or upper contact surface 110 (FIG. 3) structure of the base unit 15. Fig. 7 and 8 illustrate mechanically attaching a metal contact ring 105 to the base unit 15, such as by welding or crimping the metal contact ring 105 onto the base unit 15. Thus, when retracted, the contact members 135a, 135b contact the conductive portion 85 of the antenna, thereby shorting the matching circuit 40 and directing the signal downward through the base member 15 into the radiotelephone. Other alternative contact surface configurations include desired features molded into the base unit 15 in a predetermined contact geometry (fig. 9), or by positioning the contact features 110 as discrete features on the base unit 15. In a preferred embodiment, the contact (e.g., a metal contact ring as shown in fig. 8) includes a spring pin 135, which spring pin 135 facilitates electrical contact with the antenna conductive portion 85.

Further, in an additional embodiment as shown in fig. 9, 10 and 11, the configuration of the antenna 35 and base unit 15 is adapted to provide a transition mechanism 175 for exiting the matching means and circuit 40 when retracted. Thus, this embodiment (similar to fig. 2) brings the matching circuit 40 out of the signal path, in contrast to the embodiment shown in fig. 7 and 8 (for short-circuiting across the matching circuit 40, similar to the circuit diagram shown in fig. 1A). The exit of the matching circuit 40 may naturally be beneficial to improve certain operating characteristics by eliminating reactive components in the signal circuit, such as to provide a wider operating bandwidth.

Referring now to fig. 11, the base unit 15' is configured to enable the matching circuit 40 to be withdrawn by contact with the second conductive portion 85 when the antenna is retracted. As shown, the antenna base unit 15 'includes a (preferably spring-loaded) switch contact 125'. The base unit 15' also includes an electrical contact portion with a surface 110 that is configured to electrically connect to the upper load of the antenna via the second conductive portion 85 of the antenna. Switch contact 125 'is shown as a laterally extending spring contact, i.e., spring switch contact 125' is movable toward and away from central axis 50. The switch contact 125 'is preferably configured and positioned on the base unit 12' such that it, together with the matching circuit 40, defines a normally closed switch. Whereby in this embodiment, when the antenna 35 is extended, the contact structure will operate as in the previously described embodiment, i.e. the lower contact on the antenna is in electrical contact with the inner surface of the base unit 15 to engage the matching circuit 40. However, as schematically illustrated in fig. 2, when the antenna 35 is retracted, the switch contact 125 'and the base unit 15' are configured as a switch 175 that electrically disconnects the matching circuit 40.

Referring now to fig. 9 and 10, the switch contacts 125 'include a pair of spring pins that extend circumferentially in opposite directions 126a, 126 b' and are configured to engage conductive surfaces 146a, 146b, respectively, on the base unit when the antenna 35 is extended. This configuration may provide electrical continuity with the matching circuit 40 included in the signal path when the antenna 35 is in the extended position. The switch contact 125 'is typically pressed into a cavity and thermally engaged therein to secure to the base 15'. Preferably, the switch contacts are resilient and are formed of beryllium copper, or other material having spring-like properties. Alternatively, the structure of the switch contacts 125 ' may be fabricated in a unitary base member 15 ', wherein the polymer material of one embodiment of the base unit 15 ' is used as a common type of spring, which may be designed for the material used with regard to fatigue and creep resistance concerns.

Preferably, as described above, the switch contact 125 'is normally closed, such that the switch contact 125' is in the signal path and is in electrical communication with the matching circuit 40 when the antenna 35 is extended. It is also preferred that the base unit 15 'include a pair of contact pads 146a, 146b positioned opposite the spring switch contacts 125' such that the contact spring pins 126a, 126b engage the respective contact pads 146a, 146b when the antenna 35 is extended to provide electrical continuity in the signal path.

As shown in fig. 9A, the spring switch contact 125' is pushed outward and the spring pins 126a, 126b are moved away from and electrically separated from the contact pads 146a, 146b by movement of the second conductive portion 85 of the antenna (located below the helical element 36 and adjacent to the helical element 36). The helical element 36 and the conductive portion 85 of the antenna are thicker than the antenna rod or stub 37. Thus, when the antenna 35 is retracted, this additional width pushes the switch contact 125 ', breaking contact with the signal path, and opening the normally closed switch determined by the structure of the base unit 15' of this embodiment. Thus, in this embodiment, when the antenna is retracted, the second conductive portion 85 contacts the contact surface 110 on the base 15 ', moving the spring switch contact 125 ', the spring switch contact 125 ' disconnecting the spring pins 126a, 126b from the contact pads 146a, 146b and thereby electrically connecting the matching circuit 40. In contrast, as described above, when the antenna 35 is extended, the matching circuit 40 is turned on through the normally closed position of the spring switch contact 125'. Of course, those skilled in the art will appreciate that there are numerous ways in which the present invention may be implemented and that a variety of variations and configurations may be used to provide the desired matching and switching capabilities between the base unit 15 and the antenna 35.

The base unit 15 shown in figure 7 has an external guide 105 which is located around the upper surface 16 of the base unit. The outer guide 105 helps to guide the antenna in the correct orientation, the outer guide 105 being electrically conductive. Thereby, the outer guide 105 facilitates electrical contact with the corresponding antenna contact when the antenna is retracted. Similarly, fig. 11 includes a ring 105a constituting the periphery of the upper surface of the base unit

In addition, the base (as shown in FIG. 11) may include a sheath 106, the sheath 106 being positioned around the upper surface of the base unit. This sheath may enhance the aesthetic appearance of the unit, help guide the extension and retraction of the antenna, and may protect the components therein. Preferably, the sheath 106 shown in FIG. 11 is a polymer sheath positioned over the base 15' to provide an aesthetically pleasing end product and to protect circuit components, such as shorting contacts, electrical components, and contact pads. Similarly, the mating members 92, 93 may be overcoated with a protective coating to insulate and provide environmental protection.

Referring now to fig. 5A, 5B, and 5C, a preferred method of manufacturing a three-dimensional circuit carrier, and more particularly, a one-piece base unit that includes and defines a circuit carrier, is described. In this embodiment, a two-shot layer molding process is used to form the structure of the base unit 15. It is preferred to use two materials or combinations of materials, one having an affinity for the conductive coating and the other not, a first material for the first injection layer and a second material for the second injection layer. Examples of materials that may be used include, but are not limited to, polymers with or without catalysts, such as liquid crystal polymers, ULTEMTM, and nylon, or materials that may be coated with a non-metallic coating material; such as various brands of nylon.

Preferably, during the first shot (fig. 5A), a catalyzed polymeric material is molded into the first layer 200 in a manner and configuration that provides an exposed surface 210, which surface 210 is desirably electrically conductive in the final part. These exposed surfaces 210 are then treated in succession, for example by applying a metallic or conductive coating, after the second molding injection layer 300 is disposed on the first injection layer. In a second shot (fig. 5B), a second material (e.g., uncatalyzed polymer) is molded over those surfaces of the second layer 300 that are not desired to be electrically conductive, during which the catalyzed polymer of the first layer 200 is exposed on those surfaces 210 that are desired to be coated or the like. After molding, this portion may be coated with a third layer 400 (fig. 5C). This coating adheres to the surface 210 only with an affinity for this coating, thereby creating conductive and non-conductive patterns 400, 300 on which it is desired to define separate signal and ground paths. As will be appreciated by those of ordinary skill in the art, other methods may also be used with this dual injection layer method to add or supplement the desired conductive and non-conductive track patterns, such as (but not limited to) one or more of the following: dipping, plating, or spraying the desired surface treatment. In a preferred embodiment, an electrocoat deposition layer is provided on the exposed catalytic component. Typical electroless plating materials include copper, nickel, tin, and gold.

Alternatively, photoimaging or electroplating and photoresist techniques may be used, wherein multiple exposures are used to form the desired structure. Of course, a combination of photoimaging and dual injection layer approaches may also be used. For example, a dual injection layer process is used to form the circuitry surrounding the edges, while photo-imaging can be used to increase the pattern of higher resolution circuitry on one surface.

Certain of the above-described aspects of the present invention may be provided by hardware, software, or a combination thereof, as known to those of ordinary skill in the art. Thus, although the various components are described as integral components, in practice, one or more of the components may be implemented by a microcontroller including input and output ports for running software code, by custom or hybrid chips, by discrete components, or by a combination of the above. For example, one or more components of the matching circuit 40 may be implemented as a programmable controller device, or as a separate discrete component (as schematically illustrated herein). Similarly, "printed circuit board" is meant to include any microelectronic assembly structure.

The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although only a few exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. It should be understood, therefore, that the foregoing is illustrative of the present invention and is not to be construed as limiting the particular embodiments of the invention disclosed herein; and it is to be understood that modifications to the disclosed embodiments, as well as other embodiments, are intended to be included within the scope of the appended claims. The invention is defined by the following claims, with equivalents of the claims to be included therein.

Claims (26)

1. An antenna assembly, comprising:

a circuit carrier base unit, said base unit comprising an exterior surface having predetermined conductive and non-conductive configurations thereon, said base unit further having opposite upper and lower ends with a longitudinal conductive path extending between said upper and lower ends, wherein conductive portions of said exterior surface and said path define separate signal and ground paths;

a retractable antenna having opposite first and second ends and defining a central axis through the center thereof, said first and second ends including respective first and second conductive portions on the upper edges thereof, said antenna slidably passing through said passage about said central axis between a first extended position and a second retracted position; wherein said first conductive portion is electrically connected to said antenna base when said antenna is extended.

2. The antenna assembly of claim 1, characterized by: said circuit carrier base unit includes a matching circuit on its upper side, wherein said matching circuit is switched on in said signal path when said antenna is extended.

3. The antenna assembly of claim 2, characterized by: the signal path includes a single RF feed point.

4. The antenna assembly of claim 1, characterized by: in combination with an inductor and a capacitor.

5. The antenna assembly of claim 2, characterized by: said base upper end including a circuit switch contact and at least one corresponding switch contact surface, wherein said switch contact and said switch contact surface are electrically normally closed so that the signal path electrically connects with said matching circuit when the antenna is extended, and wherein said switch contact and said switch contact surface are opened when said antenna is retracted and said switch contact surface are configured to electrically transition said matching circuit out of said signal path.

6. The antenna assembly of claim 2, characterized by: the antenna includes an upper load element, a second conductive portion, and a first conductive portion connected in series in a longitudinal sequence, each of which is in electrical communication with the upper load element.

7. The antenna assembly of claim 1, characterized by: when the antenna is retracted, the second conductive portion is electrically connected to an upper portion of the base, so that the matching circuit is disconnected.

8. The antenna assembly of claim 1, characterized by: the material of the non-conductive part of the base is a polymer.

9. The antenna assembly of claim 8, wherein: the base material is one of a liquid crystal polymer, ULTEM, and NYLON.

10. The antenna assembly of claim 1, characterized by: the configuration of the conductive and non-conductive portions of the base includes catalyzed and uncatalyzed materials.

11. The antenna assembly of claim 1, characterized by: the conductive configuration is defined by an electrocoated catalytic material.

12. The antenna assembly of claim 2, characterized by: the antenna and the base are configured to be inserted into a radiotelephone housing to provide a first impedance when the antenna is extended and a second impedance when the antenna is retracted.

13. The antenna assembly of claim 12, wherein: when the antenna is extended, the inner diameter of the passageway contacts a first conductive portion of the antenna to thereby electrically connect the matching circuit, and wherein when the antenna is retracted, the second conductive portion is a contact ring positioned adjacent a lower portion of an upper load element of the antenna and electrically connects an upper portion of the base to the antenna to short the matching circuit out of the signal path.

14. The antenna assembly of claim 13, wherein said base unit further comprises:

a disconnect switch positioned in an upper portion of said base, said disconnect switch being structured to contact said antenna contact loop and electrically disconnect said matching circuit from the signal path when said antenna is in the retracted position, thereby causing said matching circuit to exit said signal path when said antenna is retracted.

15. The antenna assembly of claim 1, characterized by: further comprising an upwardly extending sheath positioned about the upper end of said base.

16. The antenna assembly of claim 1, characterized by: the base unit includes a threaded portion intermediate the upper and lower ends for mounting to a radiotelephone housing.

17. The antenna assembly of claim 16, wherein: the upper surface of said base includes an externally accessible underside opposite thereof, wherein said threaded portion is configured to engage a ground plug disposed in the radiotelephone housing, and wherein said underside of the upper surface of said base is in electrical contact with said ground plug.

18. The antenna assembly of claim 1, characterized by: said antenna further comprising a longitudinally extending rod portion intermediate said upper load element and said first conductive portion, wherein said matching circuit is energized in the extended position by electrical contact between a first conductive end of said antenna and an inner diameter of said base, and wherein said upper load element, said antenna rod, and said base define a signal path therebetween.

19. The antenna assembly of claim 1, characterized by: the structure of the antenna and the base disconnect the reactive components of the matching circuit when the antenna is in the retracted position, thereby allowing a wider radiotelephone operating bandwidth.

20. An antenna base member comprising:

a cylindrical body having an exterior surface and a channel having an interior surface;

a circuit carrier disposed on selected portions of said inner and outer surfaces for defining a first radio signal path and a separate second ground signal path; wherein said channel is configured to receive a portion of a retractable antenna therein.

21. The antenna base unit of claim 20, wherein: the outer surface includes a threaded portion for electrically connecting to a ground plug in the radiotelephone housing, wherein the recessed area prevents shorting of the signal path and ground plug when the radiotelephone is attached.

22. A method of forming a circuit carrier defining a switchable signal path and a separate ground path for a radiotelephone retractable antenna matching system, the method comprising the steps of:

molding a portion of the base member of a first layer of a first material;

forming a second layer of a second material on selected areas of said first layer;

positioning said second layer to maintain a predetermined portion of said first layer of said base member exposed; and

coating the exposed surface of said first layer with a conductive coating, thereby forming three-dimensional conductive signal circuitry and ground circuitry on said base member.

23. The method of claim 22, wherein: the second layer is formed of a non-catalytic material and the first layer is formed of a catalytic material.

24. The method of claim 22, wherein: the first layer is formed of a material that is receptive to the metal coating and the second material is not receptive to the metal coating.

25. The method of claim 22, further comprising the step of:

discrete circuit components are mounted on the base member for electrical communication with the signal path to define a matching circuit with the signal path when the antenna is extended from the radiotelephone.

26. The method of claim 22, further comprising the steps of:

exposing a selected surface for photoimaging to form a portion of said circuit carrier.