HK1190830B - Helical antenna apparatus and method of forming helical antenna - Google Patents

Description

Helical antenna apparatus and method of forming a helical antenna

Technical Field

The present invention relates to the field of small, broadband antennas, and more particularly, to helical antennas that can be used with wireless microphones transmitting in the UHF band range.

Background

It may be desirable in one or more of various wireless applications, such as wireless microphones, computers, mobile devices, and other wireless transmission devices, to implement a small, robust, and inexpensive antenna that is easy to assemble.

One such example is disclosed in U.S. patent No. 7,301,506 to Kenkel (Kenkel), which is incorporated herein by reference in its entirety. Kenkel discloses a helical antenna assembly formed by using a non-metallic tape and placing a metallic tape strip diagonally on the non-metallic tape. The tape is then used to wrap the dielectric core. An electrical connector and a center conductor located in the center of the dielectric core contact the metal tape. One or both tabs on the tape are bent over the ends of the dielectric core to prevent the tape assembly from separating from the dielectric core. An eyelet is also attached to the center conductor to pin the tab. When the tape assembly is wrapped around the dielectric core, the pitch and width of the conductive portions of the tape assembly may be varied to obtain desired electrical characteristics.

Disclosure of Invention

In an exemplary embodiment, the present invention contemplates an antenna assembly comprising: a dielectric core having an antenna tape with a conductive portion wrapped around the dielectric core, and a printed circuit board extendable from a chassis. The printed circuit board may be electrically coupled with the conductive portion on the tape.

In another exemplary embodiment, the present invention contemplates a wireless microphone assembly comprising a voice housing, a chassis, and an antenna assembly coupled to the chassis. The antenna assembly includes a dielectric core extending into the chassis. An antenna tape including a conductive portion is wrapped around the dielectric core. A printed circuit board may extend from the base plate with at least a portion of the printed circuit board located in the base plate. The printed circuit board is electrically coupled to the conductive portion on the tape.

In another exemplary embodiment, the invention contemplates a method for forming an antenna, the method comprising wrapping an antenna tape comprising a conductive portion around the dielectric core; mounting a printed circuit board to a base plate at a point located away from the base plate; and electrically coupling the printed circuit board and the conductive portion.

Drawings

FIG. 1 illustrates a perspective side view of an exemplary antenna assembly;

FIG. 2 shows a perspective side view of the antenna assembly of FIG. 1 with the addition of an antenna cover;

FIG. 3 shows a perspective top view of the antenna assembly of FIG. 1 with the dielectric core and the antenna cover removed;

FIG. 4 shows another perspective side view of the antenna assembly of FIG. 1 with the dielectric core and the antenna cover removed;

FIG. 5 shows a perspective view of an exemplary dielectric core;

fig. 5A shows a perspective view of another exemplary dielectric core;

FIG. 6 shows a perspective view of the dielectric core of FIG. 5 wrapped with an antenna tape;

fig. 7A-7C illustrate exemplary antenna tape configurations; and

fig. 8A-8C show the exemplary antenna tape construction of fig. 7A-7C wrapped around a dielectric core.

Detailed Description

Other objects and features of the present invention will be understood by reference to the following description and drawings.

The present invention is illustrated by way of example and not limitation in the accompanying figures.

In the following description of various exemplary structures according to the present invention, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration various structures in accordance with the invention as recited in the claims. Moreover, it is to be understood that other specific configurations of parts and structures may be used, and structural and functional modifications may be made, without departing from the scope of the present invention. Also, while the terms "top" and "bottom" and the like may be used in this specification to describe various example features and elements of the invention, for convenience, such terms are used herein based on, for example, the example orientations shown in the figures and/or the orientations in typical use. Nothing in this specification should be construed as requiring a specific three-dimensional or spatially-oriented structure so as to fall within the scope of the claims.

Fig. 1 and 2 generally depict an antenna 100 having a dielectric core 130 with an antenna wrap or tape 120, a Printed Circuit Board (PCB)110, and an antenna cover 114. The antenna 100 is fixed to the bottom plate 104 of the hand microphone. The handheld microphone may include a wireless transmitter for wireless transmission. The microphone typically has a sensor element or voice housing for receiving voice input. The sensor element may be a dynamic, condenser, tape sensor, or any other known sensor element.

Conductive elements, such as coupling wires 106 or flex cables (not shown), which serve as a strain relief connection interface between the two components, may electrically couple the conductive portion 122 of the antenna tape 120 to the PCB 110. A ground element, which may be a screw 112, may be used to connect the PCB110 to the base plate 104 near the lead 106 to allow for an appropriate ground reference.

The dielectric core 130 can be mounted adjacent to the PCB110 and in the base plate 104. The PCB110 extends through the floor wall 105 and into the opening 144 of the handheld microphone. Additionally, if the antenna is mishandled, a shock absorbing member 146 comprising a small piece of shock absorbing foam may be placed between the interior region of the antenna cover 114 and the end of the dielectric core 130 to provide additional shock absorbing capability to absorb shock energy during a drop impact. In an exemplary embodiment, the shock absorbing member 146 may be formed of a micro-porous polymer pad (poron pad). The coupling wire 106 provides strain relief between the PCB110 and the antenna 100. In particular, the coupling wire 106 may be provided with additional length to provide additional slack in the wire so that the coupling wire 106 may move freely during a drop impact without separation. It enhances the shock absorbing capability of the antenna 100 if the antenna 100 is dropped or mishandled or if the antenna 100 is otherwise moved relative to the PCB 110.

To properly feed the antenna 100, a Radio Frequency (RF) signal needs to be properly referenced to ground. A ground screw 112 may be added between the base plate 104 and the PCB110 to act as a ground reference.

As shown in fig. 3 and 4, the base plate 104 is provided with L-shaped tabs or flanges 116 extending from the base plate 104 to hold the PCB 110. The PCB110 is secured to the tab 116 by a ground screw 112 at a point remote from the base plate 104. This allows the PCB110 to extend further out from the bottom plate 104 of the microphone and provides a shorter distance between the antenna 100 and the PCB110, ultimately providing better RF transmission to the antenna 100. In addition, the base plate 104 may be provided with threads 118 for receiving mating threads on a sleeve 148, the sleeve 148 serving as an external handle or clamp on the wireless microphone and also serving as an external housing covering the battery for operating the microphone. One or more screws 140 are aligned with screw holes 142 to maintain the antenna cover 114 and the dielectric core 130 in place on the base plate 104. However, other methods for securing the antenna cover 114 to the chassis 104 are also contemplated.

Fig. 5 and 6 generally depict an embodiment of the dielectric core 130. Fig. 5 shows the dielectric core 130 before being wrapped with the antenna tape 120, and fig. 6 shows the dielectric core 130 after being wrapped with the antenna tape 120. The dielectric core 130 is non-rigid and helps absorb the descending stress to protect the electrical contacts in the PCB110 and the antenna 100. A suitable material for forming the dielectric core 130 is a thermoplastic urethane (TPU) that provides good absorption of shock energy during a drop impact of the antenna 100.

The dielectric core 130 has a first cylindrical portion 132 and a second elongated portion 134. The first cylindrical portion 132 is configured to receive the antenna tape 120 and the second elongated portion 134 is configured to be inserted into the base plate 104 of the microphone. The first cylindrical portion 132 may have a circular cross-section for receiving the antenna tape 120. The second elongated portion 134 can have a D-shaped cross-section or a partially curved profile with a flat surface for interfacing with the L-shaped tabs 116 of the bottom plate 104 and the PCB110 such that the dielectric core 130 does not interfere with the PCB110 during assembly. In particular, the D-shaped profile corresponds to the interior profile of the bottom plate 104 formed by the opening 144 in the bottom plate 104, the tab 116, and the PCB110, and allows the dielectric core 130 to be placed in the bottom plate 104 surrounding the tab 116 and the PCB 110. The addition of the second elongated portion 134 provides good shock absorbing properties to the antenna 100. The second elongated portion 134 also has an opening 133, the opening 133 may extend through the length of the second elongated portion 134 and to the first cylindrical portion 132. The second elongated portion 134 also has two holes 136 for securing the dielectric core 130 and the antenna cover 114 to the base plate 104 via one or more screws 140. The recess 138 in the second elongated portion 134 provides a groove that provides clearance between an end of the ground screw 112 and the dielectric core 130. Which allows the ground screw 112 to extend completely past the tab 116 of the base plate 104 without contacting the dielectric core 130 so that the screw 112 does not affect the positioning of the dielectric core 130 relative to the PCB 110. The two holes 136 may be formed to fit to screws 140 (shown in fig. 3), which may be self-tapping screws. Which makes it less expensive to interface a mechanical connection to the backplane 104.

In addition, the dielectric core 130 can be modified into other shapes and configurations. For example, as shown in fig. 5A, the first portion 132A may be formed in an elliptical shape to account for other desired mechanical characteristics.

Fig. 7A-7C depict antenna tapes 120A, 120B, 120C that may be used in conjunction with the antenna 100 and the dielectric core 130. Fig. 8A-8C show the antenna tape of fig. 7A-7C, respectively, wrapped around the dielectric core 130.

As shown in fig. 7A-7C, the antenna tape 120A, 120B, 120C can include conductive portions 122A, 122B, 122C and substrate portions 124A, 124B, 124C. The conductive portions 122A, 122B, 122C may be formed of copper foil, and the substrate portions 124A, 124B, 124C may be formed of a polyester material with an adhesive backing. However, other materials are also contemplated. The antenna tape 120A, 120B, 120C may be formed by attaching the conductive portion 122A, 122B, 122C to the substrate portion 124A, 124B, 124C by any known method. The size, length, orientation, shape, etc. of the conductive portions 122A, 122B, 122C may be configured to optimize antenna performance.

As shown in fig. 7A, the conductive portion 122A may be formed with a first horizontal portion 126A, an inclined portion 128A, and a second substantially horizontal upper portion 129A to provide appropriate transmission characteristics.

An alternative embodiment is shown in fig. 7B. This embodiment is similar to the embodiment shown in fig. 7A in that the conductive portion 122B has a first horizontal portion 126B, an inclined portion 128B, and a second substantially horizontal upper portion 129B; however, the conductive portion 122B is formed with a vertical portion 125B formed approximately at a right angle to the first horizontal portion 126B and a top element 127B formed in a circular shape positioned offset from a second substantially horizontal upper portion 129B. The antenna tape design improves the performance of the microphone at lower frequency band transmissions.

In the embodiment depicted in fig. 7A and 7B, the width of the conductive portions 122A, 122B may be sized to be 0.100 inches or 2.54 millimeters, in addition to the top element 127B being formed from a larger diameter. It should be noted, however, that other dimensions may also provide suitable performance characteristics of the antenna 100.

In another alternative embodiment shown in fig. 7C, the conductive portion 122C may be formed with a first conductive element 123C and a second conductive element 125C formed at slopes that both follow a substantially straight line. The first conductive element 123C and the second conductive element 125C can cross at the bottom of the antenna tape 120C. The conductive portion 122C is formed with a vertical portion 126C, the vertical portion 126C being formed near the intersection of the first conductive element 123C and the second conductive element 125C and at approximately right angles to the antenna tape 120C. When the antenna tape 120C is wrapped around the dielectric core 130, two top vertical portions 127C may be formed at approximately right angles to the antenna tape 120C to form a connection between the first conductive element 123C and the second conductive element 125C. Furthermore, in an alternative exemplary embodiment, a rounded top element (not shown) similar to the top element 127B shown in fig. 7B may be formed near the top of the first and second conductive elements 123C and 125C to form contact between the two elements.

In an alternative embodiment, the antenna 100 may be formed on a flexible PCB or formed as part of the PCB110 and wrapped onto the dielectric core 130 after the PCB110 is assembled into the chassis 104. In particular, because the conductive portions 122 on the antenna tape 120 are merely traces of a particular length and pitch, the conductive portions 122 can be fabricated as part of the PCB 110. In this embodiment, an adhesive backing may be added to the antenna tape 120 to wrap the adhesive backing over the dielectric core 130. Which would eliminate the soldering operation associated with connecting the leads 106 to the PCB110 and the conductive portion 122 and the costs associated therewith, but may also increase costs due to PCB material usage.

Fig. 8A illustrates the antenna tape 120A shown in fig. 7A wrapped around the first cylindrical portion 132 of the dielectric core 130. As shown in fig. 8A, the conductive portion 122A wraps two and a half turns around the dielectric core 130.

Fig. 8B illustrates the antenna tape 120B wrapped around the first cylindrical portion 132 of the dielectric core 130. As shown in fig. 8B, the conductive portion 122B wraps around the dielectric core 130 for about two and a half turns. In addition, the vertical portion 125B is folded down over the bottom of the dielectric core 130, and the top element 127B is folded over the top of the first cylindrical portion 132 of the dielectric core 130.

Fig. 8C illustrates the antenna tape 120C wrapped around the first cylindrical portion 132 of the dielectric core 130. When the antenna tape 120C is wrapped around the dielectric core 130, the first element 123C and the second element 125C form a double helix around the dielectric core 130. The first conductive element 123C and the second conductive element 125C are each wrapped about the dielectric core 130 about two turns. This forms a helical antenna that wraps dielectric core 130 corresponding to the first conductive element 123C up and then crosses the top surface of the dielectric core 130 via the two top vertical portions 127C and a second helix that wraps dielectric core 130 corresponding to the second conductive element 125C down.

In addition, the first conductive element 123C that forms an upward spiral wrap in a first direction and the second conductive element 125C that forms a downward spiral wrap in the opposite direction will both terminate at the RF feed from the PCB 110. Both the first conductive element 123C and the second conductive element 125C are operably connectable to an RF feed on the PCB110, which differs from the embodiment shown in fig. 7A and 7B in that the conductive portion 122C is terminated back to an RF feed on the PCB 110. However, alternatively, in another exemplary embodiment, the second conductive element 125C may be attached to ground instead of an RF feed on the PCB 110.

To assemble the antenna, the dielectric core 130 is wrapped with the antenna tape 120. The PCB110 is then secured to the L-shaped tab 116 of the base plate 104 by the screw 112. When the ground screw 112 is installed, it compresses the conductive area on the PCB110 against the conductive area on the L-shaped tab 116 of the paint or coating that has been masked, forming an electrical ground connection to provide RF grounding between the PCB110 and the base plate 104. To improve the contact between the PCB110 and the bottom plate 104, solder masks may be removed near screw holes, and paste may be added to increase the contact area and uniformity of ground references. The coupling wires 106 or flex cables can then be soldered to the PCB110 with copper pads or copper plated through holes on the PCB 110. The wire 106 or flex cable can then be soldered to the conductive portion 122 on the antenna tape 120. The dielectric core 130 is then inserted into the base plate 104 and the antenna cover 114 is placed over the dielectric core 130. The dielectric core 130 and the antenna cover 114 are secured to the chassis 104 by two self-tapping screws 140 inserted through the antenna cover 114 and into holes 136 in the second elongated portion 134 of the dielectric core 130.

In an alternative exemplary embodiment, a rigid flex tape may be used to extend from the PCB110, and the ends of the rigid flex tape may be plated with copper. This copper plated rigid flex tape is then soldered directly to the conductive portion of the antenna to remove the necessary coupling conductors 106 and thus eliminate the need to solder the coupling wires 106 or flex cable to the antenna 100 or the PCB 110.

The antenna embodiments disclosed herein can achieve a 13% fractional bandwidth of greater than 470MHz to 950MHz with tuning by varying the conductor length while mounting it into the small microphone backplane. The embodiments disclosed herein may be implemented in any future handheld wireless device including, but not limited to, devices that operate in a similar frequency band using a metal chassis and antenna cover.

The reader should understand that the specific examples are set forth merely to illustrate examples of the invention, and the examples should not be construed as limiting the invention. Many changes may be made to the specific structure described above without departing from the invention.

While the invention has been described in detail with respect to specific examples including presently preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and methods. Accordingly, the spirit and scope of the present invention should be construed broadly as set forth in the appended claims.

Claims (26)

1. An antenna assembly, comprising:

a dielectric core comprising a shock absorbing material, the dielectric core having a first portion and a second portion, wherein the first portion has a circular or elliptical cross-section and the second portion has a D-shaped cross-section;

an antenna tape wrapped around the first portion of the dielectric core, the tape comprising a conductive portion; and

a printed circuit board extending from the base plate; wherein the printed circuit board is electrically coupled to the conductive portion on the tape and the second portion of the dielectric core is configured to be inserted into the chassis.

2. The antenna assembly of claim 1 wherein the dielectric core has an opening in the second portion and the second portion has at least one hole for receiving a fastener to secure the dielectric core to the chassis.

3. The antenna assembly of claim 1, wherein a conductive element electrically couples the printed circuit board and the conductive portion.

4. The antenna assembly of claim 3 wherein the conductive element comprises a wire soldered to both the printed circuit board and the conductive portion.

5. The antenna assembly of claim 1 further comprising an antenna cover positioned over the dielectric core and a shock absorbing member positioned between the dielectric core and the antenna cover.

6. The antenna assembly of claim 1, wherein the printed circuit board is mounted to a tab extending from the chassis, and wherein a ground element provides electrical contact between the printed circuit board and the tab to ground the antenna.

7. The antenna assembly of claim 6, wherein the ground element comprises a screw.

8. The antenna assembly of claim 1, wherein the conductive portion comprises a first conductive element and a second conductive element forming a double helix around the dielectric core.

9. The antenna assembly of claim 1, wherein the conductive portion comprises a top element positioned over an end of the dielectric core.

10. A wireless microphone assembly, comprising:

a voice shell;

a base plate; and

an antenna assembly coupled to the chassis, wherein the antenna assembly comprises:

a dielectric core comprising a first portion and a second portion;

an antenna tape wrapped around the first portion of the dielectric core, the antenna tape comprising a conductive portion;

a printed circuit board, wherein the printed circuit board is electrically coupled with the conductive portion on the tape; and

a cover removably connected to and extending from the base plate, wherein a first portion of a dielectric core is received in the cover and a second portion of the dielectric core is at least partially received in the base plate.

11. The wireless microphone assembly of claim 10 wherein the printed circuit board is attached to a tab extending from the chassis.

12. The wireless microphone assembly of claim 10 wherein the first portion has a circular or elliptical cross-section and the second portion has a D-shaped cross-section.

13. The wireless microphone assembly of claim 12 wherein the dielectric core has an opening in the second portion and the second portion has at least one hole for receiving a fastener to secure the dielectric core to the chassis.

14. The wireless microphone assembly of claim 10 wherein a conductive element electrically couples the printed circuit board and the conductive portion.

15. The wireless microphone assembly of claim 14 wherein the conductive element comprises a wire soldered to both the printed circuit board and the conductive portion.

16. The wireless microphone assembly of claim 10 further comprising a shock absorbing member positioned between the dielectric core and the antenna cover.

17. The wireless microphone assembly of claim 10 wherein the printed circuit board is mounted to a tab extending from the base plate, and wherein a ground element provides an electrical contact between the printed circuit board and the tab.

18. The wireless microphone assembly of claim 17 wherein the ground element comprises a screw.

19. The wireless microphone assembly of claim 10 wherein the conductive portion comprises a first element and a second element forming a double helix around the dielectric core.

20. The wireless microphone assembly of claim 10 wherein the conductive portion comprises a top element positioned over an end of the dielectric core.

21. A method for forming an antenna, comprising:

wrapping an antenna tape around a dielectric core, the antenna tape including a conductive portion;

mounting a printed circuit board to a base plate at a point located away from the base plate;

electrically coupling the printed circuit board and the conductive portion;

soldering a conductive element to both the printed circuit board and the conductive portion and securing the printed circuit board with a grounding element.

22. The method of claim 21, further comprising forming the dielectric core of shock absorbing material and placing the dielectric core in the backplane.

23. The method of claim 21, further comprising securing the dielectric core to the backplane with a fastener.

24. The method of claim 21, further comprising forming the dielectric core with a first portion and a second portion, and encasing the antenna tape around the first portion and inserting the second portion into the chassis.

25. The method of claim 21, further comprising forming the conductive portion with a first element and a second element that form a double helix around the dielectric core.

26. The method of claim 21, further comprising forming the conductive portion with a top element positioned over an end of the dielectric core.