Wireless device including optimized antenna system on metal frame

Abstract

A wireless device such as a mobile device comprises a metal frame antenna (MFA) solution developed to cover the multiple range of frequencies required in the wireless device. An MFA includes a ground plane layer, at least a single-strip metal frame element spaced apart from an edge of the ground plane layer, and at least a feeding system that connects the at least one single-strip metal frame element to an RF transceiver of the wireless device.

Claims

1. A metal frame antenna system for a wireless device comprising: a ground plane layer; at least a single-strip metal frame element spaced apart from one edge of the ground plane layer; and at least a feeding system connecting the at least one single-strip metal frame element to the RF transceiver of said device, wherein a length of the single-strip metal frame element is greater than 1/25 times a free-space wavelength corresponding to a lowest frequency of operation of the wireless device and less than 1/2.8 times a free-space wavelength corresponding to a highest frequency of operation of the wireless device.

2. The metal frame antenna system of claim 1, wherein the length of the single-strip metal frame element is between 1/23 times a highest wavelength of operation of the wireless device and 1/3.7 times a lowest wavelength of the device operation.

3. The metal frame antenna system of claim 1, wherein the at least a feeding system comprises a strip line connecting to a matching network at a first end and to the single-strip metal frame element at a second end.

4. The metal frame antenna system of claim 1, wherein the at least a feeding system further comprises at least a boosting element.

5. The metal frame antenna system of claim 1, wherein the at least a feeding system further comprises at least a boosting element connected to the single-strip metal frame element.

6. A metal frame antenna system for a wireless or mobile device comprising: a ground plane layer; at least a single-strip metal frame element spaced apart from one edge of the ground plane layer; and at least a feeding system connecting the at least one single-strip metal frame element to an RF transceiver of the wireless or mobile device, wherein the wireless or mobile device operates within a 600 MHz to 3000 MHz frequency range and a length of the single-strip metal frame element is between 20 mm and 35 mm.

7. The metal frame antenna system of claim 6, wherein the length of the single-strip metal frame element is between 22 mm and 27 mm.

8. The metal frame antenna system of claim 6, wherein the at least a feeding system comprises a strip line connecting to a matching network at a first end and to the single-strip metal frame element at a second end.

9. The metal frame antenna system of claim 6, wherein the at least a feeding system further comprises at least a boosting element.

10. The metal frame antenna system of claim 6, wherein the at least a feeding system further comprises at least a boosting element connected to the single-strip metal frame element.

11. A metal frame antenna system for a wireless or mobile device comprising: a ground plane layer; a single-strip metal frame element spaced apart from one edge of the ground plane layer; a feeding system connecting the single-strip metal frame element to an RF transceiver of said device; a floating metal frame element adjacent to the single-strip metal frame element and unconnected from the single-strip metal frame element, with a gap between the single-strip metal frame element and the floating metal frame element, wherein the wireless or mobile device operates within a 600 MHz to 3000 MHz frequency range and a length of the single-strip metal frame element is between 20 mm and 35 mm, and the length of the floating metal frame element is between 15 mm and 40 mm.

12. The metal frame antenna system of claim 11, wherein the length of the single-strip metal frame element is between 22 mm and 27 mm.

13. The metal frame antenna system of claim 11, wherein the at least a feeding system comprises a strip line connecting to a matching network at a first end and to the single-strip metal frame element at a second end.

14. The metal frame antenna system of claim 11, wherein the at least a feeding system further comprises at least a boosting element.

15. The metal frame antenna system of claim 11, wherein the at least a feeding system further comprises at least a boosting element connected to the single-strip metal frame element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 shows a graph on the achievable bandwidth (BW) as a function of frequency for a full strip MFA solution (1) compared to the performance of embodiments in FIGS. 2 and 3 of the present invention (curves (2) and (3) respectively).

[0019] FIG. 2 illustrates an example of an MFA solution with a single strip metal frame of length on the order of the length of the upper edge of a phone.

[0020] FIG. 3 shows an MFA solution including a single strip metal frame MFA with an optimized length according to the present invention.

[0021] FIG. 4 provides the matching network used to match the embodiment presented in FIG. 2.

[0022] FIG. 5 shows the input reflection coefficient related to the embodiment shown in FIG. 2 matched with the matching network provided in FIG. 4.

[0023] FIG. 6 presents the radiation and antenna efficiencies related to the embodiment shown in FIG. 2 matched with the matching network provided in FIG. 4.

[0024] FIG. 7 illustrates an MFA solution including a single strip metal frame MFA with an optimized length according to the present invention and an adjacent floating, non-coupled element.

[0025] FIG. 8 presents the matching network used to match the example from FIG. 7.

[0026] FIG. 9 shows the input reflection coefficient related to the example provided in FIG. 7.

[0027] FIG. 10 shows the radiation and antenna efficiencies related to the example from FIG. 7.

DETAILED DESCRIPTION

[0028] An MFA antenna system according to the present invention is shown in the following examples without any limiting purpose. An MFA antenna system comprises a ground plane typically implemented as a ground metal layer on a multilayer printed circuit board (PCB). The size of such a ground plane might be, for a smart phone, on the order of 50 mm to 65 mm on the shorter edge, and about 120 mm to 150 mm on the longer edge and quite typically, around 55 mm135 mm.

[0029] FIG. 3 shows an example comprising a ground plane layer 2 and a single-metal frame element 3 connected to the RF transceiver of the device by means of a feeding system. A feeding system connecting said frame element to the RF transceiver includes an L-shaped floating line 4 which is connected to a matching network 5 at a first end and to an antenna booster or boosting element 6 to a second end. Said antenna booster is in this example a Fractus mXTEND product (e.g., FR01-54-250, FR01-54-232, FR01-54-224). Said antenna booster is connected at a first point to said single-strip metal frame element and to the L-shaped floating line at a second point. In this example, the ground plane layer is also surrounded by 3 metal grounding strips 7 for a metal frame whose main function is providing a structural mechanical element for the phone while using such an element for the aesthetics finishing of the device. One of the edges of the device (the upper edge in FIG. 3) features a clearance area 8 where the ground plane layer is removed. Such a clearance area spaces apart the edge of the ground plane with a first single-strip metal frame element that is connected to the RF transceiver of the phone by means of a feeding system. For the typical frequencies of a phone ranging 600 MHz up to about 3,000 MHz, the spacing between a first metal frame element and the edge of the ground plane is between 1 mm and 20 mm, and typically between 10 to 15 mm.

[0030] FIG. 4 provides the matching network 5 comprised in the feeding system of the embodiment shown in FIG. 3 and used to match it. FIG. 5 shows the input reflection coefficient related to said embodiment, which covers LTE700, GSM850, GSM900, LTE1700, GSM1800, GSM1900, UMTS2100, LTE2300, LTE2500 and LTE2600 mobile bands, if taking into account a maximum threshold of 6 dB. FIG. 6 represents the radiation RE and antenna efficiencies AE of the example provided in FIG. 3. Such example features an antenna efficiency average of 67.3% in the range of low frequencies 698 MHz-960 MHz and an antenna efficiency average of 79.9% in the range of high frequencies 1.71 GHz-2.69 GHz.

[0031] FIG. 7 provides an embodiment that additionally comprises a floating second metal frame element 9 adjacent to the first single-strip metal frame element and unconnected from said single-strip metal frame element. Said floating, unconnected second strip features a similar size to the first one (e.g., 15 mm to 40 mm) so that, all together, they cover about the whole upper edge of the device in FIG. 7. Such example includes a gap 10 of width 1 mm that spaces said first and second metal frame elements. Such a gap minimizes the coupling between metal frame elements and preserves the achievable bandwidth about the same as the one achievable without the presence of the floating metal frame element.

[0032] FIG. 8 provides the feeding system matching network used to match the embodiment shown in FIG. 7 that comprises an additional floating second metal frame element. FIG. 9 shows the input reflection coefficient related to said embodiment, which covers LTE700, GSM850, GSM900, LTE1700, GSM1800, GSM1900, UMTS2100, LTE2300, LTE2500 and LTE2600 mobile bands, when taking into account a maximum threshold of 6 dB criteria. FIG. 10 provides the radiation efficiency RE and the antenna efficiency AE related to the embodiment pictured in FIG. 8. This example features an antenna efficiency average of 68.3% in the 698 MHz-960 MHz range of low-frequency region and an antenna efficiency average of 75.4% in the 1.71 GHz-2.69 GHz range of high-frequency region.