INTRODUCTION AND BACKGROUND

This invention relates to mobile devices and more particularly to a multiple- input multiple-output (MIMO) antenna adaptor for a mobile device, such as a smart phone.

Many wireless devices have no external antenna connectors and function with embedded internal antennas only. These internal antennas are typically enclosed in an enclosure which is electromagnetically transparent, such as plastic or a similar material. In cases where the signal at the location of use is insufficient, it would sometimes be useful to link such device to an external antenna.

It is known to use electromagnetic (EM) couplers to link the internal antenna via a coaxial cable to an external antenna, to improve signal transmission and reception.

With recent advances in wireless standards, the use of MIMO has proved to be fundamental in increasing wireless data speeds. MIMO involves having multiple antennas at a base station (or, in general, one side of a link) as well as multiple antennas on an end user device (or, in general, other side of the link). Cellular LTE, WiMAX and WiFi standards are common examples of wireless communication standards of which latest releases incorporate MIMO technology. To achieve maximum benefit from MIMO networks, outdoor antennas are used which either consist of multiple discrete antennas, but more commonly, multiple antennas housed in a single housing. The simplest case is 2x2 MIMO which implies two antennas used at the one end of the link communicating with two antennas at the other end. Hence, a 2x2 MIMO outdoor antenna device would have two coaxial cables leading to a MIMO terminal device.

Connecting two such external antennas to a MIMO handheld device with internal antennas, such as a smart phone, using couplers is more complex.

The position of the internal antennas and orientation of the couplers relative to the internal antennas are important to achieve both maximum coupling to the internal antennas and also maximum de-correlation between the signals from the two connected external antennas.

The internal MIMO antennas of different brands of handheld devices are not in a similar arrangement relative to one another on the body and even the antennas of different models of devices of the same brand, are not similarly arranged.

OBJECT OF THE INVENTION

Accordingly, it is an object of the present invention to provide a multiple- input multiple-output (MIMO) antenna adaptor for a mobile device, a kit and MIMO device and adaptor assembly with which the applicant believes the aforementioned disadvantages may at least be alleviated or which may provide a useful alternative for similar solutions.

SUMMARY OF THE INVENTION

According to the invention there is provided an adaptor for a multi-input multi-output (MIMO) mobile device comprising at least first and second spaced internal antennas, the adaptor comprising:

- a cover comprising at least one mounting formation for cooperating with a corresponding formation on the mobile device, so that the cover is mountable on the mobile device;

- at least first and second spaced electromagnetic couplers which are respectively associated with the at least first and second internal antennas;

- radio frequency cables extending from the at least first and second couplers to one of a) respective signaling devices on the cover and b) respective connector parts which are removably connectable to at least first and second external signaling devices, respectively; and

- engagement formations on the cover for holding each of the at least first and second couplers in a respective position and orientation with respect to the respective associated internal antenna which collectively ensure a coupling factor between the coupler and the respective internal antenna of at worst 2dB lower than the highest possible coupling factor obtainable by an optimal position and orientation of the coupler relative to the respective internal antenna when the cover is mounted on the device.

Said coupling factor may be at worst 1 ,5dB lower than the highest possible coupling factor and preferably at worst 1 dB lower than the highest possible coupling factor.

At least some of the signaling devices may typically be in the form of antennas.

Hence, at least one of the signaling devices on the cover may comprise an antenna and at least one of the external signaling devices may comprise an antenna.

The radio frequency cables may extend from the at least first and second couplers to respective connector parts which are provided on the cover.

The cover may be removably mountable on the device. The at least one mounting formation may for example enable the cover to be clipped onto the device alternatively to be slid onto the device. The adaptor may be intended or specified for at least one predetermined mobile device in terms of brand and model.

Hence, the cover may be specific to at least a first predetermined model of device to ensure that the respective positions and orientations are suitable to ensure said coupling factor between the couplers and the respective associated internal antennas when the cover is mounted on the first predetermined model of device.

In some embodiments, the couplers with cables may be removably securable to the cover by means of the engagement formations.

Hence, the cover may comprise at least first and second engagement formations for removably receiving and holding the first and second couplers in the respective position and orientation to ensure said coupling factor.

Each engagement formation may comprise a recess which is defined in a first face of the cover which in use faces the device, the recess being shaped and configured to hold the coupler in said position and orientation.

The recess may be configured such that the coupler received therein is flush with the first face. The cables may be provided in channels defined in the first face, so that the cables are flush with the first face.

In other embodiments, the couplers and cables may be permanently embedded in the cover.

Each connector part may for example comprise a first part of a SubMiniature version A (SMA) connector. In some embodiments the cover may be configured selectively to be mountable on at least a first model of device and a second different model of device, the cover may further comprise third and fourth engagement formations for holding third and fourth couplers respectively associated with first and second internal antennas of the second model of device in a respective position and orientation to ensure said coupling factor between the third and fourth couplers and the respective associated internal antennas of the second model of device when the cover is mounted on the second model of device. The first and second models may be of the same brand, alternatively of first and second different brands. According to a further aspect of the invention there is provided an adaptor for a multi-input multi-output (MIMO) mobile device comprising at least first and second spaced internal antennas, the adaptor comprising:

- a cover comprising at least one mounting formation for cooperating with a corresponding formation on the mobile device, so that the cover is mountable on the mobile device;

- at least first and second spaced electromagnetic couplers which are respectively associated with the at least first and second internal antennas;

- radio frequency cables extending from the at least first and second couplers to one of a) respective signaling devices on the cover and b) respective connector parts which are removably connectable to at least first and second external signaling devices, respectively; and

- engagement formations on the cover for holding each of the at least first and second couplers in a respective position and orientation for coupling to the respective associated internal antennas when the cover is mounted on the device.

The invention further extends to a kit comprising the adaptor as defined above wherein the radio frequency cables extend from the at least first and second couplers to respective first connector parts; and at least first and second external signaling devices which are respectively removably connectable to the respective first connector parts.

The kit may further comprise respective radio frequency cables extending from the at least first and second external signaling devices to respective second connector parts which are removably connectable to the respective first connector parts.

The respective first connector parts may comprise one of a male and a female part of a SubMiniature version A (SMA) connector.

The respective second connector parts may comprise the other of the male and the female part of the SMA connector.

The invention also extends to an assembly comprising i) a MIMO mobile device comprising at least first and second spaced internal MIMO antennas; and ii) an adaptor comprising: a cover comprising at least one mounting formation cooperating with a corresponding formation on the mobile device to arrest the cover to the mobile device; at least first and second spaced electromagnetic couplers which are respectively associated with the at least first and second internal antennas; radio frequency cables extending from the at least first and second couplers to one of a) respective signaling devices on the cover and b) respective connector parts which are removably connectable to at least first and second external signaling devices, respectively; and engagement formations on the cover for holding each of the at least first and second couplers in a respective position and orientation with respect to the respective associated internal antenna which collectively ensure a coupling factor between the coupler and the respective internal antenna of at worst 2dB lower than the highest possible coupling factor obtainable by an optimal position and orientation of the coupler relative to the respective internal antenna when the cover is mounted on the device.

BRIEF DESCRIPTION OF THE ACCOMPANYING DIAGRAMS

The invention will now further be described, by way of example only, with reference to the accompanying diagrams wherein:

figure 1 is a diagrammatic front view of a known mobile phone showing first and second internal MIMO antennas;

figure 2 is a diagrammatic rear view of the phone;

figure 3 is a diagrammatic exploded perspective view of the phone and an adaptor for the phone; and

figure 4 is a diagrammatic representation of a kit comprising the adaptor and external MIMO antennas which are connectable to the adaptor. DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

An example embodiment of an adaptor for a multi-input multi-output (MIMO) mobile device, such as a mobile phone 100 (shown in figures 1 , 2 and 3), is generally designated by the reference numeral 10 in figures 3 and 4.

In a preferred embodiment, the cover is intended or specified for at least one predetermined and known mobile device in terms of brand and model.

The known mobile device 100 comprises a MIMO antenna arrangement comprising at least a first internal antenna 102 and a spaced second internal antenna 104. The antennas are normally provided in or immediately adjacent a rear wall 106 of the device.

Referring to figure 3, the adaptor 10 comprises a cover 12 comprising at least one mounting formation 14 for cooperating with a corresponding formation 108 on the device 100, so that the cover 12 is mountable, preferably removably mountable, on the device. The adaptor comprises at least first and second spaced electromagnetic couplers 1 6, 18 which are respectively associated with the at least first and second internal antennas 102, 104. Radio frequency cables 20, 22 extend from the at least first and second couplers 16, 18 to one of a) respective signaling devices (not shown) on the cover and b) respective first connector parts 24, 26 which are removably connectable to at least first and second external signaling devices, typically in the form of external antennas 28, 30 (shown in figure 4), respectively. The cover 12 comprises engagement formations 32 for holding the at least first and second couplers 16, 18 in a respective position and orientation with respect to the respective associated internal antennas 102, 104 which position and orientation would collectively ensure a coupling factor between the coupler and the respective internal antenna of at worst 2dB lower than the highest possible or optimal coupling factor (OdB) obtainable by an optimal position and orientation of the coupler relative to the respective internal antenna when the cover 10 is mounted on the device 100.

Each engagement formation 32 may be in the form of a recess defined in a first face surface 34 of the cover which in use faces the device. The couplers are flush with the surface 34, so that they are as near as possible to the associated antennas. Similarly, the cables 20, 22 may be located in channels (not shown) in the first face 34, so that they are also flush with the first face.

In the example embodiment shown, the cables 20, 22 terminate in respective first connector parts 24, 26. The first connector parts may be provided adjacent an end 12.1 , 12.2 of the cover, but preferably adjacent a side 12.4 of the cover. The first connector parts may be in the form of a female part of a SubMiniature version A (SMA) connector. Referring to figure 4, the external antennas 28, 30 are connected to cooperating second connector parts in the form of male parts 36, 38 of the SMA connectors via respective cables 40, 42. The external antennas 28, 30 may be separate and free standing, alternatively they may be carried on a single carrier or housed in a single housing 44.

The invention also extends to a kit 50 comprising the adaptor 10 and an assembly 52 comprising the external signaling devices 28,30 connected by cables 40, 42 to second connector parts 36, 38 respectively.

The invention still further extends to an assembly comprising i) a MIMO mobile device 100 comprising at least first and second antennas 102, 104; and ii) an adaptor 10 as herein defined and/or described mounted on the mobile device.