High isolation multiple port antenna array handheld mobile communication devices

#Not Applicable

#The present invention relates generally to antennas for handheld, wireless communication devices, and more particularly to multiple-input, multiple-output antennas.

#Different types of wireless mobile communication devices, such as personal digital assistants, cellular telephones, and wireless two-way email communication equipment are available. Many of these devices are intended to be easily carried on the person of a user, often compact enough to fit in a shirt or coat pocket.

#FIG. 1 is a schematic block diagram of a mobile wireless communication device that incorporates a MIMO antenna arrangement;

#FIG. 2 is a plane view of a printed circuit board on which a version of a dual port antenna assembly is formed, wherein the antennas are slot antennas;

#FIG. 3 is an enlarged view of a portion of the printed circuit board in FIG. 2;

#The present multiple port antenna assembly for use in multiple antenna systems, such as MIMO communication devices, provide isolation between two ports in a wide bandwidth, for example covering 2.25-2.8 GHz and supporting multiple communication standards. The exemplary antenna assembly has a pair of radiating elements, which, in the illustrated embodiments, comprise slot antennas, inverted F antennas, and patch antennas. It should be understood, however, that alternative radiating element types may be used, such as patch, planar inverted F (PIFA), monopole and other antenna types. The illustrated slot antennas are formed by creating two straight, open-ended slots at two opposing side edges of a conducting layer etched at one side of a printed circuit board (PCB), to form a pair of quarter wavelength slot antennas. The slots are located along one edge of the PCB opposing each other, and symmetrically with respect to the center line of the PCB. The other side of the PCB is available for mounting other components of the communication device. Each slot antenna in this configuration operates as a quarter wavelength resonant structure, with a relatively wide bandwidth. It should be understood, however, that alternative orientations, dimensions, and shapes may be used. The dimensions of the slots, their shape and their location with respect to the any edge of the PCB can be adjusted to optimize the resonant frequency, bandwidth, impedance matching, directivity, and other antenna performance parameters. It should also be understood that a slot may penetrate through the substrate of a board, in addition to the conducting layer. In addition, loaded slots may be used, with resistive material either at an end or within a slot. Furthermore the slots may be designed as a reconfigurable antenna element, with the frequency of operation being dynamically controlled by a controlling unit. The controlling unit with switches can be used to effectively change the electrical length of the slots and consequently change the frequency of operation for different frequency bands of interest. In one implementation, controllable switches are used, for example, a microelectromechanical system (MEMS), which enables different operating frequencies to be obtained by opening or closing conductive bridges across the slot. Other types of switches such as a PIN diode switch, FET, NEMS, varactor diodes, among others can be used for this purpose.

#Each slot has a port to which a signal is applied to excite the slot which causes the respective slot to act as a radiating element of the antenna.

#A patterned slot is formed in the conducting layer of the PCB between the pair of slot antennas to provide isolation between the radiators, thereby minimizing electromagnetic propagation from one antenna element to the other antenna element. This is specifically achieved by isolating the currents from the antennas that are induced on the ground plane. The isolation element pattern may be symmetrical with respect to a center line between the two antenna elements, or may be non-symmetrical. The isolating slot of a preferred embodiment has a meandering pattern. In some embodiments, the meandering shape is a serpentine slot that winds alternately toward and away from each antenna. In some embodiments, the electrical length of the isolation element slot is about quarter of the wavelength of the operating frequency.