Abstract:
A wireless area network communication system comprising at least one phased array antenna frame, a phased array antenna circuit connected to the at least one phased array antenna frame wherein said phased array circuit and said at least one phased array antenna frame are adapted to transmit and receive wireless area network compliant signals from or to wireless area network devices.

Description:
RELATED APPLICATIONS 
     Patent applications serial number PCT/IL2006/001144 filed on Oct. 3, 2006 and titled PHASE SHIFTED OSCILLATOR AND ANTENNA and PCT/IL2006/001039 filed on Sep. 6, 2006 and titled APPARATUS AND METHODS FOR RADAR IMAGING BASED ON INJECTED PUSH PUSH OSCILLATORS the disclosures of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates generally to the field of broadband access and more particularly to a method and system using a phase array antennas in Wireless Communication Networks. 
     BACKGROUND OF THE INVENTION 
     As the amount of home and office wireless accessories is rapidly increasing, there is an increasing demand for broadband wireless access solutions. 
     As an example, a standard that has been defined to regulate this communication domain is the IEEE 802.15 which is divided to five sub groups 802.15.1-802.15.5. Among these standards, 802.15.3 which deals with High Rate WPAN (Wireless Personal Area Network) is very important for mainly indoor wireless communication. 
     The IEEE 802.15.3 Task Group 3c (TG3c) was formed in March 2005. TG3c is developing a millimeter-wave-based alternative physical layer (PHY) for the existing 802.15.3 Wireless Personal Area Network (WPAN) Standard 802.15.3-2003. 
     This mm-Wave WPAN will operate in the new and clear band including 57-64 GHz unlicensed band defined by FCC 47 CFR 15.255. The millimeter-wave WPAN will allow high coexistence (close physical spacing) with all other microwave systems in the 802.15 family of WPANs. 
     In addition, the millimeter-wave WPAN will allow very high data rate over 1 Gbit/s applications such as high speed internet access, streaming content download (video on demand, HDTV, home theater, etc.), real time streaming and wireless data bus for cable replacement. Optional data rates in excess of 3 Gbit/s will be provided. 
     The need to implement communication system in this frequency range, with such broadband capabilities and at the same time to comply with a commercial requirement of low-cost imposes severe technical difficulties. 
     One of the candidates to implement this communication domain is MIMO (multiple input multiple output). However for several reasons, (as simulations calculations and mechanical considerations), MIMO is considered not suitable for the foregoing requirements. 
     There is a need for an innovative technology in order to provide a cost effective system that will be able to fulfill the requirements of high frequency, high bandwidth and low cost. The technical system performance recognized as indispensable for the mentioned achievements is the improvement of the antenna beam focus, together with the ability of wide beam steering of the antenna. 
     A possible solution is the use of phased arrays antenna system, which had recently shown significant improvements. 
     SUMMARY OF THE INVENTION 
     An aspect of an embodiment of the invention relates to a method and system for implementing a WPAN by phased array antenna devices. 
     In accordance with a preferred embodiment of the present system, there is provided a wireless area network communication system comprising at least one phased array antenna frame, a phased array antenna circuit connected to the at least one phased array antenna frame wherein the phased array circuit and said at least one phased array antenna frame are adapted to transmit and receive wireless area network compliant signals from or to wireless area network devices. 
     In some exemplary embodiments of the system the phased array antenna frame transmits or receives radiation. 
     In some exemplary embodiments of the system the phased array antenna circuit serves for driving and controlling said at least one phased array antenna frame. 
     In some exemplary embodiments of the system the wireless area network is a wireless personal area network. 
     In some exemplary embodiments of the system the phased array antenna frame comprises at least two groups of radiators wherein one of the groups of radiators is defined as a reference group. 
     In some exemplary embodiments of the system one of the groups of radiators is controlled by said phased array circuit to transmit or receive with a phase shift relative to said reference group. 
     In some exemplary embodiments of the system the phase shift is programmable or hard coded. 
     In some exemplary embodiment of the system phased array antenna frame comprises at least two substantially linear one dimensional arrays of radiators. 
     In some exemplary embodiment of the system the phased array antenna frame comprises an even number of substantially linear one-dimensional arrays of radiators, wherein each substantially linear one-dimensional array of radiators consists of two power of N radiators, where N is an integer greater than 1. 
     In some exemplary embodiment of the system the phased array antenna frame includes radiators that are substantially hexagonal in shape. 
     In some exemplary embodiment of the system the system is selectively switching between different radiation modes associated with each group of radiators. 
     In some exemplary embodiment of the system a radiation mode is defined according to the number of groups of radiators that transmit and receive in different phase shift and according to said programmable phase shift. 
     In some exemplary embodiment of the system the phased array circuit controls said phased array antenna frame to radiate in a horizontal beam aperture. 
     In some exemplary embodiment of the system the horizontal beam aperture width is substantially from 3 to substantially 15 degrees. 
     In some exemplary embodiment of the system the system is adapted to communicate with multiple wireless area network devices. 
     In some exemplary embodiment of the system the system is adapted to communicate with Personal Computers. 
     In some exemplary embodiment of the system the system is adapted to communicate with at least one TV device. 
     In some exemplary embodiment of the system the programmable phase shift is +/−180 degrees. 
     In some exemplary embodiment of the system the programmable phase shift is +/−180 degrees and the programmable phase shift is created by using transmission lines for inversing the signal phase. 
     In some exemplary embodiment of the system the wireless area network compliant signals are transmitted in the about 57 to about 64 GHz band. 
     In some exemplary embodiment of the system the system is selectively switching between two radiation modes. 
     In some exemplary embodiment of the system the system is selectively switching between two radiation modes and wherein the phased array antenna frame comprises two linear one-dimensional arrays of radiators. 
     In some exemplary embodiment of the system the system is selectively switching between different radiation modes according to the level of signals that are received in said different phase modes. 
     In some exemplary embodiment of the system the horizontal beam aperture is steered horizontally according to a programmable pattern. 
     In some exemplary embodiment of the system the transmitting and receiving wireless area network compliant signals from or to wireless area network devices is optionally performed through building walls. 
     In accordance with a preferred embodiment of the present method, there is provided a method for implementing a wireless communication comprising the steps of providing at least one phased array antenna frame and phased array antenna circuit connected to the at least one phased array antenna frame; and controlling said at least one phased array antenna frame by said phased array antenna circuit to transmit and receive wireless personal area network compliant signals from or to wireless area network devices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings. Identical structures, elements or parts, which appear in more than one figure, are generally labeled with a same or similar number in all the figures in which they appear, wherein: 
         FIG. 1A  is a top view illustration of a room with two fixed phased array antenna systems and two PCs with phased array antenna system according to an exemplary embodiment of the invention. 
         FIG. 1B  is a top view illustration of a room with one fixed phased array antenna system and several PCs with phased array antenna system according to an exemplary embodiment of the invention. 
         FIG. 1C  is a front view illustration of a room with two fixed phased array antenna frames and two PCs with phased array antenna system, in a first radiation mode, according to an exemplary embodiment of the invention. 
         FIG. 1D  is a front view illustration of a room with two fixed phased array antenna frames and two PCs and a TV with phased array antenna systems, in a second radiation mode, according to an exemplary embodiment of the invention. 
         FIG. 1E  is a top view illustration of signal distribution among the rooms on a same floor, according to an exemplary embodiment of the invention. 
         FIG. 2A  is a schematic illustration of a phased array antenna frame according to an exemplary embodiment of the invention; 
         FIG. 2B  is a schematic illustration of a phased array antenna frame that is composed of separate units for receiving and transmitting, according to an exemplary embodiment of the invention; 
         FIG. 3A  is a side view of the radiation pattern of a phased array antenna frame in a first mode of operation according to an exemplary embodiment of the invention; 
         FIG. 3B  is a top view of the radiation pattern of a phased array antenna frame in a first mode of operation according to an exemplary embodiment of the invention; 
         FIG. 3C  is a side view of the radiation pattern of a phased array antenna frame in a second mode of operation according to an exemplary embodiment of the invention; 
         FIG. 3D  is a top view of the radiation pattern of a phased array antenna frame in a second mode of operation according to an exemplary embodiment of the invention; 
         FIG. 4  is a schematic illustration of a circuit for implementing a phased array antenna circuit that supports a combination of two modes of operation according to an exemplary embodiment of the invention; 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Patent applications serial number PCT/IL2006/001144 filed on Oct. 3, 2006 and in PCT/IL2006/001039 filed on Sep. 6, 2006 the disclosures of which are incorporated herein by reference describe elements and circuit designs for providing low cost and light weight distributed T/R multi-module for active phased array antennas. 
     The applications describe circuits, which can be implemented as low cost and small sized circuits or manufactured as integrated chips to generate and control the signals transmitted and detected by phase array antennas. The current application implements the concepts described in the above applications to provide suitable phase array antennas for implementing the current invention as further described below. 
       FIG. 1A  shows a top view of a phased array antenna system deployment according to the invention  100 A.  FIG. 1  shows a living room  101  where two PCs  130 ,  140  are located at different sections of the room. Each PC is equipped with one phased array antenna system  117 ,  122  respectively. Each phased array antenna system includes a phased array antenna frame  115 ,  120  respectively, and a phased array antenna control and driving circuit  116  and  121  respectively (hereinafter “phased array antenna circuit”). 
     In an exemplary embodiment of the invention there are two fixed phased array antenna systems  107 ,  112 , located at different corners of the room. Each of the systems  107  and  112  also includes a phased array antenna frame  105 ,  110  respectively, and a phased array antenna circuit  106  and  111  respectively. 
     Each of the phased array antenna frames is transmitting and/or receiving data. The ellipses  150 ,  160 ,  155  and  165  are schematic representations of the radiation patterns of the phased array antenna frames  105 ,  115 ,  110  and  120  respectively. It should be noted that the ellipses are general illustrations intended to describe a general beam direction and a coarse representation of the beam width. However it does not intend to provide a quantitative representation of the beam pattern. This comment refers also to the ellipses shown in  FIGS. 1B   1 C  1 D and  3 . 
     In an exemplary embodiment of the invention a phased array antenna system  107  is steering its beam  150  horizontally (azimuth steering) until it reaches an optimal reception level from the phased array antenna system  117 . The same procedure also applies for the phased array antenna system  117  which performs a horizontal steering of its beam  160  until acquiring an optimal reception level from the phased array antenna system  107 . 
     The same procedure applies also to the phased array antenna systems  112  and  122 . 
     It should be noted that the narrow horizontal beam aperture and the low side lobes of a phased array antenna system according to the invention guarantee the ability to avoid the event of locking on side lobes. 
     Optionally, once an optimal level of signal reception is reached, the phased array antenna system memorizes the azimuth for enabling a quick initialization at later power-on events. 
     As can be noticed, using only two systems the entire area of a rectangular room can be covered. 
     In another exemplary embodiment of the invention a single phased array antenna system  107  as shown in  FIG. 1B  is communicating with Three phased array antenna systems  117 ,  122  and  172  the phased array antenna systems  117  and  122  are connected to a PC device  130  and  140  respectively and the phased array antenna system  172  is connected to a TV device  169 . 
     The ability of the systems to interact independently is obtained by beam steering of all the antennas as will be further described. In order to transmit and receive data from multiple phased array systems, the phased array system  107  performs an azimuthally steering and electronically rotates between three positions indicated by the ellipse  150  that points to the PC  130 , the ellipse  152  that points to the PC  140  and ellipse  153  that points to TV  169 . After the locking transient between the fixed system and the PC/TV/cell phone etc, the communication with the PC devices is typically bidirectional, while the communication with the TV may be unidirectional, where the TV phased array antenna system may only receive data. 
     It should be remembered that the antenna steering by a phased array antenna system is extremely fast, typical duration of switching from a first beam direction  150  to a second beam direction  152  or  153  is in the order of magnitude of micro seconds. 
     It will be appreciated by persons skilled in the art that a single phased array antenna system is able to communicate simultaneously with a multiple of WPAN devices on a time sharing base, where the limit on the number of devices is dictated by the bandwidth requirements of the devices and the bandwidth capability of the phased array antenna system. While  FIG. 1B  shows a phased array antenna system  107  communicating with three phased array antenna systems  117  and  122  it is possible that the phased array antenna system  107  will also communicate with any WPAN compliant device other than phased array antenna system. 
       FIG. 1C  shows the same room  101  from the front in order to describe the phased array antenna beam in the vertical plan.  FIG. 1C  shows the beam vertical cross section when operating in a first mode of radiating. In the first mode of radiating there is one main lobe of radiating e.g.  150 , 155 , 160  and  165 , the lobe has an aperture of around 30 degree in the vertical plan, which should provide good coverage when there is a clear line of sight between two communicating devices. However in a dynamic environment, when obstacles, e.g. a person moving across the room, may obscure the line of sight between communicating devices, another approach is required. 
       FIG. 1D  shows the same room  101  when a person  180  breaks the line of sight between the two phased array antenna systems  112  and  122 .  FIG. 1D  shows that when the system detects deterioration of signal level reception it switches to a second mode of radiation, where each of the single main lobes  165  and  155  splits to two main lobes, i.e.  155  splits into  155 A and  155 B, and  165  splits into  165 A and  165 B. The two main lobes that are radiated by the phased array antenna frame are intended to transmit and receive radiation by indirect path, namely to enable transmission and reception of electromagnetic echo from the environment, mainly from surrounding walls, e.g. the path indicated by the broken line marked with numeral  170 . 
       FIG. 1E  shows a signal distribution among nine rooms  193  on the same floor  100 E. In the input bound the signal is intercepted by an antenna  190  and received by a master phased array antenna  191 . The signal is transmitted and received by the set of phased array antennas  192   a - 192   r . As shown in  FIG. 1E  the signal is transmitted and received across room walls, for example when transmitted from the phased array antenna  192   b  to  192   e  while crossing the wall  194 . The relative low attenuation of high frequency radiation provides the ability to cross common room walls such as concrete, plywood, clay brick, glass and the like. For example, the attenuation of a 5.8 GHz signal caused by a typical concrete wall is about 7 dB. Thus, a single master and a set of phased array antennas can provide full wireless coverage for an entire door. The output bound is symmetric but on the opposite direction. 
     It should be noted that the phased array antennas  192   a - 192   r  are adapted to serve also as repeaters in order to compensate on the attenuation of the signal along its path, while the technique of signal distribution by a set of repeaters is known in the art its detailed description is omitted. 
       FIG. 2A  shows a radiating part of a distributed active phased array antenna (APAA) (referred to as “phased array antenna frame”)  200 A that includes two one-dimensional arrays of micro-strip radiators (referred to as “radiators”)  210 ,  215  located on a rectangular casing  205 , consisting on a dielectric substrate with the related base plate. The one-dimensional arrays of radiators consist of 8 radiators marked as A 1  to A 4 , B 1  to B 4 . Each radiator is shaped as a hexagonal patch, for example radiator A 1 ,  230 . Each radiator has a feeder (an I/O port that conveys the electromagnetic wave to and from the radiator)  235 ,  245  either at the upper vertex of the radiator (A 1  to A 4 ), or at the lower vertex of the radiator (e.g. B 1  to B 4 ). The hexagonal shape of the radiator has been shown by simulation to provide better results than a square radiator or a circular radiator, in terms of transmission gain and/or receiving gain and also by providing better isolation between adjacent radiators, for the same distance between them. 
     In an exemplary embodiment of the present invention, the positioning of the radiator&#39;s feeder forms a symmetric structure. In the first one-dimensional array of radiators the radiator&#39;s feeders are located at the upper vertex of the hexagonal patch, while at the second one-dimensional array of radiators the radiator&#39;s feeders are located at the lower vertex of the patch. It should be noted that this symmetric positioning of the radiator&#39;s feeder optionally contributes to improving the symmetry of the radiation pattern. 
     The antenna dimensions depend on the wave&#39;s frequency and the dielectric constant of the substrate. As an example, a WPAN radiator at 60 GHz, implemented on substrate with dielectric constant 6, has dimensions in the order of magnitude of about one millimeter. This compact embodiment enables the inclusion of the phased array antenna described in this invention in various hand-held devices such as palm-computers, Personal data Organizers (Blackberry), Cellular Phones, notebook computers, etc. 
     In an exemplary embodiment of the invention, to achieve wider coverage angle with still high power density for communicating with the device described in  FIG. 2A , different radiation patterns (referred to as “radiation modes”) arc generated with the same physical array of radiators. 
     Optionally, production of the multiple radiation modes by antenna  200  is defined by the relative phase shift to a signal among the two one-dimensional arrays of radiators  210 ,  215 . 
     In an exemplary embodiment of the present invention, a first radiation mode is defined by providing the requested phases to the two one-dimensional arrays of radiators  210  and  215 , in such a way that there is no phase difference between every element “A” of the first one-dimensional array and the correspondent element “B” of the second one-dimensional array. A second radiation mode is defined by providing the requested phases to the two one-dimensional arrays of radiators  210  and  215 , in such a way that there is phase difference of 180 degrees between every element “A” of the first one-dimensional array and the correspondent element “B” of the second one-dimensional array. 
     It should be noted that it is possible to both transmit and receive via the same radiators and it is sometimes more efficient architecture. However in an exemplary embodiment of the invention, the transmission and receiving is split between transmitting radiators and receiving radiators. Deployment of different radiators for transmission and receiving may be carried out in various topologies, such as separating the functions to two different phased array frames or alternatively define sub groups of the radiators in a phased array frame for transmission while the complementary sub group is used for receiving. 
     It should be noted that in order to create the two radiation modes as mentioned above and when using the phased array antenna control and driving circuit as will be further described, the phased array antenna frame should be positioned horizontally, as shown in  FIG. 2A . 
       FIG. 2B  shows a schematic view of a phased array antenna transceiver where transmission and receiving is conducted by two separate units according to an exemplary embodiment of the invention. As will be further described, separation of the receiving unit and the transmitting unit is expected to provide technical and economical advantages when the radiating frequency is relatively high. 
     The receiving and transmitting units have basically the same structure.  FIG. 2B  shows the transmitting unit on the left side with transmitting radiators A 1 T-A 4 T and B 1 T-B 4 T. The receiving radiators are shown on the right side of  FIG. 2B  marked A 1 R-A 4 R and B 1 R-B 4 R. The feeders of the transmitting unit are marked  261   a - 264   a  and  261   b - 264   b , and the feeders of the receiving unit are marked  265   a - 268   a  and  265   b - 268   b.    
       FIG. 2B  further shows a schematic view of the connection between silicon chips  270 - 279  that contain the electronic circuits that provide the antenna control (referred to as phased array circuit). 
     Micro strip lines  261   a - 268   a    261   b - 268   b  of defined length are the feed of the radiators, and lays on the upper surface of a dielectric substrate (not shown). The hexagonal patches are laying on the upper surface of a second substrate (not shown), overlapping the previous one, such that there will be an efficient electro magnetic transfer of energy from the feeds to the patches. 
     The difference between the transmitting and receiving units is not shown in  FIG. 2B . However in the transmitting unit, the feeders  261   a - 264   a  and  261   b - 264   b  serve for transferring the carrier generated and handled by the circuits  270 - 274  to the radiators A 1 T-A 4 T B 1 T-B 4 T, while in the receiving unit the signal, received through the radiators A 1 R-A 4 R, B 1 R-B 4 R, will be down converted to base band by the signal generated and handled by the circuits  275 - 279 . 
     The circuits defined as  270 - 274  and  265 - 279  in  FIG. 2B  are described in details in the applications referred to above. 
       FIG. 3A  shows a side cross sectional view of the radiation pattern that is created by the first radiation mode. The radiation pattern  310  has a vertical aperture of about 30 degree  312 , which is wide enough to cover static devices that may reside in a typical room either at home or in an office at the height of a standard table. The beam is intended not to be steered in elevation, so that the section of  FIG. 3A  is intended to be standing. 
       FIG. 3B  shows a top cross sectional view of the radiation pattern  320  that is created by the first radiation mode. The radiation pattern has a horizontal aperture of about 5 degree  325 . It should be noted that a narrow horizontal beam aperture enables to concentrate the power in a narrow angle, with low side lobes level. The beam is intended to be steered in azimuth, so that the section of  FIG. 3B  is intended to sweep a wide azimuth angle. 
       FIG. 3C  shows a side cross sectional view of the radiation pattern that is created by the second radiation mode. The radiation pattern has two main lobes  330 A and  330 B. In an exemplary embodiment of the invention the second mode of radiation radiates the same amount of power of the first mode, but the gain of each lobe is half the gain of the first mode. However this mode results with wide spread distribution of the radiated data (as well as wide angles for reception of data), to enable indirect communication. The two main lobes created at the second mode of radiation are targeted to both the floor and the ceiling, and part of the radiation is reflected from the ceiling and floor (as well as from other objects in the room) reaches the target antenna. 
     The beam is intended not to be steered in elevation, so that the section of  FIG. 3C  is intended to be standing. 
       FIG. 3D  shows a top cross sectional view of the radiation pattern that is created by the second radiation mode. However in the horizontal plan, the radiation patterns of the first and second mode of radiation have the same aperture, and therefore  FIG. 3D  shows the same geometrical shape. 
     The beam is intended to be steered in azimuth, so that the section of  FIG. 3D  is intended to sweep a wide azimuth angle. 
     With reference to  FIG. 2A : 
     The first mode of radiation, ( FIGS. 3A &amp; 3B ), is generated when the signals at the radiators A 1 -A 4  ( FIG. 2A ) and corresponding B 1 -B 4  ( FIG. 2A ) have phase difference of 0 degrees. 
     The second mode of radiation, ( FIGS. 3C &amp; 3D ), is generated when the signals at the radiators A 1 -A 4  ( FIG. 2A ) and corresponding B 1 -B 4  ( FIG. 2A ) have phase difference of 180 degrees. 
       FIG. 4  is an exemplary illustration of the base of a circuit for providing the carrier signals to an array of radiators, according to an exemplary embodiment of the invention. 
     While at relatively low frequencies it is commercially more effective to use the same antenna for both receiving (R/X) unit and transmitting (T/X) unit, at the higher frequencies like the 60 GHz the circuitry connected to this function involve semiconductor real estate not compatible with the small size of the array of radiators, so that it will be preferable to separate the T/X and R/X functions in two different subsystems. As will be further described, the differences between the physical structure of the transmitting unit and a receiving unit are minor, as long as the only different functions are the UP-converter for the T/X  491   i - 491   p , and the DOWN-converter for the R/X.  491   a - 491   h . They are basically the same circuit, but used in different ways. The UP-converter is located at the input of the T/X power amplifier, while the DOWN-converter is located at the output of the R/X low noise amplifier. 
     The circuit uses an oscillator unit  405  whose output is provided to two splitting units  409 ,  410 . The power divider  409  provides the reference signal to the R/X unit while the power divider  410  provides the reference signal to the T/X unit. The following description will mainly refer to the R/X unit-expanding the description to the T/X unit only where there are substantial differences. The signals then arrive to a first level of PSIPPO (phase shift push-push oscillator)  420 - 421 . Persons skilled in the art will readily appreciate that the phase shift that is determined at this level of PSIPPO serves to steer the beam. 
     The signal then passes through another level of splitting elements  430 - 431  (power splitters) and proceeds to a second level of PSIPPO  435   a - 435   d . Persons skilled in the art will readily appreciate that the phase shift that is determined at this level of PSIPPO contributes in steering the beam. Applying a zero degree phase shift at the first  420 ,  421 , and second level  435   a - 435   d  of PSIPPO results in a substantially vertical beam, where its symmetry axis is perpendicular to the antenna surface. 
     At the next stage the signals are delivered to four power splitters  440 - 443  and then proceed to the multi-function blocks  450 - 453 . As long as the mentioned blocks have the same structure, only one phase shift unit  450  is described. 
     The block  450  consists of two branches, each one connected to radiators  495   a  &amp;  495   b . With reference to  FIG. 2A , the mentioned radiators are A 1  &amp; B 1 . The branch  484   a  delivers the carrier signal to the connected mixer with a certain phase. The second branch,  480   a - 482   a , delivers the same signal to the connected mixer with a phase equal to branch  484   a , or shifted by 180 degrees, depending on the position of the switches  480   a  &amp;  482   a . This way the array of radiators will be able to generate the two radiation modes described above. Optionally the transmission line  481   a  applies a phase shift that is greater or smaller than 180 degrees. The down converter mixers  491   a ,  491   b  get signals that were received in the antenna patch  495   a ,  495   b  respectively and were amplified by the low noise amplifiers  492   a ,  492   b  respectively and produce the incoming signal  490   a ,  490   b  respectively. 
     The T/X path differs from the R/X path by that the mixers are up converter mixers  491   i - 491   p  that receive the data signals  490   i - 490   p  and produce an outgoing signal that goes to the antenna patches  495   i - 495   p  after being amplified by the amplifiers  495   i - 495   p.    
     The phase difference between the two branches can be accomplished, in principle, by inserting an additional level of PSIPPO before each mixer. Though, this solution will involve a higher number of components. 
     It should be noted that the delay elements  481   a - 481   h  are simple and low cost transmission lines, as are the electronic switches  480   a - 480   h    482   a - 482   h . The usage of electronic switches and delay elements reduces both cost and size, compared to the solution with an additional level of PSIPPO. 
     In another exemplary embodiment the path from the splitter  440  to the down converter mixer  490   a  (and all the equivalent paths) also includes an optional phase shift path, enabling the circuit to be programmed for more phase shift combinations. 
     In some embodiments of the invention, the WPAN phased array antenna system will switch between more than two radiation modes, using an equal or different number of linear arrays of radiators. 
     In some embodiments of the invention, the WPAN phased array antenna system may provide a phase shift that is greater or smaller than 180 degrees to the one-dimensional arrays of radiators. 
     In some embodiments of the invention, the WPAN phased array antenna system may include more or less than two one linear arrays of radiators. 
     In some embodiments of the invention, the WPAN phased array antenna system may include various combinations of radiators other than linear arrays of radiators, where any sub-group of the radiators will be associated with a programmable phase shift with reference to any reference sub-group. 
     In some embodiments of the invention, the WPAN phased array antenna system may include radiation modes where the azimuth angle beam is narrower or wider than the one that was described in the foregoing description. 
     In some embodiments of the invention, the WPAN phased array antenna system may include radiation modes where the vertical beam aperture is narrower or wider than the one that was described in the foregoing description, and where the vertical beam distribution is different from the forms that were described in the foregoing description. 
     In some embodiments of the invention, the WPAN phased array antenna system may perform a periodical horizontal antenna steering to search for transmitting devices that should be communicated by the system. 
     While operating the WPAN phased array antenna system according to an exemplary embodiment of the invention, the system switches among the two radiation modes. The switching may be a periodic switching pattern or any desired pattern. In an exemplary embodiment of the invention, the system is able to alter the switching pattern to accommodate dynamic situations, for example when receiving or transmitting sources join or leave the area that is covered by the system, or when different needs and priorities are required. Optionally, alteration of the switching pattern provides priority in coverage of one area over another, for example to increase the bandwidth to a specific client device. 
     The use of radiation modes where the phase shift between the one-dimensional arrays of radiators is either zero degrees or 180° enables to simplify the electronic circuits that support the transmission and receiving in the WPAN compliant phased array system as shown in  FIG. 4 . 
     It should be appreciated that the above described methods and systems may be varied in many ways, including omitting or adding steps, changing the order of steps and the type of devices used. It should be appreciated that different features may be combined in different ways. In particular, not all the features shown above in a particular embodiment are necessary in every embodiment of the invention. Further combinations of the above features are also considered to be within the scope of some embodiments of the invention. 
     It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather the scope of the present invention is defined only by the claims, which follow.