Patent Description:
Disclosed aspects are directed to communication systems. More specifically, exemplary aspects are directed to extending the range of wireless systems efficiently.

Antenna systems are commonly thought of as fixed hardware components of a communication system. Advantages can, however, be gained by viewing the antenna system as a cooperating component of the overall communications chain. Industry factors such as miniaturization of components, the desire to conserve power in portable systems, the desire to maximize communication range, the push to higher carrier frequencies, and particularly the availability of increasing processor power make it worthwhile to examine methods to improve antenna system performance. Attention is drawn to <CIT>, describing an antenna system capable of optimizing communication link quality with one or multiple transceivers while suppressing one or multiple interference sources. The antenna is designed to form nulls in the radiation pattern to reduce interference from unwanted interferers. The antenna system operates in both line of sight and high multi-path environments by adjusting the radiation pattern and sampling the received signal strength to reduce signal levels from interferers while monitoring and optimizing receive signal strength from desired sources. Further attention is drawn to <CIT>, describing an active antenna system and algorithm that provides LTE communication systems operating in Category <NUM> mode, using one antenna. For the LTE SISO case (category <NUM>), a modal antenna capable of generating multiple radiation patterns provides improved resistance to fading. Modal (Null Steering) antenna technology is implemented in a multi-antenna system to provide for single and multiple antenna operation wherein one or more antennas have two or more radiation modes. An algorithm is provided that determines when to switch from SISO to MIMO operation. Further attention is drawn to <CIT>, describing a smart antenna including a ground plane, an active antenna element adjacent the ground plane and having a radio frequency input associated therewith, and passive antenna elements adjacent the ground plane. Impedance elements are connected to the ground plane and are selectively connectable to the passive antenna elements for antenna beam steering. Tuning elements are adjacent the passive antenna elements for tuning thereof so that an input impedance of the RF input of the active antenna element remains relatively constant during the antenna beam steering.

The accompanying drawings are presented to aid in the description of aspects of the invention and are provided solely for illustration of the aspects and not limitation thereof.

Aspects of the teachings herein are disclosed in the following description and related drawings directed to specific aspects of this disclosure. Alternate aspects may be devised without departing from the scope of the teachings herein. Additionally, well-known elements of the system disclosed will not be described in detail or will be omitted so as not to obscure the relevant details of the disclosure.

The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. It will be further understood that the terms "comprises" "comprising," "includes," and/or "including," when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Additionally, these sequence of actions described herein can be considered to be embodied entirely within any form of computer-readable storage medium having stored therein a corresponding set of computer instructions that upon execution would cause an associated processor to perform the functionality described herein. Thus, the various aspects of the invention may be embodied in a number of different forms, all of which have been contemplated to be within the scope of the claimed subject matter.

<FIG> is an illustration of a single antenna system <NUM> radiating a signal <NUM>. The concentric dotted circles <NUM> that surround antenna <NUM> represent peaks of a transmitted waveform. A single antenna <NUM> will generally transmit waveforms as seen in <FIG>.

<FIG> is an illustration of a two antenna system <NUM> radiating signals. For purposes of illustration both antennas <NUM> and <NUM> are radiating signals of the same frequency. When two or more antennas are radiating signals of the same frequency, they interfere with each other. For the purposes of this disclosure there are two types of interference with respect to radiating signals. The first type of interference is called destructive interference. Destructive interference occurs when a maximum of one signal is at the same point in space and time as the minimum of a second signal. Assuming that signals are of equal strength, the maximum of one signal will cancel out the minimum of the second signal, resulting in no signal. Constructive interference occurs when a maximum of one signal is at the same point in space and time as the maximum of a second signal. Assuming that the signals are equal strength, resulting signals will have double the amplitude of either signal. A maximum wave front <NUM> from an antenna <NUM>, and a maximum wave front <NUM> from antenna <NUM>, will constructively interfere with each other producing a maximum at points 215a and 215b. Points 215a and 215b are at a midpoint <NUM> between antennas <NUM> and <NUM>. In the example illustrated in <FIG>, the midpoint <NUM> is equally distance between antennas <NUM> and <NUM> because antennas <NUM> and <NUM> are radiating signals of the same phase in this example.

Because of this constructive interference, the strongest signal from antennas <NUM> and <NUM> will lie in zone <NUM>, which for the purposes of this disclosure shall be referenced as the constructive interference zone or beam. In the constructive interference zone <NUM> the combined signal from antennas <NUM> and <NUM> will be stronger than at any other place equally distance from either antenna <NUM>, <NUM>. Because signal is strongest in the constructive interference zone <NUM> if a point is in the constructive interference zone, such as point <NUM> is, it will receive essentially the strongest signal that is the product of constructive interference. For the purposes of this disclosure, we will assume that any points in a constructive interference zone, as drawn, will receive adequate signal to be properly decoded by a receiver such as point <NUM>, which is in the constructive interference zone <NUM>. Accordingly a signal received by a receiver in the constructive interference zone <NUM> can receive that signal with less overall system transmission power from antennas <NUM> and <NUM> than if it were out of that zone. It is therefore desirable from a signal strength standpoint and a transmitted power standpoint that any receiver be in the constructive interference zone <NUM>. The constructive interference zone <NUM> is sometimes referred to as a beam, because it is along that line, or beam, that the highest signal strength signal will be found. It is obviously advantageous to have a receiver in the beam of the transmitter to try to maximize a received signal. It is further advantageous for the transmitter to be able to steer the beam towards a target in order to increase the received signal power by the target.

<FIG> is an illustration of a two antenna system <NUM> radiating signals one of which is phase delayed. In <FIG>, a signal to be transmitted <NUM> is coupled to a two antenna system <NUM>. The signal to be transmitted <NUM> is coupled into power amplifier <NUM> and subsequently into antenna <NUM>. The signal <NUM> is also coupled into a phase shifter <NUM> and then further coupled into power amplifier <NUM> and then further coupled into antenna <NUM>. For the sake of simplicity, we shall assume that both antennas <NUM> and <NUM> receive signals of the same magnitude. When the phase shifter <NUM> is at <NUM>° the midline of the constructive interference zone (or beam) of the two antennas <NUM> and <NUM> is as illustrated at 317a. When a phase delay is introduced by the phase shifter <NUM>, antenna <NUM> will receive a signal that is phase delayed from the signal <NUM> received by antenna <NUM>. As a consequence of the phase delay, the midline of the beam shifts as shown in 317b. By shifting the phase delay, the center line of the beam can be shifted as shown in 317b, and pointed in a different direction. This allows the beam to be directed or pointed at a receiver or other desired point. This process is commonly known as beam steering.

<FIG> is an illustration of a four antenna system <NUM> such as may be used for <NUM>-dimensional beam steering. In <FIG>, antennas <NUM>, <NUM>, <NUM> and <NUM> are driven by power amplifiers <NUM>, <NUM>, <NUM>, and <NUM>, respectively. Each of the power amplifiers <NUM>, <NUM>, <NUM>, and <NUM> contain phase shifters, which are not explicitly illustrated. A signal to be broadcast <NUM> is coupled into power amplifiers <NUM>, <NUM>, <NUM>, and <NUM>. Zones of constructive interference <NUM> and <NUM> result. By changing phase delay of the power amplifiers <NUM>, <NUM>, <NUM>, and <NUM>, the zones of constructive interference <NUM> and <NUM> can be adjusted, and hence can be steered in two dimensions.

<FIG> is an illustration of a four antenna system <NUM>, having two driven antennas <NUM> and <NUM> and two parasitic antennas <NUM> and <NUM>, such as may be used for <NUM>-dimensional beam steering. <FIG> also illustrates that not all antennas need be actively driven. Driven antennas <NUM> and <NUM> are driven by power amplifiers <NUM> and <NUM> respectively. Parasitic antennas <NUM> and <NUM> may be essentially eliminated from the antenna configuration if switches <NUM> and <NUM> are open. However if switches <NUM> and <NUM> are closed then parasitic antennas <NUM> and <NUM> are coupled through tuning networks <NUM> and <NUM> to ground. Once switches <NUM> and <NUM> are closed, driven antennas <NUM> and <NUM> may cause a resonance in parasitic antennas <NUM> and <NUM>. The frequency of this resonance will be the same as frequency of driven antennas <NUM> and <NUM>, which are driven by the same signal <NUM>. However the phases of the resonances of parasitic antenna <NUM> and <NUM> can be adjusted by tuning networks <NUM> and <NUM>. Tuning networks <NUM> and <NUM> may be adjusted by using varying inductances and capacitances. Those variables may be adjusted electronically using components that react to electrical signals, such as switching capacitances and/or inductances in and out of the circuity within tuning networks <NUM> and <NUM>, or using electrically adjustable components such as varactor diodes. Once switches <NUM> and <NUM> are closed, parasitic antennas <NUM> and <NUM> will start to resonate at the frequency of signal <NUM>. Because parasitic antennas <NUM> and <NUM> resonate, they will reradiate energy with the phase shift introduced by tuning networks <NUM> and <NUM>. This will essentially make the antenna system of <FIG> a two dimensional beam steering system as in <FIG>. A common term for unpowered antennas that resonate with power antennas, then reradiate a portion of that resonance energy at a phase delay determined by a tuning network coupled to the unpowered antennas is "reactive directed array. " The power is reactive because it is a reaction to powered antennas, and the power re-radiated is directed by the tuning network coupled to each of the antennas.

In <FIG>, the antennas <NUM><NUM><NUM> and <NUM> may be driven with any amount of power that the power amplifiers, <NUM>, <NUM>, <NUM> and <NUM> can deliver. For example, in <FIG>, antennas <NUM> and <NUM> can create constructive interference represented by <NUM>, similarly antennas <NUM> and <NUM> can create constructive interference represented by <NUM>. By using the antennas in a quadrature arrangement beam steering in <NUM>-dimensions can be achieved. Of course many more reactive, or even powered, antennas may be used in order to further refine the beam steering capabilities, range capabilities or for other reasons.

Range extenders commonly rely on adding a beam steering front end that directs the beam for improved channel SNR (Signal to Noise Ratio). Additionally having multiple power amplifiers can provide signal, thereby extending the range beyond that that can be achieved by a single power amplifier and omnidirectional antenna. However, the additional hardware cost to support multiple RF paths, phase shifters and Power Amplifiers to feed antennas is usually high. Implementation of phase and amplitude control in the RF path is challenging and often implemented with analog phase shifters or complex digital phase shifters, which require high speed, high throughput and high power consumption, at least in a portable device which has limited battery power. Accordingly antenna tuning with reactive elements can be used to take advantage of being able to beam steer with a single powered antenna using reactively coupled directed antenna(s) to create a beam. If the antenna system has more than one antenna a second antenna may be a powered or reactive antenna or switchable. When a Power Amplifier is not feeding an antenna these antennas can be reactive loads and, appropriately loaded may be used for beam forming purposes even though not actively powered. Reactive directive arrays is a known method that uses reactive tuning elements and resonant antennas to provide beam steering and directivity. Using such arrays beam forming can be accomplished using one active PA; along with reactively loaded (parasitic) antennas particularly if the reactive tuning of the resonant antennas is variable. Depending on how the system is used in terms of directivity we would like to be able to configure our antennas and PA accordingly and achieve an acceptable communications link using less power. These and other aspects of the concepts herein will be discussed with respect to the following figures.

In <FIG>, parasitic antennas <NUM> and <NUM> can be designed to resonate at the same frequency that driven antennas <NUM> and <NUM> broadcast. Additionally parasitic antennas <NUM> and <NUM> can adjust the phase that they resonate at with respect to the phase of signals from driven antennas <NUM> and <NUM> using tuning networks <NUM> and <NUM> when they are activated using switches <NUM> and <NUM> respectively. Since antennas are not actively driven by power amplifiers the amount of power that parasitic antennas <NUM> and <NUM> can re-radiate is limited by the amount of power they receive from driven antennas <NUM> and <NUM>. The re-radiated power from antennas <NUM> and 505however will still affect the beamforming function of the antenna system. By adjusting tuning networks <NUM> and <NUM> the direction of the radiated beam (the "radiated beam" or "beam" is a spatial locality where constructive interference increases the signal significantly).

In <FIG>, <NUM> represents the zone of constructive interference from driven antennas <NUM> and <NUM>. In <FIG>, <NUM> represents the zone of constructive interference from parasitic antennas <NUM> and <NUM>. The space where the zones of constructive interference <NUM> and <NUM> constructively interfere with each other, as represented by <NUM> and <NUM> are the locations where the beam is at its strongest.

<FIG> is an exemplary system, A practically infinite variation of antenna system arrangements and configurations are possible. For example in the four antenna system <NUM> both driven antennas <NUM> and <NUM> were powered antennas driven by power amplifiers <NUM> and <NUM>. That need not be the case. For example driven antenna <NUM> could have also been a passive antenna similar to parasitic antennas <NUM> or <NUM>. Additionally the system discussed above might have parasitic antenna <NUM> as a powered antenna. For ultimate flexibility all antennas could be switchable between powered and parasitic modes, but obviously a minimum of one must be powered.

Additionally more parasitic antennas <NUM> and <NUM> can be added to capture and reradiate the energy provided by the powered antennas. In the drawings herein the drawings depict antennas which are numbered. Instead of each antenna depicted being a single antenna each depiction may represent a group of antennas. For example there is parasitic antenna <NUM> might a group of parasitic antennas instead of only one. Some individual designs may gain advantages from an array of parasitic antennas some other designs may require only one parasitic antenna. From a practical standpoint one reason parasitic antennas may be added instead of simply adding more driven antennas is that, generally speaking adding driven antennas adds to power consumption and system complexity.

<FIG> is an illustration of a five antenna system <NUM> which will be used, concurrently with <FIG>, <FIG>, <FIG> and <FIG> to explain some of the aspects of the present disclosure.

<FIG> is a graphical representation <NUM> of areas of constructive interference, as may be produced by different illustrative configurations of the antenna system of <FIG> to explain some aspects of the present disclosure. They are not intended to be scale, but rather to impart a relative comparative understanding of the different antenna configurations that may be created according to aspects of the present disclosure.

In <FIG> a five antenna system <NUM> is depicted. The arrangement illustrated in <FIG> will be used for purposes of illustration and description, a virtually infinite number of configurations are possible, limited only by practical considerations.

The five antenna system <NUM> of <FIG> can be used in a variety of configurations, for example, to accomplish range extension using beam steering of signal <NUM>.

Assume that <FIG> represents patterns of maxima of signal strength of the five antenna system <NUM> of <FIG> in several configurations. Further assume that any points outside of the gray area are points where the five antenna system <NUM> cannot reach its intended receiver with an acceptable signal. The patterns of maxima are different sizes and shapes to illustrate different aspects of the teachings herein, however they are conceptualizations are not intended to represent actual signal strength charts.

The five antenna system <NUM> of <FIG> will be used to illustrate an antenna system having four separate antenna configurations. In a first configuration, only antenna <NUM> is driven and no other antenna is active. Since only one antenna is active no beam forming can take place and the points where an acceptable signal can be found form a circular pattern <NUM> and an acceptable signal can be found in the interior (gray area) of pattern <NUM>.

Assume that the antenna system cannot achieve an acceptable connection with its intended receiver in the first antenna configuration; a second configuration can be tried. In the second configuration, antennas <NUM>, <NUM> and <NUM> are used. Antenna controller <NUM> may control a variety of devices. For example the antenna controller <NUM> may control the gain and phase delay in power amplifiers, such as <NUM> and <NUM>, and switches <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. In the second configuration, switch <NUM> is closed by the antenna controller <NUM> using Control Bus <NUM>. The antenna controller <NUM> may also select from several tuning parameters in tuning element <NUM>. Tuning element <NUM> may have variable tuning elements which can be selected by the antenna controller <NUM>. In the second configuration, switch <NUM> is closed by the antenna controller <NUM> using control bus <NUM>. The antenna controller <NUM> may also select from several tuning parameters present in tuning elements <NUM>, <NUM> and <NUM>.

In the second configuration, there is still only one antenna, <NUM>, coupled to an active power amplifier <NUM>. However parasitic antennas <NUM> and <NUM> can serve as reactively directed antennas once they are coupled to the tuning elements <NUM> and <NUM>. In such a case the zone where an acceptable communication link can be established is represented as the grey area inside <NUM> in <FIG>. Generally shape <NUM> is narrower, illustrating that some of the energy transmitted along the width has been absorbed by parasitic antennas <NUM> and <NUM> hence the narrowing of the pattern. The pattern of shape <NUM> however is longer in width as the parasitic antennas <NUM> and <NUM> have been tuned to augment the width of the pattern in order to extend the range of the antenna system. If the second configuration cannot establish an acceptable communications link a third configuration may be tried. In the third configuration, antenna <NUM> and antenna <NUM> are driven by power amplifiers <NUM> and <NUM> respectively. No other antennas are used in this exemplary mode. In this third configuration, antennas <NUM> and <NUM> are both powered so the range of acceptable performance in increased and is represented in <FIG> as <NUM>. Having two powered antennas can extend the range considerably, however having two powered amplifiers can consume a considerable amount of energy. If the third configuration is unable provide an acceptable communication link a fourth configuration may be tried.

In the fourth configuration, both power amplifiers <NUM> and <NUM> are on. Additionally switches <NUM>, <NUM>, and <NUM> couple tuning elements <NUM>, <NUM>, and <NUM> to antennas <NUM>, <NUM>, and <NUM> respectively. In this fourth configuration, antennas <NUM>, <NUM> and <NUM> are tuned for beam forming. Consequentially pattern <NUM> in <FIG> can represent this fourth antenna configuration. The three parasitic antennas <NUM>, <NUM>, and <NUM> absorb some of the power provided by the powered by powered antennas <NUM> and <NUM>, narrowing the height of pattern <NUM> with as the parasitic antennas absorb some of the energy. A portion of the power absorbed by the parasitic <NUM>, <NUM>, and <NUM> re-radiated. The three parasitic antennas <NUM>, <NUM>, and <NUM>, as phase adjusted by tuning elements <NUM>, <NUM>, and <NUM> respectively, and as such can contribute to beam forming thereby lengthening the width of pattern <NUM> with respect to the other patterns of <FIG>.

Antenna <NUM> is used in an unusual configuration <NUM> in that it is configured such that it may be used in <NUM> different modes. In the first mode antenna <NUM> is powered by power amplifier <NUM> by closing switch <NUM>, and opening switch <NUM>. In the second mode both switches <NUM> and <NUM> are open, and antenna <NUM> is essentially invisible to the overall system. In a third mode switch <NUM> is open and switch <NUM> is closed thereby coupling antenna <NUM> to a tuning element <NUM>. In a third mode the antenna <NUM> can resonate with the powered antenna(s), and re-radiate a portion of that energy phase shifted by an amount determined by tuning element <NUM>.

<FIG> is an illustration of an example communication system <NUM> that may advantageously use various aspects of the teachings herein. In the communication system <NUM> a broadcast tower is represented at <NUM>. Broadcast tower <NUM> is communicating with mobile unit <NUM>. <NUM> represents the antenna system of mobile unit <NUM>. Although antenna system <NUM> only shows a single antenna it is representative of an antenna system. The antenna system may have several powered antennas. Further the powered antennas may be driven by power amplifiers that allow a phase delay to be inserted. Because phase delays can be inserted between powered antennas the antennas can be actively directed, that is can perform beam steering. Additionally parasite antennas may also be present. The parasitic antenna can be coupled into the antenna system by applying a tuning termination, such as <NUM> or <NUM>. The parasitic antenna can be tuned to resonate at the same frequency as the powered antenna. Additionally, by using termination such as <NUM> or <NUM> a phase delay can be inserted into the resonance of the parasitic antenna. The resonance will then re-radiate some of its resonance energy at a phase angle (with respect to the powered antenna) which will in turn allow the beam formed by the re-radiation of resonance energy to be directed just as a beam from a powered pair of antenna might. The antenna system then comprises two components. A first actively directed array, formed by the driven antennas and phase delays inserted, and a second reactively directed array formed by the parasitic antennas and tuning elements, which allow the reradiated beam from the parasitic antenna to be steered.

The angle of communication <NUM> represents the angle between the antenna systems of the mobile unit <NUM> and broadcast tower <NUM>. In certain implementations a communication system tower may provide an attributes message <NUM>. A number of pieces of information may be included in the attributes message. An attributes message can be useful in deciding whether a communications link is satisfactory. It may contain variables such as received power, signal to noise ratio, quality of service, angle of reception i.e. <NUM>, transmitted power, GPS location of the broadcast tower <NUM>, and a number of other various attributes describing how the broadcast tower <NUM> is receiving the signal from mobile unit <NUM> as well as providing information about the broadcast tower <NUM>, such as location transmitted power, etc..

The attributes can be used, in one aspect, to decide if an acceptable communications link can be established. For example the acceptability of a communication link <NUM> in the present example illustrated in <FIG> and described with support from <FIG> and <FIG> and others. In <FIG> the broadcast tower <NUM> provides an attributes message to the mobile unit <NUM>. The attributes message <NUM> will contain information about a transmission from the mobile unit <NUM> as well as data concerning broadcast tower <NUM>. The mobile unit <NUM> can then use information from the attributes message to help the mobile unit <NUM> establish an extended range which is economical in terms of battery power use. The attributes message from the broadcast tower <NUM> may contain: received power, signal to noise ratio of received power, QOS (Quality Of Service), received angle of transmission, location of the broadcast tower, location of nearby broadcast tower and a host of other information. The mobile unit <NUM> can use the information or a subset of the information provided in the Attributes Message <NUM> to decide if the communications link <NUM> between the mobile unit <NUM> and the broadcast tower <NUM> is satisfactory or it should change antenna <NUM> configurations to attempt to achieve an acceptable communications link <NUM>. It should be noted that antenna <NUM>, although drawn as a single antenna, represents an antenna system and may actually contain a plurality of physical antennas. Conversely, the mobile sys unit tern <NUM> may also use the attributes message to attempt to establish an acceptable communications link <NUM> at reduced power cost, but for the sake of simplicity the emphasis will be on finding an economical (in terms of power consumption) communication link <NUM> that is satisfactory. What actually is a satisfactory communications link <NUM> will depend on the application, and a communications link that is satisfactory for one application may be completely inadequate for another and may be excessive for a third. A factor that is important in one application can be relatively unimportant in a second application and vice-versa. What actually constitutes an acceptable communication link <NUM> in any particular application is not within the scope of this application.

<FIG> is a first portion of a flowchart illustrating aspects of an exemplary system employing the teachings herein.

<FIG> is a second portion of a flowchart illustrating aspects of an exemplary system employing the teachings herein. <FIG> and <FIG>, taken together, illustrate an embodiment in which a mobile unit <NUM> is attempting communication with a broadcast tower <NUM> and is trying to establish a satisfactory communication link <NUM>. It may be useful to think of the example in <FIG> as a cell phone communicating with a cell tower, however in the description that follows no such assumption is made and the communication system in <FIG> can represent a variety of systems.

<FIG> and <FIG> are flow charts which describe an exemplary use of many of the teachings herein. Many variations and tweaks of the process described in <FIG> and <FIG> are possible so the described process should not be regarded as the only or even the best way of using the disclosed teachings herein, they are designed to be illustrative and not exclusive. The method of <FIG> and <FIG> is described illustratively with respect to <FIG>.

In block <NUM>, the exemplary process <NUM> of seeking an acceptable communications link <NUM> begins when broadcast tower <NUM> sends a message to establish communications with mobile unit <NUM>. Control then passes to block <NUM>.

In block <NUM>, mobile unit <NUM> turns on power amplifier <NUM> and communicates with broadcast tower <NUM> thus entering the first configuration. This is a minimal power setting, with only power amplifier <NUM> and antenna <NUM> active. The beam is symbolically represented by figure <NUM> as the power amplifier <NUM> has just been turned on and, in the present example in antenna configuration, no beam steering control has been implemented as only one antenna is active. At this point angle <NUM> is unknown since the broadcast tower has not received a transmission from mobile unit <NUM>. The mobile unit <NUM> then broadcasts equally in all directions using only antenna <NUM> to communicate with the broadcast tower <NUM>. The antenna system <NUM> of the mobile unit <NUM> is in antenna configuration <NUM> broadcasting with only a single powered antenna <NUM> and no parasitic antenna(s). Control then passes to block <NUM>.

In block <NUM>, broadcast tower <NUM> responds with an attributes message <NUM> indicating that the broadcast tower <NUM> has received the transmission from the mobile unit <NUM> and knows the antenna system of the mobile unit <NUM> has entered a new configuration. As previously discussed the attributes message <NUM> may contain a variety of information. In the present example the attributes message <NUM> may contain all the information that is necessary for mobile unit <NUM> to decide whether an acceptable communications link <NUM> has been attained. The mobile unit <NUM> may use a number of criteria to decide as to whether a satisfactory communications link <NUM> has been established. The criteria as to whether a satisfactory link has been attained can come from the attributes message, the general communications environment (such as received signal strength, signal to noise ratio of the signal received by the mobile unit or a combination of both. What constitutes a satisfactory communications link <NUM> is dependent on the use to which it will be put and may vary widely from one application to another. Once the broadcast tower <NUM> responds with attributes message <NUM> control passes to block <NUM>.

In block <NUM>, the attributes message is examined and a judgment as to whether the communications link <NUM> is acceptable is made. If the attributes are suitable to create an acceptable communications link <NUM> then in block <NUM> the process stops and the current configuration is used. If the communications link <NUM> is not acceptable then the antenna system <NUM> can attempt to reconfigure. In the present example control passes to block <NUM>.

In block <NUM>, the angle of arrival <NUM> is determined. This may be done by placing this information in the attributes message <NUM> that is sent from the broadcast tower <NUM> to mobile unit <NUM>. It may also be done within the mobile unit <NUM> by observing a time difference in arrival of a communication link <NUM> broadcast from the broadcast tower <NUM> by two separate receiving antennas within the antenna system <NUM> located within the mobile unit <NUM>. Additionally other methods of finding the angle of arrival <NUM> (also known as the angle of reception) are known and may be equivalently used. Once the angle of arrival <NUM> is determined in block <NUM> control may pass to block <NUM>.

In block <NUM>, the second antenna configuration <NUM> is entered. In the second configuration only one antenna <NUM> is powered and parasitic antennas <NUM> and <NUM> are coupled, via switches <NUM> and <NUM> to tuning elements <NUM> and <NUM> respectively. Tuning elements <NUM> and <NUM> are adjusted so the antenna system beam pattern is elongated via beam steering, illustrated conceptually at <NUM>, to point more power at the broadcast tower <NUM>. In this case parasitic antennas <NUM> and <NUM> form a reactive directed array, in which antennas <NUM> and <NUM> are coupled into the antenna system <NUM> by achieving a resonance (the reactive part) with antenna <NUM> and tuning elements <NUM> and <NUM> which are tuned (the directed part) to point the antenna system <NUM> beam towards broadcast tower <NUM>. Control is then transferred to block <NUM>.

In block <NUM>, the broadcast tower responds to the antenna configuration change with an updated attributes message <NUM>. Then control is transferred to block <NUM>.

In block <NUM>, portions of the attributes message are examined to help determine whether an acceptable communications link <NUM> has been established. If the communications link is acceptable control is transferred to block <NUM> and the communications link continues with the current configuration. If the communications link is not acceptable then control is transferred to block <NUM>.

In block <NUM>, other parasitic antennas may be added to the antenna system array if there are additional parasitic antennas that have not yet been added. For example antenna <NUM> can be added to the system at this point if it has not already been added. Accordingly if further parasitic antenna configurations may be added to the antenna system control is transferred to block <NUM>. If no more parasitic antennas are available to add to the antenna array control is transferred to block <NUM>.

In block <NUM>, antenna configuration <NUM> is entered. In the present example that means using power amplifiers <NUM> and <NUM> to drive antennas <NUM> and <NUM> respectively. That will increase the areas of effective communication of the communication system <NUM>, as graphically illustrated at <NUM> in <FIG>. Since there is now at least a second powered antenna, the signal to the second power amplifier <NUM> can be phase delayed and the antenna beam aimed at the broadcast tower using its last known position. In block <NUM> the mobile unit <NUM> then sends a message to the broadcast tower <NUM> indicating that antenna system <NUM> is in configuration <NUM>. Control then passes to block <NUM>.

In block <NUM>, a decision is made as to whether the communications link <NUM> is acceptable. If the communications link <NUM> is judged acceptable then block <NUM> is entered and the communication link <NUM> is judged as acceptable for use.

If in block <NUM> the mobile unit <NUM> decides that a satisfactory communications link <NUM> has not been established. If the current communications link <NUM> is not control is transferred to block <NUM> where the antenna system is changed to configuration <NUM> and a message indicating that the antenna system has changed configurations, and is now in configuration <NUM>, is sent to broadcast tower <NUM>. In configuration <NUM> all antennas <NUM>, <NUM>, <NUM>, <NUM> and <NUM> are used. Antennas <NUM> and <NUM> are powered, and the remaining parasitic antennas <NUM>, <NUM>, and <NUM> are tuned using tuning modules <NUM>, <NUM> and <NUM>. Pattern <NUM> in <FIG> represents configuration <NUM>. The pattern <NUM> of constructive interference is narrower; indicating some of the previous power used to power antennas <NUM> and <NUM> is being used to resonate the parasitic antennas <NUM>, <NUM>, and <NUM>. Additionally pattern <NUM> is wider because the zone of constructive interference is augmented by the tuned resonance of the added parasitic antennas which steers the beam towards the broadcast tower <NUM> target and adds constructive interference. Control is then transferred to <NUM>.

In block <NUM>, broadcast tower <NUM> responds with an attributes message <NUM> and control is then transferred to block <NUM>. In block <NUM> the communications link <NUM> is evaluated to see if satisfactory performance has been achieved. If satisfactory performance has been achieved then control is transferred to block <NUM> where the current satisfactory antenna configuration is used.

If block <NUM> does not find a satisfactory communications link <NUM> control passes to block <NUM>.

In block <NUM>, it is determined whether further parasitic configurations are available, that is are there further parasitic antenna that can be added to the system? If there are further parasitic antennas that can be added, control is transferred to block <NUM> to add more parasitic antennas to the antenna system. If, in block <NUM> there are no further parasitic elements to add to the antenna system <NUM> then control transfers to block <NUM> and the communication system has failed to establish a satisfactory communications link.

The illustrative process <NUM> has been simplified to enhance understanding. In process <NUM>, the antenna system <NUM> has f configurations and the process increments through successive configurations until a satisfactory communication link <NUM> is established or until the process <NUM> is unable to establish a satisfactory communications link. In an actual system each antenna configuration could have many sub configurations. For example in configuration <NUM> the setting of power amplifier is likely to have multiple power levels. In such a case it is likely that power amplifier <NUM> will be started at a low level and the power level increased to a maximum value prior to entering antenna configuration <NUM>. Similarly in antenna configuration <NUM> the number of parasitic antennas used as reactive directed array elements may be variable as well similarly to the variable amounts of power directed to antenna <NUM> by power amplifier <NUM>.

Configuration <NUM> is similar to configuration <NUM> except that two power amplifiers <NUM> and <NUM> are used the first time configuration <NUM> is entered. The power level of amplifiers <NUM> and <NUM> may both be varied.

Configuration <NUM> is similar to configuration <NUM> in that both the power of the amplifiers and the number of parasitic elements comprising a reactive directed array may be varied. If the system is in configuration <NUM> and all the powered antennas are receiving maximum power and all the parasitic antennas have been included in the antenna system and the antenna system still cannot establish a satisfactory communications link <NUM> then the system is not suitable for use in the present application.

Process <NUM> is illustrative of how the range of a communications link might be extended in steps so as to extend the range in a way economical to the power consumption of the mobile unit <NUM>. Power consumption is an important consideration in portable devices, but even in fixed devices power consumption should be a consideration.

Those of skill in the art will appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. Skilled artisans may implement the described functionality in varying ways for each particular application, but such choices are implementation decisions which should not be interpreted as causing a departure from the scope of the present disclosure.

The methods, sequences and/or algorithms described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two.

Additionally the "processor" can take a variety of forms from an elementary state machine to an internet connection having access to cloud computing resources. What form it takes commonly may depend on the environment and design and implementation requirements.

Claim 1:
A method (<NUM>) of controlling an antenna system configuration to provide a satisfactory communication link with a target, the method comprising:
turning on (<NUM>) a first powered antenna, thereby entering a first antenna system configuration;
determining (<NUM>) if the first antenna system configuration can provide the satisfactory communication link with the target; and
if the first antenna system configuration cannot provide the satisfactory communication link entering (<NUM>) a second antenna system configuration, wherein in addition to the first powered antenna at least one further antenna is used to form a portion of a directed array in order to steer an antenna system beam towards the target, the further antenna being selectably configurable into one of a powered mode in which the further antenna operates as a second powered antenna in the second antenna system configuration and a resonating mode in which the further antenna operates as a directionally tuned parasitic antenna in the second antenna system configuration, the further antenna also having an inactive mode in which the further antenna is disconnected from the antenna system in the first antenna system configuration.