Method and system for controlling modal antennas

Abstract

An antenna system is provided. In one example, the system includes a modal antenna having a driven element and a parasitic element. The system includes a radio frequency circuit. The system includes a transmission line coupling the radio frequency circuit to the modal antenna. The radio frequency circuit is configured to modulate a control signal onto an RF signal to generate a transmit signal for transmission to a tuning circuit through the transmission line. The control signal may include a frame having a plurality of bits associated with a selected antenna mode. The radio frequency circuit is configured to encode the plurality of bits associated with the selected mode according to a coding scheme. The coding scheme specifies a unique code for each mode among the plurality of modes. The unique code for each mode among the plurality of modes differs by at least two bits compared to the unique codes for each other mode among the plurality of modes.

Description

[Technical field]

[0001] Priority claim

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 881,464, entitled "Method and System for Controlling a Modal Antenna," filed August 1, 2019, which is incorporated herein by reference in its entirety.

[0002] Field Example aspects of the present disclosure relate generally to the field of antenna control, and, illustratively, to controlling modal antennas configured to operate in multiple different modes.

[0003]

[0003] Modal antennas are increasingly being used in wireless communications, for example in smartphone handsets. Such antennas generally offer higher signal quality and smaller form factors than traditional passive antennas. One modal antenna configuration includes a parasitic element configured to modify the radiation pattern associated with a driven element. Summary of the Invention [Means for solving the problem]

[0004]

[0004] Aspects and advantages of embodiments of the present disclosure will be set forth in part in the description that follows, or can be learned from the description, or may be learned by practice of the embodiments.

[0005]

[0005] An example aspect of the present disclosure is directed to an antenna system. The system includes a modal antenna having a driven element and a parasitic element. The modal antenna is operable in a selected mode from a plurality of modes. Each mode in the plurality of modes is associated with a different radiation pattern or polarization. The system includes a tuning circuit configured to control an electrical characteristic associated with the parasitic element to operate the modal antenna in each of the plurality of modes. The system includes a radio frequency circuit. The system includes a transmission line coupling the radio frequency circuit to the modal antenna. The radio frequency circuit is configured to modulate a control signal onto an RF signal to generate a transmit signal for communication through the transmission line to the tuning circuit. The control signal may include a frame having a plurality of bits associated with the selected mode of the antenna. The radio frequency circuit is configured to encode the plurality of bits associated with the selected mode according to an encoding scheme. The encoding scheme assigns a unique code to each mode in the plurality of modes. The unique code of each mode in the plurality of modes differs by at least two bits compared to the unique codes of each other mode in the plurality of modes. The tuning circuit is configured to demodulate the control signal such that the tuning circuit can adjust a mode of the modal antenna based at least in part on the control signal.

[0006]

[0006] These and other features, aspects, and advantages of various embodiments will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles involved.

[0007]

[0007] The specification, which refers to the accompanying drawings, sets forth a detailed discussion of embodiments directed to those skilled in the art. [Brief description of the drawings]

[0008] [Figure 1A] 1 illustrates an embodiment of a modal antenna according to an example embodiment of the present disclosure. [Figure 1B] Figure 1A shows the two-dimensional antenna radiation pattern associated with the modal antenna. [Figure 1C] 1B illustrates an example frequency plot of the modal antenna of FIG. 1A in accordance with an example embodiment of the present disclosure. [Diagram 2] 1 shows a schematic diagram of an example antenna system according to an example embodiment of the present disclosure. [Diagram 3] 1 illustrates a schematic diagram of an example control circuit for an antenna system according to an example embodiment of the present disclosure. [Figure 4] 1 shows a series of time-aligned charts illustrating simplified examples of amplitude shift keying and on-off keying modulation. [Diagram 5] 1 shows a schematic diagram of an example tuning circuit for an antenna system according to an example embodiment of the present disclosure. [Figure 6] 1 shows a schematic diagram of an antenna system according to an example embodiment of the present disclosure. [Figure 7] 1 illustrates a flow diagram of an example method according to an example embodiment of the present disclosure. [Figure 8] 1 illustrates an example coding scheme for multiple antenna modes according to an example embodiment of the present disclosure. [Figure 9] 1 illustrates an example of modal antenna control according to an example embodiment of the present disclosure. [Figure 10] 1 illustrates an example of error detection according to an example embodiment of the present disclosure. [Figure 11] 1 illustrates an example coding scheme for multiple antenna modes according to an example embodiment of the present disclosure. [Figure 12] 1 illustrates an example of modal antenna control according to an example embodiment of the present disclosure. [Figure 13] 1 illustrates an example of error detection according to an example embodiment of the present disclosure. [Figure 14] 1 illustrates an example of error detection according to an example embodiment of the present disclosure. [Figure 15] 1 illustrates an example method according to an example embodiment of the present disclosure. [Figure 16]1 illustrates an example of modal antenna error detection and control according to an example embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009]

[0026] DETAILED DESCRIPTION OF THE EMBODIMENTS The embodiments will now be described in detail, one or more examples of which are illustrated in the drawings. Each example is provided to illustrate the embodiments, not to limit the disclosure. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments without departing from the scope or spirit of the disclosure. By way of illustration, features illustrated or described as part of one embodiment can be used with other embodiments to yield still further embodiments. Thus, it is intended that aspects of the disclosure include such modifications and variations within their scope.

[0010]

[0027] Example aspects of the present disclosure are directed to an antenna system. The antenna system can include a modal antenna including a driven element and a parasitic element positioned proximate to the driven element. The modal antenna can be operable in a number of different modes, each mode can be associated with a different radiation pattern and / or polarization state. The antenna system can include a tuning circuit. The tuning circuit is configured to control an electrical characteristic associated with the parasitic element to operate the modal antenna in a number of different modes.

[0011]

[0028] The antenna system can include a radio frequency circuit and a transmission line (e.g., a single coaxial cable) coupling the radio frequency circuit to the modal antenna. The radio frequency circuit can be configured to, illustratively, modulate a control signal onto an RF signal using amplitude shift keying or other suitable modulation to generate a transmit signal for communication through the transmission line to a tuning circuit. The tuning circuit can be configured to demodulate the control signal such that the tuning circuit can adjust a mode of the modal antenna based at least in part on the control signal. Illustratively, the tuning circuit can control the modal antenna to operate in a selected mode from a plurality of modes based at least in part on the control signal.

[0012]

[0029] According to example aspects of the present disclosure, the control signal can be communicated over a transmission line in one or more frames. Each frame can include a number of bits. The frame(s) can illustratively include one or more bits associated with a header and / or one or more bits associated with a payload (e.g., a mode selected from a number of modes). A tuning circuit can be configured to decode one or more bits in the payload of the frame and extract a selected mode for configuring a modal antenna.

[0013]

[0030] In some instances, the frame may contain one or more errors. More specifically, one or more bits of the frame may be improper as a result of modulation and / or demodulation of the control signal onto an RF signal for transmission over a transmission line and / or as a result of noise and / or interference. Controlling the mode of the modal antenna based on errors in the control signal may cause the modal antenna to be improperly configured, resulting in communication errors, reduced efficiency of the modal antenna, and other concerns.

[0014]

[0031] According to an example embodiment of the present disclosure, the RF signal can be configured to encode the control signal according to an encoding scheme that increases error detection by the tuning circuit. Illustratively, the encoding scheme can assign a unique code to each mode among the multiple modes. In an embodiment, the unique code can be encoded using 11 bits or more (e.g., 11 bits, 21 bits). The unique code of each mode can differ from the unique code of each other mode in the multiple modes by at least 2 bits, such as by at least 3 bits, such as by at least 4 bits, such as by at least 5 bits, such as by at least 6 bits, such as by at least 7 bits, such as by at least 8 bits, etc. In this way, the unique code of each mode among the multiple modes is separated by a significant distance (e.g., in terms of number of bits) from the unique code of each of the other antennas.

[0015]

[0032] When demodulating the control signal, the tuning circuit can be configured to determine whether one or more bits in the frame(s) are associated with one of the unique codes assigned to one of the multiple modes. If so, the tuning circuit can determine that no error exists and can select a mode specified by the unique code and control the modal antenna according to the mode. If the tuning circuit determines that one or more bits in the frame(s) are not associated with one of the unique codes assigned to one of the multiple modes, the tuning circuit can determine that an error exists. By encoding each mode of the multiple modes using a large number of bits (e.g., 6 bits or more, 11 bits or more, 21 bits or more), the unique codes are separated by a sufficient distance for the multiple modes to allow easy detection of the error even when only one or two of the bits in the frame(s) are in error.

[0016]

[0033] Upon detection of an error, the tuning circuitry can be configured to maintain the modal antenna in its current mode until it receives another control signal. Alternatively, the tuning circuitry can determine the closest unique code based on the bits received in the frame(s). The tuning circuitry can control the modal antenna according to the mode associated with the closest unique code.

[0017]

[0034] In an embodiment, to further increase the robustness of the system, the RF circuitry can be configured to communicate the control signal(s) using alternating frames of different sizes. Illustratively, the RF circuitry can communicate alternating frames of a first frame size (e.g., 11 bits) and a second frame size (e.g., 21 bits). The first frame can include a number of bits encoded with a unique code according to a first encoding scheme. The first encoding scheme can assign each mode of the multiple modes a unique code having a number of bits of the first frame size (e.g., 11 bits). The second frame can include a number of bits encoded with a unique code according to a second encoding scheme. The second encoding scheme can assign each mode of the multiple modes a unique code having a number of bits of the second frame size (e.g., 21 bits).

[0018]

[0035] The tuning circuit can be configured to alternately process frames of different sizes. Illustratively, the tuning circuit can process a first frame associated with a first frame size using a first encoding scheme to extract a first select mode. The tuning circuit can then process a second frame having a second frame size using a second encoding scheme to extract a second select mode. The tuning circuit can be configured to detect an error when the frame does not match the unique code from the extracted encoding scheme.

[0019]

[0036] Systems and methods according to example embodiments of the present disclosure provide numerous technical effects and advantages. Illustratively, by communicating control signals according to example aspects of the present disclosure, error detection can be increased, illustratively leading to a reduction in operational errors that may be caused by noise and / or interference. Additionally, in certain embodiments, being able to identify the correct mode from the frame can result in more frequent extraction of the correct antenna mode from the control signal, resulting in a more robust, efficient, and reliable antenna system.

[0020]

[0037] FIG. 1A illustrates an example embodiment of a modal antenna 10 according to aspects of the present disclosure. The modal antenna 10 can include a circuit board 12 (e.g., including a ground plane) and a driven antenna element 14 disposed on the circuit board 12. An antenna volume can be defined between the circuit board (e.g., and the ground plane) and the driven antenna element. A first parasitic element 15 can be positioned at least partially within the antenna volume. A first active tuning element 16 can be coupled to the parasitic element 15. The first active tuning element 16 can be a passive or active component or series of components and can be configured to vary the reactance on the first parasitic element 14, either by a variable reactance or by a short to ground, resulting in a frequency shift of the antenna.

[0021]

[0038] In one embodiment, the second parasitic element 18 can be located proximate the circuit board 12 and can be located outside the antenna volume. The second parasitic element 18 can further include a second active tuning element 20. The second active tuning element 20 can individually include one or more active and / or passive components. The second parasitic element 18 can be located adjacent to the driven element 14 and can also be located outside the antenna volume.

[0022]

[0039] The described configuration can provide the ability to shift the radiation pattern characteristics of the driven antenna element by varying the reactance. Shifting the antenna radiation pattern can be referred to as "beam steering." If the antenna radiation pattern includes a null, a similar action can be referred to as "null steering" since the null can be shifted to an alternative location around the antenna (e.g., to reduce interference). In one embodiment, the second active tuning element 20 can include a switch that connects the second parasitic to ground when "on" and terminating the short when "off." However, it should be noted that the variable reactance can also accommodate variable shifting of the antenna pattern or frequency response, for example, by using a variable capacitor or other variable tuning component in either the first or second parasitic element. For example, first active tuning element 16 and / or second active tuning element 18 may include at least one of a tunable capacitor, a MEMS device, a tunable inductor, a switch, a tunable phase shifter, a field effect transistor, or a diode.

[0023]

[0040] Figure 1B illustrates a two-dimensional antenna radiation pattern associated with the modal antenna of Figure 1A. By controlling the electrical characteristics associated with at least one of the first and second parasitic elements 16, 18 of the modal antenna 10, the radiation pattern can be shifted. For example, in some embodiments, the radiation pattern can be shifted from a first mode 22 to a second mode 24 or to a third mode 26.

[0024]

[0041] FIG. 1C illustrates an example frequency plot of the modal antenna of FIG. 1A, according to certain embodiments of the present disclosure. The frequency of the antenna can be shifted by controlling an electrical characteristic associated with at least one of the first and second parasitic elements 16, 18 of the modal antenna 10. For example, a first frequency (f0) of the antenna can be reached when the first and second parasitic elements are switched "off," and a second frequency (f1) can be reached when the first and second parasitic elements are switched "off," and a third frequency (f2) can be reached when the first and second parasitic elements are switched "off," and a fourth frequency (f3) can be reached when the first and second parasitic elements are switched "off," and a fourth frequency (f4) can be reached when the first and second parasitic elements are switched "off," and a fourth frequency (f5) can be reached when the first and second parasitic elements are switched "off," and a fourth frequency (f6) can be reached when the first and second parasitic elements are switched "off," and a fourth frequency (f1) can be reached when the first and second parasitic elements are switched "off," and a fourth frequency (f1) can be reached when the first and second parasitic elements are switched "off," and a fourth frequency (f2) can be reached when the first and second parasitic elements are switched "off," and a fourth frequency (f1) can be reached when the second and second parasitic elements are switched "off," and a fourth frequency (f1) can be reached when the second and third parasitic elements are switched "off." L ) and (f H ) can be generated when the second parasitic is shorted to ground, and frequencies (f4, f0) can be generated when the first and second parasitic elements are each shorted to ground. It should be understood that other configurations are possible within the scope of this disclosure. For example, more or fewer parasitic elements may be employed. By varying the positioning of the parasitic elements, further modes may be achieved that can result in different frequencies and / or combinations of frequencies.

[0025]

[0042] 1A-1C depict an example of a modal antenna having multiple modes for illustrative and discussion purposes only. One of ordinary skill in the art using the disclosure provided herein will recognize that other modal antennas and / or antenna configurations may be used without departing from the scope of the present disclosure. As used herein, "modal antenna" means an antenna that can operate in multiple modes, each mode associated with a distinct radiation pattern.

[0026]

[0043] 2 illustrates a schematic diagram of an embodiment of an antenna system 100 according to an example aspect of the present disclosure. The antenna system 100 may include a modal antenna 102. The modal antenna 102 may include a driven element 104 and a parasitic element 106 positioned proximate to the driven element 104. The modal antenna 102 may be operable in a number of different modes, each of which may be associated with a different radiation pattern and / or polarization characteristics, for example, as described above with reference to FIGS. 1A-1C.

[0027]

[0044] The tuning circuit 108 can be configured to control an electrical characteristic associated with the parasitic element 106 to operate the modal antenna 102 in a number of different modes. According to example embodiments of the present disclosure, the tuning circuit 108 can be configured to demodulate a control signal from the transmitted signal and control the electrical characteristic of the parasitic element 106 based on a control instruction associated with the control signal, for example, as described in further detail with reference to FIGS. 4 and 5.

[0028]

[0045] A tunable component 110 can be coupled to the parasitic element 106, and the tuning circuit 108 can be configured to control the tunable component 110 to change the electrical connectivity of the parasitic element 106 with a voltage or current source or sink, such as by connecting the parasitic element 106 to ground.

[0029]

[0046] The radio frequency circuitry 112 may be configured to transmit an RF signal to the driven element 104 of the modal antenna 102. For example, a transmission line 114 may couple the radio frequency circuitry 112 to the modal antenna 102. In one embodiment, the transmission line 114 may be a single coaxial cable. The radio frequency circuitry 112 may be configured to amplify or otherwise generate an RF signal, which is transmitted (as a component of a transmit signal) via the transmission line 114 to the driven element 104 of the modal antenna 102.

[0030]

[0047] In one embodiment, the radio frequency circuitry 112 may include a front end module 116 and / or a control circuit 118. The front end module 116 may be configured to generate and / or amplify an RF signal that is transmitted to and / or received from the driven element 104. The front end module 116 may include one or more power amplifiers, low noise amplifiers, impedance matching circuits, etc., to illustrate. The control circuitry 118 may be configured to modulate a control signal onto the RF signal using amplitude-shift keying, for example, as described in more detail below with reference to FIG. 4, to generate a transmit signal.

[0031]

[0048] The transmission line 114 may be coupled to various components (e.g., using bias-T circuits) configured to aid in the combination and / or separation of signals occupying various frequency bands. For example, a first bias-T circuit 120 may couple the front-end module 116 and the control circuit 118 to the transmission line 114. The first bias-T circuit 120 may include a capacitor 122 that couples the transmission line 114 to the front-end module 116 and an inductor 124 that couples the control unit 118 to the transmission line 114. A second bias-T circuit 126 may couple the driven element 104 and the tuning circuit 108 to the transmission line 114. The second bias-T circuit 126 may include a capacitor 128 that couples the transmission line 114 to the driven element 104 and an inductor 130 that couples the transmission line 114 to the tuning circuit 108.

[0032]

[0049] The front-end module 116 can transmit an RF signal via a capacitor 122 of the first bias-T circuit 120. The control circuit 118 can modulate a control signal onto the RF signal via an inductor 124 of the first bias-T circuit 120 to generate a control signal in the transmission line 114. The tuning circuit 108 can demodulate the control signal from the transmit signal via an inductor 130 of the second bias-T circuit 126. The RF signal component of the transmit signal can be transmitted to the driven element 104 of the modal antenna 102 via a capacitor 128 of the second bias-T circuit 126.

[0033]

[0050] In one embodiment, the antenna system 100 may include a first circuit board 129 and a second circuit board 131 that is physically separate from the first circuit board 129. The radio frequency circuit 112 may be disposed on the first circuit board 129. At least one of the tuning circuit 108 or the modal antenna 102 may be disposed on the second circuit board 131. This allows the radio frequency circuit 112 to be physically separated from the tuning circuit and / or the modal antenna 102 without employing multiple transmission lines and without adversely affecting the operation of the antenna system 100.

[0034]

[0051] In an embodiment, the RF signal may be defined within a first frequency band. The control signal may be defined within a second frequency band separate from the first frequency band. For example, the first frequency band may range from about 500 MHz to about 50 GHz, in some embodiments from about 1 GHz to about 25 GHz, in some embodiments from about 2 GHz to about 7 GHz, for example, to about 5 GHz. The second frequency band may range from about 10 MHz to about 1 GHz, in some embodiments from about 20 MHz to about 800 MHz, in some embodiments from about 30 MHz to about 500 MHz, in some embodiments from about 50 MHz to about 250 MHz, for example, to about 100 MHz.

[0035]

[0052] 3 illustrates a schematic diagram of one embodiment of the control circuitry 118 of the antenna system 100 shown in FIG. 2. The control circuitry 118 may include a processor 132. The processor 132 may be configured to generate or receive control instructions to change the mode of the modal antenna 102 (as shown in FIG. 2) or to otherwise adjust the azimuth or frequency of the radiation pattern of the modal antenna 102. For example, the processor 132 may receive control instructions from another processor (represented by HOST in FIG. 3) and may generate data describing the instructions (represented by DATA in FIG. 3). NA digital output may also be generated that includes a digital representation of the data (represented as: data = data_input_output_output_output (data_input_output_output_output_output) of the digital data. The data may have any suitable bit depth. For example, in one embodiment, the data may be in binary format. In other embodiments, the data may be in hexadecimal format, decimal format, etc. As discussed in more detail below, the data may be encoded in a coding scheme that increases error detection in accordance with example embodiments of the present disclosure.

[0036]

[0053] The control circuitry 118 may also include a carrier signal source 134. In one embodiment, the carrier signal source 134 may be configured to generate a carrier signal that includes a sine wave that may have a generally constant frequency. In other embodiments, the carrier signal may be or include any suitable signal. For example, in one embodiment, the carrier signal may be or include any suitable repeating pattern and is not limited to being a sine wave or having a generally constant frequency.

[0037]

[0054] The control circuit 118 may also include a modulator 136. The modulator 136 modulates the output of the processor onto a carrier signal to generate a control signal (TXCH N 3 , the modulator 136 may include a multiplexer 138. The multiplexer 138 may be configured to combine an output including data (represented as DATAN in FIG. 3 ) that may describe a control command with a carrier signal from the carrier signal source 134. For example, the modulator 136 may be configured to generate the control signal by scaling the amplitude of the carrier signal from the carrier signal source 134, for example, by performing amplitude shift modulation (e.g., on-off keying modulation), as described in more detail below with reference to FIG. 4 . The modulator 136 may also include an amplifier 140 and a bias T circuit 142.

[0038]

[0055] FIG. 4 shows a series of time-aligned charts 400 representing simplified examples of amplitude shift keying and on-off keying modulation. The binary signal 401 may alternate between a first voltage level 402 and a second voltage level 404 to describe a binary data set. The binary signal 401 may correspond to a simplified example of an output of the processor 132, which may include data describing control instructions, for example, as described above with reference to FIG. 3. Amplitude-shift keying may include representing the binary signal 401 by representing the first voltage level 402 as a sinusoidal signal 406 having a variable amplitude. For example, the sinusoidal signal 406 may have a first amplitude 408 representing the first voltage 402 of the binary signal 401 and may further have a second amplitude 410 representing the second voltage level 404 of the binary signal 401.

[0039]

[0056] On-Off Keying Modulation is a type of Amplitude-Shift Keying Modulation. In On-Off Keying Modulation, the binary signal 401 may be represented by a sinusoidal signal 411 having a variable amplitude. The sinusoidal signal 411 may have a first amplitude 412 that represents the first voltage level 402 of the binary signal 401. However, the second voltage level 404 may be represented by the absence of the sinusoidal signal 410. In other words, the sinusoidal signal 410 may have an amplitude of about zero to represent the second voltage 404 of the binary signal 401.

[0040]

[0057] 5 illustrates a schematic diagram of one embodiment of a tuning circuit 500 according to aspects of the disclosure, for example, corresponding to tuning circuit 108 discussed above with reference to FIG. 2. Tuning circuit 500 may include a demodulator 502 and a bias 504. Demodulator 502 may include a bias T circuit 506 coupled to bias 504 and a multiplexer 507 coupled to communication line 114 (shown in FIG. 2).

[0041]

[0058] The tuning circuit 500 may also include a low pass filter 508 configured to filter at least one frequency band. For example, the low pass filter 508 may be configured to filter at least one frequency band that is higher than the frequency of the carrier signal frequency. Thus, the low pass filter 508 may isolate or relatively increase the strength of the carrier signal frequency. The demodulator 502 may also include a diode 510, such as a Zener diode. The diode 510 may be coupled to a logic circuit 512 configured to interpret (e.g., contained within) a control command associated with the control signal.

[0042]

[0059] The logic circuitry 512 (e.g., a processor, ASIC, etc. configured to execute computer readable instructions to perform logical operations) may also be configured to control the operation of the switch 514 based on control instructions associated with (e.g., contained within) the control signal. The switch 514 may be configured to be coupled to ground and to switch between a plurality of states. For example, the switch 514 may be configured to selectively couple an output 516 of the switch 514 to ground or otherwise vary an electrical connection state of the output 516 to control an electrical characteristic associated with the parasitic element 106 (shown in FIG. 2) and operate the modal antenna in a plurality of different modes. For example, the switch 514 may be configured to adjust the operation of the tunable component 110 (shown in FIG. 2) to vary an electrical connection state of the parasitic element 106 to a source or sink (e.g., a voltage source / sink or a current source / sink). For example, the switch 514 may be configured to selectively couple the parasitic element 106 to ground.

[0043]

[0060] The tuning circuit 500 (e.g., logic circuit 512) may include a tunable frequency source, such as a locally tuned harmonic local oscillator (e.g., a ring oscillator), configured to provide a local clock frequency associated with the tuning circuit 500. The logic circuit 512 may be configured to sample a signal that the logic circuit 512 receives (e.g., from diode 510) and perform a frequency search operation on the signal. The frequency search operation may determine a corresponding sampling frequency. For example, the logic circuit 512 may sample the control signal (or an adjusted version thereof output by diode 510) for a time period corresponding to an expected phrase. The expected phrase may include a signal pattern that is expected to be present in the control signal. As an example, the expected phrase may be present as a "preamble" or "postamble" at the beginning and / or end of one or more transmitted data "frames." The logic circuit 512 may be configured to recognize or detect the expected phrase and locate the beginning or end of the frame(s). The logic circuit 512 can then compare the number of local oscillator “clock edges” present in the sample to the number of local oscillator “clock edges” predicted to be present in the sample based on the prediction phrase to measure and determine a phase error in terms of the number of “clock edges.”

[0044]

[0061] The logic circuitry 512 can then perform a frequency search operation. For example, the frequency search operation can include repeating the steps of: (1) sampling over a time period corresponding to the length of the expected phrase; (2) determining a phase error by comparing the number of clock edges present in the samples to the expected number of clock edges; and (3) adjusting the local clock frequency (e.g., the frequency of the local oscillator) until the local clock frequency is sufficiently synchronized with a master clock frequency associated with the control circuitry 118. For example, the local clock frequency can be determined to be sufficiently synchronized when the phase error is less than a threshold (e.g., a predetermined threshold).

[0045]

[0062] In one embodiment, the tuning circuit may employ a numerically controlled oscillator. The numerically controlled oscillator is configured to count data edge transitions of a signal received by the tuning circuit. If the number of data edge transitions falls outside an expected range (e.g., a predetermined range), the tuning circuit may reject or ignore the associated data frame. If the count of data edge transitions falls within the expected range, the tuning circuit may adjust a frequency (e.g., a local clock frequency) associated with an internal oscillator of the tuning circuit. For example, the tuning circuit may be configured to increase or decrease the frequency of the internal oscillator to compensate for drift that may occur during normal operation between the frequency of the internal oscillator frequency of the tuning circuit and a clock or oscillator frequency associated with the RF and / or control circuits.

[0046]

[0063] Logic circuitry 512 may also be configured to perform error detection. Example techniques implemented by logic circuitry 512 are discussed with reference to Figures 7-16.

[0047]

[0064] 6 illustrates a schematic diagram of another embodiment of an antenna system 600 according to an aspect of the present disclosure. The antenna system 600 may be configured generally similarly to the antenna system 100 previously described with reference to FIG. 2. For example, the antenna system 600 may include a modal antenna 602 including a driven element 604 and a parasitic element 606, a tuning circuit 608, an RF circuit 612, a transmission line 614, a front end module 616, a control circuit 618, a first bias T circuit 620 including a capacitor 622 and an inductor 624, and a second bias T circuit 626 including a capacitor 628 and an inductor 630.

[0048]

[0065] The antenna system 600 may also include a second modal antenna 632 including a driven element 634 and a parasitic element 636. A second tuning circuit 638 may be configured to control an electrical characteristic associated with the parasitic element 636 to operate the modal 632 in a number of different modes. For example, a second tunable component 640 may be coupled to the parasitic element 636, and the tuning circuit 638 may be configured to control the second tunable component 640 to change an electrical connection between the parasitic element 636 of the second modal antenna 632 and a voltage or current source or sink, such as by connecting the parasitic element 106 to ground.

[0049]

[0066] The radio frequency circuit 612 may include a second front end module 642 and a second transmission line 644. The second front end module 642 may be configured to generate and / or amplify a second RF signal. The control circuit 618 may be configured to modulate a second control signal onto the second RF signal to generate a second transmission signal. In an embodiment, the control circuit 618 may also modulate the second control signal onto the second RF signal using amplitude-shift keying, e.g., as described above with reference to Figures 3 and 4.

[0050]

[0067] The second transmission line 644 can be coupled to various components using bias-T's configured to aid in combining and / or separating signals occupying various frequency bands. For example, a third bias-T circuit 646 can couple the second front-end module 642 and the control circuit 618 to the second transmission line 644. The third bias-T circuit 646 can include a capacitor 648 that couples the second front-end module 642 to the second transmission line 644 and an inductor 650 that couples the control unit 618 to the second transmission line 644.

[0051]

[0068] The fourth bias-T circuit 652 can couple the second transmission line 644 to the driven element 634 of the second modal antenna 632 and the tuning circuit 108. The fourth bias-T circuit 652 can include a capacitor 654 that couples the second transmission line 644 to the driven element 634 of the second modal antenna 632 and an inductor 656 that couples the second transmission line 644 to the second tuning circuit 638.

[0052]

[0069] The second front-end module 642 can transmit a second RF signal via a capacitor 648 of the third bias-T circuit 646. The control circuit 618 can modulate a second control signal onto the second RF signal via an inductor 650 of the third bias-T circuit 646 to generate a second transmit signal. The second tuning circuit 638 can demodulate the control signal from the second transmit signal via an inductor 656 of the fourth bias-T circuit 652. An RF signal component of the second transmit signal can be transmitted to the driven element 634 of the second modal antenna 632 via a capacitor 654 of the fourth bias-T circuit 652.

[0053]

[0070] In this embodiment, the control circuit 618 can have a separate output associated with each of the transmission lines 614, 644. The control circuit 618 can be configured similarly to the control circuit 118 described above with reference to FIG. 3 and can further include additional components configured to provide a separate output to the second transmission line 644. For example, the control circuit 618 can also include the second processor 132, the sine wave source 134, the modulator 136, the multiplexer 138, the amplifier 140, and / or the bias T circuit 142 to provide the second output.

[0054]

[0071] In some embodiments, the antenna system may include multiple antennas in a multiple-in-multiple-out (MIMO) configuration. Multiple pairs of control circuits and tuning circuits may be configured to control multiple passive antennas as well as multiple modal antennas. For example, the antenna system may include N tuning circuits (each paired with a respective control circuit) configured to control the operation of M modal antennas and (NM) passive antennas, where N and M are each positive integers and N is greater than or equal to M. Additionally, in some embodiments, a control circuit may include multiple outputs and be paired with multiple tuning circuits, as described with reference to FIG. 6, for example. In any event, the number of tuning circuits N may range up to any suitable number. For example, in some embodiments, N may range from 2 to 20 or more, and M may range from 2 to 20 or more.

[0055]

[0072] It should be understood that various modifications are possible within the scope of the present disclosure. For example, in other embodiments, a separate control circuit may be associated with each transmission line 614, 644. Additionally, in other embodiments, a single front end module may be configured to generate each RF signal. In some embodiments, a single tuning circuit may be configured to control the electrical characteristics associated with the parasitic elements of each modal antenna of the system. Furthermore, in some embodiments, the system may include more than two modal antennas. Additionally, in some embodiments, the system may include a combination of one or more modal antennas and one or more non-modal antennas that are not configured to operate in multiple modes, i.e., passive antennas. In some embodiments, one or more modal antennas may include more than one parasitic element. A single control circuit may be configured to adjust each tunable element associated with the parasitic element and control the electrical characteristics associated with the parasitic element to operate the modal antenna in multiple different modes. In other embodiments, multiple control circuits may be used to adjust each tunable element. It should be understood that other modifications, variations, combinations, etc. are possible within the scope of the present disclosure.

[0056]

[0073] FIG. 7 illustrates a flow diagram of an example method 700 according to an example embodiment of the present disclosure. FIG. 7 illustrates steps performed in a particular order for illustrative and discussion purposes only. It should be understood that, using the disclosure provided herein, one of ordinary skill in the art would be able to omit, extend, simultaneously perform, rearrange, and / or modify various steps of any of the methods described herein in various ways without departing from the scope of the present disclosure. Additionally, various steps (not shown) may be performed without departing from the scope of the present disclosure. Additionally, the method 700 will be generally discussed with reference to the antenna systems 200, 600 previously described with reference to FIGS. 2 and 6. However, it should be understood that aspects of the method 700 may be applied to any suitable antenna system, including modal antennas.

[0057]

[0074] The method 700 may include, at (702), modulating a control signal onto an RF signal to generate a transmit signal. For example, the control signal may include control instructions to change a mode of a modal antenna or otherwise adjust an orientation or frequency of a radiation pattern of the modal antenna. For example, the radio frequency circuitry 112 may include a control circuitry 118 configured to modulate the control signal onto an RF signal to generate a transmit signal, e.g., as described above with reference to Figures 3 and 4.

[0058]

[0075] The control signals can be implemented in one or more frames. Each frame can include multiple bits. The frame or frames can specify a mode to be selected for operation of the modal antenna from multiple modes. The control signals (e.g., commands) can be encoded by a coding scheme that increases error detection by the tuning circuit. Illustratively, the coding scheme can assign a unique code to each mode among the multiple modes.

[0059]

[0076] In some embodiments, 11 or more bits (e.g., 11 bits, 21 bits) can be used to encode the unique code. The unique code for each mode can differ from the unique code for each other mode in the multiple modes by at least 2 bits, such as by at least 3 bits, such as by at least 4 bits, such as by at least 5 bits, such as by at least 6 bits, such as by at least 7 bits, such as by at least 8 bits, etc. As a result, the unique code for each mode in the multiple modes is separated by a significant distance (e.g., in terms of number of bits) from the unique code for each of the other antenna codes.

[0060]

[0077] To illustrate, Figure 8 shows an example coding scheme 810 according to an example embodiment of the present disclosure. The coding scheme 810 assigns a unique 11-bit code to each of four different antenna modes, mode 0, mode 1, mode 2, and mode 3. More specifically, code 802 is assigned to mode 0. code 804 is assigned to mode 1. code 806 is assigned to mode 2. code 808 is assigned to mode 3.

[0061]

[0078] For purposes of illustration and discussion only, aspects of the present disclosure are discussed with reference to four modes, although one of ordinary skill in the art, using the disclosure provided herein, will understand that any number of modes, such as 8 modes, 16 modes, 32 modes, etc., may be used without departing from the scope of the present disclosure. Additionally, aspects of the present disclosure are discussed with reference to unique codes implemented in binary format, although one of ordinary skill in the art, using the disclosure provided herein, will understand that other numeric tables (e.g., decimal, hexadecimal) may be used without departing from the scope of the present disclosure.

[0062]

[0079] 8, codes 802, 804, 806, and 808 in coding scheme 806 differ from each other by at least 2 bits, such as by at least 5 bits, such that codes 802, 804, 806, and 808 are separated from each other by a significant distance, which facilitates error detection, as discussed below.

[0063]

[0080] 7, the method 700 can include, at (704), communicating a transmit signal through a single coaxial transmission line to a tuning circuit. For example, the method can include a front end module 116, as described above with reference to the radio frequency circuit 112. The front end module 116 can communicate an RF signal through a capacitor 122 of a first bias T 120, through the transmission line 114, and through a capacitor 128 of a second bias T 128 to a driven element 104 of a modal antenna 102. The control circuit 118 can modulate a control signal onto the RF signal through an inductor 124 of the first bias T 120, and communicate it through the transmission line 114 and through an inductor 130 of the second bias T 128 to the tuning circuit 108.

[0064]

[0081] The method 700 may include, at (706), demodulating the control signal in a tuning circuit. For example, as previously described with reference to Figures 2 and 5, the tuning circuit 108, 500 may be configured to demodulate the control signal from the transmit signal via the inductor 130 of the second bias T 126. The tuning circuit 108, 500 may also be configured to filter and / or amplify the control signal to isolate or relatively enhance a strength of a carrier signal frequency associated with the carrier signal. The logic circuit 512 may be configured to interpret control instructions associated with (e.g., included within) the control signal.

[0065]

[0082] Illustratively, at (708), the method may include processing a frame(s) of control signals (e.g., bits in the control signals) for error detection. Illustratively, logic circuitry 512 may process a number of bits in the frame(s) to determine whether a unique code matches a unique code assigned to a mode in an encoding scheme.

[0066]

[0083] 9 shows an example tuning circuit logic circuit 512 processing a number of bits in a frame(s) received over a transmission line. The logic circuit 512 may process the bits and determine that the bits match the unique code 806. As a result, the logic circuit 512 may determine that the control signal has control instructions for operating the modal antenna in mode 2.

[0067]

[0084] 10 illustrates logic circuitry 512 of an example tuning circuit that processes multiple bits 812. The multiple bits 812 differ from the unique code 806 by one bit. However, because the multiple bits 812 do not match a unique code in the encoding scheme 810, the logic circuitry 512 can easily detect an error even if only one bit is incorrect. This error detection is aided by the fact that the unique codes in the encoding scheme are separated by a significant distance, reducing errors that match other unique codes.

[0068]

[0085] 7, if there is no error at (710), the method may proceed to (712) to select a mode specified by the unique code and control the modal antenna according to the mode. Illustratively, the method 700 may include controlling an electrical characteristic associated with a parasitic element of the modal antenna based at least in part on the control signal for controlling the modal antenna in the selected mode.

[0069]

[0086] 7, if an error is detected at (710), the method proceeds to (714) where the tuning circuit maintains the current mode of the antenna. In other words, the tuning circuit does not respond to the erroneous control signal and maintains the modal antenna in its current mode.

[0070]

[0087] 11 illustrates an example coding scheme 830 according to an example embodiment of the present disclosure. The coding scheme 830 assigns a unique 21-bit code to each of four different modes, namely, mode 0, mode 1, mode 2, and mode 3. More specifically, code 822 is assigned to mode 0. code 824 is assigned to mode 1. code 826 is assigned to mode 2. code 828 is assigned to mode 3. Codes 822, 824, 826, and 828 in coding scheme 806 differ from each other by at least two bits, such as by at least five bits, such as by at least eight bits. As a result, codes 822, 824, 826, and 828 are separated from each other by a significant distance, which facilitates error detection.

[0071]

[0088] 12 shows an example tuning circuit logic circuit 512 processing a number of bits in a frame(s) received over a transmission line. The logic circuit 512 may process the bits and determine that the bits match the unique code 824. As a result, the logic circuit 512 may determine that the control signal has control instructions to operate the modal antenna in mode 1.

[0072]

[0089] 10 shows logic circuitry 512 of an example tuning circuit that processes a plurality of bits 832. The plurality of bits 832 differs from the unique code 824 by two bits. However, because the plurality of bits 832 does not match a unique code in the encoding scheme 810, the logic circuitry 512 can easily detect an error even though only two bits are incorrect. This error detection is aided by the fact that the unique codes in the encoding scheme are separated by a significant distance, reducing errors that match other unique codes.

[0073]

[0090] In one embodiment, to further enhance system robustness, the RF circuitry can be configured to communicate the control signal(s) using alternating frames of different sizes. Illustratively, the RF circuitry can communicate alternating frames of a first frame size (e.g., 11 bits) and a second frame size (e.g., 21 bits). The first frame can include a number of bits encoded with a unique code according to a first coding scheme, such as coding scheme 810 shown in FIG. 8. The first coding scheme can assign each mode among the multiple modes a unique code having a number of bits of the first frame size (e.g., 11 bits).

[0074]

[0091] The second frame can include a number of bits encoded with a unique code according to a second encoding scheme, such as encoding scheme 830 shown in Figure 11. The second encoding scheme can assign each mode among the multiple modes a unique code having a number of bits equal to the second frame size (e.g., 21 bits).

[0075]

[0092] The tuning circuitry may be configured to alternately process frames of different sizes. As an illustrative example, FIG. 15 shows logic circuitry 512 of an example tuning circuitry processing a number of bits in a first frame having a first frame size of 11 bits received over a transmission line. Logic circuitry 512 may process the bits and determine that the bits match unique code 802. As a result, logic circuitry 512 may determine that the control signal has a control instruction to operate the modal antenna in mode 0.

[0076]

[0093] The logic circuit 512 of the example tuning circuit may process bits in a second frame having a second frame size of 21 bits received over the transmission line. The logic circuit 512 may process the bits and determine that the bits match the unique code 824. As a result, the logic circuit 512 may determine that the control signal has a control instruction to operate the modal antenna in mode 1.

[0077]

[0094] The logic circuit 512 of the example tuning circuit processes a number of bits in the third frame having a first frame size of 11 bits received over the transmission line. The logic circuit 512 can process the bits and determine that the bits match the unique code 808. As a result, the logic circuit 512 can determine that the control signal has a control instruction to operate the modal antenna in mode 3.

[0078]

[0095] Logic circuitry 512 of the example tuned circuit can process bits in a second frame having a second frame size of 21 bits received over the transmission line. Logic circuitry 512 can process bits 834 and determine that these bits do not match a unique code in encoding scheme 830. As a result, logic circuitry 512 can detect an error.

[0079]

[0096] FIG. 15 illustrates a flow diagram of an example method 900 according to an example embodiment of the present disclosure. FIG. 15 illustrates steps performed in a particular order for illustrative and discussion purposes only. It should be understood that, using the disclosure provided herein, one of ordinary skill in the art would be able to omit, extend, simultaneously perform, rearrange, and / or modify various steps of any of the methods described herein in various ways without departing from the scope of the present disclosure. Additionally, various steps (not shown) may be performed without departing from the scope of the present disclosure. Additionally, the method 900 will be generally discussed with reference to the antenna systems 200, 600 previously described with reference to FIGS. 2 and 6. However, it should be understood that aspects of the method 900 may be applied to any suitable antenna system, including modal antennas.

[0080]

[0097] The method 900 may include, at (902), modulating a control signal onto an RF signal to generate a transmit signal. For example, the control signal may include control instructions to change a mode of a modal antenna or otherwise adjust an orientation or frequency of a radiation pattern of the modal antenna. For example, the radio frequency circuitry 112 may include a control circuitry 118 configured to modulate the control signal onto an RF signal to generate a transmit signal, e.g., as described above with reference to Figures 3 and 4.

[0081]

[0098] The control signals can be implemented in one or more frames. Each frame includes a number of bits. The frame or frames can specify a mode to be selected for operation of the modal antenna from a number of modes. The control signals (e.g., commands) can be encoded by a coding scheme that increases error detection by the tuning circuit. Illustratively, the coding scheme can assign a unique code to each mode among the multiple modes.

[0082]

[0099] In some embodiments, 11 or more bits (e.g., 11 bits, 21 bits) can be used to encode the unique code. The unique code for each mode can differ from the unique code for each other mode in the plurality of modes by at least 2 bits, such as by at least 3 bits, such as by at least 4 bits, such as by at least 5 bits, such as by at least 6 bits, such as by at least 7 bits, such as by at least 8 bits, etc. As a result, the unique code for each mode in the plurality of modes is separated by a significant distance (e.g., in terms of a binary code) from the unique codes of each of the other antenna modes.

[0083]

[0100] The method 900 may include, at (904), communicating a transmit signal through a single coaxial transmission line to a tuning circuit. For example, as described above with reference to the radio frequency circuit 112, the radio frequency circuit 112 may include a front end module 116. The front end module 116 may communicate the RF signal through a capacitor 122 of a first bias T 120, through the transmission line 114, and through a capacitor 128 of a second bias T 128 to the driven element 104 of the modal antenna 102. The control circuit 118 may modulate a control signal onto the RF signal through an inductor 124 of the first bias T 120 and communicate it through the transmission line 114 and through an inductor 130 of the second bias T 128 to the tuning circuit 108.

[0084]

[0101] The method 900 may include, at (906), demodulating the control signal in a tuning circuit. For example, as previously described with reference to Figures 2 and 5, the tuning circuit 108, 500 may be configured to demodulate the control signal from the transmit signal via the inductor 130 of the second bias T 126. The tuning circuit 108, 500 may also be configured to filter and / or amplify the control signal to isolate or relatively enhance a strength of a carrier signal frequency associated with the carrier signal. The logic circuit 512 may be configured to interpret control instructions associated with (e.g., included within) the control signal.

[0085]

[0102] Illustratively, at (908), the method may include processing a frame(s) of a control signal (e.g., bits in the control signal) for error detection. Illustratively, the logic circuit 512 may process a number of bits in the frame(s) to determine whether a unique code matches a unique code assigned to a mode in an encoding scheme.

[0086]

[0103] If there are no errors at (910), the method may proceed to (912) where a mode specified by the unique code is selected and the modal antenna may be controlled according to the mode. Illustratively, the method 700 may include controlling an electrical characteristic associated with a parasitic element of the modal antenna based, at least in part, on the control signal that controls the modal antenna in the selected mode.

[0087]

[0104] If an error is detected at (910), the method proceeds to (914) where the tuning circuit determines the closest unique code. Illustratively, the tuning circuit may determine that the bits differ by one or two bits from a particular unique code in the coding scheme. The tuning circuit may correct the error bits to match the unique code specified in the coding scheme. The method may proceed to (916) where the mode specified by the closest unique code is selected and the modal antenna may be controlled according to the mode.

[0088]

[0105] As an illustrative example, FIG. 16 shows an example tuning circuit logic circuit 512 processing a plurality of bits 815. The plurality of bits 832 differs from the unique code 806 by one bit. Thus, the logic circuit 512 can detect the error even if only two bits are incorrect. The logic circuit 512 can correct the bits to match the closest unique code 806. The logic circuit 512 can then determine that the control signal has a control instruction to operate the modal antenna in mode 2. In this manner, the antenna system can control the modal antenna according to a specified mode even if an error occurs in the transmission of the control signal through the transmission line.

[0089]

[0106] Although the subject matter of the present invention has been described in detail above with reference to specific exemplary embodiments thereof, it will be appreciated that those skilled in the art, upon gaining an understanding of the above, can easily make modifications, variations, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is illustrative rather than limiting, and the present disclosure does not exclude such modifications, variations, and / or additional inclusions to the subject matter of the present invention, as will be readily appreciated by those skilled in the art.

Claims

1. 1. An antenna system comprising: a modal antenna including a driven element and a parasitic element, the modal antenna operable in a selected mode from a plurality of modes, each mode in the plurality of modes being associated with a different radiation pattern or polarization; a tuning circuit configured to control an electrical characteristic associated with the parasitic element to operate the modal antenna in each of the plurality of modes; A radio frequency circuit; a transmission line coupling said radio frequency circuit to said modal antenna; Equipped with the radio frequency circuitry is configured to modulate a control signal onto an RF signal to generate a transmit signal for transmission to the tuning circuit over the transmission line, the control signal including a frame having a plurality of bits associated with a selected mode of the antenna, the radio frequency circuitry is configured to encode the plurality of bits associated with the selected mode in accordance with a coding scheme, the coding scheme designating a unique code for each mode among the plurality of modes, the unique code for each mode among the plurality of modes differing by at least two bits as compared to the unique codes for each other mode among the plurality of modes; the tuning circuit is configured to demodulate the control signal and adjust a mode of the modal antenna based at least in part on the control signal; the tuning circuit is configured to detect an error in the control signal when the plurality of bits is not associated with any unique code in the coding scheme. Antenna system.

2. 2. The antenna system of claim 1, wherein said frame is comprised of 11 bits.

3. 2. The antenna system of claim 1, wherein said frame is comprised of 21 bits.

4. 2. The antenna system of claim 1, wherein the unique code for each mode in the plurality of modes differs by at least 3 bits as compared to the unique code for each other mode in the plurality of modes.

5. 2. The antenna system of claim 1, wherein the unique code for each mode in the plurality of modes differs by at least four bits as compared to the unique code for each other mode in the plurality of modes.

6. 2. The antenna system of claim 1, wherein the plurality of modes includes at least four modes.

7. 2. The antenna system of claim 1, wherein the tuning circuit is configured to maintain a current mode of the modal antenna when an error is detected in the control signal.

8. 2. The antenna system of claim 1, wherein the radio frequency circuit is configured to modulate a control signal onto an RF signal by alternating between a first frame having a first frame size and a second frame having a second frame size to generate a transmit signal for transmission over a transmission line to the tuning circuit, the second frame size being different from the first frame size.

9. 9. The antenna system of claim 8, wherein said first frame is at least 11 bits and said second frame is at least 21 bits.

10. 2. The antenna system of claim 1, further comprising a first circuit board and a second circuit board physically separate from the first circuit board, the radio frequency circuit being disposed on the first circuit board and at least one of the tuning circuit or modal antenna being disposed on the second circuit board.

11. 2. The antenna system of claim 1, wherein the radio frequency circuitry includes a front end module configured to generate the RF signal and a control circuit configured to modulate the control signal onto the RF signal to generate the transmit signal.

12. 1. A method for controlling a modal antenna, comprising the steps of: modulating a control signal onto an RF signal to generate a transmit signal; transmitting the transmit signal through a single coaxial transmission line to a tuning circuit; demodulating the control signal; controlling electrical characteristics associated with parasitic elements of the modal antenna based at least in part on the control signal to operate the modal antenna in a selected mode from a plurality of modes, each mode in the plurality of modes being associated with a different radiation pattern of the modal antenna; detecting an error in the control signal when a plurality of bits is not associated with any unique code in a coding scheme; Including, 11. A method according to claim 10, wherein the control signal includes a frame having the plurality of bits associated with a selected mode of the antenna, and wherein a radio frequency circuit is configured to encode the plurality of bits associated with the selected mode in accordance with the encoding scheme, the encoding scheme assigning a unique code to each mode among the plurality of modes, the unique code for each mode among the plurality of modes differing by at least two bits as compared to the unique codes of each other mode among the plurality of modes.

13. 13. The method of claim 12, further comprising the step of maintaining a current mode of the modal antenna when an error is detected in the control signal.

14. 13. The method of claim 12, wherein the frame is comprised of 11 bits.

15. 13. The method of claim 12, wherein the frame is comprised of 21 bits.

16. 13. The method of claim 12, wherein the unique code for each mode in the plurality of modes differs by at least 3 bits as compared to the unique code for each other mode in the plurality of modes.

17. 13. The method of claim 12, wherein modulating a control signal onto an RF signal to generate a transmission signal includes alternating between modulating a first frame having a first frame size and a second frame having a second frame size, the second frame size being different from the first frame size.

18. 20. The method of claim 17, wherein the first frame is at least 11 bits and the second frame is at least 21 bits.

Images