Antenna structures and methods thereof for determining a frequency offset based on a differential magnitude

Abstract

A system that incorporates the subject disclosure may include, for example, a circuit for measuring from a first probe a first magnitude of radiated energy by an antenna, where the first probe serves as a first near field probe for measuring radiated energy from the antenna, measuring from a second probe a second magnitude of a transmit signal supplied to the antenna, where the second probe is placed at a location for measuring the transmit signal, comparing the first and the second magnitudes to generate a differential magnitude, and providing the differential magnitude to a controller for detecting an offset in an operating frequency of the antenna based on the differential magnitude, and for adjusting the operating frequency of the antenna to mitigate the offset. Other embodiments are disclosed.

What is claimed is: 
     
         1 . A method, comprising:
 measuring, by a circuit, from a first probe a first magnitude of radiated energy by an antenna, wherein the first probe serves as a first near field probe for measuring radiated energy from the antenna;   measuring, by the circuit, from a second probe a second magnitude of a transmit signal supplied to the antenna, wherein the second probe is placed at a location for measuring the transmit signal;   comparing, by the circuit, the first and the second magnitudes to generate a differential magnitude; and   providing, by the circuit, the differential magnitude to a controller for detecting an offset in an operating frequency of the antenna based on the differential magnitude, and for adjusting the operating frequency of the antenna to mitigate the offset.   
     
     
         2 . The method of  claim 1 , wherein the operating frequency of the antenna is adjusted by modifying an electrical length of the antenna, wherein the second probe comprises a directional coupler placed in a transmission path of the transmit signal. 
     
     
         3 . The method of  claim 1 , wherein the first magnitude is measured by a first magnitude detector, wherein the second magnitude is measured by a second magnitude detector, and wherein the first and second magnitudes are compared with a differentiator circuit. 
     
     
         4 . The method of  claim 3 , wherein the offset in the operating frequency of the antenna is caused by the antenna being exposed to an environmental effect. 
     
     
         5 . The method of  claim 1 , further comprising placing a third probe near the antenna at a different location from the first probe, wherein the third probe serves as a second near field probe for measuring radiated energy from the antenna at the different location. 
     
     
         6 . The method of  claim 5 , further comprising:
 measuring a plurality of magnitudes of the radiated energy from the first probe and the second probe; and   monitoring the plurality of magnitudes measured to improve an accuracy of an adjustment of the operating frequency of the antenna.   
     
     
         7 . The method of  claim 1 , wherein the antenna comprises an aperture tuner to adjust a resonant frequency range of the antenna, and wherein the adjusting of the operating frequency of the antenna is performed by supplying one or more signals to the aperture tuner. 
     
     
         8 . The method of  claim 7 , wherein the aperture tuner comprises a variable reactive element to adjust the resonant frequency range of the antenna. 
     
     
         9 . The method of  claim 7 , wherein the aperture tuner comprises a switchable array of reactive elements to adjust the resonant frequency range of the antenna. 
     
     
         10 . The method of  claim 7 , wherein the aperture tuner comprises one of a variable capacitor, a variable inductor, or a combination thereof. 
     
     
         11 . An antenna structure, comprising:
 a first antenna for receiving and transmitting radio frequency signals within an operating frequency range;   a probe for measuring a transmit signal;   a first aperture tuner for adjusting an operating frequency of the antenna; and   a first near field sensor for sensing radiated energy from the first antenna, wherein the first near field sensor, the probe, the first antenna, and the first aperture tuner are coupled to a circuit that performs operations comprising:
 measuring from the first near field sensor a first magnitude of radiated energy by the first antenna; 
 measuring from the probe a second magnitude of a signal supplied to the first antenna; 
 comparing the first and the second magnitudes to generate a first differential magnitude; and 
 sending the differential magnitude for detecting a change in a first operating frequency of the first antenna based on the first differential magnitude, and for controlling the first aperture tuner to adjust the first operating frequency of the first antenna. 
   
     
     
         12 . The antenna structure of  claim 11 , wherein the probe comprises a directional coupler. 
     
     
         13 . The antenna structure of  claim 12 , wherein the directional coupler is coupled to a transmit path that supplies the transmit signal to the antenna. 
     
     
         14 . The antenna structure of  claim 11 , wherein the differential magnitude is sent to a controller for performing the detecting and controlling steps, and wherein the circuit does not perform the detecting and controlling steps of the controller. 
     
     
         15 . The antenna structure of  claim 11 , wherein the circuit comprises a processor of a communication device utilizing the antenna structure. 
     
     
         16 . The antenna structure of  claim 11 , wherein the first antenna is tuned by modifying an electrical length of the antenna, and wherein the differential magnitude is proportional to the change in the operating frequency of the first antenna. 
     
     
         17 . The antenna structure of  claim 11 , further comprising a second antenna. 
     
     
         18 . The antenna structure of  claim 17 , wherein the first antenna is electrically coupled to the second antenna by way of a coupling element, and wherein the coupling element causes differential currents and common mode currents flowing through the first antenna and the second antenna to combine in a manner that increases signal isolation between a first port of the first antenna and a second port of the second antenna. 
     
     
         19 . The antenna structure of  claim 17 , further comprising:
 a second near field sensor;   a second probe; and   a second aperture tuner, wherein the second antenna is coupled to the second near field sensor and the second aperture tuner, and wherein the operations further comprise:
 measuring from the second near field sensor a third magnitude of radiated energy by the second antenna; 
 measuring from the probe a fourth magnitude of a signal supplied to the second antenna; 
 comparing the third and the fourth magnitudes to generate a second differential magnitude; and 
 sending the second differential magnitude for detecting a change in a second operating frequency of the second antenna based on the second differential magnitude, and causing the second aperture tuner to adjust the second operating frequency of the second antenna. 
   
     
     
         20 . The antenna structure of  claim 17 , wherein the first antenna and the second antenna are configured for one of a multiple-input and multiple-output (MIMO) or a diversity antenna configuration. 
     
     
         21 . A communication device, comprising:
 an antenna structure;   a probe for measuring a magnitude of a transmit signal supplied by a transmitter circuit;   a near field sensor coupled to the antenna structure for measuring radiated energy generated by the antenna; and   a circuit coupled to the probe and the near field sensor, wherein the circuit performs operations comprising:   measuring from the near field sensor a first magnitude of radiated energy by the antenna structure;   measuring from the probe a second magnitude of a signal supplied to the antenna structure by the transmitter circuit;   comparing the first and the second magnitudes to generate a magnitude comparison; and   supplying the magnitude comparison for detecting an offset in an operating frequency of the antenna structure based on the magnitude comparison, and for tuning a frequency of the antenna structure to mitigate the offset in the operating frequency of the antenna structure.   
     
     
         22 . The communication device of  claim 21 , wherein the frequency of the antenna structure is tuned by modifying an electrical length of the antenna structure. 
     
     
         23 . The communication device of  claim 22 , wherein the electrical length of the antenna structure is varied with one of a first device having tunable capacitance, a second device having a tunable inductance, or a combination thereof. 
     
     
         24 . The communication device of  claim 21 , wherein the probe comprises a directional coupler. 
     
     
         25 . The communication device of  claim 21 , wherein the communication device comprises one of a cellular telephone or a wireless access point.