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

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 is placed near the antenna, obtaining a second magnitude of a signal supplied to the antenna, comparing the first and the second magnitudes, detecting an offset in an operating frequency of the antenna based on a difference between the first and the second magnitudes, and adjusting the operating frequency of the antenna to mitigate the offset in the operating frequency of the antenna. 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 is placed near the antenna;   obtaining, by the circuit, a second magnitude of a signal supplied to the antenna;   comparing, by the circuit, the first and the second magnitudes;   detecting, by the circuit, an offset in an operating frequency of the antenna based on a difference between the first and the second magnitudes; and   adjusting, by the circuit, the operating frequency of the antenna to mitigate the offset in the operating frequency of the antenna.   
     
     
         2 . The method of  claim 1 , wherein the frequency of the antenna is adjusted by modifying an electrical length of the antenna. 
     
     
         3 . The method of  claim 1 , wherein the difference between the first and the second magnitudes is proportional to the offset in the operating frequency of the antenna, wherein the circuit comprises a processor of a mobile communication device. 
     
     
         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 , wherein a second probe is placed near the antenna to form a plurality of near field probes. 
     
     
         6 . The method of  claim 5 , further comprising:
 measuring a plurality of magnitudes of the radiated energy from the plurality of near field probes; and   monitoring the plurality of magnitudes measured to improve an accuracy of the comparing, the detecting and the adjusting steps.   
     
     
         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 element for receiving and transmitting radio frequency signals within an operating frequency range;   a first aperture tuner for adjusting an operating frequency of the antenna element; and   a first near field sensor for sensing radiated energy from the first antenna element, wherein the first near field sensor, the first antenna element, 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 element; 
 obtaining a second magnitude of a signal supplied to the first antenna element; 
 comparing the first and the second magnitudes; 
 detecting a change in an operating frequency of the first antenna element based on a difference between the first and the second magnitudes; and 
 directing the first aperture tuner to adjust the operating frequency of the first antenna element to counter the change in the operating frequency of the first antenna element. 
   
     
     
         12 . The antenna structure of  claim 11 , wherein the second magnitude of the signal supplied to the first antenna element is obtained from one of measuring signals provided by a directional coupler, retrieving the second magnitude from a known state of transmit signal supplied to the first antenna element, or a combination thereof. 
     
     
         13 . The antenna structure of  claim 12 , wherein the directional coupler is coupled to a path that supplies the signal to the antenna. 
     
     
         14 . The antenna structure of  claim 11 , further comprising the circuit. 
     
     
         15 . The antenna structure of  claim 11 , wherein the circuit comprises a processor of a mobile communication device utilizing the antenna structure. 
     
     
         16 . The antenna structure of  claim 11 , wherein the first antenna element is tuned by modifying an electrical length of the antenna element using the first aperture tuner, and wherein the difference between the first and the second magnitudes is proportional to the change in the operating frequency of the first antenna element. 
     
     
         17 . The antenna structure of  claim 11 , further comprising a second antenna element. 
     
     
         18 . The antenna structure of  claim 17 , wherein the first antenna element is electrically coupled to the second antenna element by way of a coupling element, and wherein the coupling element causes differential currents and common mode currents flowing through the first antenna element and the second antenna element to combine in a manner that increases signal isolation between a first port of the first antenna element and a second port of the second antenna element. 
     
     
         19 . The antenna structure of  claim 17 , further comprising:
 a second near field sensor; and   a second aperture tuner, wherein the second antenna element 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 element; 
 obtaining a fourth magnitude of a signal supplied to the second antenna element; 
 comparing the third and the fourth magnitudes; 
 detecting a change in a second operating frequency of the second antenna element based on a difference between the third and the fourth magnitudes; and 
 directing the second aperture tuner to adjust the second operating frequency of the second antenna element to counter the change in the second operating frequency of the second antenna element. 
   
     
     
         20 . The antenna structure of  claim 17 , wherein the first antenna element and the second antenna element 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 near field sensor coupled to the antenna structure; and   a circuit coupled to the antenna structure 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;   obtaining a second magnitude of a signal supplied to the antenna structure by a transmitter circuit;   comparing the first and the second magnitudes;   detecting an offset in an operating frequency of the antenna structure based on a difference between the first and the second magnitudes; and   adjusting the operating frequency of the antenna structure to mitigate the offset.   
     
     
         22 . The communication device of  claim 21 , wherein the operating 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 is modified 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 , further comprising a directional coupler for obtaining the second magnitude of the signal supplied to the antenna structure by the transmitter circuit. 
     
     
         25 . The communication device of  claim 21 , wherein the communication device comprises one of a cellular telephone or a wireless access point, and wherein the second magnitude is obtained from a look-up table.