Antenna structures and methods thereof

Abstract

A system that incorporates the subject disclosure may include, for example, a circuit for measuring from a near field sensor a first signal representing radiated energy from an antenna structure, measuring from a probe a second signal supplied to the antenna structure, determining a phase differential from a first phase of the first signal and a second phase of the second signal, detecting a frequency offset of the antenna structure based on the phase differential, and adjusting an operating frequency of the antenna structure to mitigate the frequency offset. Other embodiments are disclosed.

What is claimed is: 
     
         1 . A method, comprising:
 measuring, by a circuit, from a first probe a first phase of radiated energy by an antenna, wherein the first probe is placed near the antenna;   measuring, by the circuit, from a second probe a second phase of a transmit signal supplied to the antenna, wherein the second probe is placed in a transmission path of the transmit signal;   comparing, by the circuit, the first and the second phases to generate a phase differential;   detecting, by the circuit, an offset in an operating frequency of the antenna based on the phase differential; 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 detecting of the offset in the operating frequency comprises determining the offset according to a reactive profile of the antenna and the phase differential. 
     
     
         3 . The method of  claim 2 , further comprising retrieving the reactive profile of the antenna from a look-up table. 
     
     
         4 . The method of  claim 3 , wherein the frequency of the antenna is adjusted by modifying an electrical length of the antenna, wherein the difference between the first and the second phases is proportional to the offset in the operating frequency of the antenna, wherein the second probe comprises a directional coupler, and 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 third 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 phases of the radiated energy from the plurality of near field probes; and   monitoring the plurality of phases measured to improve an accuracy of one of the comparing step, the detecting step, the adjusting step, or any combination thereof.   
     
     
         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 a signal 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;   a first aperture tuner for adjusting an operating frequency of the antenna element;   a probe; and   a first near field sensor for sensing radiated energy from the first antenna element, wherein the first near field sensor and the first aperture tuner are coupled to a circuit that performs operations comprising:
 measuring from the first near field sensor a first phase of radiated energy by the first antenna element; 
 measuring from the probe a second phase of a first signal supplied to the first antenna element; 
 comparing the first and the second phases to generate a first phase differential; 
 detecting a change in an operating frequency of the first antenna element based on the phase differential; and 
 directing the first aperture tuner to adjust the operating frequency of the first antenna element according to the first phase differential. 
   
     
     
         12 . The antenna structure of  claim 11 , wherein the probe comprises a directional coupler coupled to a path that supplies the first signal to the first antenna element. 
     
     
         13 . The antenna structure of  claim 11 , wherein the detecting of the change in the operating frequency of the first antenna element comprises determining the change in the operating frequency of the first antenna element according to a reactive profile of the antenna. 
     
     
         14 . The antenna structure of  claim 13 , further comprising retrieving the reactive profile from a look-up table. 
     
     
         15 . The antenna structure of  claim 14 , wherein the look-up table is indexed according the operating frequency of the first antenna element. 
     
     
         16 . The antenna structure of  claim 11 , wherein the first antenna element is adjusted by modifying an electrical length of the antenna element using the first aperture tuner, and wherein the first phase differential 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 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 phase of radiated energy by the second antenna element; 
 measuring a fourth phase of a second signal supplied to the second antenna element; 
 comparing the third and the fourth phases to generate a second phase differential; 
 detecting a change in a second operating frequency of the second antenna element based on the second differential phase; and 
 directing the second aperture tuner to adjust the second operating frequency of the second antenna element according to the second phase differential. 
   
     
     
         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;   a probe; and   a circuit coupled to the near field sensor and probe, wherein the circuit performs operations comprising:   measuring from the near field sensor a first signal representing radiated energy from the antenna structure;   measuring from the probe a second signal supplied to the antenna structure;   determining a phase differential from a first phase of the first signal and a second phase of the second signal;   detecting a frequency offset of the antenna structure based on the phase differential; and   adjusting an operating frequency of the antenna structure to mitigate the frequency offset.   
     
     
         22 . The communication device of  claim 21 , wherein the operating frequency of the antenna structure is adjusted 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 , wherein the probe comprises a directional coupler coupled to a signal path of the signal. 
     
     
         25 . The communication device of  claim 21 , wherein the communication device comprises one of a cellular telephone or a wireless access point.