Patent Publication Number: US-6982672-B2

Title: Multi-band antenna and system for wireless local area network communications

Description:
TECHNICAL FIELD 
   Embodiments of the present invention pertain to antennas, and in some embodiments, to wireless local area networks. 
   BACKGROUND 
   Communication stations for wireless local area networks (WLANs) may communicate in different frequency bands depending on, for example, the region they are to be used in. For example, in the United States, a communication station may communicate in one or more certain frequency bands, while in Europe; a communication station may communicate in certain different frequency bands. In other regions, communication stations may communicate in yet different frequency bands. Conventionally, multiple antennas are provided for these different regions. These multi-antenna approaches are costly and require interface circuitry. Thus there are general needs for multi-band antenna suitable for use in WLANs operable more than one region and/or more than one frequency band. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The appended claims are directed to some of the various embodiments of the present invention. However, the detailed description presents a more complete understanding of embodiments of the present invention when considered in connection with the figures, wherein like reference numbers refer to similar items throughout the figures and: 
       FIG. 1A  illustrates a cross-sectional view of an antenna in accordance with some embodiments of the present invention; 
       FIG. 1B  illustrates a first conductive layer of an antenna in accordance with some embodiments of the present invention; 
       FIG. 1C  illustrates a second conductive layer of an antenna in accordance with some embodiments of the present invention; 
       FIG. 1D  illustrates a third conductive layer of an antenna in accordance with some embodiments of the present invention; and 
       FIG. 2  illustrates a block diagram of a communication station in accordance with some embodiments of the present invention. 
   

   DETAILED DESCRIPTION 
   The following description and the drawings illustrate specific embodiments of the invention sufficiently to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Examples merely typify possible variations. Individual components and functions are optional unless explicitly required, and the sequence of operations may vary. Portions and features of some embodiments may be included in or substituted for those of others. The scope of embodiments of the invention encompasses the full ambit of the claims and all available equivalents of those claims. Such embodiments of the invention may be referred to, individually or collectively, herein by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any single invention or inventive concept if more than one is in fact disclosed. 
     FIG. 1A  illustrates a cross-sectional view of antenna  100  in accordance with some embodiments of the present invention.  FIG. 1B  illustrates a first conductive layer of antenna  100  in accordance with some embodiments of the present invention.  FIG. 1C  illustrates a second conductive layer of antenna  100  in accordance with some embodiments of the present invention.  FIG. 1D  illustrates a third conductive layer of antenna  100  in accordance with some embodiments of the present invention. Antenna  100  includes first conductive layer  102  comprising one or more parasitic patches  112  and  114 , second conductive layer  104  comprising a plurality of radiating patches  116 ,  118  and  120 , and third conductive layer  106  comprising ground patch  134 . The first and second conductive layers may be separated by first substrate layer  108 , and the second and third conductive layers may be separated by substrate layer  110 . In some embodiments, second conductive layer  104  may include first radiating patch  116  and second radiating patches  118 ,  120 . 
   First radiating patch  116  may have dimensions selected to radiate radio-frequency (RF) signals within a first frequency spectrum. Second radiating patches  118 ,  120  may have dimensions selected to radiate RF signals within a second frequency spectrum. In some embodiments, the first frequency spectrum may be a 5 GHz frequency spectrum and the second frequency spectrum may be a 2.4 GHz frequency spectrum. In some embodiments, the 2.4 GHz spectrum may include a frequency band ranging from approximately 2.4 to 2.5 GHz, and the 5 GHz frequency spectrum may include three frequency bands between approximately 5.1 to 5.9 GHz, although the scope of the invention is not limited in this respect. 
   Parasitic patches  112  and  114  may be electrically isolated from second conductive layer  104  and third conductive layers  106 . During operation of antenna  100 , parasitic patches  112  and  114  may couple energy radiated either to or from radiating patches  116 ,  118  and  120 . 
   In some embodiments, radiating patches  116 ,  118  and  120  may be electrically coupled together and may have single feeding point  122  electrically coupling radiating patches  116 ,  118  and  120  to feed conductor  124 . Feed conductor  124  may be almost any type of conductor including a wire or coaxial cable center conductor. Feed conductor  124  may be provided through second substrate layer  110  and through third conductive layer  106  as illustrated in  FIG. 1A . 
   In some embodiments, radiating patches  116 ,  118  and  120  may have one or more grounding points  126  electrically coupling radiating patches  116 ,  118  and  120  to third conductive layer  106  by one or more conductive paths  128  provided through second substrate layer  110 . Conductive paths  128  may comprise plated thru-vias or pins, although the scope of the invention is not limited in this respect. In some embodiments, feeding point  122  may be located at a first location on one of radiating patches  116 ,  118  and  120 , and grounding points  126  may be located at second locations on one or more of radiating patches  116 ,  118  and  120 . 
   In some embodiments, a center conductor of coaxial cable  130  may serve as feed conductor  124  and may be coupled to feeding point  122 . In these embodiments, outer conductor  132  of coaxial cable  130  may be coupled to third conductive layer  106 . In some embodiments, feed conductor  124  may be coupled to a wireless network communication station to receive radio frequency RF signals in at least one frequency spectrum from the antenna  100 . In these embodiments, feed conductor  124  may also provide RF signals in the frequency spectrums to antenna  100  for transmission. 
   In some embodiments, third conductive layer  106  may substantially comprise ground patch  134 . In other words, ground patch  134  may comprise most or all of third conductive layer  106 , although the scope of the present invention is not limited in this respect. In some embodiments, third conductive layer  106  may comprise one or more slots  136  within the conductive material of ground patch  134 . 
   In some embodiments, substrate layers  108  and  110  may comprise an organic substrate material. In other embodiments, substrate layers  108  and  110  may comprise an inorganic substrate material. Suitable organic substrate materials may include polytetrafluoroethylene (PTFE) composite laminates; however other organic substrate materials including flexible and rigid organic materials including laminate materials such as FR4 and FR5, and resins, such as Bismaleimide Triazine (BT) may be suitable. Suitable inorganic substrate materials include ceramic materials. In some embodiments, substrate layers  108  and  110  may comprise a material such as polyethylene, although the scope of the invention is not limited in this respect. 
   In some embodiments, substrate layers  108  and  110  may have a dielectric constant (Er) ranging from 1 to 4; however this is not a requirement. In some embodiments, substrate layers  108  and  110  may have a dielectric constant of approximately 2.3, although the scope of the invention is not limited in this respect. In some embodiments, substrate layers  108  and  110  may have a loss tangent (D) of approximately 0.01, although the scope of the invention is not limited in this respect. In some embodiments, substrate layers  108  and  110  may have thicknesses  138  ranging from 4 mm to 6 mm, although other thicknesses for substrate layers  108  and  110  may also be suitable. 
   In some embodiments, the 2.4 GHz frequency spectrum comprises a first frequency band ranging from approximately 2.4 to 2.5 GHz. In some embodiments, the 5 GHz frequency spectrum comprises a second frequency band ranging from approximately 5.15–5.35, a third frequency band ranging from approximately 5.47–5.725, and a fourth frequency band ranging from approximately 5.727–5.875, although the scope of the present invention is not limited in these respects. In these embodiments, antenna  100  may be referred to as a multi-band or quad-band antenna. 
   In some embodiments, parasitic patch  114  may have dimensions of approximately 3 mm×3.5 mm, and parasitic patch  112  may have dimensions of approximately 1 mm×2 mm, although the scope of the present invention is not limited in this respect. In some embodiments, radiating patch  116  may be substantially rectangular and may have dimensions of approximately 3.5 mm×12 mm, and radiating patches  118  and  120  may be substantially rectangular and may have dimensions of approximately 3.5 mm×12 mm, although the scope of the present invention is not limited in this respect. In some embodiments, ground patch  134  may have dimensions of approximately 24 mm×30 mm, although the scope of the present invention is not limited in these respects. Although in some embodiments, radiating patches  116 ,  118  and  120  may each have approximately the same dimensions, radiating patches  118  and  120  may together operate to radiate signals in a lower frequency spectrum, such as the second frequency spectrum. 
   In some embodiments, parasitic patches  112  and  114 , radiating patches  116 ,  118  and  120  and ground patch  134  may comprise a conductive material such as gold, copper, tungsten, silver, brass, aluminum or steel, including alloys thereof, although the scope of the present invention is not limited in this respect. Other conductive materials may also be suitable. 
   The performance of antenna  100  may be based on the dielectric constant of substrate layers  108  and  110  and the thickness of substrate layers  108  and  110 . The performance of antenna  100  may further be based on the location of feeding point  122 , the locations of grounding points  126  and the number of grounding points  126 . The performance of antenna  100  may further be based on the number of parasitic patches  112  and  114  on layer  102  and the size and location of the parasitic patches. The performance of antenna  100  may further be based on the length and width of radiating patches  116 ,  118  and  120  as well as the distance between radiating patches  116 ,  118  and  120 . The performance of antenna  100  may further be based on the size of ground patch  134 , the number of slots  136 , the position of slots  136 , and the length and width of slots  136 . Other factors may also influence the performance of antenna  100 . By properly choosing these antenna parameters, those of ordinary skill in the art may achieve, for example, a reflection coefficient at feeding point  122  of greater than −10 dB in the first, second, third and fourth frequency bands, although the scope of the present invention is not limited in this respect. By properly choosing these antenna parameters, acceptable antenna gain may also be achieved at least in the first, second, third and fourth frequency bands, although the scope of the present invention is not limited in this respect. 
   Although embodiments of the present invention are illustrated with two parasitic patches, this is not a requirement. Other numbers of parasitic patches may be used. The actual number of parasitic patches may be determined by trial and error. 
   In some embodiments, conventional printed layer circuit board (PCB) techniques may be used to manufacture antenna  100 , although the scope of the invention is not limited in this respect. In some embodiments, the dimensions of the patches may be precisely manufactured using techniques, such as photolithography, although the scope of the invention is not limited in this respect. 
   In some embodiments, the plurality of radiating patches on second conductive layer  104  may cumulatively define the frequency spectrums of operation. 
   In some embodiments, antenna  100  may be a multi-layer, multi-band antenna. In these embodiments, antenna  100  comprises first conductive layer  102  comprising one or more parasitic patches  112  and  114 , second conductive layer  104  comprising a plurality of radiating patches  116 ,  118  and  120 , and third conductive layer  106  comprising ground patch  134 . First substrate layer  108  separates first and second conductive layers  102  and  104  and second substrate layer  110  separates second and third conductive layers  104  and  106 . Parasitic patches  112  and  114  may be electrically isolated from the second and third conductive layers, and radiating patches  116 ,  118  and  120  may be electrically coupled and may have single feeding point  122  to electrically couple radiating patches  116 ,  118  and  120  to feed conductor  124 . 
   In some embodiments, a multi-layer circuit board is provided. In these embodiments, the multi-layer circuit board may provide one or more antennas, such as one or more of antenna  100 . In these embodiments, the multi-layer circuit board may comprise, for each of the one or more antennas, one or more parasitic patches  112  and  114  disposed on first substrate layer  108 , a plurality of radiating patches  116 ,  118  and  120  disposed on second substrate layer  110 , and ground patch  134  disposed on second substrate layer  110  on a side opposite radiating patches  116 ,  118  and  120 . In these embodiments, for each of the one or more antennas, a center conductor of a coaxial cable may be coupled to a feeding point and an outer conductor of the coaxial cable may be coupled to the ground patch. 
   In some embodiments, antenna  100  may be a first multi-band antenna of the multi-layer circuit board. In these embodiments, the circuit board may further comprise a second multi-band antenna which may comprise a second one or more parasitic patches disposed on the first substrate layer, a second plurality of radiating patches disposed on the second substrate layer, and a second ground patch disposed on the second substrate layer on the side opposite the second radiating patches. In some embodiments, the ground patches may be shared among the antennas of the circuit board. 
     FIG. 2  is a block diagram of a communication station in accordance with some embodiments of the present invention. Communication station  200  may be a wireless communication device and may transmit and/or receive wireless communications signals with transmitter circuitry  202  and/or receiver circuitry  204  using one or more antennas  206 . Antenna  100  ( FIGS. 1A through 1D ) is an example of an antenna that may be suitable for use as one or more of antennas  206 . 
   Signal processing circuitry  208  may process digital signals provided by receiver circuitry  204 . Signal processing circuitry  208  may also provide digital signals to transmitter circuitry  202  for transmission by one or more of antennas  206 . In some embodiments, receiver circuitry  204  and transmitter circuitry  202  may be cumulatively referred to as transceiver circuitry. 
   In some embodiments, communication station  200  may be referred to as a receiving station, and in some embodiments, communication station  200  may be referred to as a transmitting station. In some embodiments, communication station may communicate orthogonal frequency division multiplexed (e.g., OFDM) communication signals with one or more other communication stations as described in more detail below. 
   In some embodiments, communication station  200  may communicate with one or more other communication stations over an OFDM communication channel. In some embodiments, the OFDM communication channel may comprise either a standard-throughput channel or a high-throughput communication channel. In these embodiments, the standard-throughput channel may comprise one subchannel and the high-throughput channel may comprise a combination of one or more subchannels and one or more spatial channels associated with each subchannel. Spatial channels may be non-orthogonal channels associated with a particular subchannel. 
   The subchannels may be frequency-division multiplexed (i.e., separated in frequency with other subchannels) and may be within a predetermined frequency spectrum. The subchannels may comprise a plurality of orthogonal subcarriers. In some embodiments, the orthogonal subcarriers of a subchannel may be closely spaced OFDM subcarriers. To achieve orthogonality between closely spaced subcarriers, in some embodiments, the subcarriers of a particular subchannel may have null at substantially a center frequency of the other subcarriers of that subchannel. 
   In some embodiments, a high-throughput communication channel may comprise a wideband channel having up to four frequency separated subchannels, a multiple-input-multiple-output (MIMO) channel comprising a single subchannel having up to four spatial channels, or a wideband-MIMO channel comprising two or more frequency separated subchannels where each subchannel has two or more spatial channels. In these embodiments, a wideband channel may have a wideband channel bandwidth of up to 80 MHz and may comprise up to four of the subchannels, although the scope of the invention is not limited in this respect. The subchannels may have a subchannel bandwidth of approximately 20 MHz, although the scope of the invention is not limited in this respect. 
   In some embodiments, communication station  200  may comprise more than one of antennas  206  to communicate over more than one spatial channel within a subchannel and/or more than one subchannel. In these embodiments, the OFDM communication channel may be a high-throughput communication channel. 
   In some embodiments, the frequency spectrums for an OFDM communication channel may comprise subchannels in either a 5 GHz frequency spectrum or a 2.4 GHz frequency spectrum. In these embodiments, the 5 GHz frequency spectrum may include frequency bands from approximately 4.9 to 5.9 GHz, and the 2.4 GHz spectrum may include a frequency band ranging from approximately 2.4 to 2.5 GHz, although the scope of the invention is not limited in this respect, as other frequency spectrums may be equally suitable. 
   In some embodiments, communication station  200  may be a personal digital assistant (PDA), a laptop or portable computer with wireless-networking communication capability, a web tablet, a wireless telephone, a wireless headset, a pager, an instant messaging device, a digital camera, an access point or other device that may receive and/or transmit information wirelessly. In some embodiments, communication station  200  may transmit and/or receive radio-frequency (RF) communications in accordance with specific communication standards, such as the Institute of Electrical and Electronics Engineers (EEE) standards including EEE 802.11(a), 802.11(b), 802.11(g/h), and/or 802.11 (n) standards for wireless local area networks. In other embodiments, communication station  200  may transmit and/or receive communications in accordance with other techniques including the Digital Video Broadcasting Terrestrial (DVB-T) broadcasting standard, and the High performance radio Local Area Network (HiperLAN) standard. 
   Although communication station  200  is illustrated as having several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including digital signal processors (DSPs), and/or other hardware elements. For example, the circuitry illustrated may comprise processing elements which may comprise one or more microprocessors, DSPs, application specific integrated circuits (ASICs), and combinations of various hardware and logic circuitry for performing at least the functions described herein. 
   The Abstract is provided to comply with 37 C.F.R. Section 1.72(b) requiring an abstract that will allow the reader to ascertain the nature and gist of the technical disclosure. It is submitted with the understanding that it will not be used to limit or interpret the scope or meaning of the claims. 
   In the foregoing detailed description, various features are occasionally grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the subject matter require more features than are expressly recited in each claim. Rather, as the following claims reflect, invention lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment.