Abstract:
A compressed multiple band loop antenna that has multiple superimposed compressed loops. Each compressed loop is formed from numerous segments arrayed in multiple diverse directions so that the enclosed area of that loop and the overall size of the antenna are decreased. Multiple loops are arrayed and superimposed to provide multiple frequency bands of operation and are used to broaden the useful bandwidth of individual-bands. The small size of the compressed antenna facilitates its use in small mobile communications devices requiring internal antennas that operate in close proximity to conductive surfaces. Multiple loops are arrayed in several configurations that include nested and non-nested loops as well as closely located and spatially separated superimposed loops.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to the field of communication devices that communicate using radiation of electromagnetic energy and particularly relates to antennas and antenna connections for such communication devices, particularly for communication devices carried by persons or otherwise benefitting from small-sized antennas.  
           [0002]    Communication Antennas Generally. In communication devices and other electronic devices, antennas are elements having the primary function of transferring energy to or from the electronic device through radiation. Energy is transferred from the electronic device into space or is received from space into the electronic device. A transmitting antenna is a structure that forms a transition between guided waves contained within the electronic device and space waves traveling in space external to the electronic device. A receiving antenna is a structure that forms a transition between space waves traveling external to the electronic device and guided waves contained within the electronic device. Often the same antenna operates both to receive and transmit radiation energy.  
           [0003]    J. D. Kraus “Electromagnetics”, 4th ed., McGraw-Hill, New York 1991, Chapter 15 Antennas and Radiation indicates that antennas are designed to radiate (or receive) energy. Antennas act as the transition between space and circuitry. They convert photons to electrons or vice versa. Regardless of antenna type, all involve the same basic principal that radiation is produced by accelerated (or decelerated) charge. The basic equation of radiation may be expressed as follows: 
             IL=Q ν( Am/s ) 
           [0004]    where:  
           [0005]    I=time changing current (A/s)  
           [0006]    L=length of current element (m)  
           [0007]    Q=charge (C)  
           [0008]    ν=time-change of velocity which equals the acceleration of the charge (m/s)  
           [0009]    The radiation is perpendicular to the direction of acceleration and the radiated power is proportional to the square of IL or Qν.  
           [0010]    A radiated wave from or to an antenna is distributed in space in many spatial directions. The time it takes for the spatial wave to travel over a distance r into space between an antenna point, P a , at the antenna and a space point, P, at a distance r from the antenna point is r/c seconds where r=distance (meters) and c=free space velocity of light (=3×10 8  meters/sec). The quantity r/c is the propagation time for the radiation wave between the antenna point P a  and the space point P s .  
           [0011]    An analysis of the radiation at a point P at a time t, at a distance r caused by an electrical current I in any infinitesimally short segment at point P a  of an antenna is a function of the electrical current that occurred at an earlier time [t−r/c] in that short antenna segment. The time [t−r/c] is a retardation time that accounts for the time it takes to propagate a wave from the antenna point P a  at the antenna segment over the distance r to the space point P.  
           [0012]    For simple antenna geometries, antennas are typically analyzed as a connection of infinitesimally short radiating antenna segments and the accumulated effect of radiation from the antenna as a whole is analyzed by accumulating the radiation effects of each antenna segment. The radiation at different distances from each antenna segment, such as at any space point P s , is determined by accumulating the effects from each infinitesimally short antenna segment at point P a  of the antenna at the space point P. The analysis at each space point P is mathematically complex because the parameters for each segment of the antenna may be different. For example, among other parameters, the frequency phase of the electrical current in each antenna segment and distance from each antenna segment to the space point P can be different.  
           [0013]    A resonant frequency, f, of an antenna can have many different values as a function, for example, of dielectric constant of material surrounding antenna, the type of antenna and the speed of light.  
           [0014]    In general, wave-length, λ, is given by λ=c/f=cT where c=velocity of light (=3×10 8  meters/sec), f=frequency (cycles/sec), T=1/f=period (sec). Typically, the antenna dimensions such as antenna length, A l , relate to the radiation wavelength λ of the antenna. The electrical impedance properties of an antenna are allocated between a radiation resistance, R r , and an ohmic resistance, R o . The higher the ratio of the radiation resistance, R r , to the ohmic resistance, R o  the greater the radiation efficiency of the antenna.  
           [0015]    Antennas are frequently analyzed with respect to the near field and the far field where the far field is at locations of space points P where the amplitude relationships of the fields approach a fixed relationship and the relative angular distribution of the field becomes independent of the distance from the antenna.  
           [0016]    Antenna Types. A number of different antenna types are well known and include, for example, loop antennas, small loop antennas, dipole antennas, stub antennas, conical antennas, helical antennas and spiral antennas. Such antenna types have often been based on simple geometric shapes. For example, antenna designs have been based on lines, planes, circles, triangles, squares, ellipses, rectangles, hemispheres and paraboloids. The two most basic types of electromagnetic field radiators are the magnetic dipole and the electric dipole. Small antennas, including loop antennas, often have the property that radiation resistance, R r , of the antenna decreases sharply when the antenna length is shortened. Small loops and short dipoles typically exhibit radiation patterns of ½λ and ¼λ, respectively. Ohmic losses due to the ohmic resistance, R o  are minimized using impedance matching networks. Although impedance matched small circular loop antennas can exhibit 50% to 85% efficiencies, their bandwidths have been narrow, with very high Q, for example, Q&gt;50. Q is often defined as (transmitted or received frequency)/(3 dB bandwidth).  
           [0017]    An antenna goes into resonance where the impedance of the antenna is purely resistive and the reactive component goes to 0. Impedance is a complex number consisting of real resistance and imaginary reactance components. A matching network can be used to force resonance by eliminating the reactive component of impedance for a particular frequency.  
           [0018]    Electric Dipole. A linear antenna is often considered as a large number of very short conductor elements connected in series. For purpose of explanation, the minimum element of linear antenna is a short electric dipole (see FIG. 6). The electric dipole is “short” in the sense that its physical length (L) is much smaller than the wavelength (λ) of the signal exciting it, that is, L/λ&lt;&lt;1. For purpose of analysis, the two ends of a electric dipole are considered plates with capacitive loading. These plates and the L&lt;&lt;λ condition, provide a basis for assuming a uniform electric current I along the entire length of the electric dipole. Also, the electric dipole is assumed to be energized by a balanced transmission line, is assumed to have negligible radiation from the end plates, and is assumed to have a very thin diameter, d, that is, d&lt;&lt;L, such that the electric dipole consists simply of a thin conductor of length L carrying a uniform current I with point charges +q and −q at the ends. With such an assumed structure, the current I and charge q are related by:  
              q          t       =   I                         
 
           [0019]    For any point P a  on the electric dipole, the electric and magnetic fields at a point P a distance r from the point P a  as a result of the uniform electric current I through the element are represented as vector components in a spherical polar coordinate system having orthogonal XYZ axes (see FIG. 6 and FIG. 7). For an electric dipole normal to the XY plane, the projection of the vector r in the XY-plane has an angle of φ with respect to the XZ plane and an angle of θ from the Z axis normal to the XY plane.  
           [0020]    The general equation of both electric (E r , E θ , E φ ) and magnetic (H r , H θ , H φ ) components at point P, offset from point P a  by vector r, are as follows:  
         E   r     =           [   I   ]        L                 cos                 θ       2      π                 ɛ            (       1     c                   r   2         +     1     j                 ω                   r   2           )                 E   θ     =           [   I   ]        L                 sin                 θ       2                 π                 ɛ            (         j                 ω         c   2        r       +     1     c                   r   2         +     1     j                 ω                   r   3           )                 H   φ     =           [   I   ]        L                 sin                 θ       4      π            (         j                 ω       c                 r       +     1     r   2         )                             
 
           [0021]    where components E φ , H r , H θ  are zero for every P and  
           [0022]    where:  
           [0023]    [I]=I o e jω(t−r/c)    
           [0024]    I o =Peak value in time of current (uniform along dipole)  
           [0025]    c=Velocity of light  
           [0026]    L=Length of dipole  
           [0027]    r=Distance from dipole to observation point  
           [0028]    Considering the above equations, the 1/r 2  term is called the induction field or intermediate field component and the 1/r 3  term represents the electrostatic field or near field component. These two terms are significant only very close to the dipole and therefore are considered in the near field region of the antenna. For very large r, the 1/r 2  and 1/r 3  terms can be neglected leaving only the 1/r term as being significant. This 1/r terms is called the far field. Consequently, the revised equations of electric and magnetic components at the far field are given as:  
         E   r     =   0             E   θ     =         j                 60                   π        [   I   ]          sin                 θ     r          L   λ                 H   φ     =           j        [   I   ]          sin                 θ       2      r            L   λ                             
 
           [0029]    Examining the E θ  and H φ  components in the far field, it can be seen that E θ  and H φ  are in time phase (with respect to each other) in the far field, and that the field patterns of both are proportional to sin(θ) but independent of φ. The space patterns of those fields are a figure of revolution and doughnut-shaped in three dimensions (see FIG. 10) figure-8 shaped in two dimensions (see FIG. 11). Note that the near field patterns for E θ  and H φ  are proportional to only sin(θ); so, the shapes of the near field patterns are the same as for the far field and that the E r  component in the near field is proportional to cos θ.  
           [0030]    Magnetic Dipole. A magnetic dipole is the dual of the electric dipole and hence an analogy to the electric dipole can be used for purpose of analysis. A magnetic dipole is a short circular antenna element arrayed to form a magnetic field and is represented by a very short loop (see FIG. 8) in the XY-plane. For purpose of analysis, the magnetic dipole conducts an electric current I that causes a magnetic current (I m ) normal to the plane of the magnetic dipole. The magnetic current (I m ) of the magnetic dipole is the dual of the electric current (I) of the electric dipole. The analysis of the far field pattern of a magnetic dipole (see FIG. 8) is similar to the analysis of the far field pattern of the electric dipole. The only difference is that the electric current I is replaced by a magnetic current I m  and the electric field is replaced by magnetic field.  
           [0031]    For purpose of analysis, the magnetic dipole is a small loop of area A carrying a uniform in-phase electric current I which is the dual of the electric dipole of length L in the far field. The fields of the short magnetic dipole are the same as the fields of a short electric dipole with the E and H fields and I and I m  currents interchanged as follows:  
                                                         Small Electric Dipole   Small Magnetic Dipole                                                     E   θ     =         j60                   π        [   I   ]                     sin                 θ     r                     L   λ                                           H   θ     =           j              [     I   m     ]        sin                 θ       240                 πr            L   λ                                                               H   φ     =           j        [   I   ]                     sin                 θ       2      r                       L   λ                                           E   φ     =           j              [     I   m     ]                   sin                 θ       2      r            L   λ                                                                        where              [     I   m     ]     =       I   mo               j                   ω        (     t   -     r   /   c       )                                              
 
           [0032]    Considering the equation of far field pattern for magnetic dipole, both H θ  and E φ  are proportional to sin(θ) but independent of φ. Consequently, the far field pattern of the H θ  and E φ  components of a magnetic dipole are doughnut-shaped in three dimensions (see FIG. 10) and figure-8 circular in cross section (see FIG. 11).  
           [0033]    Applying Relationship Between a Loop and Magnetic Dipole. The relationship between the length of magnetic dipole and a small loop antenna are used to derive the far field pattern equation of a small loop antenna. Accordingly, [I m ]L=−j240[I] is used in the above far-field equation for a small magnetic dipole and the far field equations of a small loop antenna are written as:  
         E   φ     =         120                     π   2          [   I   ]          sin                 θ     r          A     λ   2                   H   θ     =           [   I   ]        sin                 θ     r                     A     λ   2                               
 
           [0034]    where  
           [0035]    [I]=I o e jω(t−r/c)    
           [0036]    I o =Peak value in time of current (uniform along dipole)  
           [0037]    c=Velocity of light  
           [0038]    A=Area of loop antenna  
           [0039]    r=Distance from Loop to observation point  
           [0040]    The above far field equations are good approximations for loops up to 0.1 wavelength in diameter and dipoles up to 0.1 wavelength long. A comparison of far fields between small electric dipoles and small loop antennas are given in the following table:  
                                       Field   Electric dipole   Loop Antenna                                   Electric component             E   θ     =         j60                   π        [   I   ]                     sin                 θ     r                     L   λ                                           E   φ     =         120          π   2          [   I   ]                     sin                 θ     r                     A     λ   2                                               Magnetic component             H   φ     =           j        [   I   ]                     sin                 θ       2      r                       L   λ                                           H   θ     =           [   I   ]                   sin                 θ     r                     A     λ   2                                                  
 
           [0041]    From the table, the presence of the operator j in the dipole expressions and its absence in the loop equations indicate that the fields of the electric dipole and of the loop are in time phase quadrature. This quadrature relationship is a fundamental difference between the fields of pure magnetic dipoles (circular loops) and electric dipoles (linear elements).  
           [0042]    The analytical models for showing the fields of antennas that are larger than short dipoles are mathematically complex even when the antennas have a high degree of symmetry. Even more difficulty of analysis arises when antennas have irregular shapes and require operations over multiple bands or with high bandwidth.  
           [0043]    In the mobile communications environment, antennas are frequently placed inside the case of the communication device in close proximity to conductive components. In such close proximity, the antenna near and intermediate fields become significant and cannot be neglected to determine far field radiation patterns. For these reasons, the analytical models for short dipoles do not adequately predict the behavior of antennas needed for new communication devices. Fundamentally new designs and design techniques are needed to address the new environment of personal or otherwise small communication devices.  
           [0044]    Personal communication devices, when in use, are usually located close to an ear or other part of the human body. Accordingly, use of personal communication devices subjects the human body to radiation. The radiation absorption from a communication device is measured by the rate of energy absorbed per unit body mass and this measure is known as the specific absorption rate (SAR). Antennas for personal communication devices are designed to have low peak SAR values so as to avoid absorption of unacceptable levels of energy, and the resultant localized heating by the body.  
           [0045]    For personal communication devices, the human body is located in the near-field of an antenna where much of the electromagnetic energy is reactive and electrostatic rather than radiated. Consequently, it is believed that the dominant cause of high SAR for personal communication devices is from reactance and electric field energy of the near field. Accordingly, the reactance and electrostatic fields of personal communication devices need to be controlled to minimize SAR. Regardless of the reasons, low SAR is a desirable parameter along with the other important parameters for antennas in communication devices.  
           [0046]    In consideration of the above background, there is a need for improved antennas suitable for communication devices and other devices needing small and compact antennas.  
         SUMMARY  
         [0047]    The present invention is a multiband antenna formed of superimposed compressed loops for use with a wireless communication device which operates for exchanging energy in bands of radiation frequencies. The compressed antenna includes connection means for conduction of electrical current through two or more superimposed compressed loops. Each compressed loop includes a plurality of electrically conducting segments, each segment having a segment length, where the segments are electrically connected in series to the connection means to form a loop antenna for exchange of energy in one of the bands of radiation frequencies. The segments for each of the loops are arrayed in a compressed pattern and the loops are superimposed whereby an area enclosed by one of the compressed loops covers an area enclosed by another of the compressed loops.  
           [0048]    For each compressed loop, the segments are arrayed in multiple diverse directions. The pattern formed by the antenna segments may be regular and repeating or may be irregular and non-repeating. Collectively the arrayed segments appreciable increase antenna electrical lengths while permitting the antenna to be compressed to fit within the available areas of communication devices.  
           [0049]    The multiple compressed loops provide multiple frequency bands of operation for the antenna. The multiple loops are arrayed in different configurations that include nested and and non-nested loops as well as closely located and spatially separated loops. The loops are constructed from multilayer materials that include a non-conductive substrate and one or more conducting layers.  
           [0050]    Although the antenna&#39;s electrical length is not small compared to λ, the near field portions of the reactive field and the electrical field tend to be low whereby the SAR values for the compressed loop antenna tend to be low.  
           [0051]    The multiple loops are connected in common to the connection element, either directly by electrical connection and/or by capacitive coupling.  
           [0052]    The arrayed-segment loop antennas are typically located internal to the housings of personal communicating devices where they tend to be susceptible to de-tuning due to objects in the near field in close proximity to the personal communicating devices. The multi-loop antenna with multiple layers providing mirroring and reference planes tends to increase the immunity to de-tuning.  
           [0053]    The foregoing and other objects, features and advantages of the invention will be apparent from the following detailed description in conjunction with the drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0054]    [0054]FIG. 1 depicts a wireless communication device having a compressed antenna.  
         [0055]    [0055]FIG. 2 depicts a schematic, cross-sectional end view of the FIG. 1 communication device.  
         [0056]    [0056]FIG. 3 depicts a perspective view of a multi-loop compressed antenna used in the communication device of FIG. 1 and FIG. 2.  
         [0057]    [0057]FIG. 4 depicts a cross-sectional view of one element of the multi-loop compressed antenna of FIG. 3.  
         [0058]    [0058]FIG. 5 depicts components of the communication device of FIG. 1 including a connection element connecting an antenna and a transceiver unit.  
         [0059]    [0059]FIG. 6 depicts a short electric dipole element antenna.  
         [0060]    [0060]FIG. 7 depicts a three-dimensional representation of the fields of the short electric dipole element of FIG. 6.  
         [0061]    [0061]FIG. 8 depicts a short loop element.  
         [0062]    [0062]FIG. 9 depicts a three-dimensional representation of the fields of the short loop element of FIG. 8.  
         [0063]    [0063]FIG. 10 depicts a three-dimensional representation of the E θ  and H φ  fields of the short dipole element of FIG. 6 and the E φ  and H θ  fields of the short loop element of FIG. 8.  
         [0064]    [0064]FIG. 11 depicts a two-dimensional representation of the E θ  and H φ  fields of the short dipole element of FIG. 6 and the E φ  and H θ  fields of the short loop element of FIG. 8.  
         [0065]    [0065]FIG. 12 depicts a top view of a four-loop, 6-legged compressed antenna, in a snowflake pattern, for use in a communication device.  
         [0066]    [0066]FIG. 13 depicts a top view of the two-loop, 6-legged compressed antenna similar to the antenna of FIG. 12 together with an additional irregular compressed loop for use in a communication device.  
         [0067]    [0067]FIG. 14 depicts a top view of a two-loop, 2-legged compressed antenna for use in a communication device.  
         [0068]    [0068]FIG. 15 depicts a top view of a one-loop, 3-legged compressed antenna for use together with other loops in a communication device.  
         [0069]    [0069]FIG. 16 depicts a top view of a one-loop, 4-legged compressed antenna for use together with other loops in a communication device.  
         [0070]    [0070]FIG. 17 depicts a top view of a one-loop, 5-legged compressed antenna for use together with other loops in a communication device.  
         [0071]    [0071]FIG. 18 depicts a top view of a one-loop, 6-legged compressed antenna for use together with other loops in a communication device.  
         [0072]    [0072]FIG. 19 depicts a top view of a two-loop, 6-legged compressed antenna, in a snowflake pattern like the antenna of FIG. 12, where each loop has a separate pad for separate electrical connection to the transceiver unit in the communication device of FIG. 1 and FIG. 2.  
         [0073]    [0073]FIG. 20 depicts a top view of a two-loop, 6-legged compressed antenna where the two loops are connected by a transmission line to pads for electrical connection to the transceiver unit in the communication device of FIG. 1 and FIG. 2.  
         [0074]    [0074]FIG. 21 depicts a perspective view of a one-loop, 6-legged compressed antenna mounted on a flexible dielectric substrate for use in a communication device.  
         [0075]    [0075]FIG. 22 depicts a top view of an antenna structure including compressed loops situated above and below a substrate.  
         [0076]    [0076]FIG. 23 depicts a front view of the FIG. 22 antenna including a two-layer antenna structure on opposite sides of a dielectric layer.  
         [0077]    [0077]FIG. 24 depicts a top view of the top layer of a two-loop, 6-legged compressed antenna together with an irregular loop that forms part of the antenna structure of FIG. 22.  
         [0078]    [0078]FIG. 25 depicts a top view of the bottom layer of the antenna structure of FIG. 22.  
         [0079]    [0079]FIG. 26 depicts a top view of the top layer of a two-loop, 6-legged compressed antenna together with an irregular loop, like the antenna structure of FIG. 24, with inter-loop connectors.  
         [0080]    [0080]FIG. 27 depicts a voltage standing wave ration (VSWR) representation of the antenna of FIG. 22 with a FIG. 24 top layer.  
         [0081]    [0081]FIG. 28 depicts a voltage standing wave ration (VSWR) representation of the antenna of FIG. 22 with a FIG. 26 top layer.  
         [0082]    [0082]FIG. 29 depicts a top view of the top layer of a one-loop, 6-legged compressed antenna together with an irregular loop antenna that forms part of a multilayer antenna structure.  
         [0083]    [0083]FIG. 30 depicts a top view of the bottom layer of a one-loop, 6-legged compressed antenna together with an irregular conducting patch that forms part of a multilayer antenna structure with the layer of FIG. 29.  
         [0084]    [0084]FIG. 31 depicts a top view of the top layer of a two-loop, 6-legged compressed antenna together with an irregular loop antenna that forms part of a multilayer antenna structure.  
         [0085]    [0085]FIG. 32 depicts a top view of the bottom layer of a two-loop, 6-legged compressed antenna together with irregular conducting pad that forms with the layer of FIG. 31 a multilayer compressed antenna.  
         [0086]    [0086]FIG. 33 depicts a front view of an antenna including a three-layer antenna structure on opposite sides of a two dielectric layers.  
         [0087]    [0087]FIG. 34 depicts a perspective view the antenna of FIG. 33.  
         [0088]    [0088]FIG. 35 depicts a top view of a top layer including a one-loop, 6-legged compressed antenna together with an irregular one-loop compressed antenna that forms part of a multiband, multilayer compressed antenna.  
         [0089]    [0089]FIG. 36 depicts a top view of a bottom layer including a one-loop, 6-legged compressed antenna together with an irregular conducting pad that forms part of the multiband, multilayer compressed antenna with the antenna of FIG. 35.  
         [0090]    [0090]FIG. 37 depicts a top view of the multiband, multilayer compressed antenna showing the layers of FIG. 35 and FIG. 36 superimposed as they would appear on the top and bottom of a dielectric substrate.  
         [0091]    [0091]FIG. 38 depicts a top view of a top layer including a two-loop, 6-legged compressed antenna together with an irregular one-loop compressed antenna that forms part of a multiband, multilayer compressed antenna.  
         [0092]    [0092]FIG. 39 depicts a top view of a bottom layer including a two-loop, 6-legged compressed antenna together with an irregular conducting pad that forms part of the multiband, multilayer compressed antenna with the antenna of FIG. 38.  
         [0093]    [0093]FIG. 40 depicts a top view of the multiband, multilayer compressed antenna showing the layers of FIG. 38 and FIG. 39 superimposed as they would appear on the top and bottom of a dielectric substrate.  
         [0094]    [0094]FIG. 41 depicts a top view of a top layer including a two-loop, 6-legged compressed antenna together with an irregular two-loop compressed antenna that forms part of a multiband, multilayer compressed antenna.  
         [0095]    [0095]FIG. 42 depicts a top view of a bottom layer including a two-loop, 6-legged compressed antenna together with an irregular conducting pad that forms part of the multiband, multilayer compressed antenna with the antenna of FIG. 41.  
         [0096]    [0096]FIG. 43 depicts a top view of the multiband, multilayer compressed antenna showing the layers of FIG. 41 and FIG. 42 superimposed as they would appear on the top and bottom of a dielectric substrate.  
         [0097]    [0097]FIG. 44 depicts a top view of a top layer including a one-loop, 6-legged compressed antenna together with an irregular one-loop compressed antenna that forms part of a multiband, multilayer compressed antenna.  
         [0098]    [0098]FIG. 45 depicts a top view of a bottom layer including a one-loop, 6-legged compressed antenna together with an irregular conducting pad that forms part of the multiband, multilayer compressed antenna with the antenna of FIG. 35.  
         [0099]    [0099]FIG. 46 depicts a top view of the multiband, multilayer compressed antenna showing the layers of FIG. 44 and FIG. 45 superimposed as they would appear on the top and bottom of a dielectric substrate.  
         [0100]    [0100]FIG. 47 depicts a top view of a top layer including a one-loop, 6-legged compressed antenna together with an irregular one-loop compressed antenna that forms part of a multiband, multilayer compressed antenna.  
         [0101]    [0101]FIG. 48 depicts a top view of a bottom layer including a one-loop, 6-legged compressed antenna together with an irregular conducting pad that forms part of the multiband, multilayer compressed antenna with the antenna of FIG. 35.  
         [0102]    [0102]FIG. 49 depicts a top view of the multiband, multilayer compressed antenna showing the layers of FIG. 47 and FIG. 48 superimposed as they would appear on the top and bottom of a dielectric substrate.  
         [0103]    [0103]FIG. 50 depicts a two-dimensional representation of the field pattern of the antenna structure of FIG. 40 for the GSM 900 MHz and GSM 1800 MHz bands.  
         [0104]    [0104]FIG. 51 depicts a two-dimensional representation of the field pattern of the antenna structure of FIG. 40 for the GSM 900 MHz, GSM 1800 MHz and PCS 1900 MHz bands.  
         [0105]    [0105]FIG. 52 depicts a voltage standing wave ration (VSWR) representation of the antenna of FIG. 40.  
         [0106]    [0106]FIG. 53 depicts a top view of an outer irregular compressed loop with an inner two-loop, 6-legged compressed antenna, similar to the antenna of FIG. 12, together with a separate inner one-loop, 5-legged compressed antenna, similar to the antenna of FIG. 17, for use in a communication device.  
         [0107]    [0107]FIG. 54 depicts a top view of an antenna structure including compressed loops above and below a substrate and is a variant of the FIG. 22 antenna.  
         [0108]    [0108]FIG. 55 depicts a top view of the top layer having a compressed irregular loop that forms part of the antenna structure of FIG. 54.  
         [0109]    [0109]FIG. 56 depicts a top view of the bottom layer of the antenna structure of FIG. 54.  
         [0110]    [0110]FIG. 57 depicts a top view of an outer irregular compressed loop with an inner two-loop, 6-legged compressed antenna where the inner loop is relatively narrow.  
         [0111]    [0111]FIG. 58 depicts a top view of an outer irregular compressed loop with an inner two-loop, 6-legged compressed antenna where the inner loop is relatively wide.  
         [0112]    [0112]FIG. 59 depicts a top view of the bottom layer of the antenna structure, similar to the bottom layer of FIG. 56, where the inner loop of the two-loop compressed antenna is closed and floating.  
         [0113]    [0113]FIG. 60 depicts a top view of the bottom layer of the antenna structure, similar to the bottom layer of FIG. 56, where the inner loop of the two-loop compressed antenna is formed of six legs where each of the legs is closed and floating.  
         [0114]    [0114]FIG. 61 depicts a top view of the top layer, similar to the top layer of FIG. 55, additionally having an internal tuning stub.  
         [0115]    [0115]FIG. 62 depicts a top view of the top layer, similar to the top layer of FIG. 55, additionally having an external tuning stub.  
         [0116]    [0116]FIG. 63 depicts a top view of a one-loop, 6-legged compressed antenna where different segments have different thicknesses and shapes.  
         [0117]    [0117]FIG. 64 depicts a top view of a two-loop, 6-legged compressed antenna where the two loops are on different layers and are connected in series using through-layer vias to form a two-turn compressed loop antenna.  
         [0118]    [0118]FIG. 65 depicts a top view of a multilayer compressed loop antenna where the top two layers are similar to the antenna of FIG. 63. 
     
    
     DETAILED DESCRIPTION  
       [0119]    In FIG. 1, communication device  1  is a cell phone, pager or other similar communication device that can be used in close proximity to people. The communication device  1  includes an antenna area  2  allocated for an antenna  4  which receives and/or transmits radio wave radiation for the communication device  1 . In FIG. 1, the antenna area  2  has a width D W  and a height D H . A section line  2 ′- 2 ″ extends from top to bottom of the communication device  1 . Typically, the loop antenna  4  is affixed to the inside of the case  1 ′ of communication device  1  by a pressure sensitive adhesive, injection molding, insert molding or any other convenient manner of attachment. The case  1 ′ may be flat or curved so that antennas in some embodiments lie in one or more planes where those planes take the shape of the case  1 ′ which can be flat or curved.  
         [0120]    In FIG. 1, the antenna  4  is a multi-loop antenna that includes a first compressed radiation loop  4   T1  generally surrounded by a second compressed radiation loop  4   T2 . The loops  4   T1  and  4   T2  are connected in common by connection pads  30   T1  and  30   T2 . The connection pads  30   T1  and  30   T2  are the termination points for antenna  4 . Typically one of the termination points is the dive point and the other termination point is the common or ground point. The loops  4   T1  and  4   T2  generally lie in the XY-plane and have magnetic current in the Z-axis direction normal to the XY-plane.  
         [0121]    In FIG. 1, antenna  4   T2  has a plurality of electrically conducting radiation segments  4   T2 - 1 ,  4   T2 - 2 ,  4   T2 - 3 , . . . ,  4   T2 -n, . . . ,  4   T2 -N each having a segment length. The segments  4   T2 - 1 ,  4   T2 - 2 ,  4   T2 - 3 , . . . ,  4   T2 -n, . . . ,  4   T2 -N are connected in series to form a loop electrically connected between the first and second conductor pads  30   T1  and  30   T2 . The loop  4   T2  has an electrical length, A l,T2 , that is proportional to the sum of segment lengths for each of the radiation segments  4   T2 - 1 ,  4   T2 - 2 ,  4   T2 - 3 , . . . ,  4   T2 -n, . . . ,  4   T2 -N so as to facilitate an exchange of energy at radiation frequencies for antenna  4   T2 . Similarly, the loop  4   T1  has an electrical length, A l,T1 , that is proportional to the sum of segment lengths for each of the radiation segments so as to facilitate an exchange of energy at radiation frequencies for antenna  4   T1 .  
         [0122]    The term “segment” means any portion of a straight or curved line. Multiple segments are connected together end to end to form a loop. The interconnection of segments can appear discontinuous, for example where two straight-line segments form an angle less than 180 degrees, or can appear continuous, for example, where curved segments connect with a smooth continuous transition without a perceptible intersection. A continuous loop or continuous portions of a loop, where segment intersections are not apparent, can be arbitrarily partitioned into any number of short continuous segments with arbitrary locations of the intersections. The number of segments for a compressed loop is not particularly important. The important characteristic of a compressed loop is that the loop trace is one that has many turns that have the effect of lengthening the loop trace (electrical length of the loop) while reducing the enclosed area of the loop. A loop with such characteristics is defined to be a compressed loop having a compressed pattern. A compressed loop is compared with an equivalent circular loop formed with a circumference equal to the sum of all the lengths of the segments of the compressed loop. The enclosed area of the compressed loop is substantially less than the enclosed area of the equivalent circular loop.  
         [0123]    In FIG. 1, antenna  4  has each of the loops  4   T1  and  4   T2  formed of straight-line segments arrayed in irregular compressed patterns and connected electrically in series to form a loop antenna. The straight-line segments of the antenna  4   T2 , for example, fit within the antenna area  2 , which has been allocated for an antenna in the communication device  1  of FIG. 1. The antenna  4   T2  has an actual enclosed area, A area , that can be represented by an imaginary circle of radius R 1  so that A area =π(R 1 ) 2  and the imaginary circle has a circumference of π(2R 1 ). The antenna  4   T2  has an electrical length, A l,T2  which if stretched into a circle would have a circumference of π(2R 2 ) where π(2R 2 ) is significantly longer than the circumference π(2R 1 ) of the imaginary circle representing the area enclosed by antenna  4   T2 .  
         [0124]    In FIG. 1, antenna  4  has each of the loops  4   T1  and  4   T2  formed of straight-line segments arrayed in multiple divergent directions not parallel to the XY orthogonal coordinate system so as to provide a long antenna electrical length while permitting the overall outside dimensions of the loops to fit within the antenna area  2  of the communication device  1 .  
         [0125]    The FIG. 1 antenna  4 , including antenna elements  4   T1  and  4   T2 , is used for communication in frequency bands having, within the bands, nominal frequencies f 1  and f 2  with wavelengths, λ T1  and λ T2 , for one or more of the respective resonant frequencies of interest. In general, the frequencies f 1  and f 2  are not harmonically related. The wavelengths, λ T1  and λ T2 , are such that, for efficient antenna design, the electrical lengths, A lT1  and A lT2 , cannot be made small with respect to λ T1  and λ T2 . For this reason, it cannot be assumed that the simple analytical models used to describe loop antennas and electric dipole antennas apply without limitation. Rather, the analytical models are mathematically complex and not easily describable.  
         [0126]    In FIG. 2, the communication device  1  of FIG. 1 is shown in a schematic, cross-sectional, end view taken along the section line  2 ′- 2 ″ of FIG. 1. In FIG. 2, a circuit board  6  includes, by way of example, an outer conducting layer  6 - 1 , internal insulating layers  6 - 2   1 ,  6 - 2   2 ,  6 - 2   3 , internal conducting layers  6 - 4   1  and  6 - 4   2  and another outer conducting layer  6 - 3 . Typically, the layer  6 - 4   1  is a ground plane and the layer  6 - 4   2  is a power supply plane. The printed circuit board  6  supports the electronic components associated with the communication device  1  including a display  7  and miscellaneous components  8 - 1 ,  8 - 2 ,  8 - 3  and  8 - 4  which are shown as typical. Communication device  1  also includes a battery  9 . The antenna assembly  5  includes a substrate  5 - 1  and a conductive layer  5 - 2  that forms a loop antenna  4  offset from the printed circuit board  6  by a gap which tends to reduce coupling between the antenna  5 - 2  and the printed circuit board  6 . In one embodiment, the offset of the antenna, H A , above the board  6  is 6.92 mm and the offset of the antenna from the top of a can component mounted on board  6 , such as component  8 - 4 , is 4.83 mm. Typical offsets of the antenna  4  from the circuit board  6  are less than 10 mm and desirably less than approximately 5 mm. The ability of the compressed antenna to operate well with little or no offset (less than 20 mm) from the circuit board  6  is a feature of the compressed antennas that make them attractive for use in hand-held and other small communication devices.  
         [0127]    The assembly  5  is typically constructed using well-known printed circuit materials and processes. For example, the materials include flexible laminates, polyimide flexible laminates, polyimide ridgidized substrates, polyester flexible substrates, polyester ridgidized substrates and plastics, glasses, woven glass laminates such as FR4, other laminates and other dielectrics in general. For example, the processes include printing or silk-screening of a metal onto a dielectric substrate, silk-screening onto the case of a mobile telephone or other commination device, metal deposition onto a dielectric substrate, stamping from a metal sheet, injection molding into the plastic of a mobile telephone case or other communication device, and insert molding into the plastic of a mobile telephone case or other communication device, and other layer and sheet formations of all types.  
         [0128]    In one embodiment, the conductive layer  5 - 2  is connected to printed circuit board  6  by a connection element  3 . In the embodiment shown in FIG. 1 and FIG. 2, the connection element  3  includes, for example, two tangs  3   1  and  3   2  that are spring-loaded against the two connection pads  30   T1  and  30   T2 , respectively. The two tangs have substantially the same spring compression for making balanced electrical connections to the two pads  30   T1  and  30   T2  these connections together with the pads function as first and second conductors for conducting electrical current through the antenna to operate the antenna as a loop antenna. While two tangs are typically employed, any number of one or more tangs are used depending on the number of connections required.  
         [0129]    In an alternative embodiment, the compressed antenna  5  has layer  5 ′- 2  situated closer to or directly on the printed circuit board  6  and substrate  5 ′- 1  and layer  5 ′- 3  are in close proximity to the printed circuit board  6 .  
         [0130]    The antenna  4  of FIG. 1 and FIG. 2, as described in many different embodiments hereinafter, is a compressed antenna that has small area so as to fit within the antenna area  2  of communication device  1 . The antenna  4  operates with loop antenna properties, has low SAR and exhibits good performance in transmitting and receiving signals.  
         [0131]    [0131]FIG. 3 depicts a perspective view of multi-loop antenna  4  in the communication device of FIG. 1 and FIG. 2. In FIG. 3, the multi-loop antenna  4  of FIG. 1 includes, in addition to the first compressed loop  4   T1  and the second compressed loop  4   T2 , a third compressed loop  4   B1 . The third compressed loop  4   B1  appears on layer  5 - 3  on the opposite side of substrate layer  5 - 1  as layer  5 - 2 . The third compressed loop  4   B1  connects at each end to connection pads  30   B1  and  30   B2 . For purposes of the FIG. 3 embodiment, the third compressed loop  4   B1  is substantially the same size and shape as the first compressed loop  4   T1  and is juxtaposed to the first compressed loop  4   T1  as offset in the Z-axis direction. The loops  4   T1 ,  4   T2  and  4   B1 , therefore, all generally lie in or parallel to the XY-plane and have magnetic current in the Z-axis direction normal to the XY-plane. The relative locations of juxtaposed loops, such as loops  4   T1 ,  4   T2  and  4   B1  in FIG. 3 (or loops in any of the other embodiments hereafter described) are used as tuning parameters in the design and manufacture of loop antennas.  
         [0132]    In FIG. 3, the third compressed loop  4   B1  connects at connection pads  30   B1  and  30   B2  on layer  5 - 3  which are offset from the pads  30   T1  and  30   T2  on layer  5 - 2 . In the embodiment of FIG. 3, connection pads  30   B1  and  30   B2  capacitively couple the pads  30   T1  and  30   T2  whereby the compressed loops  4   T1 ,  4   T2  and  4   B1  all are connected in common and are connected through the connection element  3  to the transceiver on circuit board  6  of FIG. 2. In alternative embodiments, through-layer conductors (vias) or other equivalent means are employed to interconnect the compressed loops  4   T1 ,  4   T2  and  4   B1 . In still other alternative embodiments, any two or more of the compressed loops  4   T1 ,  4   T2  and  4   B1  can connect independently through one or more connection elements to the transceiver on circuit board  6  of FIG. 2. In further embodiments, the compressed loops of a multi-loop antenna, with any number of loops such as two, three four or more, are located on the same circuit board  6  or multiple ones of other boards like board  5 . The compressed loops of antennas are arrayed in various embodiments to have polarization diversity, time diversity and frequency diversity.  
         [0133]    The connection pads  30   B1  and  30   B2  capacitively couple the pads  30   T1  and  30   T2  and in so doing remove the need in some multilayer embodiments for vias (internal through layer connections). The value of the capacitance between layers is determined in conventional manner. The structure is that of parallel plane conductors separated by a dielectric where the capacitance is a function of the thickness of the separating dielectric, the dielectric constant of the substrate, the type of material, the shape and the dimensions of the pads. The capacitance is selected to provide good coupling at the frequencies of interest. The pads are easily changed in position and shape to achieve the desired coupling. In some embodiments, the capacitance between pads is used as a circuit element which establishes, for example, a pass band filter between loops of a multi-loop antenna.  
         [0134]    In FIG. 4, a schematic sectional view along the section line  4 ′- 4 ″ of FIG. 4 is shown. In the example of FIG. 4, the thickness, S T , of the dielectric substrate  5 - 1  is approximately 0.08 mm. The width, A T2 , of a segment  4   T2 -n of antenna loop  4   T2  in layer  5 - 2  is approximately 1.8 mm and the thickness, A T , of the segment  4   T1 -n is approximately 1.8 mm. The width of a segment of antenna loop  4   T1  in layer  5 - 2  is approximately 1.8 mm and the thickness, A T , of the segment is approximately 0.02 mm. The antenna material of FIG. 4 in one embodiment is Kapton Polyimide with a copper thickness 1 oz. double size on a 3 mil (0.076 mm) flexible laminate. In another embodiment, the material is a 1 oz. double sided 2 mil (0.051 mm) flexible laminate. In other embodiments, these elements can have any desired dimensions.  
         [0135]    [0135]FIG. 5 depicts the major components that form the communication device  1  of FIG. 1. In particular, the transceiver unit  91  is formed by one or more of the components  8  mounted on the circuit board  6  of FIG. 2. The connection element  3  connects the transceiver unit  91  to the antenna  4 .  
         [0136]    [0136]FIG. 6 depicts a short dipole element  61  along the Z axis normal to the XY-plane of antenna  4 . The short dipole element is useful in explaining properties of antennas.  
         [0137]    [0137]FIG. 7 depicts a three-dimensional representation of the fields of the short dipole element of FIG. 6. As discussed above, the equations of electric and magnetic components of the electric dipole at the far field are given as:  
         E   r     =   0             E   θ     =         j60                   π        [   I   ]          sin                 θ     r          L   λ                 H   φ     =           j        [   I   ]          sin                 θ       2      r            L   λ                             
 
         [0138]    Examining the E θ  and H φ  components in the far field, it can be seen that E θ  and H φ  are in time phase (with respect to each other) in the far field, and that the field patterns of both are proportional to sin(θ) but independent of φ. The space patterns of those fields are a figure of revolution and doughnut-shaped in three dimensions (see FIG. 10) figure-8 shaped in two dimensions (see FIG. 11).  
         [0139]    [0139]FIG. 8 depicts a short loop element  81  lying in the XY-plane. A magnetic dipole for the loop element  81  conducts an electric current I that causes a magnetic current (I m ) in the Z axis direction normal to the XY-plane of the magnetic dipole. The analysis of the far field pattern of a magnetic dipole of FIG. 8 is similar to the analysis of the far field pattern of the electric dipole of FIG. 6. The difference is that the electric current I is replaced by a magnetic current I m  and the electric field is replaced by a magnetic field.  
         [0140]    [0140]FIG. 9 depicts a three-dimensional representation of the fields of the short loop element of FIG. 8. The fields of the short magnetic dipole are the same as the fields of a short electric dipole with the E and H fields and I and I m  currents interchanged as follows:  
                                                         Small Electric Dipole   Small Magnetic Dipole                                                     E   θ     =         j60                   π        [   I   ]                     sin                 θ     r                     L   λ                                           H   θ     =           j              [     I   m     ]        sin                 θ       240                 πr            L   λ                                                               H   φ     =           j        [   I   ]                     sin                 θ       2      r                       L   λ                                           E   φ     =           j              [     I   m     ]                   sin                 θ       2      r            L   λ                                                                        where              [     I   m     ]     =       I   mo               j                   ω        (     t   -     r   /   c       )                                              
 
         [0141]    Considering the equation of the far field pattern for the magnetic dipole, both H θ  and E φ  are proportional to sin(θ) but independent of φ. Consequently, the far field pattern of the H θ  and E φ  components of a magnetic dipole are doughnut-shaped in three dimensions (see FIG. 10) and figure-8 circular in cross section (see FIG. 11).  
         [0142]    [0142]FIG. 10 depicts a three-dimensional representation of the E θ  and H φ  fields of the short dipole element of FIG. 6 and the E φ  and H θ  fields of the short loop element of FIG. 8.  
         [0143]    [0143]FIG. 11 depicts a two-dimensional representation of the E θ  and H φ  fields of the short dipole element of FIG. 6 and the E φ  and H θ  fields of the short loop element of FIG. 8.  
         [0144]    In FIG. 6 through FIG. 11, properties of small elements were described to depict the nature of electric dipole operation and magnetic loop operation. Antennas that have properties that like those of the small magnetic loop of FIG. 8 are classified as “loop” antennas or as having loop antenna characteristics. While an extension of the mathematical derivation described in connection with FIG. 6 through FIG. 11 to the more complex compressed loops and antennas of the present application is not easily done, the actual performance of those compressed loops and antennas demonstrate loop antenna characteristics including good radiation properties and low SAR values.  
         [0145]    [0145]FIG. 12 depicts a top view of a four-loop, 6-legged compressed antenna, generally in a snowflake pattern, for use in a wireless communication device such as the device of FIG. 1 and FIG. 2. The compressed antenna of FIG. 12 is in a snowflake pattern in that each of the legs, specifically the six legs  12 - 1 , 12 - 2 , 12 - 3 ,  12 - 4 ,  12 - 5  and  12 - 6 , for each of the four compressed loops  12   1 ,  12   2 , 12   3  and  12   4  are symmetrically disposed with each leg having multiple segments that are not arrayed parallel or normal to any XY orthogonal coordinate system. The multiple segments in each leg are further arrayed in sublegs described, for example, for leg  12 - 5  as typical. Particularly, leg  12 - 5  has six sublegs  57 - 1 ,  57 - 2 ,  57 - 3 ,  57 - 4 ,  57 - 5  and  57 - 6  symmetrically arrayed along the axis of leg  12 - 5 . While six sublegs have been shown, any number of sublegs can be used. Typically, from one to six sublegs are selected. Three sublegs can be achieved, for example by eliminating sublegs  57 - 1 ,  57 - 4  and  57 - 5  on leg  12 - 5  and directly connecting sublegs  57 - 2  and  57 - 6 .  
         [0146]    In FIG. 12, the compressed loops  12   1 ,  12   2 , 12   3  and  12   4  each connect in common at one end to the pad  30   1  via conductors  47  and each connect in common at the other end to the pad  30   2  via conductors  48 . The compressed loops  12   1 ,  12   2 , 12   3  and  12   4  are typically nested on the same layer supported by a dielectric substrate (not shown in FIG. 12) whereby an area enclosed by one of loops (for example, loop  12   2 ) is within an area enclosed by another of the loops (for example, loop  12   1 ). When compressed loops  12   1 ,  12   2 , 12   3  and  12   4  are nested on the same layer, the area enclosed by each of the more outer ones of the loops encloses the area enclosed by the more inner ones of the loops. Specifically, the area enclosed by loop  12   1  totally encloses the areas enclosed by the loops  12   2 , 12   3  and  12   4 . Similarly, the area enclosed by loop  12   2  totally encloses the areas enclosed by the loops  12   3  and  12   4 . Still similarly, the area enclosed by loop  12   3  totally encloses the area enclosed by the loop  12   4 .  
         [0147]    Although FIG. 12 contemplates that the compressed loops  12   1 ,  12   2 , 12   3  and  12   4  are on the same layer, typically supported by a dielectric substrate (not shown in FIG. 12), the compressed loops  12   1 ,  12   2 , 12   3  and  12   4  can be on one or more different layers supported by one or more dielectric layers. When arrayed on different layers, the compressed loops  12   1 ,  12   2 , 12   3  and  12   4  need not be nested, that is, the compressed loops are arrayed such that only a portion of the area enclosed by one compressed loop on one layer is superimposed over only a portion of the area enclosed by another one of the compressed loops on another layer.  
         [0148]    For typical operation of the antenna of FIG. 12 in a communication device, the pad  30   1  connects to the driving source and is called the drive point while the pad  30   2  is connected to the common or ground point.  
         [0149]    [0149]FIG. 13 depicts a top view of a two-loop, 6-legged compressed antenna similar to FIG. 12 together with an additional irregular compressed loop  13  for use in a wireless communication device such as the device  1  of FIG. 1 and FIG. 2. The compressed antenna of FIG. 13 has the snowflake pattern where compressed loops  12   1  and  12   4 , each formed of six legs, are surrounded by an additional irregular compressed loop  13 . The compressed loops  12   1  and  12   4  and the irregular compressed loop  13  all connect at one end to the pad  30   1  and all connect at the other end to the pad  30   2 . When the compressed loops  12   1 ,  12   4  and  13  are nested on the same layer, the area enclosed by each of the more outer ones of the loops encloses the area enclosed by the more inner ones of the loops. When arrayed on different layers, the compressed loops  12   1 ,  12   4  and  13  need not be nested, that is, the compressed loops are arrayed such that only a portion of the area enclosed by one compressed loop on one layer is superimposed over a portion of the area enclosed by another one of the compressed loops on another layer. The compressed loops  12   1  and  12   4  each connect at one end to the pad  30   1  via conductors  47 ′ and each connect at the other end to the pad  30   2  via conductors  48 ′. Similarly, the conductors at each end of the antenna  13  connects to one of the pads  30   1  and  30   2 .  
         [0150]    [0150]FIG. 14 depicts a top view of a two-loop, two-legged compressed antenna for use in a communication device such as communication device  1  of FIG. 1 and FIG. 2. The compressed antenna of FIG. 14 includes two compressed loops  14   1  and  14   2  each formed into two legs  14 - 1  and  14 - 2 . The compressed loops  14   1  and  14   2  when on a single layer are nested together and connect at one end to the pad  30   1  and connect at the other end to the pad  30   2 . When arrayed on different layers, the compressed loops  14   1  and  14   2  need not be nested, that is, the compressed loops can be arrayed such that only a portion of the area enclosed by one compressed loop on one layer is superimposed over a portion of the area enclosed by the other one of the compressed loops on another layer. While only two loops are shown for the 2-legged compressed loop antenna of FIG. 14, any number of one or more compressed loops may be used to form the 2-legged compressed antenna.  
         [0151]    [0151]FIG. 15 depicts a top view of a one-loop, 3-legged compressed antenna for use together with other loops in a communication device such as communication device  1  of FIG. 1 and FIG. 2. The compressed antenna of FIG. 15 includes one compressed loop  15   1  formed into three legs  15 - 1 ,  15 - 2  and  15 - 3 . The compressed loop  15   1  connects at one end to the pad  30   1  and connects at the other end to the pad  30   2 . While only one loop  15   1  is shown for the 3-legged compressed loop antenna of FIG. 15, any number of one or more compressed loops may be used to form the 3-legged compressed antenna. When more than one 3-legged compressed antenna is arrayed on the same layer, the compressed loops are nested and when arrayed on different layers, the compressed loops need not be nested.  
         [0152]    [0152]FIG. 16 depicts a top view of a one-loop, 4-legged compressed antenna for use together with other loops in the communication device such as communication device  1  of FIG. 1 and FIG. 2. The compressed antenna of FIG. 16 includes one compressed loop  16   1  formed into four legs  16 - 1 ,  16 - 2 ,  16 - 3  and  16 - 4 . The compressed loop  16   1  connects at one end to the pad and connects at the other end to the pad  30   2 . While only one loop  16   1  is shown for the 4-legged compressed loop antenna of FIG. 16, any number of one or more compressed loops may be used to form the 4-legged compressed antenna. When more than one 4-legged compressed antenna is arrayed on the same layer, the compressed loops are nested and when arrayed on different layers, the compressed loops need not be nested.  
         [0153]    [0153]FIG. 17 depicts a top view of a one-loop, 5-legged compressed antenna for use together with other loops in the communication device such as communication device  1  of FIG. 1 and FIG. 2. The compressed antenna of FIG. 17 includes one compressed loop  17   1  formed into five legs  17 - 1 ,  17 - 2 , 17 - 3 , 17 - 4  and  17 - 5 . The compressed loop  17   1  connects at one end to the pad and connects at the other end to the pad  30   2 . While only one loop  17   1  is shown for the 5-legged compressed loop antenna of FIG. 17, any number of one or more compressed loops may be used to form the 5-legged compressed antenna. When more than one 5-legged compressed antenna is arrayed on the same layer, the compressed loops are nested and when arrayed on different layers, the compressed loops need not be nested.  
         [0154]    [0154]FIG. 18 depicts a top view of a one-loop, six-legged compressed antenna for use together with other loops in the communication device such as communication device  1  of FIG. 1 and FIG. 2. The one-loop, 6-legged compressed antenna of FIG. 18 is in a snowflake pattern including one compressed loop  18   1  formed into six legs  18 - 1 ,  18 - 2 , 18 - 3 ,  18 - 4 ,  18 - 5  and  18 - 6 . The compressed loop  18   1  connects at one end to the pad  30   1  and connects at the other end to the pad  30   2 . When more than one 6-legged compressed antenna is arrayed on the same layer, the compressed loops are nested and when arrayed on different layers, the compressed loops need not be nested.  
         [0155]    All of FIG. 14 through FIG. 18 depict antennas with legs are that are arrayed with a periodically repeating pattern. In FIG. 14, the pattern is repeated twice. In FIG. 15, FIG. 16, FIG. 17 and FIG. 18 the patterns are repeated three, four, five and six times, respectively.  
         [0156]    [0156]FIG. 19 depicts a top view of a two-loop, 6-legged compressed antenna, in a snowflake pattern, where each loop has a separate pad for separate electrical connection to the transceiver unit in the communication device such as communication device  1  of FIG. 1 and FIG. 2. The compressed antenna of FIG. 19 is in a snowflake pattern including the two compressed loops  12   1  and  12   4  formed into six legs  19 - 1 ,  19 - 2 ,  19 - 3 ,  19 - 4 ,  19 - 5  and  19 - 6 . The compressed loop  12   1  connects at one end to the pad  30   1  and connects at the other end to the pad  30   2 . The compressed loop  12   4  connects at one end to the pad  30   3  and connects at the other end to the pad  30   2 . While two compressed loops  12   1  and  12   4  are shown for the 6-legged compressed loop antenna of FIG. 19, any number of one or more compressed loops may be used to form the 6-legged compressed antenna. Each one or more of the 6-legged compressed antennas may include a separate pad for separate electrical connection. For typical operation, the pads  30   1  and  30   3  connect to the driving source and are called drive points while the pad  30   2  is connected to the common or ground point.  
         [0157]    [0157]FIG. 20 depicts a top view of a two-loop, 6-legged compressed antenna where the two loops are connected by a transmission line  22  to the two compressed loops  18   1  and  18   2  for electrical connection to the transceiver unit in the communication device such as communication device  1  of FIG. 1 and FIG. 2. The two-loop, 6-legged compressed antenna of FIG. 20 includes the two compressed loops  18   1  and  18   2  formed into six legs  20 - 1 ,  20 - 2 ,  20 - 3 ,  20 - 4 ,  20 - 5  and  20 - 6 . The two compressed loops  18   1  and  18   2  are connected by the conductors  21   1  and  21   2  of transmission line  22  to pad  30   1  and pad  30   2 , respectively.  
         [0158]    [0158]FIG. 21 depicts a perspective view of a one-loop, 6-legged compressed antenna of FIG. 20 mounted on a flexible dielectric substrate  21 - 1  for use in the communication device such as communication device  1  of FIG. 1 and FIG. 2. When the case  1 ′ of the communication device  1  of FIG. 1 is curved, the flexible dielectric substrate  21 - 1  bends to fit the curvature of the case  1 ′.  
         [0159]    [0159]FIG. 22 depicts a top view of a multi-loop antenna  44  that includes a first compressed loop  44   T1  generally surrounded by a second compressed loop  44   T2 . The loops  44   T1  and  44   T2  are connected in common at each end by connection pads  30   T1  and  30   T2 . The loops  44   T1  and  44   T2  generally lie in the XY-plane and have magnetic current in the Z-axis direction normal to the XY-plane. The loop  44   T1  is formed of two concentric loops, namely, sub-loops  44   T1-1  and  44   T1-2 , where sub-loop  44   T1-2  is nested within sub-loop  44   T1-1 . The antenna  44  of FIG. 22 in one embodiment measures approximately 38 mm by 15 mm.  
         [0160]    To achieve the wide bandwidth for the GSM1800 and PCS1900 frequency bands, the loop  44   T1  uses two sub-loops  44   T1-1  and  44   T1-2  with nominal resonant frequencies, having wavelengths, λ T1-1  and λ T1-2 , that are close to each other. In general, the frequencies of the GSM1800 and PCS1900 frequency bands are not harmonically related. In FIG. 22, the multi-loop antenna  44  includes a layer below the layer having the loop  44   T1  and two sub-loops  44   T1-1  and  44   T1-2  that is over a lower layer compressed loop  44   B1-1  surrounded by a second compressed loop  44   B2-2  (see FIG. 25). The lower layer also includes a conducting patch  45 ′ (see FIG. 25). In the embodiment described, the electrical length of sub-loop  44   T1-1  is approximately 55.1 mm and the sub-loop fits within a rectangle of approximate height 9.4 mm and width 19.5 mm and the electrical length of sub-loop  44   T1-2  is approximately 99.9 mm and the sub-loop  44   T1-2  fits within a rectangle of approximate height 7.4 mm and width 18 mm.  
         [0161]    In FIG. 22, the multi-loop antenna  44   22  includes the compressed loop  44   T2  which provides the GSM900 capabilities for antenna  44 . The loop  44   T2  is connected in common to the loop  44   T1  at each end by connection pads  30   T1  and  30   T2 . The loops  44   T1  and  44   T2  generally lie in the XY-plane and have magnetic current in the Z-axis direction normal to the XY-plane. The average offset, H G , of the loop  44   T2  from the loop  44   T1  has an effect on the radiation performance of the antenna. In FIG. 22 for PCS and DCS bands, a gap of 0.69 mm works well while a gap of 0.32 mm reduces the gain by 5-10 dB.  
         [0162]    The size of the gap between the loops, described for example in connection with FIG. 22, is important in some embodiments for good performance. In the embodiment described, when the gap is decreased from a value above 0.69 mm to 0.69 mm, the bandwidth over which the VSWR is at a good low value increases and the increase is a substantial improvement when the loops are very close together. However, as the gap is decreased as described, the gain of the antenna undesirably decreases. With a decrease from 0.69 mm to 0.32 mm, the gain fell off by 5-10 dB even though the VSWR improved. When the gap is increased to more than 0.69 mm, the gain increases slightly, but the VSWR undesirably also increases as a single band begins to transform into two bands.  
         [0163]    The “gap” between loops generally refers to an average gap, a nominal gap or an approximate gap since the shape of each loop may vary significantly and a point by point measurement of a gap may be impossible. Nonetheless, a gap as an offset between loops is readily determinable and changes in such gaps for tuning are readily determinable. Therefore, the gap is a tuning element and the magnitude of the gap is a tuning parameter proportional to the gap between loops.  
         [0164]    A “tuned gap” between superimposed loops is a gap that balances between good gain and good VSWR. Due to the complexity of distributed capacitive and inductive properties of the superimposed loops, an empirical approach is used to establish a tuned gap. To find the tuned gap, the spacing between the loops is iteratively altered while maintaining the same general shape of the loops. The tuned gap is the gap where the VSWR performance and gain performance are maximized. An alternative approach for establishing a tuned gap utilizes a computational algorithm with empirical and historical data to approximate the inductances, capacitances and other parameters of the antennas. Due to the computational complexities, computational methods tend to have great inaccuracies that still require testing of antennas constructed based upon the computations.  
         [0165]    In FIG. 22, the loop  44   T2  includes the tuning element  46  formed of segments that meander in a short close pattern and that are connected in series with the loop  44   T2 . The tuning parameter of the tuning element  46  is the length of the tuning element  46 . The lengths of the segments or the number of the segments in the tuning element  46  are easily varied without changing the general shape of the overall array of segments (trace) that forms loop  44   T2 . The tuning element  46  is used to “tune” the the loop  44   T2  by adding or deleting length to loop  44   T2  thereby tuning loop  44   T2  and antenna  44 . Other segments can be modified to add or delete length to loop  44   T2  while at the same time changing the general shape of the overall array of segments (trace) that forms loop  44   T2 . Variations in antenna size and other physical parameters can result when a design is ported from one communication device to another and hence tuning features of the antenna  44  are important in achieving the desired antenna performance over all bands of interest for each particular communication device.  
         [0166]    The line length, and hence the inductance and resistance of the compressed loop  44   T2  is increased when the length the tuning section  46  is increased. In the embodiment shown, the tuning section  46  is in a sawtooth pattern of segments inserted in series with the antenna trace of compressed loop  44   T2 . Other embodiments of the tuning section  46  have any convenient shape including sinusoidal, rectangular wave and irregular elements or segments. An irregular tuning element is typically formed of non-repeating, short segments of varied orientations.  
         [0167]    The tuning section  46  allows the compressed loop  44   T2  to be decreased in size for the same electrical length so as to fit into a pre-defined space without substantially altering the overall shape and area of the compressed loop which define the reactive structure. In this manner, the tuning section  46  is utilized to tune the antenna  44  without substantially altering the defining radiative structures of the antenna  44 . In addition to the segments  46 , the size and location of the pads  30  and other antenna elements can be easily adjusted for tuning.  
         [0168]    [0168]FIG. 23 depicts a front view of the antenna structure of FIG. 22. In FIG. 15, an antenna layer  5 - 2  is on top of the substrate  5 - 1  and an antenna  5 - 3  is below the substrate layer  5 - 1 . The thickness, S T , of the dielectric substrate  5 - 1  is approximately 0.08 mm the thickness, A T , of the layers  5 - 2  and  5 - 3  are approximately 1.8 mm  
         [0169]    [0169]FIG. 24 depicts a top view of the top layer  5 - 2  of the antenna structure of FIG. 22. The multi-loop antenna of FIG. 24 includes the first compressed loop  44   T1  surrounded by a second compressed loop  44   T2 . The loop  44   T1  includes sub-loop  44   T1-1  and sub-loop  44   T1-2  that are spaced apart on an average by approximately 0.02 mm and are connected in common with the ends of loop  44   T2  at each end by connection pads  30   T1  and  30   T2 . The loops  44   T1  and  44   T2  generally lie in the XY-plane and have magnetic current in the Z-axis direction normal to the XY-plane.  
         [0170]    [0170]FIG. 25 depicts a top view of the bottom layer  5 - 3  of the antenna  44   22  of FIG. 22. The layer  5 - 3  portion of the multi-loop antenna of FIG. 25 includes the first compressed loop 44   B1-1  surrounding a second compressed loop  44   B1-2 . The loops  44   B1-1  and  44   B1-2  on layer  5 - 3  are on the opposite side of substrate layer  5 - 1  as layer  5 - 2  and are juxtaposed and have the same size and shape as the loops  44   T1-1  and  44   T1-2  of layer  5 - 2  and hence loops  44   B1-1  and  44   B1-2  are “mirror images” of the loops  44   T1-1  and  44   T1-2 . The loops  44   B1  and  44   B2  connect at each end to connection pads  30   B1  and  30   B2 . The loops 44   T1 , 44   T2  and  44   B1  all generally lie in or parallel to the XY-plane and have magnetic current in the Z-axis direction normal to the XY-plane. The layer  5 - 3  also includes a conductive patch  45 ′ that serves as a ground or parasitic patch for the antenna  44   22 . The patch  45 ′ functions to tune the antenna  44   22  and particularly loop  44   T2 . Although it is often difficult to obtain low VSWR in an internal antenna environment, the patch  45 ′ is a parasitic element that is effective in tuning the overall impedance of antenna  44   22  to 50 ohms or some other desired impedance at the output.  
         [0171]    In the embodiment of FIG. 22 through FIG. 25, connection pads  30   B1  and  30   B2  capacitively couple the pads  30   T1  and  30   T2  whereby the compressed loops  44   T1 ,  44   T2  and  44   B1  all are connected in common and are connected through the connection element  3  to the transceiver on circuit board  6  of FIG. 2. In alternative embodiments, through-layer conductors or other equivalent means are employed to interconnect the compressed loops  44   T1 ,  44   T2  and  44   B1 . In still other alternative embodiments, any two or more of the compressed loops  44   T1 ,  44   T2  and  44   B1  can connect independently through one ore more connection elements to the transceiver on circuit board  6  of FIG. 2. In other embodiments, the compressed loops of a multi-loop antenna, with any number of loops such as two, three four or more, are located on the same circuit board  6  or multiple ones of other boards like board  5  having single, double or more layers. For the particular embodiments disclosed, the antenna  44   22  is designed to perform better when the antenna has an offset, H A , from the ground plane  6 - 4   2  and grounded components (such as  8 - 4 ) of the board  6  of FIG. 2.  
         [0172]    The dimensions of the sub-loops  44   T1-1  and  44   T1-2  including line traces (see A T  and A B1  and A T1  in FIG. 4) and their overall lengths determine the desired resonant frequencies. The length expected for each loop does not agree with the length of a single loop determined for free space. It has been found that the line length that is effective in each loop does not necessarily agree with the line length described by classical loop antenna equations. In addition, the dimensions of the tangs and antenna together are combined to obtain resistance close to 50 ohms for good VSWR and strong radiation.  
         [0173]    The connection element ensures good electrical (close to 50 ohms for all required bandwidth) and strong mechanical properties with the necessary height for connection to circuit board  6  in FIG. 2. Since current tends to be divided in each of the loops of antenna  44   22  in proportion to the loop impedance at that frequency (“Current Divider Rule”), the impedance in each loop is approximately the same at the connection point. Using common feeding points from the antenna for all the sub-loops simplifies the design and insures balanced connection over all the frequency ranges. The multi-loop antenna  44   22  has a gap between each sub-loop where the gap has been selected for good performance. A larger distance between the sub-loops may displace the resonant frequencies that are combined for obtaining wider bandwidth. A smaller distance between the sub-loops may result in a poorer radiation pattern.  
         [0174]    In summary, the FIG. 22 through FIG. 25 embodiment of a multi-loop antenna provides a triband antenna with the following specifications.  
                                                                     Frequency Range                GSM 800 MHz   880-960 MHz           European PCS 1800 MHz   1710-1880 MHz           US PCS 1900 MHz   1850-1990 MHz            VSWR                GSM (Tx Bandwidth)   less than 3.0:1           European PCS (Tx Bandwidth)   less than 2.5:1           US PCS (Tx Bandwidth)   less than 2.5:1                      
 
         [0175]    [0175]FIG. 26 depicts top view of an alternate antenna layer  5 - 2 , similar to the layer of FIG. 24, of the antenna structure of FIG. 22. The multi-loop antenna of FIG. 26 includes the first compressed loop  44   T1  surrounded by a second compressed loop  44   T2 . The loop  44   T1  includes sub-loop  44   T1-1  and sub-loop  44   T1-2  that are spaced apart on an average by approximately 0.02 mm and are connected in common with the ends of loop  44   T2  at each end by connection pads  30   T1  and  30   T2 . The loops  44   T1  and  44   T2  generally lie in the XY-plane and have magnetic current in the Z-axis direction normal to the XY-plane. The antenna of FIG. 26 additionally includes loop interconnects  55 - 1 ,  55 - 2  and  55 - 3  interconnecting the sub-loop  44   T1-1  and sub-loop  44   T1-2 . The antenna of FIG. 26 additionally includes an alternate loop interconnect  55 - 4  interconnecting the sub-loop  44   T1-2  and loop  44   T2  that in some embodiments is not used and in other embodiments is used with the loop interconnects  55 - 1 ,  55 - 2  and  55 - 3 .  
         [0176]    [0176]FIG. 27 depicts a voltage standing wave ration (VSWR) representation of the antenna of FIG. 22 with FIG. 24 top layer not having any of the loop interconnects  55 - 1 ,  55 - 2 ,  55 - 3  or  55 - 4  of FIG. 26. The FIG. 22 antenna with the FIG. 24 top layer has VSWR as follows:  
                                       ARROW   FREQUENCY   VSWR                   1    880 MHz   3.75       2    980 MHz   5.03       3   1.71 GHz   4.35       4   1.99 GHz   2.19       5   2.03 GHz   3.90                  
 
         [0177]    [0177]FIG. 28 depicts a voltage standing wave ration (VSWR) representation of the antenna of FIG. 22 with the FIG. 26 top layer having only the loop interconnects  55 - 1 ,  55 - 2  and  55 - 3  and not the loop interconnects  55 - 4 . The FIG. 22 antenna with the FIG. 26 top layer has VSWR as follows:  
                                       ARROW   FREQUENCY   VSWR                   1   880 MHz   4.44       2   980 MHz   3.31       3   1.71 GHz   1.05       4   1.99 GHz   2.22       5   2.03 GHz   4.51                  
 
         [0178]    A comparison of FIG. 28 with FIG. 27 demonstrates that the VSWR is improved when the loop interconnects  55 - 1 ,  55 - 2  and  55 - 3  interconnecting the sub-loop  44   T1-1  and sub-loop  44   T1-2  are employed. Further, in alternate embodiments, the antenna of FIG. 26 employs loop interconnects like loop interconnect  55 - 4  interconnecting the sub-loop  44   T1-2  and loop  44   T2 . In such alternate embodiments, the effect of the loop interconnect  55 - 4  is to significantly shift the frequency of the low band of frequencies. The loop interconnects  55  can be situated anywhere to tune the high band of the antenna.  
         [0179]    [0179]FIG. 29 depicts a top view of the top layer of a one-loop, 6-legged compressed antenna together with an irregular loop antenna that forms part of a multilayer antenna structure. The compressed antenna of FIG. 29 includes a one-loop, 6-legged compressed loop antenna  44   T1-2  surrounded by an irregular loop antenna  44   T2  that forms part of a multilayer antenna structure  44 . The compressed loop  44   T1-2  connects at one end to the pad  30   T1  and connects at the other end to the pad  30   T2 . The irregular loop  44   T2  connects at one end to the pad  30   T1 , and connects at the other end to the pad  30   T2  and contains a tuning element  46 ′ T1 , having a rectangular wave shape, that is modified in length during manufacture to tune adjust the frequency of the irregular loop antenna  44   T2 .  
         [0180]    [0180]FIG. 30 depicts a top view of the bottom layer including a one-loop, 6-legged compressed antenna together with irregular conducting region (patch) that forms part of a multilayer antenna structure with the layer of FIG. 29. The one-loop, 6-legged compressed antenna of FIG. 30 includes the one compressed loop  44   B1-2  together with the irregular conducting patch  45 ″. The compressed loop  44   B1-2  connects at one end to the pad  30   B1  and connects at the other end to the pad  30   B2 .  
         [0181]    [0181]FIG. 31 depicts a top view of the top layer of a two-loop, 6-legged compressed antenna together with an irregular loop antenna that forms part of a multilayer antenna structure. The two-loop, 6-legged compressed antenna layer of FIG. 31 includes the two compressed loops  44   T1-1  and  44   T1-2  surrounded by two irregular loop antennas  44   T2  and  44   T1 . The compressed loops  44   T1-1  and  44   T1-2  connect at one end to the pad  30   T1  and connect at the other end to the pad  30   T2 . The irregular loops  44 T 1  and  44   T2  connect at one end to the pad  30   T1  and connect at the other end to the pad  30   T2  and contain variable adjustment segments  46 ′″ T1  (having an irregular wave shape) and  46 ″ T2  (having a sinusoidal wave shape), respectively.  
         [0182]    [0182]FIG. 32 depicts a top view of the bottom layer of a two-loop, six-legged compressed antenna together with irregular conducting pad that forms with the layer of FIG. 31 a multilayer compressed antenna. The two-loop, 6-legged compressed antenna layer of FIG. 32 includes the two compressed loops  44   B1-1  and  44   B1-2  together with the conducting patch  45 ″. The compressed loops  44   B1-1  and  44   B1-2  connect at one end to the pad  30   B1 , and connect at the other end to the pad  30   B2 .  
         [0183]    [0183]FIG. 33 depicts a front view of an antenna including a three-layer antenna structure on opposite sides of a two dielectric layers. The top layer is an antenna layer  5 - 5  with a thickness A T  located juxtaposed a dielectric layer  5 - 4  with a thickness S T  in turn juxtaposed an antenna layer  5 - 3  with a thickness A T , in turn juxtapose a dielectric layer  5 - 2  with a thickness S T  juxtaposed an antenna layer  5 - 3  with a thickness A T . The thicknesses, S T , of the dielectric substrate  5 - 1  and  5 - 4  are typically approximately 0.08 mm. The thicknesses, A T , are typically approximately 1.8 mm.  
         [0184]    [0184]FIG. 34 depicts an isometric view of the antenna of FIG. 33. A multi-loop antenna  4 ′ includes a compressed loop antenna  4 ′ T1  nested with a compressed loop antenna  4 ′ T2  together superimposed with a compressed loop antenna  4 ′ M1  and a compressed loop antenna  4 ′ B1 . The compressed loop antenna  4 ′ M1  is situated on layer  5 - 2  in between dielectric layers  5 - 1  and  5 - 4 . The compressed loop antenna  4 ′ M1  connects at each end to connection pads  30   M1  and  30   M2 . The compressed loop antenna  4 ′ B1  is situated on layer  5 - 1  on the opposite side of substrate layer  5 - 3  as layer  5 - 2 . The compressed loop antenna  4 ′ B1  connects at each end to connection pads  30   B1  and  30   B2 . The compressed loop antenna  4 ′ M1  and the compressed loop antenna  4 ′ B1  in some embodiments are substantially the same size and shape as the compressed loop antenna  4 ′ T1  and are juxtaposed the compressed loop antenna  4 ′ T1  and are offset in the Z-axis direction. Th Z-axis dimensions are somewhat exaggerated in order to show more clearly the alignment of the compressed antennas. The loops  4 ′ T1 ,  4 ′ T2 ,  4 ′ M1  and  4 ′ B1  all generally lie in or parallel to the XY-plane and have magnetic current in the Z-axis direction normal to the XY-plane.  
         [0185]    In the embodiment shown in FIG. 34, the compressed loop antenna  4 ′ M1  is somewhat larger than the compressed loop antennas  4 ′ T1  and  4 ′ B1 . Accordingly, the compressed loop antenna  4 ′ M1  has an offset M o  in the Y-axis direction so that the compressed antennas on different layers are not nested nor identically aligned. However, a substantial portion of the area enclosed by the compressed loop antenna  4 ′ M1  covers the area enclosed by the compressed loop antennas  4 ′ T1  and  4 ′ B1 . Note, however, that the connection pads  30   T1  and  30   T2 , the connection pads  30   M1  and  30   M2  and the connection pads  30   B1  and  30   B2  remain aligned to facilitate capacitive coupling from layer to layer.  
         [0186]    [0186]FIG. 35 depicts a top view of a top layer including a one-loop, 6-legged compressed antenna together with an irregular one-loop compressed antenna that forms part of a multiband, multilayer compressed antenna. The one-loop, 6-legged compressed antenna of FIG. 35 includes one compressed loop antenna  44   T1  surrounded by an irregular loop antenna  44   T2 . The compressed loop antenna  44   T1  connects at one end to the pad  30   T1  and connects at the other end to the pad  30   T2 . The irregular loop antenna  44   T2  connects at one end to the pad  30   T1  and connects at the other end to the pad  30   T2. . Typically, the pad  30   T1  is the “driving” pad for connection to the driving connection of the transceiver unit  91  and the pad  30   T2.  is a “ground” pad for connecting to the ground plane  6 - 4   2  of the circuit board  6  of FIG. 2. In some embodiments, loop antennas have filter networks inserted into the antennas to achieve high Q in one of the bands.  
         [0187]    [0187]FIG. 36 depicts a top view of a bottom layer including a one-loop, 6-legged compressed antenna together with an irregular conducting pad that forms part of the multiband, multilayer compressed antenna with the layer of FIG. 35. The one-loop, 6-legged compressed antenna of FIG. 36 includes the one compressed loop  44   B1-2  together with a conducting patch  45 . The compressed loop  44   B1-2  connects at one end to the pad  30   B1  and connects at the other end to the pad  30   B2 .  
         [0188]    [0188]FIG. 37 depicts a top view of the multiband, multilayer compressed antenna  44   37  showing the layers of FIG. 35 and FIG. 36 superimposed as they would appear on the top and bottom of a dielectric substrate. The compressed antenna of FIG. 35 includes one compressed one-loop, 6-legged loop  44   T1-2  surrounded by an irregular loop antenna  44   T2  together with the irregular conducting patch  45 . The compressed loop  44   T1  connects at one end to the pad  30   T1  and connects at the other end to the pad  30   T2 . The irregular loop  44   T2  connects at one end to the pad  30   T1  and connects at the other end to the pad  30   T2. .  
         [0189]    [0189]FIG. 38 depicts a top view of a top layer including a two-loop, 6-legged compressed antenna together with an irregular one-loop compressed antenna that forms part of a multiband, multilayer compressed antenna. The two-loop, 6-legged compressed antenna of FIG. 38 includes the two compressed loops  44   T1-1  and  44   T1-2  surrounded by one irregular loop antenna  44   T2  The compressed loop antennas  44   T1-1  and  44   T1-2  connect at one end to the pad  30   T1  and connect at the other end to the pad  30   T2 . The irregular loop  44   T2  connects at one end to the pad  30   T1  and connect at the other end to the pad  30   T2 .  
         [0190]    [0190]FIG. 39 depicts a top view of a bottom layer including a two-loop, 6-legged compressed antenna together with an irregular conducting pad that forms part of the multiband, multilayer compressed antenna of FIG. 38. The two-loop, 6-legged compressed antenna of FIG. 39 includes the two compressed loop antennas  44   B1-1  and  44   B1-2  together with the irregular conducting patch  45 . The compressed loop antennas  44   B1-1  and  44   B1-2  connect at one end to the pad  30   B1  and connect at the other end to the pad  30   B2 .  
         [0191]    [0191]FIG. 40 depicts a top view of the multiband, multilayer compressed antenna  44   40  showing the layers of FIG. 38 and FIG. 39 superimposed as they would appear on the top and bottom of a dielectric substrate. The compressed antenna of FIG. 40 includes the two two-loop, 6-legged compressed loop antennas  44   T1-1  and  44   T1-2  surrounded by an irregular loop antenna  44   T2  together with the irregular conducting patch  45 . The compressed loops  44   T1-1  and  44   T1-2  connect at one end to the pad  30   T1  and connect at the other end to the pad  30   T2 . The irregular loop  44   T2  connects at one end to the pad  30   T1  and connects at the other end to the pad  30   T2. . The antenna of FIG. 40 employs loops that are nested to create a dual-band, band-pass antenna with good rejection between bands. Also, the antenna of FIG. 40 employs loops that are nested to a tri-band, band-pass antenna with good rejection between bands. The same basic antenna layout may be employed in different applications, such as dual-band and tri-band applications, using tuning techniques to adjust frequencies for any particular application.  
         [0192]    [0192]FIG. 41 depicts a top view of a top layer including a two-loop, 6-legged compressed antenna together with an irregular two-loop compressed antenna that forms part of a multiband, multilayer compressed antenna. The two-loop, 6-legged compressed antenna of FIG. 41 includes the two compressed loop antennas  44   T1-1  and  44   T1-2  surrounded by two irregular loop antennas 44   T   1  and  44   T2 . The compressed loop antennas  44   T1-1  and  44   T1-2  connect at one end to the pad  30   T1  and connect at the other end to the pad  30   T2 . The irregular loop antennas  44   T1  and  44   T2  connect at one end to the pad  30   T1  and connect at the other end to the pad  30   T2 . In FIG. 41, a pad interconnect  56  connects between the pad  30   T1  and the pad  30   T2. . In FIG. 41, a pad interconnect  56  connects between the pad  30   T1  and the pad  30   T2. . The pad interconnect  56  functions as a high-pass filter for the high frequency loop allowing low frequency signals (for example, 800-900 MHz) to short to ground. In some embodiments, filter networks are inserted into the antenna to achieve a high Q.  
         [0193]    [0193]FIG. 42 depicts a top view of a bottom layer including a two-loop, 6-legged compressed antenna together with an irregular conducting pad that forms part of the multiband, multilayer compressed antenna of FIG. 41. The two-loop, 6-legged compressed antenna of FIG. 42 includes the two compressed loop antennas  44   B1-1  and  44   B1-2  together with the irregular conducting patch  45 . The compressed loop antennas  44   B1-1  and  44   B1-2  connects at one end to the pad  30   B1  and connect at the other end to the pad  30   B2 .  
         [0194]    [0194]FIG. 43 depicts a top view of the multiband, multilayer compressed antenna  44   43  showing the layers of FIG. 41 and FIG. 42 superimposed as they would appear on the top and bottom of a dielectric substrate. The compressed antenna of FIG. 43 includes the two two-loop, 6-legged compressed loop antennas  44   T1-1  and  44   T1-2  surrounded by two irregular loop antennas 44   T1  and  44   T2  together with the irregular conducting patch  45 . The compressed loop antennas  44   T1-1  and  44   T1-2  connect at one end to the pad  30   T1  and connect at the other end to the pad  30   T2 . The irregular loop antennas  44   T1  and  44   T2  connect at one end to the pad  30   T1  and connect at the other end to the pad  30   T2 .  
         [0195]    [0195]FIG. 44 depicts a top view of a top layer including a one-loop, 6-legged compressed antenna together with an irregular one-loop compressed antenna that forms part of a multiband, multilayer compressed antenna. The one-loop, 6-legged compressed antenna of FIG. 44 includes one compressed loop antenna  44   T1  surrounded by an irregular loop antenna  44   T2 . The compressed loop antenna  44   T1  and irregular loop antenna  44   T2  are closed loops that do not connect to any pads.  
         [0196]    [0196]FIG. 45 depicts a top view of a bottom layer including a one-loop, 6-legged compressed antenna together with an irregular conducting pad that forms part of the multiband, multilayer compressed antenna with the layer of FIG. 44. The one-loop, 6-legged compressed antenna of FIG. 45 includes the one compressed loop  44   B1  together with two irregular conducting patches  45 - 1  and  45 - 2 . The compressed loop  44   B1  connects at one end to the pad  30   B1  and connects at the other end to the pad  30   B2 . The irregular loop  44   B2  connects at one end to the pad  30   B1  and connects at the other end to the pad  30   B2 . The two irregular conducting patches  45 - 1  and  45 - 2  are eclectically connected to the irregular loop  44   B2  and function together with the loop  44   T2.  to establish the desired frequency band.  
         [0197]    [0197]FIG. 46 depicts a top view of the multiband, multilayer compressed antenna  44   46  showing the layers of FIG. 44 and FIG. 45 superimposed as they would appear on the top and bottom of a dielectric substrate. The compressed antenna of FIG. 44 includes one compressed one-loop, 6-legged loop  44   T1  surrounded by an irregular loop antenna  44   T2  together with the irregular conducting patches  45 - 1  and  45 - 2 . The compressed loop  44   T1  connects at one end to the pad  30   T1  and connects at the other end to the pad  30   T2 . The irregular loop  44   B2  situated below the irregular loop  44   T2  connects at one end to the pad  30   T1  and connects at the other end to the pad  30   T2 .  
         [0198]    [0198]FIG. 47 depicts a top view of a top layer including a one-loop, 6-legged compressed antenna together with an irregular one-loop compressed antenna that forms part of a multiband, multilayer compressed antenna. The one-loop, 6-legged compressed antenna of FIG. 35 includes one compressed loop antenna  44   T1  surrounded by an irregular loop antenna  44   T2 . The compressed loop antenna  44   T1  connects at one end to the pad  30   T1  and connects at the other end to the pad  30   T2 . The irregular loop antenna  44   T2  connects at one end to the pad  30   T1  and connects at the other end to the pad  30   T2. .  
         [0199]    [0199]FIG. 48 depicts a top view of a bottom layer including a one-loop, 6-legged compressed antenna together with an irregular conducting pad that forms part of the multiband, multilayer compressed antenna with the layer of FIG. 44. The one-loop, 6-legged compressed antenna of FIG. 48 includes the one compressed loop  44   B1  electrically connected to an irregular conducting patches  45 . The compressed loop antenna  44   B1  and irregular loop antenna  44   B2  are closed loops that do not connect to any pads. The irregular conducting patches  45  is eclectically connected to the irregular loop  44   B2  and function together with the loop  44   T2.  to establish the desired frequency band.  
         [0200]    [0200]FIG. 49 depicts a top view of the multiband, multilayer compressed antenna  44   49  showing the layers of FIG. 47 and FIG. 48 superimposed as they would appear on the top and bottom of a dielectric substrate. The compressed antenna of FIG. 49 includes one compressed one-loop, 6-legged loop  44   T1  (over a compressed loop  44   B1 ) surrounded by an irregular loop antenna  44   T2  (over a compressed loop  44   B2 ) together with the irregular conducting patch  45 . The compressed loop  44   T1  connects at one end to the pad  30   T1  and connects at the other end to the pad  30   T2 . The irregular loop  44   T2  situated over the loop  44   T2  connects at one end to the pad  30   T1  and connects at the other end to the pad  30   T2 .  
         [0201]    [0201]FIG. 50 depicts a two-dimensional representation of the field pattern of the antenna structure of FIG. 40 for the GSM 900 MHz and GSM 1800 MHz bands.  
         [0202]    [0202]FIG. 51 depicts a two-dimensional representation of the field pattern of the antenna structure of FIG. 40 for the GSM 900 MHz, GSM 1800 MHz and PCS 1900 MHz band s.  
         [0203]    [0203]FIG. 52 depicts a voltage standing wave ratio (VSWR) representation of the antenna of FIG. 40. The FIG. 40 antenna has VSWR as follows:  
                                       ARROW   FREQUENCY   VSWR                   1   880 MHz   2.93       2   920 MHz   1.13       3   980 MHz   2.94       4   1.71 GHz   2.09       5   1.88 GHz   1.72                  
 
         [0204]    [0204]FIG. 53 depicts a top view of an outer irregular compressed loop with an inner two-loop, 6-legged compressed antenna, similar to the antenna of FIG. 12, together with a separate inner one-loop, 5-legged compressed antenna, similar to the antenna of FIG. 17. The antenna of FIG. 53 is a quad-band antenna and by addition of additional loops may add still additional bands.  
         [0205]    In FIG. 53, the two-loop, 6-legged compressed antenna  4   T1  is nested within the irregular compressed loop  4   T2 . The compressed antenna  4   T1  has a snowflake pattern formed of compressed loops  12   1  and  12   4 , as described in connection with FIG. 13. The compressed loops  12   1  and  12   4  and the irregular compressed loop  4   T2  all connect at one end to the pad  30   1  and all connect at the other end to the pad  30   2 . The compressed loops  12   1 ,  12   4  and compressed loop  4   T2  are nested on the same layer and the area enclosed by each of the more outer ones of the loops encloses the area enclosed by the more inner ones of the loops  
         [0206]    In FIG. 53, the one-loop, 5-legged compressed antenna  4   T3 , is similar to that shown in FIG. 17, and connects at one end to the pad  30 ′ 1  and connects at the other end to the pad  30 ′ 2 . The 5-legged compressed antenna  4   T3  is arrayed on the same layer and nested within the antenna  4   T2 . The compressed loops  12   1 ,  12   4  and the compressed loop  4   T2  are not superimposed, but are separated from each other while being nested within compressed loop  4   T2 .  
         [0207]    [0207]FIG. 54 depicts a top view of an antenna structure including compressed loops above and below a substrate and is a variant of the FIG. 22 antenna. The multi-loop antenna  44  of FIG. 54 includes a first compressed loop  44   B1  on a bottom layer generally surrounded by a second compressed loop  44   T2  on a top layer layer. The loop  44   T2  is connected at each end to connection pads  30   T1  and  30   T2 . The loops  44   B1  and  44   T2  generally lie in the XY-plane and have magnetic current in the Z-axis direction normal to the XY-plane. The loop  44   B1  is formed of two concentric loops, namely, sub-loops  44   B1-1  and  44   B1-2 , where sub-loop  44   B1-2  is nested within sub-loop  44   B1-1 .  
         [0208]    [0208]FIG. 55 depicts a top view of the top layer of the antenna structure of FIG. 54. The loop  44   T2  is connected at each end to connection pads  30   T1  and  30   T2 . The top layer of FIG. 55 differs from the top layer of FIG. 22 in that top layer of FIG. 55 does not include a double loop which corresponds to the compressed loop 44   B1-1  on the bottom layer.  
         [0209]    [0209]FIG. 56 depicts a top view of the bottom layer of the antenna of FIG. 54. The bottom layer includes the double nested loop  44   B1  including the first compressed loop  44   B1-1  surrounding a second compressed loop  44   B1-2 . The bottom layer also includes a conductive patch  45 ′ that serves as a ground or parasitic patch that functions to tune the antenna  44  and particularly loop  44   T2 .  
         [0210]    In the embodiment of FIG. 54 through FIG. 56, connection pads  30   B1  and  30   B2  capacitively couple the pads  30   T1  and  30   T2  whereby the compressed loops  44   T2  and  44   B1  are connected in common and are connected through the connection element  3  to the transceiver on circuit board  6  of FIG. 2. The capacitive coupling between the connection pads  30   B1  and  30   B2  and the pads  30   T1  and  30   T2  for the compressed loops  44   T2  and  44   B1  functions as a high-pass filter. The high-pass filter allows the higher frequencies to pass to the compressed loop  44   B1  and to be filtered from the lower frequency band of compressed loop  44   T2 . This filtering aides in the separation of the pass bands for the compressed loops  44   T2  and  44   B1 .  
         [0211]    [0211]FIG. 57 depicts a top view of an antenna  44   57  including an outer irregular compressed loop  44   T2  and an inner two-loop, 6-legged compressed loop  44 ′ T1 . The compressed loop antennas  44   T1-1  and  44 ′ T1-2  connect at one end to the pad  30   T1  and connect at the other end to the pad  30   T2 . The irregular loop  44   T2  connects at one end to the pad  30   T1  and connects at the other end to the pad  30   T2 . In the embodiment of FIG. 57, the width of the trace of the inner loop  44 ′ T1-2  is narrower than the trace of the inner loop  44   T1-1 .  
         [0212]    [0212]FIG. 58 depicts a top view of an antenna  44   58  including an outer irregular compressed loop  44   T2  and an inner two-loop, 6-legged compressed loop  44 ″ T1.  The compressed loop antennas  44   T1-1  and  44 ″ T1-2  of the compressed loop  44 ″ T1  connect at one end to the pad  30   T1  and connect at the other end to the pad  30   T2 . The irregular loop  44   T2  connects at one end to the pad  30   T1  and connects at the other end to the pad  30   T2 . The trace of the inner loop  44 ″ T1-2  is wider than the trace of the inner loop  44 ′ T1-2  of the two-loop compressed antenna of FIG. 57. This variation in trace width (variation of A T2  in FIG. 4) between the compressed loop  44 ″ T1  of FIG. 58 and the compressed loop  44 ′ T1  of FIG. 57 alters the parameters of the antenna and a variation is used to tune antennas. In general, increasing the trace width of any loop, or segment of a loop, decreases the inductance of the loop and generally increases the coupling to nearby traces of other loops. In one example, a change from a width (A T2  in FIG. 4) of about 3 mil (0.08 mm) to about 13 mil (0.33 mm) changes the frequency from 10 to 15 MHz between 800 MHz and 2000 MHz. Other similar changes might be expected up to 50 MHz and more.  
         [0213]    [0213]FIG. 59 depicts a top view of an alternate embodiment of a bottom layer of an antenna structure like that of FIG. 22, where the FIG. 59 bottom layer is similar to the bottom layer of FIG. 25. In FIG. 59, the inner loop  44   B1-2  of the two-loop compressed antenna  44   B1  is closed and floating while the outer loop  44   B1-1  is connected to the connection pads  30   B1  and  30   B2 . The inner loop  44   T1  is closed and floating, that is, not connected to any pad. With the inner loop  44   T1-1  floating, the antenna characteristics are altered as compared with a non-floating embodiment such as shown in FIG. 24. Because the inner and outer loops of antenna  44   T1  are in close proximity, they remain coupled and the floating compressed loop  44   B1  has a substantial effect on the properties of the overall antenna. Among other reasons, because the inner loop  44   B1-2  is a mirror image of the inner loop  44   T1-2  of an upper layer (for example, see the upper layer of FIG. 24), the inner loop  44   B1-2  of FIG. 59 is coupled to and forms part of the overall multi-loop antenna that is formed.  
         [0214]    [0214]FIG. 60 depicts a top view of an alternate embodiment of a bottom layer of an antenna structure like that of FIG. 22, where the FIG. 60 bottom layer is similar to the bottom layer of FIG. 25. In FIG. 60, the inner loop  44   B1-2  of the two-loop compressed antenna  44   B1  is formed of six legs, specifically the six legs  12 ′- 1 , 12 ′- 2 , 12 ′- 3 ,  12 ′- 4 ,  12 ′- 5  and  12 ′- 6 , where each of the legs is closed and floating. Among other reasons, because each of the six legs  12 ′- 1 , 12 ′- 2 , 12 ′- 3 ,  12 ′- 4 ,  12 ′- 5  and  12 ′- 6  is substantially a mirror image of a leg of the inner loop  44   T1-2  of an upper layer (for example, see the upper layer of FIG. 24), the inner loop  44   B1-2  formed of the six legs  12 ′- 1 , 12 ′- 2 , 12 ′- 3 ,  12 ′- 4 ,  12 ′- 5  and  12 ′- 6  is coupled to and forms part of the overall multi-loop antenna that is formed.  
         [0215]    [0215]FIG. 61 depicts a top view of a top layer having a tuning element in the form of tuning stub  60   1 . The top layer of FIG. 61 is similar to the top layer of FIG. 55. The top layer of FIG. 61 replaces the top layer in the loop antenna 44   54  of FIG. 54 to form an alternate loop antenna embodiment with a tuning element. The tuning stub  60   1  is internal to a loop in that it is situated internal to an area enclosed by loop  44   T2  of FIG. 61. The tuning stub  60   1  adds inductance to the irregular compressed loop  44   T2  in proportion to the length and other dimensions of tuning stub  60   1 . As a part of the design and manufacture of the loop antenna, the length of the tuning stub  60   1  is a tuning parameter varied to tune the irregular loop  44   T2  and the overall loop antenna formed. The tuning method includes forming a first instantiation of said loop antenna with a first value for the length of tuning stub  60   1 . Thereafter, the first instantiation of the loop antenna is tested to determine the loop antenna properties. Thereafter, one or more subsequent instantiations of the loop antenna are made with subsequent instantiations having modifications of the length of stub  60   1 . The steps of forming, testing and modifying are repeated until the properties of the loop antenna are acceptable.  
         [0216]    In general, one or more tuning parameters (such as length, width, thickness, pattern, location and relative location) exist for any loop antenna element including, for example, tuning stubs, pads, loops, traces, substrates and connectors. The tuning parameters are selected individually or in combination. Loop antennas are made with tuning parameters so that the loop antennas ultimately manufactured are suitable for use with a communication device to exchange energy in particular selected bands of radiation frequencies. The method of making a loop antenna includes the steps of forming loops, testing the antenna formed of the loops and modifying the loop antenna so formed. One or more of the steps are repeated until the properties of the loop antenna are acceptable. In particular, the forming step forms two or more radiation loops having a tuning parameter on a dielectric substrate wherein at least one of the loops is arrayed in a compressed pattern and wherein the loops are superimposed such that an area enclosed by one of the loops covers an area enclosed by another of the loops. The testing step tests the loop antenna to determine properties of the loop antenna. The modifying step modifies a tuning parameter. The method includes a number of tuning embodiments including embodiments where a tuning parameter is the length of a tuning section connected in series with a loop (see FIG. 22, FIG. 29, FIG. 31); a tuning parameter is a gap between loops (see FIG. 22); a tuning parameter is a width of one or more segments (see FIG. 57, FIG. 58, FIG. 63); a tuning parameter is one or more tapered segments (see FIG. 63); a tuning parameter is a length of a stub situated internal to a loop (see FIG. 61); a tuning parameter is a length of a stub situated external to a loop (see FIG. 62); a tuning parameter is a relative location of juxtaposed loops (see FIG. 3); a tuning parameter is a length of one or more of the loops (see FIG. 22). The steps in still further embodiments include the step of simulating the antenna operation and, when desired, the step of simulating the antenna operation is repeated after one or more of the modifying steps. The simulation employs computer program analysis, test equipment analysis and/or other well-known methods of antenna simulation.  
         [0217]    [0217]FIG. 62 depicts a top view of a top layer, similar to the top layer of FIG. 55, having an external tuning stub  60   2 . The stub  60   2  is external in that it is situated external to an area enclosed by a loop antenna, specifically antenna loop  44   T2  of FIG. 62. The tuning stub  60   2  adds inductance to the irregular compressed loop  44   T2  in proportion to the length of trace of tuning stub  60   1 . Additionally, the tuning stub  60   2  acts as a linear antenna that provides additional frequencies (proportional to the electrical length of the stub  60   2 ) to the frequency band of the overall antenna formed.  
         [0218]    The tuning of compressed loops and compressed antennas is important in designing and manufacturing of antennas with the desired bands of operation. The tuning may include variations of an entire loop, for many segments of a loop or for one or a few segments. Also, the use of a first trace (loop), for example on one layer, and the use of a juxtaposed trace (loop), for example on another layer, permits changes in the dimensions or the locations of either one or both of the juxtaposed traces to tune the antenna. Changing the dimensions of juxtaposed traces changes the capacitive and other coupling between the traces thereby facilitating tuning. Frequency shifts by as much as 100 MHz or more are possible. The use of tuning elements such as tuning stubs, variations in trace widths, variations in trace lengths, changes in loop locations, gaps between loops, the size and location of capacitive pads and other elements of antennas can all be used alone or in combination for tuning.  
         [0219]    [0219]FIG. 63 depicts a top view of a one-loop, 6-legged compressed antenna that forms part of an overall antenna where different segments of the 6-legged compressed loop have different thicknesses and shapes. Specifically, segment  62   1  has a narrow width compared with other segments of loop  44   63 . Segment  62   2  has an intermediate width compared with other segments of loop  44   63 . Segment  62   3  has a large width compared with segment  62   1  and segment  62   2 . Segments  62   4  and  64   5  have irregular widths (tapering from narrow at the ends to wide at the middle) compared with other segments of loop  44   63 . The different widths and shapes of segments are used to tune loops in order to achieve the desired overall antenna characteristics.  
         [0220]    [0220]FIG. 64 depicts a top view of a two-loop, 6-legged compressed antenna  44   64  formed by a first loop  18   1  on a first layer and formed by a second loop  18   2  on a second layer. The second loop  18   2  is a slightly reduced in size mirror image of the first loop  18   1 . Since the loops are on different layers, they can be the same size and shape. Alternatively, the loops can be of different sizes and shapes and be fully or partially superimposed. One end of the loop  18   1  connects to pad  30   2  and the other end connects to the via  64   2 . One end of the loop  18   2  connects through the via  64   1  to pad  30   1  and the other end connects to the via  64   2 . With these connections, an electric current from pad  30   2  to pad  30   1  is serially first in loop  18   1  and then second in loop  18   2 . The current is counterclockwise in both loops  18   1  and  18   2  and therefore, loops  18   1  and  18   2  form a two-turn antenna  44   64 . Alternatively, the via connections can be changed so that the loops are connected in parallel (similar to the loops  18   1  and  18   2  in FIG. 20 except not on the same layer and having vias in place of the transmission line conductors).  
         [0221]    [0221]FIG. 65 depicts a top view of a two-loop, 6-legged compressed antenna  44   64  formed on multiple layers  65   1 ,  65   2 , . . . ,  65   L . Each of the layers is a dielectric material supporting conducive traces. The first two layers  65   1  and  65   2  are like the antenna  44   64  shown in FIG. 64. The first loop  18   1  is situated on the top of layer  65   1 . The second loop  18   2  is situated on the top of layer  65   2  or alternatively on the bottom of layer  65   1 . One end of the loop  18 , connects to pad  30   2  and the other end connects to the part of the via  64   2 - 1  on layer  65   1 . The pad  30 , connects to the part of the via  64   1 - 1  on layer  65   1 .  
         [0222]    In FIG. 65, the loop  18   2  connects at one end to the part of the via  64   2 - 2  on layer  65   2  and the other end connects to the part of the via  64   1 - 2  on layer  65   2 . With these connections, an electric current from pad  30   2  to pad  30   1  is serially first in loop  18   1  and then second in loop  18   2 . The current is counterclockwise in both loops  18   1  and  18   2  and therefore, loops  18   1  and  18   2  form a two-turn antenna  44   64  in the same manner as FIG. 64.  
         [0223]    In FIG. 65, the loop  18   L  connects at one end to the part of the via  64   2 -L on layer  65   L  and the other end connects to the part of the via  64   1 -L on layer  65   L . With these connections the loop  18   L  is connected in parallel with the loop  18   2    
         [0224]    The loop antennas described in the various antenna embodiments operate in cellular frequencies of the world including those of North America, South America, Europe, Asia Australia. The cellular frequencies are used when the communication device is a mobile phone, PDA, portable computer, telemetering equipment or any other wireless device. The loop antennas described in the various antenna embodiments operate to transmit and/or receive in mobile telephone frequency bands, for example, anywhere from 800 MHz to 2500 MHz.  
         [0225]    While many different embodiments of compressed antennas have been described, the different features and variations of each embodiment may be readily transferred to other embodiments. A feature on one loop of an antenna may be transferred to another loop of the antenna. The interaction of multiple loops in a multi-loop antenna fosters the interchangeability of features from loop to loop.  
         [0226]    While the invention has been particularly shown and described with reference to preferred embodiments thereof it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention.