Broadband circularly polarized bent-dipole based antennas

Technologies are presented for providing circularly polarized antenna topologies based on multiple bent-dipole elements over a ground plane configuration. In some examples, Moxon based cross radiating elements may be fed through a hybrid 90° quadrature coupler. The radiating element may be widened and tapered relative to a standard bent-dipole configuration forming bow tie structures with approximately 90° bends to achieve broadband operation. The tapered branches may be split into two sub-branches and the bend angle increased to further increase bandwidth and gain of the antenna.

BACKGROUND

Wide band needs of modern communication applications on airborne and ground platforms at high frequency (HF), very high frequency (VHF), and ultra-high frequency (UHF) bands result in desired antenna specifications such as high forward gain, low cross-polarization, low back lobe radiation, compact size, and low cost. Some widely used SATCOM antennas in the UHF band include, for example, the eggbeater antenna including two cross circular loop antennas coupled to a hybrid quadrature coupler.

In Radio Frequency Identification (RFID) mobile applications, an RFID reader antenna needs to have high performance including a broadband operation, circular polarization, and a large angular coverage from horizon to zenith. For systems at RFID frequencies (e.g., 900 MHz range), wavelength may be on the order of one third to one quarter of a meter and conventional antennas may be physically too large for commercial use. In GPS applications, antennas need to have precise narrow band performance at specific frequency bands (e.g., L1 and L2 bands).

SUMMARY

The present disclosure generally describes technologies for providing broadband circularly polarized bent-dipole based antennas.

According to some example embodiments, broadband, circularly polarized, bent-dipole based antennas are provided. The antennas may include one or more of two or more bent-dipole based radiating elements, where the radiating elements have a tapered cross-sectional shape, a common input for the two or more radiating elements, and/or a ground plane at an approximately equal distance from the radiating elements.

According to other example embodiments, methods for providing broadband, circularly polarized wireless communication through a bent-dipole based antenna are provided. The methods may include one or more of providing an antenna that includes two or more bent-dipole based radiating elements, where the radiating elements have a tapered cross-sectional shape terminated with a horizontal bend, and a ground plane at an approximately equal distance from the radiating elements. The methods may also include providing a signal to a common input for the two or more radiating elements.

According to further example embodiments, broadband, circularly polarized, bent-dipole based antennas are provided. The antennas may include one or more of two bent-dipole based radiating elements, each element having a tapered cross-sectional shape widening from a feed point outward and a split forming two sub-branches terminated with a horizontal bend, where the radiating elements are in a substantially perpendicular configuration forming a bow tie structure, a common input for the two or more radiating elements, and a ground plane at an approximately equal distance from tips of the radiating elements.

DETAILED DESCRIPTION

This disclosure is generally drawn, inter alia, to apparatus, systems, and/or devices related to broadband circularly polarized obliquely bent-dipole based antennas.

Briefly stated, technologies are presented for providing circularly polarized antenna topologies based on multiple obliquely bent-dipole elements over a ground plane configuration. In some examples, Moxon based cross radiating elements may be fed through a hybrid 90° quadrature coupler. The radiating element may be widened and tapered relative to a standard bent-dipole configuration forming bow tie structures with approximately 90° bends to achieve broadband operation. The oblique tapered branches may be split into two sub-branches terminated with a horizontal bend and the bend angle increased to further increase bandwidth and gain of the antenna.

FIG. 1illustrates an example Moxon-like bent-dipole antenna over a ground plane, arranged in accordance with at least some embodiments described herein.

A dipole antenna is one of the basic radiating components in antenna engineering and can be produced from a simple wire, with a center-fed driven element. Two conductive elements, oriented parallel and collinear with each other may form a dipole antenna. An alternating voltage applied to the antenna at the center, between the two conductive elements is converted into radio waves and transmitted from the antenna. Dipole antennas are the basic elements of a multitude of more complex antennas such as multi-element Yagi-Uda antennas, egg beater antennas, and Moxon antennas commonly used in amateur radio communications.

A Moxon antenna includes a bent-dipole104over the ground reflector106, which produces enhanced front-to-back ratio of radiated power, a match over relatively wide frequency band, and lowered elevation height. A Moxon antenna may be viewed as a two-element Yagi-Uda antenna. A Moxon antenna may be formed using one or more bent-dipole elements, for example, two perpendicular bent-dipoles. As shown in a diagram100, a bent-dipole104with a voltage feed102may have two arms, each arm having a length of L+W (lengths of the first and second portions of each arm bent in a substantially perpendicular fashion). Thus, each arm may be bent toward the ground reflector106from L distance away from the center of the dipole. The end points of the bent-dipole104may be H away from the ground reflector106as shown in the diagram100. The bent-dipole104may be fed from the center of the antenna with a differential input.

Circular polarization is desired in many communication systems such as RFID, Global Positioning Service (GPS), and other satellite communications since it reduces signal loss due to receiving/transmitting antenna orientation. In a bent-dipole based system, right hand circular polarization (RHCP) may be obtained simply by placing two bent-dipole antennas substantially perpendicular to each other, one in x-z plane, the other in y-z plane and feeding them through a hybrid quadrature coupler.

FIGS. 2A and 2Billustrate two example Moxon based bow tie antenna structures in three dimensional views, arranged in accordance with at least some embodiments described herein.

For broadband operations, the radiating elements of an antenna according to embodiments may be tapered resulting in a “bow tie” antenna. Bow tie antennas have a wider impedance bandwidth than a dipole antenna with thin elements due to the tapered widening of the elements. By selecting suitable lengths, heights, and tapering parameters for the radiating elements of the bowtie antenna, as well as number of elements, the broad bandwidth may be optimized around selected frequencies such as VHF, UHF, or GPS frequency ranges. For example, a broadband, circularly polarized SATCOM antenna with relatively high gain optimized for the 200-400 MHz range may have following dimensions: length of horizontal arms (L): approx. 60 mm, length of vertical arms (W): approx. 82 mm, distance from the ground plane (H): approx. 120 mm, width of the arms at the center of the antenna (D): approx. 4 mm, and a taper angle (α): approx. 22.5 deg. Such an antenna may be produced using any suitable conductive material such as copper.

Diagram200A inFIG. 2Aillustrates an example antenna configuration210according to some example embodiments. The example antenna configuration210may include a two cross-element, bent-dipole, bow tie antenna204over a ground plane206. Diagram200B inFIG. 2Billustrates another example antenna configuration220including a similar bow tie antenna, where each arm226, or radiating element, of the antenna is split into two pieces (e.g.,222,224). The split (wedge) of each of the antenna arms may provide additional control over the selection of the bandwidth and a center frequency of the antenna. Thus, by selecting an angle of the wedge, the bandwidth of the antenna may be increased (or decreased) and the center frequency shifted to a desired resonance frequency. Each arm226of the antenna may have a first bend228associated with a first bend angle230, a second bend232associated with a second bend angle234, and a third bend236associated with a third bend angle238, as illustrated in the diagram200B. In some embodiments, the second bend angle234may be a sharper angle than the first bend angle230. For example, the second bend angle234may be a 90° angle, where the first bend angle230may be an obtuse angle greater than 90° and less than 180°, as illustrated in the diagram200B. In other embodiments, the third bend angle238may also be a sharper angle than the first bend angle230. Furthermore, the third bend angle238may be an angle equal to the second bend angle234. For example, the third bend angle238may be a 90° angle, which may be equal to the 90° angle of the second bend angle234, and accordingly sharper than the obtuse first bend angle230, as illustrated in the diagram200B. Consequently, the third bend236may cause a portion of each arm226of the antenna to substantially fold under the antenna in a substantially parallel configuration to the ground plane.

FIG. 3illustrates design parameters of a bow tie antenna, arranged in accordance with at least some embodiments described herein.

As shown in diagram300, from a cross-sectional view, the bow tie antenna304is similar to the bent-dipole antenna ofFIG. 1with a horizontal arm length of L, a vertical arm length of W, and a height from the ground plane306of H. Thus, antenna pattern characteristics (e.g., gain, directionality), antenna bandwidth, standing wave ratio, etc. may be adjusted by selecting suitable values for these parameters based on a desired use (center frequency, bandwidth, etc.). Differently from the thin element bent-dipole antennas, each arm308(radiating element) of a bow tie antenna has a tapered shape. The tapered shape may be defined by a width of the element D at the base (i.e., where the element is fed) and a taper angle α, which defines how wide the element is at the other end.

The ground plane306is finite. In some examples, the ground plane's dimensions may be selected as 4L×4L. In a two-element, cross configuration antenna, the two dipoles may be fed by a 90 degree phase shift from the two lumped ports of the hybrid coupler.

FIG. 4illustrates radiation patterns of an example bow tie antenna, arranged in accordance with at least some embodiments described herein.

Diagram400shows simulated antenna patterns for right hand (RHCP) and left hand (LHCP) circular polarizations for a bent-dipole, bow tie antenna according to some examples. For example, the antenna may be RH circularly polarized (414) within 60 degree from the zenith. In a UHF application, a maximum gain of approximately 12 dB may be obtained around 240 MHz, with gain dropping to approximately 9 dB at about 400 MHz. Radiation pattern412reflects performance of the same antenna for left hand circular polarization.

The example antenna providing the patterns in diagram400may include two bent Moxon type split bowtie elements. The two bent elements may be located perpendicular to each other as shown inFIG. 2and fed at the center via differential input through a hybrid coupler to produce Right Hand Circular Polarization (RHCP) or Left Hand Circular Polarization (LHCP).

FIG. 5illustrates major design parameters of a single triangularly tapered shaped antenna arm with a split bow tie antenna, arranged in accordance with at least some embodiments described herein.

As discussed above, in a bent-dipole based antenna according to some example embodiments the arms may be split into two sub-branches to further increase bandwidth and gain of the antenna. Diagram500illustrates an example split arm516and design parameters of such an antenna that may be adjusted for achieving desired antenna characteristics.

The design parameters may include horizontal arm length L, vertical arm length W, distance between the arm516and the ground plane506H, taper angle α of the tapered arm, and split angle γ of the arm516. In other example embodiments, a portion of the horizontal arm may be further bent at an angle β, which may be adjusted to select a desired beam width for the antenna pattern.

FIG. 6illustrates some parameters of the single triangular shaped antenna arm ofFIG. 5that may be modified to optimize various antenna characteristics, arranged in accordance with at least some embodiments described herein.

The example arm616of a split bow tie antenna in diagram600includes multiple design parameters that may be selected for desired antenna characteristics. Table 1 below describes some of those design parameters and effects of changing them (e.g., increase or decrease the value) on antenna performance.

TABLE 1Example design parameters and their effects on antenna performanceDesignDesign parameterparam.descriptionEffects on antenna performance1Wedge cutoutMoving wedge tip closer to the z-axis,lengtheffectively makes the first section of thewedge larger, which shifts central.frequency lower and reduces bandwidth2Wedge cutoutReducing the angle sharpens the wedgespread anglecutout, which increases the bandwidth andshifts central frequency higher.3Vertical lengthIncreasing the length may result indecreased low resonance point and higherS11 and/or decreased high resonance pointand lower S11. The total bandwidth maydecrease.Decreasing the length may result in higherlow resonance point and lower S11 and/orhigher high resonance point and higherS11. The total bandwidth may increase.4Length of the firstIncreasing the length may result in lowerbendlow resonance point and higher S11 and/orlower high resonance point and higher S11with an increased total bandwidth in RFIDfrequencies (UHF) and a decreased totalbandwidth in GPS frequencies.Decreasing the length may result in higherlow resonance point and lower S11 and/orhigher high resonance point and lower S11with a decreased total bandwidth in RFIDfrequencies (UHF) and an increased totalbandwidth in GPS frequencies.5Outer angle of theIncreasing the angle may result in lowerfirst bendlow resonance point and higher S11 and/orlower high resonance point and lower S11with a decreased total bandwidth in RFIDfrequencies (UHF).Increasing the angle may result in higherlow resonance point and lower S11 and/orlower high resonance point and lower S11with a decreased total bandwidth in GPSfrequencies.Decreasing the angle may result in higherlow resonance point and lower S11 and/orhigher high resonance point and higher S11with an increased total bandwidth in RFIDfrequencies (UHF).Decreasing the angle may result in lowerlow resonance point and higher S11 and/orhigher high resonance point and higher S11with an increased total bandwidth in GPSfrequencies.6Outer angle of theDecreasing the outer angle of the verticalvertical sectionsection, i.e. sharpening the angle, may(typically 90 degrees)improve reflection impedance around lowerresonance frequency, while matchingaround higher resonance frequency may bereduced. Bandwidth loss may not besubstantial with sharper outer angle.7Inner angle of theIncreasing the angle may result in lowervertical sectionlow resonance point and lower S11 and/orlower high resonance point and lower S11with a substantially same total bandwidthin RFID frequencies (UHF).Increasing the angle may result in higherlow resonance point and lower S11 and/orlower high resonance point and higher S11with a decreased total bandwidth in GPSfrequencies.Decreasing the angle may result in higherlow resonance point and higher S11 and/orhigher high resonance point and higher S11with a substantially same total bandwidthin RFID frequencies (UHF).Decreasing the angle may result in lowerlow resonance point and higher S11 and/orhigher high resonance point and lower S11with an increased total bandwidth in GPSfrequencies.8Horizontal lengthIncreasing the length may result in lower(no tip)low resonance point and higher S11 and/orlower high resonance point and lower S11with a decreased total bandwidth.Decreasing the length may result in higherlow resonance point and lower S11 and/orhigher high resonance point and higher S11with an increased total bandwidth.9Outer angle of theIncreasing the angle may result in higherhorizontal sectionlow resonance point and lower S11 and/orlower high resonance point and higher S11with a decreased total bandwidth.Decreasing the angle may result in lowerlow resonance point and higher S11 and/orhigher high resonance point and lower S11with an increased total bandwidth.

Of course, other design aspects of an antenna according to embodiments may be selected or modified to adjust various antenna performance characteristics to achieve desired performance at selected operating frequency ranges.

FIG. 7illustrates radiation pattern of an example broadband, circularly polarized, bent-dipole based antenna in comparison with a standard antenna in RFID band, arranged in accordance with at least some embodiments described herein.

Diagram700includes two radiation patterns in a polar coordinate system. Radiation pattern732corresponds to an example bent-dipole based, Moxon-like antenna with tapered and split arms according to some embodiments. Radiation pattern734corresponds to a standard dipole based antenna. Both patterns are in the RFID frequency range (i.e., approx. 900 MHz).

As diagram700shows, the radiation pattern of a bent-dipole based, Moxon-like antenna is relatively uniform without substantial nulls. The forward gain of the antenna is about 6 dB higher than the standard antenna, while side gains may be as much as 20 dB higher. Thus, the directionality as well as overall gain of the antenna according to embodiments is enhanced over the standard dipole-based antennas.

In addition to RFID frequencies, a tapered and split arm, bent-dipole, Moxon-like antenna may also be employed in GPS bands (i.e., 1227.60+/−10.23 MHz and 1575.42+/−10.23 MHz). Example dimensions of such an antenna (as shown inFIG. 6) may include:

TABLE 2Example dimensions of a tapered and splitarm, bent-dipole, Moxon-like antennaDimensionValueWedge cutout spread angle3.8degVertical length11mmLength of the first bend32mmOuter angle of the first bend8degOuter angle of the vertical section90mmHorizontal length (no tip)12mmOuter angle of the horizontal section10deg

The radiation patterns in diagram700and the example antenna providing those patterns are provided for illustrative purposes and do not constitute a limitation on embodiments. Any other form of bent-dipole based antennas with different number of arms, splits, taper and/or bend angles, etc. may be implemented using the principles described herein.

FIG. 8illustrates simulated return loss for the example antenna ofFIG. 7, arranged in accordance with at least some embodiments described herein.

Diagram800shows return loss (S11) of a tapered and split arm, bent-dipole, Moxon-like antenna designed for RFID frequency range. The simulated return loss graph840is approximately 3 dB in the frequency range from about 710 MHz to about 1200 MHz. The gain of such an example antenna may be approximately 7 dB with a front-to-rear ratio of −15 dB. In RFID reader applications, an antenna according some embodiments may yield at least a one quarter size by volume as compared to standard RFID antennas with similar parameters.

In case of UHF satellite communication applications, an antenna according to embodiments may yield at least a third size by volume as compared to a standard UHF eggbeater antenna with higher performance in frequency bandwidth, gain, and front-to-back ratios compared to the eggbeater antenna.

Thus, a circularly polarized, bent-dipole, Moxon type antenna according to embodiments with tapered and/or split elements over a ground plane may provide enhanced directionality, gain, return loss, and/or front-to-back ratio, while providing smaller size, especially suitable for mobile applications. Optimized antenna characteristics may be implemented in UHF, RFID, GPS, and satellite communication applications.

According to some examples, a broadband, circularly polarized, bent-dipole based antenna is described. An example antenna may include two or more bent-dipole based radiating elements, where the radiating elements may have a tapered cross-sectional shape, a common input for the radiating elements, and a ground plane at an approximately equal distance from the radiating elements.

In other examples, the common input may include a hybrid 90° quadrature coupler, where the hybrid 90° quadrature coupler may provide right hand circular polarization for the antenna. Each radiating element may be widened in a tapered manner relative to a thin-element bent-dipole, wherein the radiating elements may be in a configuration forming a bow tie structure with approximately 90° bends to achieve broadband operation. The tapered radiating elements may include a split forming two sub-branches on each radiating element, where a bend angle of each radiating element is increased to further increase a bandwidth and a gain of the antenna. The tapered widening of each radiating element may be defined by a width of each radiating element at a coupling location with the common input and a taper angle. A wedge tip of each radiating element may be moved toward a z-axis to shift a central frequency of the antenna lower and to reduce an antenna bandwidth. A wedge cutout spread angle may be reduced to shift a central frequency of the antenna higher and to increase an antenna bandwidth.

In further examples, an increase of a length of a vertical portion of each radiating element may result in an antenna bandwidth decrease; a low resonance point decrease and a return loss increase; and/or a high resonance point decrease and a return loss decrease. A decrease of the length of the vertical portion of each radiating element may result in an antenna bandwidth increase; a low resonance point increase and a return loss decrease; and/or a high resonance point increase and a return loss increase. An increase of a length of a first bend of each radiating element may result in a low resonance point decrease and a return loss increase; and/or a high resonance point decrease and a return loss increase. A decrease of the length of the first bend of each radiating element may result in a low resonance point increase and a return loss decrease; and/or a high resonance point increase and a return loss decrease. The increase of the length of the first bend of each radiating element may result in an increase of an antenna bandwidth in a Radio Frequency Identification (RFID) frequency range and a decrease of the antenna bandwidth in a Global Positioning Service (GPS) frequency range, and the decrease of the length of the first bend of each radiating element may result in a decrease of the antenna bandwidth in the RFID frequency range and an increase of the antenna bandwidth in the GPS frequency range.

In yet further examples, an increase of an outer angle of a first bend of each radiating element may result in an antenna bandwidth decrease; a low resonance point decrease and a return loss increase; and/or a high resonance point decrease and a return loss decrease in an RFID frequency range. The increase of the outer angle of the first bend of each radiating element may result in an antenna bandwidth decrease; a low resonance point increase and a return loss decrease; and/or a high resonance point decrease and a return loss decrease in a GPS frequency range. A decrease of the outer angle of the first bend of each radiating element may result in an antenna bandwidth increase; a low resonance point increase and a return loss decrease; and/or a high resonance point increase and a return loss increase in an RFID frequency range. The decrease of the outer angle of the first bend of each radiating element may result in an antenna bandwidth increase; a low resonance point decrease and a return loss increase; and/or a high resonance point increase and a return loss increase in a GPS frequency range. A decrease of an outer angle of a vertical portion of each radiating element may result in reduced reflection impedance around a lower resonance frequency. An increase of an inner angle of a vertical portion of each radiating element results in at least one from a set of: a low resonance point decrease and a return loss decrease; and/or a high resonance point decrease and a return loss decrease in an RFID frequency range. The increase of the inner angle of the vertical portion of each radiating element may result in an antenna bandwidth decrease; a low resonance point increase and a return loss decrease; and/or a high resonance point decrease and a return loss increase in a GPS frequency range.

In other examples, a decrease of the inner angle of the vertical portion of each radiating element may result in a low resonance point increase and a return loss increase; and/or a high resonance point increase and a return loss increase in an RFID frequency range. The decrease of the inner angle of the vertical portion of each radiating element may result in an antenna bandwidth increase; a low resonance point decrease and a return loss increase; and/or a high resonance point increase and a return loss decrease in a GPS frequency range. An increase of a horizontal length of each radiating element may result in an antenna bandwidth decrease; a low resonance point decrease and a return loss increase; and/or a high resonance point decrease and a return loss decrease. A decrease of the horizontal length of each radiating element may result in an antenna bandwidth increase; a low resonance point increase and a return loss decrease; and/or a high resonance point increase and a return loss increase. An increase of an outer angle of a horizontal portion of each radiating element may result in an antenna bandwidth decrease; a low resonance point increase and a return loss decrease; and/or a high resonance point decrease and a return loss increase. A decrease of the outer angle of the horizontal portion of each radiating element may result in an antenna bandwidth increase; a low resonance point decrease and a return loss increase; and/or a high resonance point increase and a return loss decrease. The antenna may be configured to operate an RFID frequency range, a GPS frequency range, or an ultra-high frequency (UHF) satellite communication frequency range.

According to some embodiments, a method for providing broadband, circularly polarized wireless communication through a bent-dipole based antenna may be provided. An example method may include providing an antenna that includes two or more bent-dipole based radiating elements, where the radiating elements may have a tapered cross-sectional shape, and a ground plane at an approximately equal distance from the radiating elements. The example method may also include providing a signal to a common input for the radiating elements.

In other embodiments, each radiating element may be widened in a tapered manner relative to a thin-element bent-dipole. The radiating elements may be configured to form a bow tie structure with approximately 900 bends to achieve broadband operation. A split may be formed in the tapered radiating elements to create two sub-branches on each radiating element. A bend angle of each radiating element may be increased to further increase a bandwidth and a gain of the antenna. A wedge tip of each radiating element may be moved toward a z-axis to shift a central frequency of the antenna lower and to reduce an antenna bandwidth. A wedge cutout spread angle may be reduced to shift a central frequency of the antenna higher and to increase an antenna bandwidth. A length of a vertical portion of each radiating element may be increased to achieve an antenna bandwidth decrease; a low resonance point decrease and a return loss increase; and/or a high resonance point decrease and a return loss decrease. The length of the vertical portion of each radiating element may be decreased to achieve an antenna bandwidth increase; a low resonance point increase and a return loss decrease; and/or a high resonance point increase and a return loss increase.

In further embodiments, a length of a first bend of each radiating element may be increased to achieve a low resonance point decrease and a return loss increase; and/or a high resonance point decrease and a return loss increase. The length of the first bend of each radiating element may be decreased to achieve a low resonance point increase and a return loss decrease; and/or a high resonance point increase and a return loss decrease. The length of the first bend of each radiating element may be increased to achieve an increase of an antenna bandwidth in a Radio Frequency Identification (RFID) frequency range and a decrease of the antenna bandwidth in a Global Positioning Service (GPS) frequency range; and the length of the first bend of each radiating element may be decreased to achieve a decrease of the antenna bandwidth in the RFID frequency range and an increase of the antenna bandwidth in the GPS frequency range. An outer angle of a first bend of each radiating element may be increased to achieve an antenna bandwidth decrease; a low resonance point decrease and a return loss increase; and/or a high resonance point decrease and a return loss decrease in an RFID frequency range. The outer angle of the first bend of each radiating element may be increased to achieve an antenna bandwidth decrease; a low resonance point increase and a return loss decrease; and/or a high resonance point decrease and a return loss decrease in a GPS frequency range. The outer angle of the first bend of each radiating element may be decreased to achieve an antenna bandwidth increase; a low resonance point increase and a return loss decrease; and/or a high resonance point increase and a return loss increase in an RFID frequency range. The outer angle of the first bend of each radiating element may be decreased to achieve an antenna bandwidth increase; a low resonance point decrease and a return loss increase; and/or a high resonance point increase and a return loss increase in a GPS frequency range.

In yet further embodiments, an outer angle of a vertical portion of each radiating element may be decreased to achieve reduced reflection impedance around a lower resonance frequency. An inner angle of a vertical portion of each radiating element may be increased to achieve a low resonance point decrease and a return loss decrease; and/or a high resonance point decrease and a return loss decrease in an RFID frequency range. The inner angle of the vertical portion of each radiating element to achieve an antenna bandwidth decrease; a low resonance point increase and a return loss decrease; and/or a high resonance point decrease and a return loss increase in a GPS frequency range. The inner angle of the vertical portion of each radiating element may be decreased to achieve a low resonance point increase and a return loss increase; and/or a high resonance point increase and a return loss increase in an RFID frequency range. The inner angle of the vertical portion of each radiating element may be decreased to achieve an antenna bandwidth increase; a low resonance point decrease and a return loss increase; and/or a high resonance point increase and a return loss decrease in a GPS frequency range.

In other embodiments, a horizontal length of each radiating element may be increased to achieve an antenna bandwidth decrease; a low resonance point decrease and a return loss increase; and/or a high resonance point decrease and a return loss decrease. The horizontal length of each radiating element may be decreased to achieve an antenna bandwidth increase; a low resonance point increase and a return loss decrease; and/or a high resonance point increase and a return loss increase. An outer angle of a horizontal portion of each radiating element may be increased to achieve an antenna bandwidth decrease; a low resonance point increase and a return loss decrease; and/or a high resonance point decrease and a return loss increase. The outer angle of the horizontal portion of each radiating element may be increased to achieve an antenna bandwidth increase; a low resonance point decrease and a return loss increase; and/or a high resonance point increase and a return loss decrease.

According to some examples, a broadband, circularly polarized, bent-dipole based antenna may be described. An example antenna may include two bent-dipole based radiating elements, each element having a tapered cross-sectional shape widening from a feed point outward and a split forming two sub-branches, where the radiating elements may be in a substantially perpendicular configuration forming a bow tie structure. The example antenna may also include a common input for the two or more radiating elements, and a ground plane at an approximately equal distance from tips of the radiating elements.

In other examples, the common input may include a hybrid 90° quadrature coupler for providing right hand circular polarization for the antenna. A bend angle of each radiating element may be increased to further increase a bandwidth and a gain of the antenna. The tapered widening of each radiating element may be defined by a width of each radiating element at a coupling location with the common input and a taper angle. A wedge tip of each radiating element may be moved toward a z-axis to shift a central frequency of the antenna lower and to reduce an antenna bandwidth. A wedge cutout spread angle may be reduced to shift a central frequency of the antenna higher and to increase an antenna bandwidth. An increase of a length of a vertical portion of each radiating element may result in an antenna bandwidth decrease; a low resonance point decrease and a return loss increase; and/or a high resonance point decrease and a return loss decrease. A decrease of the length of the vertical portion of each radiating element may result in an antenna bandwidth increase; a low resonance point increase and a return loss decrease; and/or a high resonance point increase and a return loss increase.

In further examples, an increase of a length of a first bend of each radiating element may result in a low resonance point decrease and a return loss increase; and/or a high resonance point decrease and a return loss increase. A decrease of the length of the first bend of each radiating element may result in a low resonance point increase and a return loss decrease; and/or a high resonance point increase and a return loss decrease. The increase of the length of the first bend of each radiating element may result in an increase of an antenna bandwidth in a Radio Frequency Identification (RFID) frequency range and a decrease of the antenna bandwidth in a Global Positioning Service (GPS) frequency range, and the decrease of the length of the first bend of each radiating element may result in in a decrease of the antenna bandwidth in the RFID frequency range and an increase of the antenna bandwidth in the GPS frequency range. An increase of an outer angle of a first bend of each radiating element may result in an antenna bandwidth decrease; a low resonance point decrease and a return loss increase; and/or a high resonance point decrease and a return loss decrease in an RFID frequency range. The increase of the outer angle of the first bend of each radiating element may result in an antenna bandwidth decrease; a low resonance point increase and a return loss decrease; and/or a high resonance point decrease and a return loss decrease in a GPS frequency range. A decrease of the outer angle of the first bend of each radiating element may result in an antenna bandwidth increase; a low resonance point increase and a return loss decrease; and/or a high resonance point increase and a return loss increase in an RFID frequency range. The decrease of the outer angle of the first bend of each radiating element may result in an antenna bandwidth increase; a low resonance point decrease and a return loss increase; and/or a high resonance point increase and a return loss increase in a GPS frequency range.

In yet further examples, a decrease of an outer angle of a vertical portion of each radiating element may result in reduced reflection impedance around a lower resonance frequency. An increase of an inner angle of a vertical portion of each radiating element may result in a low resonance point decrease and a return loss decrease; and/or a high resonance point decrease and a return loss decrease in an RFID frequency range. The increase of the inner angle of the vertical portion of each radiating element may result in an antenna bandwidth decrease; a low resonance point increase and a return loss decrease; and/or a high resonance point decrease and a return loss increase in a GPS frequency range. A decrease of the inner angle of the vertical portion of each radiating element may result in a low resonance point increase and a return loss increase; and/or a high resonance point increase and a return loss increase in an RFID frequency range. The decrease of the inner angle of the vertical portion of each radiating element may result in an antenna bandwidth increase; a low resonance point decrease and a return loss increase; and/or a high resonance point increase and a return loss decrease in a GPS frequency range.

In other examples, an increase of a horizontal length of each radiating element may result in an antenna bandwidth decrease; a low resonance point decrease and a return loss increase; and/or a high resonance point decrease and a return loss decrease. A decrease of the horizontal length of each radiating element may result in an antenna bandwidth increase; a low resonance point increase and a return loss decrease; and/or a high resonance point increase and a return loss increase. An increase of an outer angle of a horizontal portion of each radiating element may result in an antenna bandwidth decrease; a low resonance point increase and a return loss decrease; and/or a high resonance point decrease and a return loss increase. A decrease of the outer angle of the horizontal portion of each radiating element may result in an antenna bandwidth increase; a low resonance point decrease and a return loss increase; and/or a high resonance point increase and a return loss decrease. The antenna may be configured to operate in an RFID frequency range, a GPS frequency range, or an ultra-high frequency (UHF) satellite communication frequency range.