Described and disclosed herein is a wideband polarized patch antenna and the antenna array that can cover mmWave frequency band from 24.3 to 29.6 GHz for 5G applications, and a feeding structure for such an antenna comprising a single element of a polarized helical-shaped L-probe fed patch antenna (HLF-PA) package.

BACKGROUND

Millimeter wave (mmWave), especially the frequency range from 24.25 to 29.5 GHz, has been allocated for 5G networks in many different countries. For example, the U.S. has 5G network frequency ranges between 26.5 and 28.35 GHz and between 37 and 40 GHz; South Korea has frequency ranges between 26.5 and 29.5 GHz; China has frequency ranges between 24.25 and 27.5 GHz and between 37 and 43.5 GHz; Europe has frequency ranges between 24.25 and 27.5 GHz; and Japan has frequency ranges between 27.5 and 28.28 GHz. Although mmWave-based communication can provide wide bandwidths, and thus a high data rate, the communication is limited by a high signal attenuation due to atmospheric absorption. Therefore, a high-gain phased array antenna with beamforming capability is needed. Also, antenna structure embedded within an integrated circuit (IC) package, namely antenna-in-package (AiP), instead of a discrete antenna is in high demand due to compactness, fabrication reliability, and cost-effectiveness. Hence, various mmWave phased array antennas using AiP design, which operate at 28 GHz frequency bands, have been widely investigated. The probe-fed dual-polarized patch antenna shows the 10-dB impedance bandwidth of 2.2 GHz (7.7%: 27.4-29.6 GHz). The height of antenna (Hant) in AiP is 490 μm (0.045 λLwhere λLis the air wavelength of the lowest frequency in the operation band). To further improve impedance bandwidth of the phased array antenna, an air cavity structure was introduced into a dual-polarized aperture-coupled patch AiP. Thereby, the impedance bandwidth increased to 3.7 GHz (13%: 26.3-30 GHz). Also, the stacked patch antenna with a Hantof 540 μm (0.048λL) shows the impedance bandwidth of 4 GHz (14%: 26.5-30.5 GHz). However, the impedance bandwidth of the reported antennas is not broad enough to cover the allocated 5G frequency band within 28 GHz band.

Therefore, a wideband polarized patch antenna and the antenna array that can cover mmWave frequency band from 24.3 to 29.6 GHz for 5G applications is desired.

SUMMARY

Described and disclosed herein is a wideband polarized patch antenna and the antenna array that can cover mmWave frequency band from 24.3 to 29.6 GHz for 5G applications, and a feeding structure for such an antenna comprising a single element of a polarized helical-shaped L-probe fed patch antenna (HLF-PA) package. In some instances, the antenna is dual-polarized.

DETAILED DESCRIPTION

Described herein are embodiments of a wideband polarized patch antenna and the antenna array that can cover mmWave frequency bands 5G applications. In some instances, the antenna may be dual-polarized. One embodiment of a single element of dual-polarized helical-shaped L-probe fed patch antenna (HLF-PA) package is illustrated inFIGS. 1A and 1B. This embodiment of an antenna package comprises a high-density interconnected (HDI) FR-4 printed circuit board (PCB) substrate, which has a dielectric constant (εr) of 4.02 and a dielectric loss tangent (tan δε) of 0.018 at 30 GHz. The element antenna package is comprised of a copper-clad laminates (CCL) layer with thickness (tCCL) of 0.3 mm, 10 layers of prepregs (PPG) with a thickness (tPPG) of 60 μm, and 12 layers of metal with a thickness (tCu) of 20 μm. Copper is used for all metal layers. The CCL, five top PPG, and six top metal (TM) layers were used for patch antenna structure (antenna portion in AiP), and five bottom PPG and six bottom metal (BM) layers were used for feeding lines. It is to be appreciated that this is just an example of one embodiment, and that the scope of this disclosure is intended to cover other aspects, including, for example, different types of materials, different numbers of layers and/or arrangement of the layers, different material thicknesses and/or dimensions, and the like. In other instances, different substrate materials can be used. For example, a variety of substrate materials can be used not only organic high-density interconnect (HDI) substrates but liquid crystal polymer-based board, glass substrates, high-(HTCC) and low-temperature co-fired ceramic (LTCC) substrates, silicon substrates, and the like. In the case of dielectric loss tangent of substrate materials, smaller values are preferred, since antenna radiation efficiency can be improved with lower loss tangent. Furthermore, either cored or coreless PCBs may be used.

The patch radiator is located on the TM6 layer. Coaxial-like feeding line structures are implemented through metal layers (e.g., from BM1 to BM6) to match the impedance, and helical-shaped L-probe feeding structures (seeFIG. 1B) are connected between layers (e.g., BM1 and TM4 metal layers). L-probe feeding methods are generally known to broaden the impedance bandwidth. However, to achieve high performance of the L-probe fed antenna, the length of the L-probe is in the range from 0.2 λceffto 0.25 λceff(λceffis the effective wavelength at the center frequency). In one example, the thickness of AiP is less than 1 mm for mmWave applications. Furthermore, the number of layers for antenna structure is limited, and height for the antenna (Hant) becomes less than 0.05λL, which is equivalent to 0.54 mm at 28 GHz. For this reason, the conventional L-probe feeding method is not suitable for AiP at 28 GHz bands.

FIG. 1Ashows an embodiment of a helical-shaped L-probe feeding structure, which provides wide impedance bandwidth. The designed feeding structure is comprised of a vertical component, which has the helical winding structure with 1.5 number of turns and is connected between BM1 to TM3, and a horizontal component, which is located at TM4. Two helical-shaped L-probe feeding structures are placed orthogonally to realize dual-polarization. Detailed antenna dimensions for one embodiment are summarized in Table I, below.

TABLE IDimensions of invented wideband dual-polarized 5 G antenna structure.LSWSLPWPLPBDFDFPdPBWHP552.352.350.180.090.1350.330.145XFDVDVPrctPPGtCCLtCuUnit in mm1.7050.040.060.50.060.30.02

EXAMPLES

Performance of the exemplary antenna package was simulated with the ANSYS high-frequency structure simulator (HFSS v.18.1).FIG. 2Ashows the simulated frequency-dependent S-parameters of the invented HLF-PA element. The 10-dB impedance bandwidth of the both V- and H-ports are 20% (5.3 GHz: 24.3-29.6 GHz). The developed antenna shows good isolation (|SHV|) between V- and H-ports greater than 18 dB. The simulated frequency-dependent realized gain at the boresight (RGoo) is the same for both V- and H-ports inFIG. 2B. The simulated minimum and maximum RG00in the operation frequency bands (24.3-29.6 GHz) are 3.7 and 5.1 dBi, respectively.FIGS. 3A and 3Bshow the simulated radiation patterns at 27 GHz in XOZ- and YOZ-planes. Both maximum gains appear at the boresight. The co-polarized radiation for V-port (Eθin XOZ-plane and Eϕin YOZ-plane) is orthogonal to the co-polarized radiation for H-port (Eϕin XOZ-plane and Eθin YOZ-plane) in the same planes, indicating the dual-polarization characteristic of the invented HLF-PA element. Small cross-polarization levels of −20 dB were also obtained from XOZ- and YOZ-planes.

Based on the optimized HLF-PA element, a 2 by 4 HLF-PA array (HLF-PAA) was designed and simulated for antenna performance.

FIG. 4is an illustration of an exemplary developed 2 by 4 HLF-PAA. The antenna performance of the the shown HLF-PAA was simulated with HFSS v.18.1. The simulated frequency dependent isolation between different ports of the 2 by 4 HLF-PAA with the distance between adjacent elements (d) of 5 mm is shown inFIG. 5A. Isolations |Sij| between two ports are higher than 15 dB.FIG. 5Bshows the frequency-dependent peak realized gain (PRG) with different d when only V-ports were excited while H-ports were terminated with 50 ohms. The maximum PRG increased from 10.6 to 14.5 dBi as d increased from 4 to 7 mm. As shown inFIGS. 6A and 6B, in the case of d with 5 mm, PRG in the operating frequency band (24.25-29.5 GHz) is in the range from 10 to 12.3 dBi, which meets the minimum required antenna gain for 5G wireless communication. The far-field radiation performance of HLF-PAA with excitation of H-ports showed the identical performance except providing orthogonal co-polarization, indicating polarization diversity of HLF-PAA.

To verify a beamforming capability of HLF-PAA, the phase progression in X- (βX) and Y-directions (βY) was varied from 0° to 120° for performance simulation.FIGS. 7A-7Eshow 2D and 3D radiation patterns of HLF-PAA (only V-ports were excited) at 28 GHz with different βXand βY. The angle for the maximum gain from the radiation pattern in XOZ-plane was steered from 0° to 330° (−30°) as βXvaried from 0° to 120° inFIG. 7A. In the case of varying βYfrom 0° to 120°, the angle for the maximum gain observed from the radiation pattern in YOZ-plane shifted from 0° to 320° (−40°) as shown inFIG. 7B. HLF-PAA yields a scanning angle up to 60° in X-direction and 80° in Y-direction. PRG slightly decreased from 12.1 to 11.9 dBi and from 12.1 to 10.1 dBi when βXand βYvaried from 0° to 120°, respectively. Also, sidelobe levels (SLLs) were less than −6.6 and −9.3 dB in XOZ- and YOZ-planes, respectively. By comparing 3D radiation patterns inFIGS. 7C, 7D, and 7E, the maximum radiation beam steered in X- and Y-direction by controlling fix and βY, respectively. Comparison of the disclosed HLF-PAA with previously reported antennas for 5G wireless communication is given in Table II. The disclosed HLF-PAA had broader impedance bandwidth (5.3 GHz: 24.3-29.6 GHz) and better antenna gain (>5.1 dBi) than other 5G AiPs with Hantof 0.048 λL. Note that the antenna gain can be further improved by using substrates having low dielectric loss tangent. More importantly, only the disclosed antenna nearly meets the frequency band from 24.25 GHz to 29.5 GHz, which can cover the lower 5G frequency band allocations, while other reported antennas can only operate at a specific country.

CONCLUSION

Disclosed and described herein are embodiments of a dual-polarized helical-shaped L-probe fed patch antenna (HLF-PA) and phased array (HLF-PAA) that cover the 5G frequency band. One antenna embodiment has a wide bandwidth (>5.3 GHz), excellent isolation between V- and H-ports (|SHV|>18 dB), and good antenna gain (<5.1 dBi) with small height for antenna portion in the antenna-in-package (AiP). Based on the single element, a 2×4 phased array is described. The exemplary HLF-PAA shows reasonable isolation between ports (|Sij|>15 dB) and excellent antenna gain. The exemplary HLF-PAA was capable of beam-forming, which is necessary for 5G wireless communication. Therefore, the developed antenna is applicable for 5G mobile devices.