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This paper explores the potential use of fused deposition modeling (FDM) technology for manufacturing microwave and millimeter-wave dielectric resonator antennas (DRAs) for 5G and beyond communication systems. DRAs operating at microwave and millimeter-wave (mmWave) frequency bands were simulated, fabricated, and analyzed in terms of manufacturing quality and radio frequency (RF) performance. Samples were manufactured using a 3D printer and PREPERM® ABS1000 filament, which offers a stable dielectric constant ( ε r = 10 ± 0.35) and low losses (tan δ = 0.003) over wide frequency and temperature ranges. Surface profile tests and microscope measurements revealed discrepancies in the dimensions in the xy-plane and along the z-axis, consistent with the observed shift in resonant frequency. Despite these variations, reasonably good agreement between RF-simulated and measured results was achieved, and the DRA array successfully covered the intended mmWave band. However, challenges in achieving high precision may restrict applications at higher mmWave bands. Nevertheless, compared with conventional methods, FDM techniques offer a highly accessible and flexible solution with a wide range of materials for home and micro-manufacturing of mmWave DRAs for modern 5G systems. [ABSTRACT FROM AUTHOR]

In this communication, a low-profile circularly polarized (CP) staircase curl antenna array with 2:1 impedance bandwidth and 50% axial ratio (AR) bandwidth is proposed for fifth-generation (5G) millimeter-wave (mmW) communications. It overcomes a vital drawback of complex multilayer structure of the wideband CP antenna array. By fully taking advantage of 3-D staircase layout, the curl element achieves 2:1 impedance bandwidth, 57.9% AR bandwidth, and a maximum gain of 7.4 dBic. Accordingly, benefiting from the tapered matching transformer, a single-layer full-corporate microstrip feeding network with 111.4% impedance bandwidth is constructed. For demonstration, an $8\times8$ staircase curl antenna array is designed on three-layer PCB laminates. The proposed antenna array is measured with an impedance bandwidth of 76.9% (20.0–45.0 GHz) and an AR bandwidth of 53.6% (23.1–40.0 GHz), demonstrating a promising candidate to be used in 5G mmW communications. [ABSTRACT FROM AUTHOR]

The function of passive wide-angle beam scanning is desired by the base station antenna to provide “green” cellular services. In this communication, such function is realized by designing a compact phase-controlled pattern-reconfigurable dielectric resonator antenna (DRA). The proposed DRA has a compact structure with a side length of 0.38 λc and excites the fundamental TE and TM modes by diverse ports. By assigning phase between diverse ports, E-plane tilted patterns are synthesized with ±66° scan angles. Its pattern-reconfigurable capability makes contributions for increasing array beam scanning angle and minimizing gain fluctuation. A passive four-element array is verified to have an enhanced beam scanning angle of ±81° with a gain fluctuation of 1.25 dB. The maximum gain of the scanning beam is located on the off-axis angle of ±66° and achieves a wide 3 dB scan coverage of ±105°. Good agreements have been shown between the measured and simulated results. The proposed phase-controlled pattern reconfigurable DRA and DRA arrays have an impedance bandwidth of 3.33% (2.95–3.05 GHz) for a sub-6 GHz wireless system. They enable the wide-angle beam scanning for base station antenna and provide a cost-effective passive system for “green” communications. [ABSTRACT FROM AUTHOR]

A millimeter-wave (mmW) wideband circularly polarized (CP) antenna based on an air-filled waveguide is proposed. By introducing two symmetrical ridges in the septum antenna, the proposed antenna can obtain a more compact antenna aperture than the septum antenna based on a rectangular waveguide (from 0.99 $\lambda \,\,\times1.25\,\,\lambda $ to 0.66 $\lambda \,\,\times0.91\,\,\lambda $). In addition, the high order modes are suppressed to less than −20 dB from 55 to 70 GHz. Then, the sharp corner in the axial-ratio (AR) and gain plots of the septum antenna based on a waveguide are eliminated. A simulated operating bandwidth of 16.4% for both $\vert \text {S}_{11}\vert < - 10$ dB and AR < 3 dB within half-power beamwidth (HPBW) is achieved from 56 to 66 GHz. To verify the design, the proposed antenna has been fabricated and measured. The differences between simulations and measurements caused by flange are evaluated. The measured operating bandwidth of 20.9% is achieved from 60 to 74 GHz [ABSTRACT FROM AUTHOR]

In this communication, a rectangular dielectric resonator antenna (DRA) is integrated with a backed cavity to enlarge the DRA side length by 1.8 times. The backed cavity also reduces the sensitivity of the DRA resonance to the DRA size, resulting in a relaxed fabrication tolerance. Based on the enlarged DRA design, a stacked DRA (sDRA) is proposed to improve the bandwidth from 8.7% to 15% and enhance the realized gain by an average of 1.5 dB. The proposed mechanisms are verified by fabricating a $4\times4$ sDRA array with an enlarged DRA side length of 1.8 mm ($0.40 {\lambda }$), an improved bandwidth of 62.7–73.9 GHz (16.4%), and an enhanced measured gain of up to 17.2 dBi. The enlarged DRA dimension permits a higher DRA operating frequency without reducing the DRA size. The proposed millimeter-wave (mmW) sDRA array provides a wide bandwidth and high-gain solution for 67 GHz unlicensed band communications. [ABSTRACT FROM AUTHOR]

A circular aperture box-horn array antenna operating in W-band, with sum and difference radiation beams, is presented in this paper. The circular aperture provides maximum usage efficiency of the area, which is well suited for a rotational platform. Nonuniform power distribution is applied for the radiating elements, contributing to a radiation pattern with suppressed sidelobe. In order to fit into the circular aperture, the feed networks are optimally arranged on a compact two-planar layer with four quadrants fed by the sum–difference network. The antenna array, along with its full-corporate feed networks, has a low profile and is easy to be machined. Measured results show that the peak gain is over 35.6 dBi from 92 to 94 GHz, with up to −21 dBi sidelobe level. In addition, the sum–difference contradictions are less than 4 dB, and the nulls of difference beams are below −25 dB. [ABSTRACT FROM AUTHOR]

In this letter, a novel method of reducing mutual coupling is proposed, and it used on a modified compact broadband antipodal Vivaldi antenna (AVA) array for future 5G millimeter-wave (mmWave) communication application. The proposed structure consists of eight antenna elements that are fed by a 1-to-8 power divider. In order to reduce the mutual coupling between AVA array elements, multiple notch structures are added on the ground plane. Thus, the isolation between the antenna elements can achieve a maximal additional 37.3 dB enhancement, impedance bandwidth is extended slightly from 24.65–28.5 GHz to 24.55–28.5 GHz, and the gain is improved simultaneously. To verify the designed method, the proposed AVA arrays were fabricated and measured. They show an overall size of 28.823 mm × 60 mm × 0.787 mm. The measured gain of the modified AVA array is 6.96–11.32 dB in the frequency band of future 5G mmWave communication, which is higher than the initial AVA array, whose gain is 5.34–8.5 dB. [ABSTRACT FROM AUTHOR]