This paper proposes a cost-effective millimeter-wave (mmWave) phased array antenna incorporating circular polarization (CP) capabilities for beam scanning applications. An initial evaluation involves the examination of an open single-loop antenna. Subsequently, the phased array design is presented, featuring a 4-element circular loop phased array antenna designed to operate at a frequency of 27.5 GHz. The precise control of the main beam steering is achieved through the implementation of a corporate feed network and four-phase shifters employing transmission line time delay techniques. To expand the CP bandwidth, the design incorporates concentric parasitic open-loop antennas. Experimental findings confirm the configuration’s ability to facilitate left-hand circular polarization (LHCP) radiation over a scanning angle span of 50°, specifically ranging from -25° to +25°. This accomplishment aligns with the stringent criteria for maintaining a radiation pattern with an axial ratio (AR) of less than 3 dB across a broad frequency spectrum. Additionally, the design achieves a peak gain of approximately 11 dBic in combination of a total efficiency surpassing 85% throughout the CP bandwidth. In addition, the proposed design offers the advantages of compact size and low cost. Prototypes were fabricated and measured, with results closely matching simulations. Owing to the achieved radiation properties, the proposed design demonstrates a potential for practical applications in satellite and wireless communications systems.

A singly fed reconfigurable circular loop antenna is proposed for millimeter-wave (mmWave) communication systems. This antenna’s distinctive feature lies in its capacity to adjust both polarization and bandwidth characteristics, a capability made possible by the strategic integration of two PIN diodes. These diodes are engineered to function in various modes, allowing for three distinct polarization states and accommodating two distinct bandwidths. A meticulous alignment of these PIN diodes enables the utilization of a single DC bias network as a highly effective RF choke, which simplifies the design and reduces the associated losses. Additionally, a planar biasing network that consists of coplanar strip-lines (CPS) has been employed eliminating the need for lumped elements. The simple and totally planar configuration offers a choice of right-hand circularly polarized (RHCP) radiation or left-hand circularly polarized (LHCP) radiation at 28 GHz. This is accompanied by impedance matching and axial ratio (AR) bandwidths of 12.9% and 8%, respectively, over the same frequency range with a gain of 7.5 dBic. Moreover, when the PIN diodes are unbiased, the antenna offers linear polarization (LP) over two narrow bandwidths at 27 GHz and 29 GHz featuring a maximum gain of 7.2 dBic. Therefore, the proposed configuration offers three operating modes: wide-band RHCP, wide-band-LHCP, and LP over dual narrow bands. Significantly, simulated results closely align with the measured outcomes, affirming the robustness and accuracy of this design.

This paper presents a comprehensive assessment of the performance of on-chip circularly polarized (CP) circular loop antennas that have been designed and fabricated to operate in the Q/V frequency band. The proposed antenna design incorporates two concentric loops, with the outer loop as the active element and the inner loop enhancing the CP bandwidth. The study utilizes gallium arsenide (GaAs) and silicon carbide (4H-SiC) semiconductor wafer substrates. The measured results highlight the successful achievement of impedance matching at 40 GHz and 44 GHz for the 4H-SiC and GaAs substrates, respectively. Furthermore, both cases yield an axial ratio (AR) of less than 3 dB, with variations in bandwidths and frequency bands contingent upon the dielectric constant of the respective substrate material. Moreover, the outcomes confirm that utilizing 4H-SiC substrates results in a significantly higher radiation efficiency of 95%, owing to lower substrate losses. In pursuit of these findings, a 4-element circularly polarized loop array antenna has been fabricated for operation at 40 GHz, employing a 4H-SiC wafer as a low-loss substrate. The results underscore the antenna’s remarkable performance, exemplified by a broadside gain of approximately 9.7 dBic and a total efficiency of circa 92%. A close agreement has been achieved between simulated and measured results.

This article delves into the capabilities of 3D-printed millimeter-wave (mmWave) layered cylindrical dielectric resonator antennas (CDRAs). The proposed design yielded promising results, boasting a remarkable 53% impedance bandwidth spanning the frequency spectrum from 18 to 34 GHz. Furthermore, the axial ratio (AR) bandwidth achieved an impressive 17%, coupled with a maximum gain of 13.3 dBic. These notable results underscore the efficacy of the proposed design, positioning it as a viable solution for applications in Beyond 5G (B5G). A novel assembly technique was also investigated, employing additive manufacturing to seamlessly merge two layers with distinct dielectric constants into a singular layer. This innovative approach systematically eliminates the potential for air gaps between layers, enhancing the antenna’s overall performance. This approach exhibited potential, particularly in the performance of a millimeter-wave circularly polarized (CP) cylindrical DRA featuring a perforated coating layer. The synergy between measurements and simulations demonstrates a remarkable alignment, providing robust validation of the effectiveness of the proposed design.

This paper presents the design and implementation of an innovative 4-element multifunctional reconfigurability array antenna (MRAA) operating at 27.5 GHz, leveraging PIN diodes for enhanced functionality. By strategically controlling the alignment of PIN diodes, the antenna utilizes only two coplanar strip line biasing networks, streamlining its design and implementation. The proposed array demonstrates exceptional versatility by easily generating scanning beams at angles up to ±25° across three distinct polarizations: right-hand and left-hand circular polarizations and linear polarization. Furthermore, the system achieves a reconfigurable frequency interface between circular and linear polarizations, enhancing its adaptability to diverse communication scenarios. Through comprehensive analysis, the proposed MRAA exhibits commendable array gain, surpassing 10 dBic, and very good radiation efficiency exceeding 74%. This work marks the pioneering effort in designing a multifunctional reconfigurable array antenna for millimeter-wave (mmWave) applications. Additionally, the proposed array offers simplicity in design and outperforms existing counterparts operating at lower frequencies. A prototype has been fabricated, and measurement results demonstrate close agreement with simulation, validating the efficacy of the proposed design.

This paper introduces an innovative and cost-effective approach for developing a millimeter-wave (mmWave) frequency-reconfigurable dielectric resonator antenna (DRA), which has not been reported before. The antenna integrates two rectangular DRA elements, where each DRA is centrally fed via a slot. A strategically positioned PIN diode is employed to exert control over performance by modulating the ON–OFF states of the diode, thereby simplifying the design process and reducing losses. In the OFF state, the first DRA, RDRA-I, exclusively supports the TE₃₁₁ resonance mode at 24.3 GHz, offering a 2.66% impedance bandwidth and achieving a maximum broadside gain of 9.2 dBi. Conversely, in the ON state, RDRA-I and RDRA-II concurrently operate in the TE₅₁₃ resonance mode at 29.3 GHz, providing a 2.7% impedance bandwidth and yielding a high gain of up to 11.8 dBi. Experimental results substantiate that the proposed antenna presents an attractive solution for applications necessitating frequency-reconfigurable and high-performance mmWave antennas in 5G and Beyond 5G (B5G) communication systems.