Ye-Bon Kim

The growing demand for intelligent and user-centric devices is accelerating the adoption of contactless sensing technologies in modern healthcare consumer electronics. In particular, indoor human tracking is vital for enabling health-aware applications such as fall detection, activity recognition, and behavior monitoring within smart homes and ambient assisted living environments. However, existing solutions based on wearables, cameras, or environmental sensors face limitations in user compliance, privacy, and spatial coverage. To address these challenges, this paper presents a cost-effective radar architecture optimized for supporting smart healthcare applications. The proposed radar integrates a dielectric grid layer (DGL)-enhanced wide-beamwidth series-fed patch antenna array with a 4-Tx/4-Rx 24 GHz CMOS radar IC on a compact, cost-effective coplanar multilayer PCB. This design enables a field-of-view (FoV) of over 160°. Experimental results demonstrate the system’s ability to perform real-time, multi-target mobility tracking with minimal blind zones, making it suitable for human-centric services requiring high performance spatial awareness.

A compact mmWave phased array antenna module (PAAM) with wide beamwidth radiators to ensure blind spotless mmWave communication is porposed in this article. Unlike the typical PAAM consisting of patch-type elements with limited half power beamwidth (HPBW) around 90°, the proposed PAAM is configured by balanced multipole elements with extended HPBW in both E- and H-planes. Due to the extended HPBW of the proposed antenna element, the proposed PAMM can steer main beams for wider angles with lower side lobe levels. First, a single mmWave wide HPBW antenna element was fabricated and verified at 28 GHz, showing the measured HPBW of 148.3° and 141.3° in E- and H- planes, respectively. The measured HPBW of the proposed antenna showed more than 96% inrease in both planes, comparing with the conventional patch at 28 GHz. Moreover, 1×4 PAAM was fabricated by integrating the antenna array directly with a 4-channel beamforming IC to further verify the mmWave communications at 28 GHz with minimized blind spots. With 64-QAM over-the-air (OTA) test, the proposed PAAM showed the measured error vector magnitude (EVM) less than 7.1% at ±75° ranges while the conventional patch-based PAAM showed the measured EVM of 27.8% at ±75°.

A new flat-panel dash mount array antenna with wide-beamwidth fan-beam steering to provide hemispherical mmWave vehicle-to-everything (V2X) communication is proposed in this article. Unlike the typical patch-based phased array antennas with narrow beamwidth and limited scan angles, the proposed antenna can ensure blind spotless communication coverage in both elevation and azimuth angles, despite of its placement on a planar dash board. To verify the proposed dash mount array antenna, a single element was first fabricated and measured at 28 GHz. The measured half power beamwidth was 148.3° and 141.3° in E- and H- planes, respectively. Then, the proposed antenna was extended to a 1×16 phased array configuration and verified to have ±80° scan coverage in both elevation and azimuth angles. Furthermore, the proposed array antenna was placed on the vehicular dashboard to validate the blind-spotless mmWave communication with a 64-QAM over-the-air (OTA) test. The measured error vector magnitude (EVM) at 28 GHz was 7.5% with the incident signal angle at 80°, proving the feasibility of blind-spotless flat-panel antenna.

A wide-coverage unmanned aerial vehicle (UAV) antenna system for air-to-ground communications is proposed in this paper. The proposed antenna system has reconfigurable beam patterns based on five sets of dual-polarization and high gain antennas. Each antenna set is configured by a dual-polarization crossed inverted-V radiator and switched feed network to drive switched beamforming operations. Depending on the switch modes of the proposed antenna, main beam direction and circular polarization types can be independently selected. Further, each antenna set is faced toward the ground level at different angles from the center of UAV to provide wide beam coverage. To verify the antenna performance, each antenna set is designed at the center frequency of 5.7 GHz and total five sets are integrated with a switched feed network and a microcontroller. To implement the wide angle switched beamforming with 2-D angle-shifted main beams, a 3-D printed conformal fixture is used to connect both the antenna module and a drone body. The maximum measured bandwidth was more than 22% and the measured peak gain with the de-embedded switch feed network loss was about 10.2 dBic.

A printed circuit board (PCB) implementable multi-slot loaded antenna with a low-profile air-gapped structure for both gain and efficiency enhancement is proposed. The proposed planar antenna is configured by the upper substrate with a radiation patch separated from the lower substrate consisting of a pair of matching pads and a ground plane by the air-gap. The radiation patch on the upper substrate is loaded by two rectangular slots and a single narrow slot with a symmetrically placed feed point and a shorting pin. The narrow slot on the center of the radiation patch with the shorting pin improves both gain and radiation efficiency. The pair of two additional rectangular slots increase the gain while maintaining the required air-gap very low. Further, the symmetric matching pads are integrated along the feed and shorting vias to improve the realized antenna gain for the whole operation band. As a result, the proposed structure obtains a high gain-to-volume ratio as well as the enhanced efficiency. The proposed structure was fabricated at 5.9 GHz with the overall volume of 1.08 λ ₀ × 1.08 λ ₀ × 0.05 λ ₀ (55 mm × 55 mm × 2.7 mm) including the whole ground plane. The measured antenna gain was 9.4 dBi at 5.9 GHz verifying the high realized gain-to-volume ratio. Also, the measured half power beamwidths in E and H planes were about 72° and 74°, respectively. Lastly, the measured 10-dB impedance bandwidth of the proposed structure showed approximately 5.5 %.

A high gain stacked antenna based on a planar magneto-electric dipole structure is proposed. The main radiator is configured by a probe-fed patch with a symmetrically arranged pair of dipole radiation elements. Further, an additional air-gapped radiator with multiple patch elements is integrated for gain enhancement. Since both the main and stacked radiators are planar structures, the overall volume can remain low-profile regardless of the airgap. To verify the performance of the proposed structure, a single magneto-electric dipole antenna and three different types of stacked radiators were implemented at 5.8 GHz. The magneto-electric dipole antenna showed measured 10-dB impedance bandwidth and gain of 5.2% and 8.0 dBi, respectively with the overall size of 0.96 λ0 x 0.96 λ0 including a ground plane. With the additional stacked radiator having the airgap of 0.1 λ0, the maximum measured gain was increased to 9.6 dBi. Further, to verify the beamforming performances, three types of 1x8 phased array stacked structures were fabricated with a volume of 0.96 λ0 x 6.38 λ0 x 0.14 λ0 at 5.8 GHz. The measurements showed a maximum peak gain of 18.1 dBi and a half-power-beamwidth scan angle of 49˚ with a side-lobe level less than -8 dB.

A new design approach for a mmWave high gain planar antenna is presented. The proposed method can increase antenna directivity with a minimally enlarged radiation patch while the operation frequency is still matched at a higher target frequency. The fundamental structure of the proposed antenna is configured by a H-shaped and slot-loaded patch with a shorting pin symmetrically located across a signal excitation port. Further, to match the operation frequency with the frequency for the highest achievable gain, a vertically stacked matching conductor was inserted along the signal feed path between the radiation patch and the ground layer. The proposed single antenna showed the simulated directivity of 9.46 dBi while the conventional patch with a same dielectric had 8.07 dBi. To verify practical performance, a 2 × 2 array antenna was fabricated at 28 GHz and showed the measured gain of 12.5 dBi including the array feed loss.

Electrically conformal antenna arrays (ECAA) for 2-dimensional (2-D) beamforming configured by wide beamwidth multipole radiation elements are proposed. Unlike the conventional conformal antenna array with physically curved shape, the proposed arrays are planar structures with wide-angle beam steering. The wide range of beam steering with a low gain variation allows the planar array structure to achieve the electrically conformal phased array patterns. In order to verify the ECAA concept, two different types of ECAA in a 1x8 configuration using planar multipole antenna elements were fabricated at 5.8 GHz and compared to the conventional patch array. Each multipole element had half-power-beamwidth (HPBW) wider than 110° at both E- and H-planes with the maximum HPBW of 175°. The first type of ECAA showed a measured peak gain of 10.8 dBi with a measured half power steering angle of 155° while maintaining a side lobe level (SLL) less than -10 dB. Further, the second ECAA showed a measured peak gain of 12.8 dBi with a measured half power steering angle of 144° while keeping the SLL less than -10 dB. These scan angles of the first and second types were extended about 66.7% and 54.8%, respectively from the conventional patch array with the same size. Lastly, two types of 8x8 array modules for 2-D beam steering were verified at 5.8 GHz and the first type showed a maximum peak gain of 21.0 dBi. Further, the 2-D half power steering angles in E- and H-planes of the second type were about 145° and 137°, respectively.