An antenna-in-package (AiP) of endfire and dual-polarization at 28 GHz is presented. It is formed by four periodic antennas of broad bandwidth and high-isolation, fabricated by the low-temperature cofired ceramics technology. The dual-polarizations are realized by integrating a horizontal metal stripline-coupled dipole with a vertical magneto-electric monopole, incorporated into a multilayer architecture for compactness. The AiP skillfully implements vertical vias and horizontal strip lines in the cavities between antennas to improve isolation and polarization purity. This AiP has numerically been examined for endfire high gain and beam steering in user equipment (UE) applications. The prototype was measured to show good isolation lower than −25 dB from 26.5 to 29.5 GHz and agree with full-wave simulations. The antenna array is finally integrated with 1 $\times $ 4 boresight radiation microstrip antennas to form a complete UE AiP.

In this paper, a real-time, contactless pulse-based ultra-wideband (UWB) radar sensor was used to precisely detect the movement of the robotic arm, heartbeats, and respiration activities. To increase the object tracking resolution, an algorithm using adaptive and digitalized post-calibration techniques were proposed and tested. Both the radiated and reflected analog pulses were converted to digital signals by a low-noise comparator and its buffer for the time interval and distance detection. Moreover, the dynamic and calibrated tracking mechanism was incorporated into the algorithm for improving tracking accuracy and to continuously localize an object’s vibration. The measured performance revealed that the proposed method successfully achieved μm movement precision, thus providing its excellent tracking ability. We performed three different experimental tests to demonstrate the UWB radar’s viability. First, the radar was employed to detect the undesired structural vibration of a delta robotic arm, which was subjected to high acceleration and structural flexibility. The measured results indicated that the accuracy of 100 μm can be achieved at a 10 Hz vibration frequency. Next, the apnea alarm was tested, which included an embedded sensitive sensor in the smart mattress in order to execute long-term physiological monitoring. The apnea was mitigated by auto-adjusting the patient’s sleeping posture on the mattress when the UWB sensor detected the apnea condition. The final experiment using the radar sensor was to monitor human vital signs, such as heart and breathing rates, simultaneously. In comparison with a commercial electrocardiography (ECG) instrument, this radar sensor measured 73.2 beats per minutes (bpm) with only 1.2% deviation. Our results showed that the contactless UWB sensor performs superbly and is well-suited for monitoring physiological parameters.

This paper presents the design of dual-port subarray modularization integrating a three-port circulator, realized by using substrate integrated waveguide (SIW) technology, and a subarray of antenna elements for dual uplink and downlink beamforming. In particular, a $2\times2$ element module is implemented and fabricated on a standard printed circuit board substrate to demonstrate its radiation characteristics and operational mechanism. In this design, the SIW structure is used to reduce the radiation from microstrip lines at millimeter-wave frequencies and avoid contaminating the radiation patterns of subarrays. Greater than 5 dBi suppression has been achieved for good compatibility with the integration of radio frequency devices. The measured results show that the subarray modularization improves the insertion loss and results in an excellent isolation for independent transmitting and receiving beamforming network implementation. Numerical and experimental results are shown to verify the performance of these designs.

An integrated configuration of the reflection-type phase shifter (RTPS) and attenuator with simultaneous phase and amplitude control is presented for a phased-array front-end beamforming. The phase shift function of the RTPS adopts a quadrature coupler with high/low pass lumped elements and the corresponding π-type C–L–C loads. An RF tuner is subsequently incorporated into the 90° coupler to provide an energy reduction path and applied at the intermediate inductor of the coupler, thereby enabling a tunable transmission power. The merged coupler/RF-tuner realizes a matched and symmetrical structure with less impact on the load impedance variation, which can be regarded as part of the RTPS that performs RF signal degradation and maintains phase shift tuning. Furthermore, the π-type attenuator is incorporated into the RTPS to obtain an adequate power control range for the side-lobe suppression of the beamforming network. The simulated and measured results demonstrate the feasibility and suitability of the network for the proposed merged configuration applied to the phased-array system.

A novel design of an embedded cardiorespiratory monitoring system for wheelchair users is proposed. The entire system is composed of a sensor node, a smartphone, and a cloud server. The sensor node contains two parts of an ultra-wideband pulse radar and the data processing module; the former is used to obtain continuous vital-sign signals, and the latter processes the sampled signals to estimate the heart rate and the respiration rate, implemented in an embedded system to achieve a fully integrated radar system. The smartphone functions as the data bridge between the sensor node and the cloud server, which is responsible for sending emergent messages. Experiment results show that the proposed system could work reliably in static and dynamic cases of wheelchairs.

A fully differential LNA with forward-body-bias (FBB) technique using an intrinsic self-balanced MOSFET is presented in this paper for low-impact device junction leakage and process, voltage, and temperature (PVT) variations. A proposed natural back-to-back connected diode directly from the source-bulk and bulk-drain junctions of a MOSFET performs as a stable and balanced pseudo resistor for minimizing leakage current at the transconductance stage of a FBB LNA. In addition, the FBB voltage is injected into the bulk of the MOSFET to allow a full-swing operation, in particular simultaneously at a gate-driven and body-driven input stage. In comparison to the conventional topologies of pseudo resistor, the simulated and measured results show that the proposed FBB technique applied at the LNA with the dual cross coupling (DCC) configuration can indeed extend the overall dynamic range of the pseudo resistor and relief PVT variations under the same extreme condition, with a larger forward bias voltage close to the breakdown leakage current transition corner of the P-N junction.