Wangwang Han

Low-Cost Wideband and High-Gain Slotted Cavity Antenna Using High-Order Modes for Millimeter-Wave Application

A novel single-fed low-cost wideband and high-gain slotted cavity antenna based on substrate integrated waveguide (SIW) technology using high-order cavity modes is demonstrated in this paper. High-order resonant modes (TE130, TE310, TE330) inside the cavity are simply excited by a coaxial probe which is located at the center of the antenna. Energy is coupled out of the cavity by a 3 × 3 slot array etched on the top surface of the cavity. Two antennas with different polarizations are designed and tested. Measured results show that the linearly polarized prototype achieves an impedance bandwidth (|S11| <; -10 dB) of > 26% (28 to 36.6 GHz), and a 1-dB gain bandwidth of 14.1% (30.3 to 34.9 GHz). In addition, a measured maximum gain of 13.8 dBi and radiation efficiency of 92% are obtained. To generate circularly polarized radiation, a rotated dipole array is placed in front of the proposed linearly polarized antenna. Measured results show that the circularly polarized antenna exhibits a common bandwidth (10-dB return loss bandwidth, 3-dB axial ratio bandwidth, and 1-dB gain bandwidth) of 11%.

A Six-Port MIMO Antenna System With High Isolation for 5-GHz WLAN Access Points

A six-port multiple-input-multiple-output (MIMO) antenna system with high port isolation for 5-GHz WLAN access points application is proposed in this letter. It consists of three vertically polarized and three horizontally polarized antenna elements alternately mounted on a pyramidal metal structure. Several techniques are used to improve the isolation performances of the antenna system, including the aperture-coupled feeding mechanism, quarter-wavelength chokes, and parasitic grooves. Measured results show that more than 45 dB isolation can be obtained between any two elements of the system within the operating band.

Single-Fed Low-Profile High-Gain Circularly Polarized Slotted Cavity Antenna Using a High-Order Mode

In this letter, a single-fed low-profile high-gain circularly polarized slotted cavity antenna using a high-order cavity mode, i.e., TE440 mode, is proposed. The proposed antenna has a simple structure that consists of a radiating linearly polarized slotted cavity antenna and a linear-to-circular polarization converter. An antenna prototype operating at WLAN 5.8-GHz band fabricated with low-cost standard printed circuit board (PCB) process is exemplified to validate the proposed concept. Measured results compared to their simulated counterparts are presented, and a good agreement between simulation and measurement is obtained.

Epsilon-Negative Transmission-Line-Based Annular-Ring-Loaded Circular Microstrip Antenna With Improved Performances

A novel epsilon-negative transmission line (ENG TL)-based annular-ring-loaded (ARL) circular microstrip antenna (CMSA) is proposed in this letter. Compared to a conventional CMSA, the proposed structure offers improved impedance bandwidth by exciting the TM11 modes on both the driven CMSA and the coupled ENG TL-based annular ring. Due to the enlarged radiation aperture, the gain is correspondingly enhanced. Moreover, the proposed structure exhibits lower levels of radiation along the horizon and toward the backside as compared to conventional CMSA. The mutual coupling characteristics of the proposed antenna are also investigated, and the simulated results show that the E-plane mutual coupling between the proposed ENG TL-based ARL CMSAs decreases much more rapidly with spacing than that for conventional CMSAs. To validate the proposed concept, prototypes with a center operating frequency of 6.5 GHz are fabricated and tested. Good agreements are achieved between simulation and measurement.

A single-feed high-gain fabry-perot antenna with reconfigurable polarization capability

A novel polarization reconfigurable fabry-perot antenna with high gain and simple feed is proposed in this paper. The proposed structure consists of a ground plane and a partially reflective surface (PRS). A microstrip patch antenna with switchable slots is embedded into the cavity to act as the primary feed. The proposed antenna can radiate with either right hand circular polarization (RHCP) or left hand circular polarization (LHCP) by controlling the status of the switches. The full-wave simulated results exhibit 21 dBi peak gain corresponding to 70% aperture efficiency for both polarization status. Good axial-ratio and impedance matching is obtained at the center operating frequency.

Fast Amplitude-Only Measurement Method for Phased Array Calibration

A novel amplitude-only measurement method is proposed to measure the signals (complex fields) of individual antenna elements for phased array calibration. The proposed method has minimum measuring time among the known amplitude-only measurement methods. The total number of power measurements with this method is about twice the number of antenna elements of phased array. Phase shifters are required to implement only three phase shifts (0°, 90°, and 180°). Array signal power is measured when the phase setting of an antenna element is one of the three phase shifts. According to the superposition principle of electromagnetic field, array signal is a linear combination of antenna element signals. As signal power is the inner product of a complex signal and itself, a set of linear equations concerning the inner products of the antenna element signals are established and solved with the measured data. The element signals are obtained with the inner products analyzed with a set of nonlinear equations. Numerical simulations and experimental results validated the effectiveness of the proposed method in calibrating phased arrays.

Multi-Element Phased Array Calibration Method by Solving Linear Equations

In this paper, we propose a new phased array calibration method that measures all antenna element excitations simultaneously. The method has the minimum number of measurements among the known similar methods. The auxiliary antenna used for measurement is placed in either near-field or far-field region to receive the complex array signals during the change of the antenna element phase settings. According to the superposition principle of electromagnetic field, a set of linear equations concerning the element signals are created with the measured array signals. With the scattering parameters between the measurement probe antenna and the element antennas prestored or simplified, we calculate the excitations of the antenna elements by solving the linear equations. The coefficient matrix of the linear equations determines the antenna element phase settings for the array signal measurements. The principles for the selection of the coefficient matrix concerning accuracy, complexity, and hardware requirements are presented. A recursive matrix-forming method is presented for the matrix selection in this paper. Numerical simulations and experiment results validated the effectiveness of the proposed method.

A Hybrid Method of Higher-Order FDTD and Subgridding Technique

A hybrid method of higher-order finite-difference time-domain (FDTD) method and subgridding technique is proposed in this letter. The whole computational domain is decomposed into two kinds of regions. One is coarse-grid higher-order region, and another is fine-grid low-order region. An interlayer is introduced to connect the two kinds of regions. The update schemes for fields in each region and in the interlayer are given. Different time-steps are used in the higher-order region and in the subgridding region to further improve computational efficiency. Numerical properties in terms of nonphysical interface reflection and late-time stability are numerically studied. Numerical examples are also given to validate the efficiency and accuracy of this method.

Single-fed high-gain circularly polarized slotted cavity antenna using TE 330 mode

In this paper, a novel single-fed high-gain circularly polarized slotted cavity antenna using TE330 mode based on substrate integrated waveguide (SIW) technology is proposed. The proposed antenna consists of two parts, i.e. the radiating linearly polarized slotted cavity antenna and a linear-to-circular polarization converter. An antenna prototype operating at WLAN 5.8 GHz band fabricated with low-cost standard printed circuit board (PCB) process is exemplified to validate the proposed concept. The overall volume of the antenna is 1.68λ0 × 1.68λ0 × 0.17λ0. Within the WLAN 5.8 GHz bandwidth, the measured boresight gain is larger than 13.5 dBic, and the measured boresight axial-ratio is smaller than 1.7 dB, indicating a good circularly polarized characteristic. The proposed antenna features low profile, high gain, ease of fabrication and high efficiency.

A low-cost wideband and high-gain slotted cavity antenna for millimeter-wave application

In this paper, a single-fed low-cost wideband and high-gain slotted cavity antenna based on substrate integrated waveguide (SIW) technology using high-order cavity modes is demonstrated. High-order resonant modes (TE130, TE310, TE330) inside the cavity are simply excited by a coaxial probe which is located at the centre of the antenna. Energy is coupled out of the cavity by a 3 × 3 slot array etched on the top surface of the cavity. Measured results show that the prototype achieves an impedance bandwidth (|S11| <; -10 dB) of > 26% (28 to 36.6 GHz), and a 1-dB gain bandwidth of 14.1% (30.3 to 34.9 GHz). In addition, a measured maximum gain of 13.8 dBi and efficiency of 92% are obtained.