Zhijiao Chen

Pattern-Reconfigurable Dual-Polarized Dielectric Resonator Antenna

We present a portable pattern-reconfigurable dual-polarized dielectric resonator antenna (DRA). Low-cost gallium arsenide (GaAs) single-pole, double-throw (SPDT) switches are utilized to select one of the feedline paths of the DRA, giving a boresight or cardioid pattern electronically. The measured results verify the proposed antenna switches its radiation patterns between cardioid and boresight shape, without significantly affecting its matching in the operating frequency range of 5-6 GHz. Results also confirm that the pattern configuration in one port with one polarization does not affect the RF characteristics of the other port with alternative polarization of the antenna. This two-port configuration makes the proposed antenna a suitable candidate for IEEE 802.11ac multi-user multiple-input-multiple-output (MU-MIMO) applications.

Pattern reconfigurable Dielectric Loaded Antenna (DLA) for polarisation diversity Wi-Fi Access Point

A novel, compact, low-cost, pattern reconfigurable Dielectric Loaded Antenna (DLA) is presented in this paper. This DLA has the advantage of broadband (5-6 GHz), dual-polarization with high isolation between two polarizations (better than 30 dB), symmetrical and directional radiation pattern with low cross-polarization. The uniqueness of this design is represented by the re-configurability of the pattern that can be achieved by altering the phase difference between the opposite feeding probes, which in turn provides a cost-effective solution for semi-smart antennas in Wi-Fi Access Point applications.

One-dimensional multiband terahertz graphene photonic crystal filters

Properties of one-dimensional graphene photonic crystals with dual-layer defects are studied. Results show that two defect modes appear within the gaps, and the defect modes shift to the lower frequencies with the chemical potential increasing, the physical mechanism are also given based on the relative dielectric constant of the graphene. It is also found that the frequency, magnitude, and numbers of the defect modes can vary with the symmetrical changes of the dual-defect layers. For oblique incidence, the defect modes of the TE polarization follow a similar trend with the TM polarization, and all the defect modes shift to the higher frequencies and disappear while new defect modes appear at the larger incident angles. These properties of graphene photonic crystals with dual-layer defects have potential applications in tunable terahertz narrow multiband filters.

A compact low-cost Dielectric Loaded Antenna for Wi-Fi Access Point applications

A novel, compact, low-cost Dielectric Loaded Antenna is presented in this paper. This antenna not only has broadband (5-6 GHz), dual-polarization characteristics but, most importantly, offers high isolation between the two polarizations. In addition, with the symmetrical antenna structure and anti-phase feed probes, the radiation pattern is symmetrical and directional with low cross-polarization. This provides a cost-efficient integration of an antenna for WLAN communication systems or future indoor BS front ends.

Polarization rotator of arbitrary angle based on simple slot-array

A novel polarization rotator of arbitrary angle was proposed and realized based on simple slot arrays. To achieve the rotation of an arbitrary angle α, the slots on the first layer have to be at an angle of α to the slots on the second layer. Consequently, 90° rotation can be realized using two perpendicularly oriented slot arrays, which overturns the conventional notion of that perpendicular slot arrays are not possible to pass electromagnetic wave. In addition, such structure provides the same bandwidth comparing to its counterpart utilized for frequency selective surface (FSS). Furthermore, such structure is much easier to be fabricated compared to the substrate integrated waveguide (SIW) array. Moreover, low insertion loss can be achieved based on metallic material.

Miniaturized Antenna Array with Co 2 Z Hexaferrite Substrate for Massive MIMO

In this paper, a miniaturized microstrip circular patch antenna operating at 1.8 GHz for 3GPP LTE communication has been designed. This antenna adopts Co2Z hexaferrite as substrate, which has permeability σr=4 and permittivity εr=12 at 1.8 GHz. It achieves both antenna miniaturization and bandwidth enhancement with patchs radius λ/26 and 61 MHz -10-dB bandwidth. Subsequently, the single antenna is extended to antenna arrays with 2, 4, and 16 elements, and all of them meet requirements for a LTE communication. The proposed arrays are very compact for potential applications in Massive MIMO systems.

UHF tunable compact antennas on Co2Z hexaferrite substrate with 2.5/1 tunable frequency range

In this paper, a compact tunable microstrip patch antenna with Co2Z hexaferrite substrate (μr=15, εr=12) that resonates on 360 MHz has been designed and fabricated, of which the frequency can be tuned by ~2.5/1. Compared with an identically sized patch antenna with dielectric material Rogers TMM13i (μr=1, εr=12) operating at 1120 MHz, the magnetic antenna on the Co2Z substrate exhibited a high bandwidth of 23% at 360 MHz, which is much higher than 0.95% for the nonmagnetic antenna on the TMM13i substrate. In addition, the resonance frequency of the patch antenna on Co2Z can be tuned from 360 MHz to ~900 MHz, or a tunability of 2.5/1, via the bias magnetic field. The combined size miniaturization, significantly enhanced bandwidth and significant tunability makes these Co2Z substrates with similar relative permeability and permittivity promising for future compact antenna substrates.

Broadband dual-frequency dual-polarization dielectric loaded antenna (DLA) for WiMAX and WLAN application

A compact, low cost dielectric loaded antenna (DLA) is presented for indoor WiMAX and WLAN application. The prototype antenna yields a bandwidth of 21.0% (3.4-4.2 GHz) and 27.6% (5.0-6.0 GHz) on vertical and horizonal linear polarizations. The isolation between two polarizations is better than 20 and 35 dB across the two bands. Furthermore, good broadside radiation patterns with moderate gain (4.7-6.5 dBi) are observed, and the cross-polarization levels are better than 25 dB at both E and H planes. This gives a cost-efficient solution for indoor base station operations.

Compact wideband circularly polarized antipodal curvedly tapered slot antenna

A method to reduce one direction width of the circularly polarized antipodal curvedly tapered slot antenna, while maintaining the wide axial ratio (AR) and impedance bandwidth and endfire radiation, is proposed in this letter. In this method, the ridge structure in the broad wall of the slotted waveguide is used to increase the current path, which makes the antenna achieving the appropriate phase difference of orthogonal electric fields within narrow antenna width. To validate the proposed method, a prototype of the antenna was fabricated and measured. Experimental results show that the proposed antenna can achieve a bandwidth of 27.6% (50–66 GHz) for both AR < 3 dB and reflection coefficient S11<–10 dB and an average gain of 8.39 dBi.

A dual-polarized wideband substrate-integrated-waveguide-fed slot antenna array for 60 GHz

A dual-polarized wideband substrate-integrated-waveguide fed aperture-coupled slot antenna array for 60 GHz is proposed. By cutting a semicircle shape on the edge of the crossed-slot antenna, the impedance bandwidth of the proposed antenna is effectively widen and achieves overlapped bandwidth of 16.7% for simulated |S11| and |S22|. In addition, over 35 dB isolation between two polarization and low cross-polarization level are achieved for dual-polarization operations. A gain up to 11.4 dB is obtained for 2×2 array. Most importantly, the proposed antenna array uses the aperture coupling method to enable the connection between PCB layers. It could be fabricated by stacking three layers of standard printed circuit board (PCB) laminates. With the advantages of low-cost, convenience of fabrication and desired performances, the proposed antenna is suitable for the millimeterwave antenna applications.