Search

A multiple-input–multiple-output (MIMO) antenna with high frequency selectivity and controllable bandwidth, is proposed for band-notched ultrawideband (UWB) applications. In other words, it has a bandstop-filter-like response (second-order notched band) at the aimed rejected band. It consists of two rectangular printed monopole (PM) elements and a simple stepped ground stub to enhance wideband isolation. For achieving the second-order rejected band of the IEEE 802.11 wireless local area network (WLAN) band from 5.15 to 5.85 GHz centered at 5.5 GHz, two parasitic modified split-ring resonators (PMSRRs) and two inverted L-shaped branches (ILBs), are utilized. Measured results prove a bandwidth of S11

This paper presents a compact multiple-input-multiple-output (MIMO) antenna for wireless portable device applications. It entirely covers the Bluetooth (2.4–2.484 GHz), Worldwide Interoperability for Microwave Access (WiMAX) (3.4–3.69 GHz), Wireless Local Area Network (WLAN) (5.15–5.825 GHz), and ultra-wideband (UWB) (3.1–10.6 GHz) operating bands. This antenna consists of two planar polygon printed monopole(PM) antennas, a rectangular slot and a triangular trim on the antenna element to lower down the low-cutoff frequency for improving the impedance matching, and a stepped ground stub to improve the isolation. Two rounded corners are simultaneously used on the ground for the impedance matching at medium-high frequency. The results of simulation and measurement prove that the −10 dB bandwidth of this antenna is from 2.4 to 11 GHz, and the isolation is less than −15 dB in the entire band, which can satisfy the actual requirements according to most literatures. The envelope correlation coefficient is less than 0.02. The size of this antenna array is 40 × 36 mm2. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:783–787, 2016

In this article, a small-size seven-band antenna covering GSM850/900/1800/1900/UMTS2100/LTE2300/2500 bands for wireless wide area network/long term evolution mobile handset is presented. The developed antenna only occupies a planar size of 15 × 25 mm2. The capacitive coupling feed is used to generate fundamental resonant λ/8 mode and high-order λ/4 mode to reduce the size. Electromagnetic (EM) coupling between the radiation strips is used to widen the operation band. The antenna consists of a feed strip and two radiation strips (RS1, RS2). RS2 is in the same side of the ground. RS1 is in the other side of substrate. Two λ/8 modes (at 850 and 925 MHz) and two λ/4 modes (at 1850 and 2200 MHz) are generated by the capacitive feed. Strip RS1 contributes to 850 and 1850 MHz modes, and strip RS2 contributes to 925 and 2200 MHz modes. In the mean time, there exists EM coupling between the two radiation strips (RS1, RS2), then dual-resonance mode at 845 and 925 MHz form a wide lower band covering GSM850/900, two high order resonant modes at 1850 and 2200 MHz form a wide upper band covering GSM1800/1900/UMTS2100/LTE2300/2500. Design mechanics is analyzed and main parameters are studied. The proposed antenna is fabricated, and the simulated and measured results agree well. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1029–1033, 2015

In this article, a compact multiband monopole antenna is proposed to cover the frequency band for wireless local area network and worldwide interoperability for microwave access application. The multiband monopole antenna has the advantage of compact size of 15 × 30 mm2. The proposed antenna is an S-shaped strip connected with a notched rectangle loop radiation patch with a ground plane, and there is a slot in the ground plane. The two lower bands are achieved by the rectangle loop patch and the higher band is achieved by the slot in the ground plane. The impedance bandwidth for 10 dB return loss at 2.46, 3.8, and 5.4 GHz, are from 2.4 to 2.51 GHz, 3.20 to 4.07 GHz, and 5.08 to 5.85 GHz, respectively. Experimental results show that the antenna gives omnidirectional radiation patterns and stable antenna gains in the operating bands with the compact size. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1809–1812, 2014

In this article, a frequency selective surface (FSS) cell is proposed. The band stop frequency performance is compared between the two and four layer FSS structure with the proposed cells. The four-layer structure has the same low frequency as the two-layer structure, but the four-layer structure has 3.6 GHz wider stop band in high frequency. Then, a reflector with the proposed EBG cells for ultrawideband antenna is developed. The performance for the reference antenna with and without the proposed reflector was compared, the average improvement of the front-to-back ratio of the UWB antenna with designed FSS reflector is 15 dB from 3.1 to 10.6 GHz and the peak even can get to 30 dB at 5 GHz. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2541–2544, 2013

New microstrip low pass filters with low insertion loss, ultra-wide stopband and transmission zero are presented by using triangular and trapezoidal patch resonators with fractal defection. With such defection and a certain parallel feed method, undesired responses and harmonics are effectively suppressed and wide band, sharp attenuation obtained. The new filters have simpler and more compact configurations even better filter properties than the traditional line based ones.