Chien-Jen Wang

Design of wideband circular polarization for the open-slot antenna

An open-slot antenna with wideband circular polarization has been designed and fabricated in this paper. The proposed antenna is composite of an open-slot, an asymmetric structure, and a patch-protruded feeding topology. The asymmetric structure can provide 90° phase difference in order to excite circular polarization for the satellite digital audio radio (SDAR) service system. By utilizing the patch-protruded feeding topology, impedance bandwidth and circular polarization can be enhanced. From the measured results, the proposed antenna achieves a 4.75-GHz impedance bandwidth (133 %) of a reflection coefficient > −10 dB and has a 3-dB axial-ratio bandwidth is about 2.47 GHz.

A reconfigurable monopole antenna for GPS and SDAR applications

A reconfigurable monopole with switchable frequency band and circular polarization has been demonstrated in this study. To achieve the switchable capability, two PIN diodes are placed into the fork-like conducted strip. When the bias voltages of the diodes are changed, the proposed monopole antenna possesses a right-hand circularly polarized (RHCP) wave at 1.57 GHz for the global positioning system (GPS) or a left-hand circularly polarized (LHCP) wave at 2.33 GHz for satellite digital audio radio (SDAR) service system. From the measured results, the 3-dB axial-ratio bandwidths are 110 MHz at the GPS band and 70 MHz at the SDAR band; meanwhile, the impedance bandwidths are 430 MHz around 1.6 GHz and 670 MHz around 2.4 GHz.

A wideband CPW-fed monopole antenna with linear and circular polarizations

A coplanar-waveguide (CPW)-fed monopole antenna for applications of the multi-system integration has been presented in this study. The enhancement of impedance bandwidth and circular polarization in the microstrip rectangular monopole antenna using following techniques: using asymmetrical CPW feeding structure and adding three grounded sleeve strips. By tuning the width of one side of the CPW ground plane, increase of impedance bandwidth and excitation of circular polarization at 1.57 GHz are achieved. Three parasitic inverted-L conducted strips are connected to the ground plane to further extend the impedance bandwidth. The measured impedance bandwidth of a S11 < −6 dB ranges from 0.65 to 2.85 GHz and the measured 3-dB axial-ratio bandwidth is about 150 MHz. The proposed antenna covers most of commercial wireless communication systems, such as GSM, GPS, DCS, PCS, IMT-2000, WLAN, and LTE.

A CPW-fed meandered-shaped monopole antenna with asymmetrical ground planes

In this work, a new coplanar-waveguide (CPW)-fed monopole antenna with dual-band operation is proposed. The antenna is composed of a meandered monopole, an extended conductor line, and asymmetrical ground planes. Tuning geometrical structure of the ground plane of the CPW feeding structure excites additional resonant frequency bands, and thus enhances the impedance bandwidth. The measured impedance bandwidths, which is defined by -6 dB reflection coefficient, are 186 MHz (863 - 1049 MHz, 19.4%) at the lower resonant mode and 1320 MHz (1490 - 2810 MHz, 61.3%) at the upper mode. It can be observed that the impedance bandwidth of the proposed antenna covers the operated bandwidths of the commercial wireless communication systems, such as GSM 900, DCS, IMT-2000, UMTS, WLAN, LTE 2300, and LTE 2500.

Small low-pass filter using slotted-ground-plane resonator

A compact low-pass filter (LPF) with a wide rejection band is presented by utilizing the defected ground structure (DGS) structure has been demonstrated in this letter. A wide rectangular stub, which overlaps the connection slots, connects to the transmission line so that this technique significantly can improve the band-stop characteristics. In our presentation, an equivalent RLC circuit is also presented to model the proposed LPF and the corresponding RLC parameters are also extracted.

A circularly polarized monopole slot antenna for multi-system applications

In this work, we present a wideband microstrip-fed monopole slot antenna with dual-band circular polarization (CP). A bent feeding and three slots contains a T-shaped and two inverted-L are used to excite two orthogonal electric fields with same amplitude and 90° phase difference (PD) for generating RHCP wave at 1.57 GHz and LHCP wave at 2.33 GHz. The proposed antenna can be operated for the global positioning system (GPS) and satellite digital audio radio (SDAR) system. Furthermore, to increase the impedance bandwidth at the low-frequency band, a parasitic rectangular patch is placed on the top plane of the substrate.

A small microstrip antenna for the digital television system by bent topology

A small dipole antenna for applications of the digital television (DTV) system has been presented in this study. The injected power is fed into the antenna by a coaxial cable. By utilizing L-shaped stub and coupling strip, the proposed antenna has a compact size is 20 × 200 × 0.8 mm3. The simulated impedance bandwidth by -6 dB is from 0.47 to 1.02 GHz, a 0.55-GHz impedance bandwidth (73.8 %).

Resonance analysis of the leaky-wave antenna

The resonance analysis of the leaky-wave antenna with the microstrip feeding has been presented in this paper. Owing to an open-end structure of the leaky-wave antenna, we analyze the antenna by using the cavity-mode technique. Two conventional leaky-wave antennas with two different lengths, defined by the short and long cases, are shown to examine their radiation mechanism and frequency characteristics. Without using commercial EM simulation tools, the location of the resonance modes of the leaky-wave antenna can be predicted.

Analysis of stepped-impedance slot antenna

The design procedure of the microstrip-fed stepped-impedance (SI) slot antenna has been derived by utilizing the transmission-line and lumped-element circuit topologies. The resonant analysis and modeling of the antenna are also included. This study does not only analyze the SI-slot antenna, but also systematically summarizes its frequency response characteristics, including the resonance condition and spurious response. The design formulas with respect to the impedance ratio of the SI slot antenna are analytically derived. Note that the resonant modes of the SI-slot antenna are predicted without utilizing expensive EM simulation software.

A monopole antenna with circular polarization

A monopole antenna with coplanar-waveguide (CPW) feeding structure is developed for multiple wireless communication system integration. By tuning one of the CPW ground-plane widths can increase the impedance bandwidth. The circular polarization at 1.57 GHz is excited without adding extra design circuits. A parasitic inverted-L radiating strip is shorted to the ground plane in order to cover the required bandwidth of the wireless local area network (WLAN) system. The measured impedance bandwidth of a S11<;-10 dB ranges from 1.37 to 2.82 GHz, and the 3-dB axial-ratio bandwidth is about 3.8 % with respect to 1.56 GHz.