Jing-Song Hong

Two Novel Band-Notched UWB Slot Antennas Fed by Microstrip Line

Two kinds of band-notched ultra wide-band slot antennas are proposed. Printed on a dielectric substrate of FR4with relative permittivity of 4.4 and fed by a 50 Ω microstrip line, the proposed antennas introduce semicircular annular strips to reject the frequency band (5.15-5.85 GHz) limited by IEEE802.11a. The parameters which affect the performance of the antennas in terms of its frequency domain characteristics are investigated in this paper.

Bandwidth Enhancement of a Polarization-Reconfigurable Patch Antenna With Stair-Slots on the Ground

A polarization-reconfigurable rectangular patch antenna for bandwidth enhancement is proposed. This antenna has stair-slots on the ground and two p-i-n diodes are used for switching the antennas polarization in linear polarization (LP), left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). The structure is concise and easy to optimize, and dc bias network is very simple. The measured impedance (-10-db S11) and 3-dB axial-ratio (AR) bandwidths are about 180 and 37 MHz, respectively, at the center frequency around 2.46 GHz for both LHCP and RHCP. Compared to the reference antennas (antenna with loop slots on the ground and antenna with L-shaped slots on the ground), the bandwidths of -10-dB S11 and 3-dB AR are greatly enhanced. The asymmetrical slotted ground excites TM10 and TM01 modes with different resonant frequency to generate CP radiation, and because of the stair-slots, instead of loop slots and L-shaped slots, the lower resonant frequency decreases and the higher one increases. Thus, the bandwidths are improved. The antenna has good switchable and radiation performances. It could be used for wireless local area network (WLAN) (2.4-2.5 GHz) in wireless communication systems.

A Novel Multi-Folded UBW Antenna Fed by CPW

A coplanar waveguide-fed uniplanar multi-folded slot antenna that has impedance bandwidth enough to cover UWB systems is presented. The −10 dB return loss bandwidth of the antenna spans from about 3 GHz to about 11 GHz. Parametric study is presented. Details of the proposed ultra-wideband design are described and simulation results are presented and discussed in this paper.

Isolation Enhancement of a Very Compact UWB-MIMO Slot Antenna With Two Defected Ground Structures

A very compact ultrawideband (UWB) multiple-input multiple-output (MIMO) antenna with high isolation is presented in this letter. The proposed antenna, consisting of two UWB slot antennas, has a very compact size of 22 ×26 mm2, which is smaller than most of UWB antennas only with single antenna element. A T-shaped slot is etched on the ground to improve the impedance matching characteristic in the low-frequency and reduce the mutual coupling for the frequencies ≥ 4 GHz. By etching a line slot to cancel out original coupling, isolation enhancement at the 3-4 GHz band is achieved. The antenna possesses a low mutual coupling of less than - 18 dB over the operating band from 3.1-10.6 GHz. The performance of this antenna both by simulation and by experiment indicates that the proposed antenna is a good candidate for UWB applications.

Gain improvement of a microstrip patch antenna using metamaterial superstrate with the zero refractive index

In this paper, a high-gain antenna based on zeroindex metamaterial (MTMs) is presented. An averaging effect over the metamaterial structure yields an effective permittivity that approaches zero at 10.2GHz, which results in a metamaterial with zero index of refraction. A comparison between the conventional patch antenna and the new metamaterial patch antenna is given. The results show that both the gain and directivity of the antenna are effectively improved based on the MTM superstrate.

A Novel Planar Monopole Antenna with an H-shaped Ground Plane for Dual-band Wlan Applications

A novel dual-band design of planar monopole antenna is presented in this paper. Printed on a dielectric substrate and fed by a 50 Ω microstrip line, a planar monopole antenna is demonstrated to generate two separate resonant modes to cover 2.4/5.2 GHz WLAN (wireless local area network) bands with satisfactory radiation properties. The impedance bandwidths of the proposed antenna are 600 MHz centered at 2.65Hz and 1.15GHz centered at 5.12 GHz for S 11 < −10 dB. The parameters which affect the performance of the antenna in terms of its frequency domain characteristics are investigated.

Radiation extraction for transmission-line interconnects

An extraction technique of radiation sources for non-uniform, transmission-lines has been introduced for the first time. The technique is to substitute solutions of the method of moments (MoM) for the lossless finite-length non-uniform transmission-line into modified transmission-line equations with dependent radiation sources to extract transmission-line parameters and the radiation source parameters.

Modeling stripline discontinuities by neural network with knowledge-based neurons

A three-layer neural network with knowledge-based neurons in the hidden layer (NNKBN) is presented for modeling stripline discontinuities. In NNKBN, prior knowledge for stripline discontinuity is incorporated into each hidden neuron. With knowledge-based neurons, the learning ability and generalization of the neural network are improved. Compared with conventional multi-layer perceptron neural network, the NNKBN can map the input-output relationships with fewer hidden neurons and has higher reliability for extrapolation beyond training data range. Two examples are given to illustrate the potential power of this approach.

Analysis of a double step microstrip discontinuity using generalized transmission line equations

In this paper, a new analysis for a double step microstrip discontinuity is presented by using generalized transmission line equations . The new analysis is based on a new concept of a finite-length transmission line integrated with its double step discontinuity so that the double step discontinuity is regarded as a finite-length nonuniform transmission line and the generalized equations could be directly implemented. Since the generalized equation coefficients are determined by dynamic numerical methods and the coefficients are invariant with the line excitation and load, the equations are dynamic rather than TEM. The interested discoveries are that the generalized equations for the whole double step structure or a partial double step structure can give us the same results and the generalized equations have broadband frequency characteristics. For the double step structure used in this paper for the analysis, the S-parameters for a frequency band from 0.5 GHz to 10 GHz can be well calculated by using only two separately generalized equations at frequency of 3 GHz and 8 GHz.

On the generalized transmission-line theory

Generalized transmission-line equations for lossless parallel planar transmission lines are derived based on exact electromagnetic theory. The hypothesis, i.e., the existence of non-zero diagonal parameters in the parameter matrix, made by Hasse and Mei is validated through a sound theoretic derivation. These non-zero parameters take into account the effects of discontinuity, radiation and higher modes of the lines.