A compact ultrawideband (UWB) antenna with 3.5/5.2GHz band-notched characteristics is proposed. The proposed antenna is composed of a half elliptic annulus radiation element fed by microstrip line and a step-shaped ground plane with truncated corners. By inserting closed-looped resonating structure onto the radiation patch and connecting open-looped resonator on the back side with patch via metallic hole, the dual notched frequency bands are achieved. The numerical and experimental results exhibit a wide impedance bandwidth ranging from 3.08 to 11GHz with the dual notched bands around 3.5 and 5.2GHz. Additionally, nearly omni-directional radiation patterns, moderate gain, and small group delay variation are also obtained.
A dual-mode dual-band bandpass filter is designed using a single stub-loaded slot ring resonator. This resonator is coupled to the two external feed lines at two positions spaced at 135° along the slot ring through a pair of microstrip-slotline Tjunctions. With a proper choice of the degree of external coupling, the first-order degenerate modes are split to make up the first passband with two transmission poles. The second passband is realized by the second-order degenerate modes, which are stimulated by symmetrically attaching four identical stubs along the slot ring. The center frequency ratio of the two operating passbands is controlled by the nature and strength of the external coupling, which is determined by the characteristics of the microstrip opencircuited stubs. Finally, a dual-band filter with center frequencies at 2.4 and 5.2 GHz is designed and fabricated. Measured results verify the design principle and predicted dual-passband performance. Benefiting from an additional transmission zero brought by the transitions, the upper stopband is expanded up to 12.75 GHz with at least 13 dB of rejection.
A microstrip bandpass filter is presented based on Complementary Split Ring Resonators (CSRRs) and a pair of open-loop resonators that has a single pair of transmission zeros at finite frequencies that causes an improvement at skirt response. An equivalent circuit is introduced to make analysis and optimization faster. Finally a filter is designed using the proposed cell and the simulation results with both equivalent model and full wave analysis are in very good agreement. The filter was fabricated and the measurement result was also in good agreement with simulation results. Besides, the size of the designed filter is very small and it occupies an area less than 0.23λg × 0.16λg, where λg is the guided wavelength at the midband frequency.
A semi-circle monopole printed antenna is proposed. Its radiation unit and the ground plane are in the same shape, and both of them are coplanar-printed. The antenna is fed by a microstrip line, which is connected to the radiation unit through a via-hole. The measured impedance bandwidth is about 3.1GHz-15.1GHz with VSWR<2, and the ratio bandwidth can reach 4.9:1. The omnidirectional characteristic is also excellent in H-plane. Moreover, because of the introduction of the semi-circle radiation unit and the ground plane, the length of the radiation unit can be miniaturized in polarization direction, which is only 14% of wavelength of the lowest operating frequency. The antenna size is just 29 mm×29.5 mm×1.0 mm, which can make it well integrate into UWB communication systems.
A compact paw-shaped multiband monopole antenna for Wireless local area network(WLAN) and worldwide interoperability for microwave access(WiMAX) applications is presented. The proposed antenna is composed of a paw-shaped monopole element and a rectangular ground plane with simple configuration. This antenna can easily be fed by using a 50ohm probe feed with SMA connector. By adjusting a few parameters of the three arms, the resonant frequencies can be easily tuned. The proposed antenna was analyzed and optimized to cover three bandwidths from 2.32 to 2.84, 3.39 to 4.34 and 5.11 to 5.91GHz that for WLAN and WiMAX applications respectively, with the return loss of better than 10 dB. The performances of the antenna are demonstrated along with measured and simulated results. Moreover, simulated and experimental results with different parameters of the antenna are given.
A circular wide-slot UWB antenna with dual band-notched characteristics is proposed in this paper. The microstrip-fed antenna mainly consists of a calabash-shaped feeding patch and a metal ground with a circular slot etched. Dual notched bands are realized by introducing arc-shaped parasitic strip and slot on the ground plane. The measured results show that the proposed antenna can operate at the range of 2.91-11.45 GHz with VSWR < 2 for UWB applications, except the notched bands of 3.38-3.71 GHz and 5.39-6.27 GHz for the 3.5 GHz WiMAX and 5.8 GHz WLAN, respectively.
A novel miniaturized microstrip six-port junction is presented. The new structure effectively reduces the occupied area to 25% of the conventional six-port junction due to two open loaded stubs. The design is validated both by using momentum of Advanced Design System and by measurement.
In this paper, a novel approach based on the support vector machine (SVM) for dielectric target detection in through-wall scenario is proposed. Through-wall detection is converted to the establishment and use of a mapping between backscattered data and the dielectric parameter of the target. Then the propagation effects caused by walls, such as refraction and speed change, are included in the mapping that can be regressed after SVM training process. The training and testing data for the SVM is obtained by finite-difference time-domain (FDTD) simulation. Numerical experiments show that once the training phase is completed, this technique only needs computational time in an order of seconds to predict the parameters. Besides, experimental results show that good consistency between the actual parameters and estimated ones is achieved. Through-wall target tracking is also discussed and the results are acceptable.
A novel compact design for ultra-wide bandwidth (UWB) planar monopole antenna is presented in this paper. The basis for achieving the UWB operation is through using semicircular microstrip monopole antenna with modified ground plane in the form of semi circular umbrella like shape. This shape produces bandwidth ranging from 3 to 35 GHz with discontinuities from 7 GHz to 10 GHz, from 12.5 GHz to 17.5 GHz and from 22 GHz to 40 GHz. The antenna size is reduced by 27% relative to the size of conventional rectangular monopole patch antenna. Metamaterial structures are used for further antenna performance improvement. Two types of metamaterial namely EBG and DGS are studied. First, embedding metallo EBG (EMEBG) is used to eliminate ripples in the operating band and also further reducing the antenna size by more than 30% as compared to the proposed patch. The antenna design provides an impedance bandwidth of more than 33 GHz. Second, four arms spiral defected ground structure (SDGS) is used as a ground plane with four arms to further improve the antenna performance. The SAMC reduced the antenna size by more than 48% as compared to the proposed antenna patch, increased bandwidth, and decreased the cross polarization effect. Finally, embedded EBG together with SDGS ground plane are studied to take advantages of both techniques.
In this paper, we propose the aperture feeding as a technique for bandwidth enhancement of multi-band microstrip ring antennas. In particular, we present a dual-band stacked annular-ring microstrip antenna fed by four bow-tie apertures with circular polarization. Furthermore, we show that the size and shape of the substrate that supports the radiating elements of the antenna plays an important role in the quality of the axial ratio.
A novel microstrip resonator, uniplanar double spiral resonant cell (UDSRC) is analytically investigated to access the controllability of its bandstop property and one hi-lo microstrip lowpass filter using UDSRCs with enhanced frequency selectivity and rejection level is also presented. The equivalent circuit corresponding to each part of UDSRC is initially proposed to describe its special bandstop property with two transmission zeros. Furthermore, analytical theories of each circuit element are introduced and the comparison of the calculated results and the fullwave-simulated ones is done to verify the proposed equivalent circuit and the analytical theories. Both the analytical investigation and parametric analysis indicate that the two transmission zeros can be controlled through tuning the primary geometrical parameters. Thus, the given property is utilized by embedding two different UDSRCs in the feed lines of the reference filter. Both the simulated and measured results indicate that the frequency selectivity and rejection level are improved effectively. The frequency selectivity of the fabricated prototype is about 65.8 dB/GHz while the stopband rejection level is more than 10dB from 2.08 GHz to 6.62 GHz. Compared with the reference filter, the performance is improved greatly while the transversal dimension of the feed line is not increased because UDSRCs are completely embedded in the feed lines.
The basic applications of pulsed solid state power amplifier are for airborne and spaceborne pulsed Radar and these applications have always demanded well performance over different environmental conditions. The success of the electronic systems for these applications relies on the ability to design high performance; reliable and high yield circuits, which will function against the demanded environmental specifications. This paper describes the detailed design and development of a spaceborne C-band pulsed solid state power amplifier to deliver 12-watt output power, 45 dB gain with 22 microsecond pulse width and 8% duty cycle. The salient features of this paper are drain modulated pulse driver circuit design, non-linear design of the power stages and electronic package design. The paper also describes pulsed SSPA configuration, RF section, Electronic Power Converter Module, RF design and other space aspects to realize the pulsed solid state power amplifier. It is fabricated on the three-layer metallized alumina substrate, and integrated with power converter module; and tested under simulated space environment. The test result validates the design specification of the pulsed solid state power amplifier, implemented at miniaturized configuration.
In this paper a miniaturized branch-line coupler is proposed. The topology of the circuit is designed using novel design of T-model approach with open stubs with high-low impedances, which provides necessary bandwidth for WLAN band at 2.45GHz. The miniaturized branch-line coupler is designed and fabricated with a low-cost FR4 substrate as a platform in producing significantly reduction by more than 64.21% compared to the conventional coupler on inexpensive board. Furthermore, the coupler can equally divide the input signal with 90° phase of difference while maintaining the initial power from the source.
In this letter, a compact planer dual-band bandpass filter(BPF) using novel split-ring resonators (SRRs) is proposed. Compared with conventional SRRs, the stepped impedance split ring resonator (SIR-SRR) has better performance on miniaturization. To verify good characteristics of the novel structure, a new resonator-embedded cross-coupled filter, constructed by a pair of new resonators, is designed. This new filter has good characteristics of compact size and high selectivity. The improved SRR unit cell has a size of 0.108λg×0.108λg (where λg is the guided wavelength) at central frequency (2.25 GHz) of upper passband. Simulated results show that two central frequencies of the filter locate at 1.90 and 2.25 GHz with 3-dB fractional bandwidths of 1.0% and 7.7%, respectively. The lower passband band is generated by inner resonator with a via hole to gound plane, while the upper passband is created by outer resonator. Moreover, a good out-band performance is shown in this letter. Its stop-bands are extended 0-1.85 GHz at lower band and 2.4-5.8 GHz at upper band with a rejection level of about 20-dB. The measured and simulated results are well complied with each other.
A broadband antenna integrated with the system ground plane of the Portable Media Player (PMP) device for digital television (DTV) signal reception is proposed. The antenna comprises of a quarter-wavelength monopole and a gaps-coupled open loop antenna that can generate two adjacent resonant modes to form a wide operation band. Result shows a wide bandwidth of 464-856 MHz to cover the DTV signal reception in 470-806 MHz band. Details of the proposed antenna designs and experimental results of the construct prototypes are presented.
In this paper, a tri-band metamaterial-inspired monopole antenna is proposed for multi-band wireless applications. A metamaterial consisting of three dual-band modified S-shaped resonators (MSRs) is directly connected to a regular monopole element, which can not only support the two WiFi bands but also bring the resonant frequency of monopole element down to the WiMAX band while the length of the antenna is maintained unchanged. The simulated and measured results verify our design for the wireless applications.
A specialized type of traveling-wave field-effect transistor (TWFET), the gate and drain lines of which contain series capacitors, series inductors, shunt capacitors, and shunt inductors, is considered to provide a platform to manage unattenuated dispersion-free envelope pulses. Because of the nonlinearity caused by the gate-source Schottky capacitance, the dispersive distortion is well compensated. Moreover, the FET gain can cancel the wave attenuation caused by electrode losses. This paper discusses the design criteria of a TWFET using the nonlinear Schrodinger equation obtained by perturbation. Several numerical calculations follow to validate it.
A delay nonlinear differential equation is proposed to investigate the condition of the microwave chaotic behavior existing between the antenna and the front-end protection circuit of a receiver such as the radar front-end limiter circuit. This investigation concerns the case of intentional or unintentional signals applied to the antenna outside of its bandwidth. Bifurcation diagrams show that the chaotic behavior appears for antenna impedance up to 10 Ω and for amplitudes greater than 1.2 V. Electrical simulation results agree well with theoretical ones.
In this paper we describe the realization of a low cost radiometer which can be used to detect and show the microwave electromagnetic field emitted from human body. The system uses components available in the consumer market: low cost LNB (Low Noise Block: low noise pre-amplifier, mixer and post-amplifiers) and a parabolic antenna for satellite TV. The base line stability problems of the system are removed using a detector in linear region and a digital integrator for correction of the base line. The PC resident software triggers an educational video on the origins of electromagnetic radiation when a person, entering in the antenna beam, is detected; in addition to this, it is possible to show an infrared image taken by a camera.
This article proposes a novel 4-sector cylindrical-rectangular microstrip array with high-gain operation and multi-beam radiation for IEEE 802.11j MIMO WLAN system. With the use of 1 x 2 array, the impedance bandwidth for the operating band of 5 GHz can reach about 2.5% (125 MHz), which is enough for IEEE 802.11j specifications. Peak antenna gains across the operating band are close to 11.0 dBi with the gain variations of 0.3 dBi.