A novel design of multiband probe-fed stacked patch antenna for Beidou Satellite Navigation System (BDS) and Global Position System (GPS) applications is proposed. The presented antenna covers BDS-1 L (1616±5 MHz), BDS-1 S (2492±5 MHz), BDS-2 B1 (1561±5 MHz), and GPS L1 (1575±5 MHz) frequency bands. Excellent high port isolation and Circular Polarized (CP) performance are achieved by introducing four metallized holes which are strictly symmetrical about the centre of the patch antenna. The proposed antenna is fabricated, and its performance is verified in measurement.
A dual-polarized L-probe fed microstrip patch antenna with high isolation and low cross-polarization levels is proposed. The proposed antenna has been designed and analyzed by using commercially available software --- High Frequency Structure Simulator (HFSS) based on the finite element method algorithm and a simple resonant equation and Computer Simulation Technology Microwave Studio (CST MWS) based on the finite-difference-time-domain algorithm. A prototype antenna is built and tested. The return loss has been compared between measured and simulated data under the criterion of VSWR less than 2 through out the designed 4.95 to 5.05 GHz frequency range. The measured isolation between two ports is higher than 22 dB and the gain is larger than 3 dBi. The cross-polarization levels in both E and H planes are better than -21 dB, along with fair regular radiation patterns.
In this paper, we present a tri-band electromagnetic absorber with insensitive properties. A rotational symmetry structure with a metallic ground is proposed for the design of the metamaterial absorber. Calculation results show that the absorber has three perfect absorption points at 4.76 GHz, 7.61 GHz and 10.84 GHz with the corresponding absorption rates of 96.7%, 97.8%, and 99.3%. An experiment is given, and the results verify our design. Such a tri-band absorber has the merits of high absorption rate, stable performance with various incident angles and different polarizations.
First, we report on the design, simulation and measurement of a 2-4 GHz conformable antenna optimized for skin contact and implemented on a flexible printed circuit for integration into a wearable device. Second, we experimentally verify the suitability of appropriately long (~10 cm) microstrip traces for the wearable system signal distribution network, which features varying radii of curvature. Consequently, the contribution of the here reported work is two-fold. First, the experimental results obtained both with breast phantoms and on-body measurements, demonstrate a return loss below -10 dB in the desired frequency band. Phantom results also show a through-breast transmission coefficient of above -40 dB at the centre frequency of 3 GHz. Second, and essential for signal integrity in our target application, the results show that the longitudinal curvature of such a microstrip does not increase transmission line losses.
In this paper, a three-band antenna with small size 50×15×0.8 mm3 is developed. The multi-broadband antenna consists of strip-1, tstrip-2, Br-1, Br-2 and S-strip. The lengths of strip-1, strip-2 are close to λ/4 at 680 MHz, 850 MHz and λ3/4 at 2.04 GHz, 2.55 GHz, respectively. S-strip is close to λ at 5.2 GHz and λ3/4 at 3.7 GHz. In addition, two tuning stubs Br-1 and Br-2 connected to strip-2 can further improve the impedance matching. Then six key resonances are excited: 680 MHz, 850 MHz, 2.04 GHz, 2.55 GHz, 3.7 GHz and 5.2 GHz. There exists electromagnetic coupling (EMC) among them, and as a result of the comprehensive effect of the structure, three wide-bands are produced: 660-1050 MHz, 1.60-3.75 GHz, 5.25-6.50 GHz. That is, the operation band covers full LTE700/2300/2500 (1710-2690 MHz)/GSM850/900/ (680 M-960 M)GSM1800/1900/WiMAX3.5G (3400~3650 MHz)/5.4-GHz (5250~5850 MHz)/ UMTS (1710-2170 MHz). The return loss is better than -6 dB. The peak gains also satisfy the requirement for practical application.
This paper presents a compact tunable bandpass filter that is based on open split ring resonator to achieve high out-of-band rejection. Exact equations and design procedures are given based on strict theoretical analysis. By loading the varactor diodes, the center frequency and bandwidth of the bandpass filter could realize reconfigurable. Then defected ground structure was adopted in the input and output ports for the sake of high out-of-band rejection. In order to verify the result of theoretical analysis, a compact tunable bandpass filter with defected ground structure, whose range of frequency was 1.61 GHz~1.82 GHz and range of relative bandwidth was 8.3%~24.8%, had been simulated and fabricated. Good agreement between the measured data and the anticipated results is achieved.
A compact printed dual-band antenna for WiMAX/WLAN applications is proposed in this paper. The dual-band monopole antenna consists of a triangular patch and two folding arms shorted to the ground plane. The proposed antenna features a low profile and compact dimension. To avoid via process in the fabrication, the triangular patch. The two folding arms are separately constructed on the two sides of a FR4 substrate. By employing this structure, five different resonances can be yielded. The triangular patch provides two resonant modes (4.62 GHz and 7.05 GHz), two folding arms produces three resonances at 2.43 GHz, 3.43 GHz, and 6.59 GHz. A prototype of the dual-band antenna is experimentally fabricated and tested. The measured results shows good impedance bandwidth and radiation pattern.
In this letter, a new image fusion methodology for integration of SAR and optical images using combined dictionary is proposed. The approach taken is based on sparse and redundant representations by employing a combined dictionary consisting of wavelets, shearlets and discrete cosine transform (DCT). Wavelets and shearlets provide pointlike and curvelike structures for the optical image, and DCT are taken as obtaining the best performance on SAR image. The experimental results demonstrate feasibility and effectiveness of the method.
A novel wideband balun filter based on a symmetric four-port balanced circuit is proposed in this paper. A pair of open coupled lines is used to realize DC suppression and in-band balance improvement for the balun bandpass filter. The bandwidth can be easily adjusted by changing the characteristic impedance of transmission lines in the balanced circuit. For the proposed balun bandpass filter, excellent in-band balance performance (amplitude and phase imbalance are less than 0.25 dB and 1.3˚ respectively) over the passband are achieved. A wideband balun bandpass filter prototype with center frequency 3.75 GHz and 3-dB bandwidth 33.8% is designed and fabricated. Good agreement can be observed between the measured results and theoretical expectations.
A novel broadband absorber using the fractal tree structure is presented in this paper, which consists of three metallic layers separated by two dielectric substrates. Five metallic vias connect these three layers which make the whole structure like a two order fractal tree. Simulated and measured results show that this absorber can provide a high absorptivity level from 4.98 to 12.58 GHz, equivalent to a relative absorption bandwidth about 87%. Further investigations show that this wideband absorption can be attributed to the multi-eigenmodes and lower quality factor of the fractal tree structure.
With the vast emergence of new mobile applications, multiband operation in a compact size is mandatory for market penetration. In this paper, a new mobile handset antenna suitable for both mobile and wireless LAN services is presented. The antenna operates for most of the mobile applications such as the GSM 900, DCS 1800, PCS 1900, UMTS 2100, and most of the LTE bands, especially the low frequency LTE 700 band at -10 dB. The antenna also supports the WIMAX, WLAN, and the ISM bands. The antenna not only has a compact size, but also supports a low SAR radiation at all the operating frequencies. The antenna consists of two concentric open rings that act as quarter wavelength monopoles. The inner ring radiates at 900 MHz, while the outer ring radiates at 700 MHz. The inner ring works as a monopole radiator as well as a slot radiator fed by another rectangular monopole. The advantage of the slot is that it supports a wide range of modes that by its role open the radiation band from 1.65 to 3.6 GHz. The antenna meets three challenging parameters: compact size, multiband operation including low frequency bands, and low SAR radiation. Good agreement is noticed between the experimental and simulated results.
A compact asymmetric coplanar strip fed wide-band monopole antenna with modified L-shaped ground plane for WLAN applications is presented. The proposed antenna operating at 5.5 GHz covering IEEE802.11WLAN/RFID/HYPERLAN2. The antenna has an overall dimension of only 21 x 7.35 mm2 when printed on a substrate of dielectric constant 4.4. The planar design, simple feeding technique and miniaturized size make it easy for the integration of the antenna into circuit boards. Details of the antenna design and simulated and experimental results are presented and discussed.
An ultra-wideband (UWB) bandpass filter (BPF) with hybrid coplanar waveguide (CPW)/microstrip structure is introduced in this paper. Then a pair of lowpass filters is integrated on the CPW feed lines to achieve a good out-of-band rejection. At last, a notched band with two transmission zeros is realized at 5.8 GHz by using a symmetric E-shaped slot-line and etching slots on microstrip resonator. Two transmission zeros are realized in the desired notched band, and out-of band rejection is more than 32 dB. In order to prove the validity, the proposed filter is fabricated and measured, and the measured results are in good agreement with simulated ones.
In this paper, a compact asymmetric coplanar strip (ACS)-fed printed monopole antenna for tri-band WLAN/WiMAX applications is presented. The proposed antenna is composed of a simple monopole with the high resonant mode at 5.8 GHz, an open-ended slot embedded on the ground plane with the low resonant mode at 2.4 GHz, and a meander trip shorted to the ground with the middle resonant mode at 3.5 GHz. The three resonance frequencies of the antenna can be controlled by adjusting the geometries and the sizes of the monopole, the slot and the strip. The antenna occupies a very compact size of 22×12 mm2 including the ground plane, has nearly omnidirectional radiation characteristics and reasonable gain in the operating bands. The simple feeding structure, compactness and uniplanar design make it easy to be integrated within the portable device for wireless communication.
This paper provides a modified formula for calculating dielectric loss of dielectric resonator of working in TE01δ mode in closed cavity. The measurement system is divided into six regions with all electromagnetic field distributions given in each region. Based on analyzing the formula of loss tangent published in literatures, a quality factor of a substrate is created, and a modified formula is proposed. Validating the modified formula, with three substrates as supports, the frequencies and unloaded quality factors of dielectric resonators made of two sorts of dielectric materials with permittivity 38 and 75 respectively are measured using a closed cavity method. The measured results are compared with those obtained by other well-known formulas and show a good agreement with the result given by the parallel plate method.
This paper presents a novel method to design filtering power divider with compact size. Based on lumped elements, a novel topology is proposed and theoretically analyzed. The equivalent power splitting circuits and filtering circuits are characterized by even-odd-mode analysis. Closed-form design equations are obtained, and all the unknown parameters can be derived. Meanwhile, two transmission zeros are produced near the passband edges, resulting in high-selectivity quasi-elliptic responses. For demonstration, a filtering power divider is implemented. The circuit operating at 600 MHz occupies only 15 mm × 14 mm.
A low-profile broadband dual-polarized antenna with high isolation and low cross polarization is presented in this letter. The proposed antenna employs two different feeding mechanisms. On one hand, two out-of-phase probes loaded with two small circular patches make the proposed antenna operate in horizontal mode. On the other hand, two pins connecting two eyebrow-shaped patches and the ground form a magnetic loop which enables the proposed antenna to achieve vertical polarization. By elaborately adjusting the feeding structures, measurements demonstrate that the proposed antenna not only achieves 10-dB return loss bandwidths of 49% (1.7-2.8 GHz) and 28% (2-2.65 GHz) for Port 1 and Port 2, respectively, but also maintains a high isolation better than 32 dB over the entire common frequency band. Meanwhile, within the main lobes, the cross polarization levels, both in E-plane and in H-plane, stay lower than -25 dB for Port 1 and -20 dB for Port 2. In addition, the proposed antenna with a profile of 0.13 achieves the maximum gains of 8.4 dBi for horizontal polarization and 8.2 dBi for vertical polarization.
For coherent jammers to wideband linear frequency modulation (LFM) radar, the ratio between jamming energy and signal energy is always constant. To enhance the jamming to signal ratio (JSR), a two-dimensional (2D) discretized coherent noise jamming (2D-DCNJ) method is first proposed in this paper, where the covering area of the noise jamming results in 2D imaging is limited to a certain shape and further discretized to centralize the jamming energy. Moreover, the idea of weighting is applied to 2D-DCNJ to control the distribution of jamming energy, which can present some particular deceptive characteristics. The relationship between jamming results and modulated noise is analyzed, based on which the procedure of generating the jamming signal is detailed, and the JSR performance is compared with the previous ones. Finally, the validity of the proposed method is demonstrated via numerical simulation.
In this article, a compact dual-band bandpass filter (BPF) using coupled open-loop resonators and an embedded center-grounded stepped-impedance resonator (CGSIR) is proposed. This filter operates at 2.1/5.2 GHz for WCDMA/WLAN applications. The first passband is generated by the proposed CGSIR, and the second one is created by the coupled open-loop resonators. Each passband can be controlled independently by adjusting the dimension parameters of corresponding resonators. Five transmission zeros (TZs) are generated due to the 0° feed structure and signal cancellation effects between electric couplings and magnetic couplings, which improve the filter band-to-band isolation level and skirt selectivity significantly. Moreover, the overall circuit size is very compact due to the embedded configuration. The measured filter performances are in good agreement with the simulated ones.
This paper presents a dual-mode stub loaded ring resonator (SLRR) to design a tunable dual-band bandpass filter (BPF) with two independently controllable passbands. The proposed resonator principally comprises a stepped-impedance ring resonator (SIRR) loaded with three stubs and two varactor diodes. Two independently tunable passbands are implemented by employing two varactors to control the dominant even-mode resonant frequency and odd-mode resonant frequency, respectively. Moreover, a new stub loaded double-ring resonator (SLDRR) is proposed to design the second tunable dual-band filter by shorting two stubs of the SLRR. With the same tuning method, the second filter can achieve two independently controllable passbands. In order to suppress the harmonics, defected ground structures (DGSs) are introduced at input and output feeding lines without degrading the passbands characteristics. The simulated and measured results are found in good agreement with each other.