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A compact tricyclic nested triband microstrip antenna is designed in this paper, which is composed of three metal rectangular rings, an input feed line, and an elliptic-shaped defected grou...

Under atmospheric pressure, dielectric barrier discharge (DBD) with a plasma layer is utilized to produce large-volume plasma without a vessel. When a 16-kV bias at 1 kHz is applied to 85 copper strips, the DBD actuator generates plasma with the dimensions 170 × 170 × 1 mm. When the incident wave with an electric wave vector perpendicular to the strip array is illuminated, the monostatic radar cross section (RCS) is reduced by a maximum of 3.5 dB. The measured results are validated using full-wave simulation based on homogeneous plasma, with estimated plasma parameters. By changing the number of copper strips connected to the feed line, the relative volume of plasma can be changed. If the relative volume decreases by 20%, the maximum RCS reduction is reduced by nearly 20%. This demonstrates the possibility of using plasma to control monostatic RCS in a wide bandwidth.

A dual-polarized base station (BS) antenna is proposed that has a spiral isolator, a T-shaped matching stub, and a metal cube. The antenna is composed of a metallic cube, micro-strip feed line board, metallic feeding cylinders, spiral isolator, isolator connecting pins, micro-strip patch, and T-shaped matching stubs. The measured frequency bandwidth is 898–970 MHz at ports-1 and 2. The measured isolation is 40 dB over the operating frequency band and the measured antenna peak gain is 7.5 dBi.

This paper presents a novel power divider with flltering responses. By using quarter- wavelength resonators with a novel feeding structure, both power division and bandpass responses are obtained, and compact size is realized. Discriminating coupling is utilized to suppress the third harmonic to obtain wide stopband. The isolation resistor is connected at two ends of the input feed line, and good isolation is obtained. Two transmission zeros are generated at two edges of the passband, resulting in high selectivity. For demonstration, a flltering power divider is implemented. Comparisons of the measured and simulated results are presented to verify the theoretical predications.

This article presents a compact, enhanced bandwidth, and variable dual band notched printed monopole antenna for ultra wideband (UWB) applications. By inserting a simple inverted L-shaped slot in the ground plane and modifying the lower edge of the patch, wider bandwidth with usable fractional bandwidth of 139.2% (3.1–17.3 GHz) is achieved whereas two inverted U-shaped slots in the corner modified patch are embedded to realize two notch bands exactly at WiMAX (3.25–3.75 GHz) and WLAN (5.1–5.9 GHz). A precise design formula is also proposed to calculate the length of the slots. The proposed simple antenna structure with a 50 Ω feed line has been obtained within a small size of 0.11λ × 0.19λ. The simulated results are validated using measured results to show potentiality of the proposed antenna structure in UWB applications.

This article presents the design of compact microstrip-fed modified half annular-shaped planar monopole antenna for ultra-wideband (UWB) (3.1–10.6 GHz) application. An electromagnetically coupled circular-shaped parasitic patch is introduced at the backside of the substrate to enhance the bandwidth of the whole antenna by shifting the lower frequency band. A rectangular slot-embedded ground plane at the bottom surface of the substrate improves the impedance bandwidth with excellent matching characteristics for the entire design frequency band. In addition to this, a half Minkowski fractal slot, a hybrid fractal slot, and Sierpinski arrowhead curve fractal slot are coupled to the feed line individually such that three UWB antennas with band-notched characteristic are realized that mitigate the interference between UWB and Wireless local area network (5.15–5.825 GHz) assigned to IEEE 802.11a and HIPERLAN/2 can be reduced. Now to increase the functionality of the antenna, a second iterated fractal binary tre...

This paper examines the transmission line structure of a planar Archimedean spiral antenna. A novel analysis is performed by unwinding the spiral into an equivalent straight transmission line to understand its impedance properties and the radiating mechanism. A relation between the input impedance of the spiral antenna and the characteristic impedance of our proposed model is established. The analytical solution completes the lossy transmission line modelling for the input impedance of the spiral antenna. The value of the stable input resistance in the spiral’s radiation region is found not due to the radiation resistance of the loop antenna, but it is dominated by the propagation characteristics of the slot-line mode, that is the travelling wave on the spiral. The accuracy of this proposed model is verified by full-wave simulations, the Babinet’s principle, and measurements. Examination of the radiation mechanism and discussion on the effects of other parameters such as feeding design are also provided.

A compact triband asymmetric coplanar strip (ACS)-fed printed monopole antenna employing open-ended slots for WLAN/WiMAX applications is proposed. The proposed antenna consists of a simple ACS-fed monopole and two different open-ended slots, which occupies a very compact size of 18.5 × 10 mm2 including the ground plane. By adjusting the dimensions of the slots, feed line, and ground plane, three desired resonant frequencies can be achieved and tuned independently. The antenna exhibits three resonances covering the 2.4/5.2 GHz WLAN bands and 3.5 GHz WiMAX band. Details of the antenna design, simulation, and measurement results are presented and discussed. Furthermore, the proposed antenna shows 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.

An isosceles triangular microstrip loop antenna is presented. The resonator is fed by two quarter wavelengths parallel-coupled sections. The proposed feed arrangement is a parallel-coupled microstrip lines with the coupling taking place over an electrical length. The edge-coupled two quarter wavelengths parallel-coupled microstrip line sections are combined capacitively. Each end of the feed arrangement is terminated in 50 Ω impedance. One 50 Ω end of the proposed feed is connected to the source similar to that of the microstrip feed line, while the second end is connected to the resonator itself. Similar antenna structure was designed and fed, first by a conventional microstrip feed line, inset feed, and inset coupled, and finally with a quarter wavelengths microstrip feed. This is done to further identify the specific advantages of the proposed feed structure. The peculiarities of the antenna with its proposed feed network are discussed as well as a theoretical explanation of the concept of the coupled ...

This paper introduces a method for designing a broadband three-element quasi-Yagi antenna (QYA) with a simple geometry and compact size. The proposed QYA consists of simple strip-type elements with unequal widths and distances between them to obtain the desired performance. The proposed QYA fed by a microstrip (MS) line is compact because it has an MS line-to-coplanar strip (CPS) line transition integrated on the CPS line, without requiring additional space for the transition. When a rectangular patch-type director is placed close to the driver dipole fed by a CPS line, the antenna becomes a triple resonance structure, and the impedance bandwidth is extensively increased up to 2.4 : 1 (82.3%) for a VSWR 4 dBi and a frequency band of 1.6–3.6 GHz is presented. The optimized antenna is fabricated on an FR4 substrate with dimensions of 90 mm × 90 mm and is tested experimentally. The results demonstrate an impedance bandwidth of 2.4 : 1 (1.56–3.74 GHz, 82.3%) for a...

A horizontally polarized ultra wideband stepped slot antenna is proposed in this paper. First, a stepped-slot structure is fed by an L shaped microstrip feed to achieve multiple resonances. Then a parasitic slot is introduced near the vertical arm of the L-shaped feed to get better impedance matching over the bandwidth of 3.7 GHz (5.0–8.7 GHz). Further, an impedance step is introduced in the feed line and the measured −10 dB impedance bandwidth covering from 2.8 to 12.8 GHz is achieved. The measured peak gain is around 4.5 dBi throughout the band. The measured radiation patterns are bidirectional in E plane and omnidirectional in H plane. The experimental results are in close agreement with the simulated results. This antenna can be used for ultra-wideband communication devices, medical imaging and vehicular radars.

In this paper, characteristic modes theory was used in analysis and design of a broad axial ratio band circular polarization LTCC microstrip antenna. An ellipse slot couple structure was proposed to take the place of traditional circular slot couple structure for enlarging circular polarization broadband. And the theory of how to improve the axial ratio band was researched in detail by characteristic mode method. The characteristic angle phase difference of two orthogonal characteristic modes and the phase difference of feed line in whole frequencies are the key points in these kind of designs. Finally, the designed broadband axial ratio band circular polarization LTCC microstrip antenna was been successfully implemented, and the experimental results are presented and discussed. Good agreement between simulation and testing was achieved.

A novel compact triple-frequency wide-slot antenna for WLAN/WiMAX applications is proposed and investigated in this paper. The presented antenna is simply composed of an inverted Ushaped slot, a microstrip feed line, a vertical conducting strip, and a L-shaped stub. By adjusting the dimensions of the feed line, strip and stub, three desired resonant frequencies can be achieved and adjusted independently. Experimental results show that the antenna impedance bandwidths for S 11 ⩽ −10 dB are 2.34–2.55 GHz, 3.23– 3.71 GHz, and 5.13–5.85 GHz, covering the 2.4/5.2/5.8 GHz WLAN bands and 3.5/5.5 GHz WiMAX bands. Furthermore, nearly omnidirectional radiation patterns and appreciable gain over the operating bands have been obtained.

To prevent potential Electromagnetic Interference (EMI), a miniaturized UWB antenna with notched band of 5.15–5.825 GHz and high frequency (over 10.6 GHz) rejection capability is proposed and investigated. The notched band of 5.15–5.825 GHz is created by etching a U-shaped slot on the feed line. The characteristic of high frequency cutoff (over 10.6 GHz) is realized by integrating a serpentine resonator on the backside of the radiating element. The results, including voltage standing wave ratio (VSWR), radiation patterns and gain responses, are evaluated by means of both simulations and experiments. The measured results matched simulated ones. Finally, the group delay of the antenna is also evaluated. Compared with original antenna (without U-shaped slot and serpentine resonator), the antenna minimized potential EMI of the out of UWB band and the WLAN band effectively.

A bandwidth adjustable ultra-wideband (UWB) bandpass filter is investigated using a simple meander-typed etched ground structure (EGS) unit on the lower ground plane. On the upper layer, the feed line of characteristics 50Ω is modified by attaching a two-directional open-circuited stub to form a modified symmetrical T-shaped microstrip line, which is proposed to achieve wide upper stopband. Three similar EGS morphologies with different dimensions are designed for comparison. We will show that a novel compact EGS UWB filters with adjustable bandwidth can be easily investigated. The center frequency and the bandwidth increase with decreasing effective length of EGS unit. The experimental results show that a EGS unit with an effective length of 23.6 mm yields a UWB filter with the bandwidth of 3.01 ∼ 10.6 GHz. The measured results also show that the fabricated UWB filter has a high out-of-band rejection and a low group delay variation.

A compact ultra-wideband (UWB) printed monopole antenna with triple band-notched characteristic is proposed. By using a single C-shaped slot etched on the radiation patch, a notched band for WiMAX (3.3–3.7 GHz) is achieved. Moreover, two layer substrates are used, and two resonators are placed between the feed line and the ground plane, which achieves another two notched bands (4.95–5.36 GHz and 5.6–5.94 GHz). The proposed antenna yields an impedance bandwidth of 2.75–11.4 GHz with VSWR < 2, except the notched bands for WiMAX and WLAN application. The simulated and measured data show that there is a good tri-band-notched characteristic. Also, near omni-directional radiation characteristics are obtained in desired frequency range.

A beam steering radial line slot array (RLSA) antenna with reconfigurable operating frequency is proposed in this paper. The RLSA antenna is fed by an aperture coupled structure, which incorporates PIN diode switches that are integrated with the feed line. It is found that the beam steering ability and reconfigurable operating frequency are greatly influenced by the spiral and radius of feed line respectively. The activation of certain PIN diode switches configuration would then determine the beam steered angle and the frequency of operation. This novel antenna design is capable of steering its radiated beam to four different angles; 0°/360°, 90°, 180°, and 270°. Furthermore, the proposed antenna can be configured to operate from a single centre frequency, up to four operating centre frequencies concurrently, at each steered beam direction. The four frequencies are 2.3 GHz, 2.6 GHz, 2.9 GHz and 3.3 GHz. This antenna is a promising candidate to be installed for a smart antenna system, cognitive radio, rada...

This paper presents a novel harmonic-suppressed microstrip open-loop resonator bandpass filter with the different transmission line characteristic impedance of the feed line and open-loop resonator for wireless local area network (WLAN) application. To improve the stopband rejection of the filter, the dumbbell-shape defected ground structure (DGS) are applied under the feed lines to suppress the harmonics and the equivalent parameters extraction formulations of double-dumbell-shaped DGSs are the first to proposed. The bandpass filter with center frequency of 2.44 GHz were designed and fabricated on a TLX substrate with thickness of 1 mm and dielectric constant of 2.55. Measurement results show the filter has a wide stopband characteristic with 30 dB attenuation up to 7.5 GHz and only has an –1.23 dB insertion loss while it is a little larger than the conventional one. The measured results are in good agreement with the simulated results. It can be widely used for WLAN application.

A broadband planar antenna fed by coplanar waveguide (CPW) with gradually changed central feeder line is proposed. Central feeder line of the CPW and the ground plane are designed to be graded structure, which endow the proposed antenna with better impedance matching characteristic and broader bandwidth than microstrip line (MSL) fed antenna. Compared with antennas in previous researches, this proposed antenna has smaller size but covers wider bandwidth, which can operate from 0.7 GHz to 5.9 GHz for return loss less than –10 dB, and shows omni-directivity in azimuth plane.

In this paper, a printed quasi-rhomboid slot antenna with an end-loaded microstrip feed line is presented. With the use of the quasi-rhomboid slot and the end-loaded microstrip feed line, bandwidth enhancement for wideband operation can be obtained. The final design is fabricated and measured. Measured results indicate that the proposed quasi-rhomboid slot antenna can operate from 4.54 GHz to 15.67 GHz with a 10 dB return loss. Details of the proposed quasirhomboid slot antenna are described.

A method of measuring the properties of micron-sized slow-wave coplanar transmission lines is presented. The transmission line's propagation constant γ and characteristic impedance Zo are determined directly from the measured S-parameters of a section of transmission line. Measurements are made with microwave "on-wafer" probes. Test data from 0.5 to 40 GHz is presented on a relatively low-loss slow-wave coplanar transmission line fabricated on silicon. The measured quality factor of the transmission line is seen to approach 10 at 11 GHz with a wavelength-compression factor of approximately 5.6.