Optoelectronically reconfigurable monopole antenna

A monopole antenna is reconfigured for 200 or 375 MHz bands by optoelectronically switching two segments together. Light levels of much less than 1 mW significantly change the antenna pattern and gain.<>     

Wideband tri-plate monopole antenna

A novel wideband tri-plate monopole antenna comprising three folded rectangular plates spaced by 120/spl deg/ and connected together at the antenna's central axis is presented. The antenna occupies a small cross-sectional area of 10 mm in diameter and yet provides a large bandwidth of >10 GHz (about 2.7-12.9 GHz here). In addition, the antenna shows improved omnidirectional radiation patterns across the passband.     

Multi-circular loop monopole antenna

A novel multi-band multiple circular loop monopole antenna is presented. The three outer loops have a size ratio of 2 while the feed monopole is a disc, resulting in a quasi-log periodic performance. A method for controlling the radiation pattern, which gives better results than the circular disc monopole at higher operating frequencies, is presented. The proposed antenna performance is also compared with that of the fractal Sierpinski gasket monopole     

宽带平面单极天线

提出了一种宽带平面单极天线,其辐射单元为底部具有斜切角的矩形铜片,馈电点偏离辐射单元的中心位置,斜切角和不对称馈电的应用有效地扩展了带宽.用Ansoft HFSS软件对天线尺寸、斜切角和馈电点位置等参数对天线特性的影响作了分析,给出了这些参数的最佳值,并根据这些最佳参数制作了天线样机.以电压驻波比小于3.5:1为标准,实测得到的天线带宽为70～3000 MHz.电压驻波比和方向图的测量结果与仿真结果吻合较好.     

Small-sized low-profile antenna to replace monopole antennas

The authors compare the operating characteristics of a compact flat plate antenna with those of a classical quarter-wavelength monopole for portable telephone applications. Similar performances are obtained for both antennas, proving that the low-profile antenna offers an attractive alternative to other monopolar antenna structures for small-sized transceiver units     

Compact CPW-fed dual-frequency monopole antenna

By introducing an extended conductor line to a rectangular meander monopole, a novel compact dual-frequency monopole antenna is proposed. The proposed antenna is fed using a 50 /spl Omega/ CPW transmission line, is printed in a single metal layer, and therefore is easily constructed. The designed antenna can operate at 900 and 1800 MHz bands and provide sufficient bandwidths for the GSM and DCS systems, respectively.     

Multiple meander strip monopole antenna

A novel multiple meander strip monopole antenna is presented. By iteratively meandering the vertical strip, compactness and broadband characteristics for the monopole antenna were achieved simultaneously. The designed monopole antenna with a radiation element volume of 14/spl times/14/spl times/14 mm/sup 3/ has the measured bandwidth ratio of 3.87:1, from 2.83 to 10.96 GHz for VSWR/spl les/2, with fairly frequency-insensitive omni-directional radiation characteristics.     

A CPW-fed dual-frequency monopole antenna

A new dual-frequency design of coplanar waveguide (CPW)-fed monopole antenna is proposed and experimentally studied. The proposed antenna utilizes the advantages of the CPW line to simplify the structure of the antenna into a single metallic level, thereby making easier the integration with the microwave integrated circuits. The two operating modes of the proposed antenna are associated with various lengths of two monopoles, in which the longer monopole works for the first resonant mode and the shorter monopole works for the second mode. Moreover, by increasing the width of the longer monopole, a broadband dual-frequency operation is demonstrated. Experimental results show that the impedance bandwidth, determined from 10-dB return loss, of the two operating frequencies can both be greater than 14%. Details of the experimental results are presented and discussed.     

The disk loaded monopole antenna

The method of moments (MoM) is used to analyze the disk loaded monopole (DLM) antenna. Results were validated by comparison with mode-matching and wire-model methods as well as with measurements covering a wide range of electrical sizes. A quasistatic treatment is shown to be both rapid and accurate for the electrically small case. Equivalent circuits are obtained for predicting communication system performance. Parameters defining the fundamental limitations of electrically small antennas are extracted and shown to be accurate for system analysis and useful as design tools.     

Shorted fractal Sierpinski monopole antenna

This paper describes novel configurations of shorted fractal Sierpinski gasket antenna. The antenna uses half the structure of a conventional Sierpinski gasket antenna and is folded over to be parallel to the ground plane, to form an element similar to that of the inverted L antenna. A quasi log periodic resonance behavior is obtained with a shorting pin placed at the far end of the antenna. Several configurations are shown and a design using two shorting pins which improves the bandwidth at the fundamental band is also demonstrated.     

A broad-banded folded monopole antenna

Electrically short folded monopole antennas with lumped mutual coupling between driven and folded sections are considered, showing that the input radiative impedance exhibits a resonance frequency depending upon the sign and magnitude of the coefficient of coupling. If extended to "n-folded" monopoles with separate lumped mutual couplings, the analysis shows the input radiative impedance will exhibitnstaggered resonance frequencies and bandwidth broadening.     

Compact wideband planar monopole antenna

When a shorting pin is added to the planar monopole antenna, an additional mode is excited below the fundamental mode. By optimising the dimensions. A compact wideband antenna can be constructed. The size reduction achievable for this antenna is ~50% compared with an equivalent planar monopole without a shorting pin. Owing to its compact size and wideband performance, this antenna is suitable for use in existing and future mobile communication terminals     

Wideband L-shaped printed monopole antenna

A wideband dual-polarized L-shaped printed monopole antenna (LSPMA) is presented. The antenna operates around the center frequency of 4 GHz. This L-shape printed antenna provides wide impedance bandwidth over 4.7 GHz. Experiments have been carried out to validate the simulated results of input impedance and dual polarized radiation patterns.     

Printed folded flared monopole antenna

Applied is a folding procedure to the conductor of a wideband triangular/flared printed monopole to yield an electrically smaller radiator that does not significantly compromise the gain or the return loss bandwidth of the antenna. The technique is useful for applications where the volume for the radiator is constrained. A theoretical and experimental investigation of the antenna is given.     

Compact 3D-MEMS-meander monopole antenna

A MEMS meander monopole antenna is fabricated in the form of a folded microstrip on the upper and bottom surfaces of the substrate. This design is based on the meander line principle with a three-dimensional structure to achieve reduced size compared to many other small size printed antennas. The MEMS technologies, such as excimer laser drilling and copper electroplating were used in the fabrication of this antenna. This antenna can be mounted on the silicon wafer by anodic bonding technology. The design features 2.45 GHz operating frequency with 190 MHz bandwidth for WLAN applications. The geometric length of the antenna is 21 mm, and the width is 4 mm. Measured results have good agreement with simulation data.     

Shorted fractal Sierpinski monopole antenna

A novel configuration of a shorted fractal Sierpinski gasket antenna is proposed. Using only half the structure of a conventional Sierpinski gasket, the antenna is folded over to be parallel to the ground plane, to form an element that is, in some ways, similar to the inverted L antenna. A shorting pin is then placed at the far end of the antenna. A quasi log periodic resonance behaviour is observed     

Built-in folded monopole antenna for handsets

A built-in folded monopole antenna for handsets (BFMA) is introduced and investigated. The characteristics of the BFMA are compared with those of a planar inverted-F antenna (PIFA), which is one of the conventional handset antennas. As a result, it has been confirmed that the BFMA has smaller size and wider bandwidth compared with the PIFA.     

Broadband dual-frequency meandered CPW-fed monopole antenna

A coplanar waveguide meandered feedline is introduced to obtain a broadband dual-frequency operation of a planar monopole antenna. The modified feeding technology can lead to good impedance matching in a wide dual-band covering 2.4/5.2 GHz WLAN operations. A prototype of the proposed antenna has been constructed and tested. Good radiation characteristics of monopole-like patterns, 23.3 and 29.5% bandwidths, and 2.41 and 4.21 dBi peak antenna gains for the lower and upper bands, respectively, have been obtained.     

A new ultra-wideband fractal monopole antenna

The paper focuses on the peculiar dynamic behaviour of the recently developed 8 mm² TO-220-packaged, high-voltage, double-interdigitated (or rwo interdigi-tation levels—TIL) GTO thyristor. This novel power device was rated under both slightly and heavily inductive resistive loads, i.e. close to the real conditions encountered in practical power circuits employing GTO thyristors. Emphasis is laid on the ability of TIL GTOs to switch safely, with minimum power losses, a certain amount of anode current under high-voltage conditions and high commutation frequencies. The merits of TIL GTO thyristors are analysed in terms of their reliability and switching efficiency, which include the total power losses (conduction and switching losses), turn-on and turn-off gains and the switching speed. It is shown that thanks to their built-in self-protective features, these novel GTOs possess an enhanced current-handling capability at commutation frequencies up to 50kHz under extremely tough load conditions. The main implications of the results for power applications are outlined.