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High altitude nuclear electromagnetic pulse (HEMP) can damage electronic equipments of radar and communication systems. Back door coupling is one of the main ways of HEMP attacks on the electronic devices. In this paper, the three-dimensional (3D) electromagnetic (EM) simulation software MicroStripes7.5, which is based on the transmission line matrix (TLM) method, are employed to investigate the HEMP coupling effect on a wire located inside a cylindrical shielding cavity having one or few apertures. The EM models of the wire and the apertured shielding cavity are constructed, and the induced wire currents through the aperture of cavity are simulated. By comparing the simulation results of the wire with and without shield of the cavity, the shielding effectiveness (SE) is calculated. Further, the effects on induced wire in various cases are compared and analyzed, including single-aperture and multiple-aperture, different incident angles, polarization angles, and wire locations. Also, the cylindrical cavity is compared with the rectangular cavity.

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Based on transmission line theory, an approach which combines the analytical model developed by Robinson et al. and the model which analyses the shielding effectiveness (SE) of enclosure with an off-centre aperture or aperture array is presented. The model is more general than other methods and includes the incident wave with varied polarization angles and incident angles. It is quicker to calculate the SE with this model, which on the other hand enables to investigate the effect of important design parameters on SE. This model is validated by comparing the SE predictions with those from literatures. Different aspects’ effect on the SE are investigated such as aperture dimension, enclosure dimension, position of observation point, number of apertures, polarization angles, and incident angles, etc.

ACES

A microstrip meander line with a single H-shaped Defected Ground Structure (HDGS) is employed to design a novel compact lowpass filter with sharp roll off and wide stop band. Two parametric studies were conducted to analyze the sensitivity of the HDGS position and the size effects on the filter response. The design is fabricated to have a 6 GHz cutoff frequency using Rogers TMM 10i substrate, with an area of 7.6 x 6 mm2 . The measured results are in a good agreement with simulation prediction.

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This paper presents the design and implementation of a novel wide bandwidth endfire antenna with log-periodic directors. The feeding structure of the proposed antenna includes a balun which is formed using a pair of microstrip-to-slotline transitions. The proposed antenna has three resonant frequencies in the operating frequency band. Both simulation and measurement results show that the operating frequency band of the antenna for S11 < -10 dB covers the wide bandwidth (5 GHz – 10 GHz), and the relative bandwidth is 67%. Far field measurements in azimuth plane and elevation plane show that the radiation patterns are stable and end fire within the operating band at frequencies of 5 GHz, 7 GHz, 8 GHz, 10 GHz. The proposed antenna radiates a well-defined endfire beam, with a front-to-back ratio > 18 dB and cross polarization level below -28 dB. The dimension of the proposed antenna is 26 mm × 27 mm. Good return loss and radiation pattern characteristics are obtained and measured results are presented to validate the usefulness of the proposed antenna structure for wide bandwidth endfire applications.

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A novel compact, ultrawideband (UWB) monopole antenna with triple band-notched characteristics are presented for MIMO/diversity applications. Triple band-notched function is achieved by inserting two folded v-slot on the radiation patch and two modified mushrooms-like EBG structure above ground plane on either side of feed line. The designed MIMO antenna has a small size compared to the previous similar designs. With the purpose of mutual coupling reduction between antenna elements, two rows of modified mushroom-like EBG structures are inserted to suppress the effect of the surface wave between antenna elements. The MIMO performance of the proposed antenna is studied through mutual coupling (S12), envelope correlation coefficient (ECC) and diversity gain.

Modern wireless communication systems require compact design, low cost and simple struc- ture antennas to insure reliability, agility, and high eciency characteristics.

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High altitude nuclear electromagnetic pulse (HEMP) can damage electronic equipments of radar and communication systems. Back door coupling is one of the main ways of HEMP attacks on the electronic devices. In this paper, using the transmission line matrix (TLM) method, based on the three-dimensional electromagnetic (EM) simulation software MicroStripes 7.5, we investigate the problem of the HEMP coupling effect on wires inside a shielding cavity with apertures. The EM model of a wire and a cylindrical shielding cavity with apertures is constructed, and the induced wire circuits through apertures of cavity is simulated and analyzed. By comparing the simulation results of wire with and without shield of the cavity, respectively, the shielding effectiveness is obtained. Further, the affect of single-aperture and multiple-aperture on the induced wire circuits is compared and analyzed.

In this paper, a broadband distributed amplifier (DA) is presented.