Modeling and design of rectangular microstrip patch printed on isotropic or anisotropic substrate are accomplished in this paper. The use of spectral domain method in conjunction with artificial neural networks (ANNs) to compute the resonant characteristics of rectangular microstrip patch printed on isotropic or anisotropic substrates. The moment method implemented in the spectral domain offers good accurateness, but its computational cost is high owing to the evaluation of the slowly decaying integrals and the iterative nature of the solution process. The paper introduces the electromagnetic knowledge combined with ANN in the analysis of rectangular microstrip antenna on uniaxially anisotropic substrate to reduce the complexity of the spectral domain method and to minimize the CPU time necessary to obtain the numerical results. The numerical comparison between neurospectral and conventional moment methods shows significant improvements in time convergence and computational cost. Hence, the use of neurospectral approach presented here as a promising fast technique in the design of microstrip antennas.

Compact modified T-slot circular patch antenna for multiple input multiple output (MIMO) applications, which has good response for four operating frequency bands is developed. Here the design consists of a circular patch with a new slot loaded T- shape on one side of the substrate and a feeder line on the other side of the substrate. A shorting pin is located between the patch and the feeder line. This proposed antenna resonates at the frequencies of 2, 4.8, 5.4, and 6.2 GHz covering the S-band, C-band, and LTE applications. The independent tuning of frequency bands is achieved by varying the length of the slots. By independent tuning of frequency bands, the selection of interested frequency band is achieved. The single element with miniaturized size of 1.945λ × 1.945 λ (30 × 30 mm2) is achieved including the feed line. The antenna has been tested for MIMO applications. The measured envelope correlation coefficient between the two elements, which are spaced 0.139 λ is <0.1(low correlation) and mutual coupling is found to be in the range of −20 dB to −80 dB. The simulation and measurement results of reflection coefficient, mutual coupling, and radiation pattern are presented.

In this report, a compact antenna system with dual-band-notched characteristics is proposed for ultra-wideband (UWB) multiple-input multiple-output (MIMO) applications. Two antenna elements are placed side by side and fed with matched microstrip lines on a substrate with an area of 35 × 30 mm2. Notched characteristics at WiMAX (3.4–3.6 GHz) and WLAN (5.725–5.825 GHz) have been achieved using complementary split ring resonator (SRR) slots etched in both the antenna elements. Electromagnetic isolation between the two elements close to each other is achieved using a ground T-stub and slots etched in the ground plane. Antenna system has been tested and measured results are close to the desired ones. Measured isolation >20 dB is obtained in most of the UWB bands. The proposed antenna system meets the requirements well for MIMO applications.

Dielectric stepped-index flat lens antennas for operation at 12 GHz are presented. A brick-shaped dielectric with a permittivity profile optimized for focusing is sandwiched between the metallic plates of an open-ended parallel-plate waveguide. A tapered slot antenna is placed at the focal point of the dielectric lens, thereby creating antennas with high directivity of 16.8 and 15.8 dBi, respectively. In the two versions of the antenna, the parallel-plate waveguide operates in TEM-mode and in the first higher-order TE-mode, respectively. The dielectric profile is realized by appropriate mixtures of alumina ceramic powder and microscopic hollow glass spheres, realizing permittivity ranging from εrel = 1.31 to εrel = 3.24. The design of the complete antennas is based on geometrical optics followed by optimizations with a full-wave electromagnetic solver. Measurements show good agreement with simulations.

A study on the microwave performance of a metallic transmission line capable of simultaneously transmitting microwave and optical signals is presented targeting millimeter-long interconnects. Conventional analytical solution is used to find the optimal structure for a given characteristic impedance. Then, functionality of the link is validated through S-parameter measurements for 3–13 mm long lines. The waveguide parameters, such as resistance, inductance, capacitance, and conductance are extracted based on a lumped circuit model. The modeling enables structure optimization for interconnect bandwidth density of 1 Gb/s/μm and more.

In this paper, a band-notched compact printed monopole super wideband (SWB) antenna has been designed and fabricated. The SWB antenna composed of a radiating patch with a 50 Ω triangular tapered feed line which is connected through a feed region, and a chamfered ground plane (CGP), that covers the frequency band from 0.9–100 GHz (ratio bandwidth of 111.1:1) with a reflection coefficient |S11| < −10 dB, except in the notched band of 4.7–6 GHz for Wireless local area network IEEE 802.11a and HIPERLAN/2 WLAN band. To realize the band notch characteristics a C-shape parasitic element is employed near the CGP etched with two symmetrical L-slots and placed under the radiating patch. Proposed antenna structure occupies a relatively small space (30 × 40 × 0.787 mm3) and achieved much wider impedance bandwidth as well as higher gain compared with the existing ultra wideband and SWB antennas.

Passive intermodulation (PIM) is a complex problem in high-power microwave devices and satellite communications. In this paper, an effective calculation method is proposed for predicting PIM power levels of the cascaded microwave devices. First of all, the analytical formula of intermodulation voltage is derived based on the nonlinear I–V characteristics of microwave devices. Then, the mathematical model of point sources is constructed by the transmission line theory and extended to the cascaded microwave devices. The passive intermodulation products (PIMP) of the cascaded microwave devices are evaluated based on the point-source model. The relationship of PIM between a single microwave device and the cascaded system is revealed. Eventually, the corresponding experiments are designed to verify the accuracy of point-source model and the cascaded model to predict the third-order PIM power level, which address the problem of PIM prediction of the cascaded microwave devices.

This paper studies the variation effects of incident plane wave on shielded coaxial cables, using Branin's method, which is called the method of characteristics. That model can be directly used for the time- and frequency-domain analyses. Moreover, it had the advantage of being used without the need of setting the preconditions of the charges applied to its ends. This makes it easy to insert in circuit simulators, such as SPICE, SABER, and ESACAP. The results obtained under ESACAP were remarkably similar to other results, which reinforce the validity of the model. Finally, we will discuss the effects of the variation of the incident plane wave.

This paper presents the design of a split-ring resonators (SRR) loaded coplanar waveguide-fed ultra-wide band (UWB) antenna. As using the electromagnetic coupling SRR connected by open-ended microstrip lines, this UWB antenna achieves wide band-notched characteristics. The frequency of the proposed antenna operates from 2.37 to 10.93 GHz with a broad notch band covers from 4.96 to 6.15 GHz (IEEE 802.11.ac), the relative stopped bandwidth of the notch band achieves 20.42%. Besides, theoretical analysis and experimental results are proposed to illustrate and validate this proposed antenna.

In this paper a new design of compact single layered triangular slotted microstrip patch antenna with spur lines and strip loading is proposed. It has been experimentally investigated that strip loading causes more size reduction where spur lines and triangular slot introduces multi frequency operation of microstrip patch antenna. The size reduction has been found to be 87% for the proposed antenna. In this article the effect of strip loading and spur lines over compactness are individually analyzed.

In this paper, a rectangular dielectric resonator antenna (DRA) with a parasitic gap-coupled microstrip resonator (MSR) is investigated; analytically, and experimentally. The proposed antenna uses an open-ended half-wavelength MSR patch as a hybrid radiator. Radiating modes are identified for both the radiators. Two separate and fully independent modes are merged together to get an enhanced bandwidth. The antenna can offer three modes of operation, mode 1 (only DRA is active), mode 2 (only MSR is active), and the mode 3 (both DRA and MSR are active). In mode 3, the antenna offers a single wideband operation with ≈11% bandwidth by merging modes 1 and 2 with a broadside radiation pattern. Two switches are proposed to realize the three modes of operation. A p–i–n diode is utilized as switching element in simulations. Multiple antennas have been fabricated using a small metal strip as a switch to validate the proposal. Analytical, simulated, and measured results are found in harmony. A parametric study is done to describe the antenna characteristics. An approximate lumped element model is also extracted and presented.

An ultra-wideband (UWB) slot antenna for diversity applications is introduced. The overall structure of the antenna consists of two similar coplanar waveguide (CPW)-fed stepped rectangular slots placed in an orthogonal position. The slots are asymmetric with respect to their placement in the ground plane. The CPW feeds are double stepped and terminated on hexagonal patches for better impedance matching. A wide impedance bandwidth (measured) from 3 to 12 GHz with an isolation better than 15 dB is obtained with this antenna. To improve the isolation, the design is modified and an I-shaped slot strip is introduced between the two slot antennas. With this, the isolation is brought about 25 dB of most of the band, while the impedance bandwidth remains the same (2.8–12 GHz for port 1, measured and 2.9–12 GHz for port 2, measured). The far-field radiation patterns are also measured and a peak gain of about 5 dBi is obtained. Finally, the diversity parameters such as envelope correlation coefficient and capacity loss are calculated and found to have low values. The antenna is expected to be useful for UWB diversity applications with good isolation.

In this paper, a microstrip-fed U-shaped dielectric resonator antenna (DRA) is simulated, designed, and fabricated. This antenna, in its simple configuration, operates from 5.45 to 10.8 GHz. To enhance its impedance bandwidth, the ground plane is first modified, which leads to an extended bandwidth from 4 to 10.8 GHz. Then by inserting a rectangular metallic patch inside the U-shaped DRA, the bandwidth is increased more to achieve an operating band from 2.65 to 10.9 GHz. To validate these results, an experimental antenna prototype is fabricated and measured. The obtained measurement results show that the proposed antenna can provide an ultra-wide bandwidth and a symmetric bidirectional radiation patterns. With these features, the proposed antenna is suitable for ultra-wideband applications.

Self-protection deceptive jammers create at the radar receiver output multiple-false targets that are impossible to isolate in both time and frequency domains. In this paper, we introduce a novel technique based on fractional Fourier transform (FrFT) to discriminate between the true target echo and those false targets in the case of frequency-shifting jammers. In fact, we exploit the capability of the FrFT to resolve, in a matched manner, spectra that are overlapping in time and frequency. This is a property that cannot be achieved using a standard matched filter. The theoretical analysis of this technique is presented and its effectiveness is verified by simulation.

To restrict electromagnetic interference at WiMAX (3.3–3.7 GHz) and wireless local area network (WLAN) (5.15–5.825 GHz) bands operating within ultra wide bandwidth (UWB) band, a novel design of lamp-shaped UWB microstrip antenna with dual band-notched characteristics is presented. The proposed antenna is composed of a lamp-shaped radiating patch with two rectangular ground planes on both the sides of the radiator with the gap of 0.57 mm. To improve impedance mismatch at middle frequencies, two triangular strips one at each of the ground plane are added; whereas a rectangular slot is etched in the radiating patch to remove impedance mismatch at higher frequencies of the UWB band. Furthermore, an L-shaped slot in the radiator and two L-shaped slots in the ground plane are used to restrict electromagnetic interference (EMI) at WiMAX and WLAN bands, respectively, without affecting the electrical performance of the UWB antenna. Effects of the key parameters on the frequency range of the notched bands are also investigated. The proposed design shows a measured impedance bandwidth of 12.5 GHz (2.7–14.4 GHz), with the two band-notched bands of 3.0–3.9 and 4.9–5.8 GHz. The antenna is suitable to be integrated within the portable UWB devices without EMI interference at WiMAX and WLAN bands.

In this paper, triple-band stacked microstrip patch antennas (MPAs) are presented with wide impedance bandwidth and suppressed cross-polarization level. Triangular and circular shaped slots are embedded in the patch of antenna. Slot-loaded microstrip patches are fed with meandered microstrip line supported by a semi-ground plane structure. Triangular shaped slot-loaded MPA shows triple resonance at frequencies 2.2, 4.45, and 5.3 GHz having bandwidth of 45.9, 19.23, and 15.67%, respectively. Circular shaped slot-loaded MPA also shows triple resonance at frequencies 2.2, 4.42, and 5.38 GHz having bandwidth of 50.24, 33.21, and 13.43%, respectively. Using circular slot in place of triangular; bandwidth of the first and the second band is improved by 4.34 and 13.98%, respectively. Both the proposed antennas show an omnidirectional radiation pattern at all three resonance frequencies in the xz-plane with almost 0 dBi gain. Both the proposed antennas are fabricated on a FR-4 epoxy substrate and show a minimum level of cross-polarization radiations.

An efficient algorithm is proposed for the radar cross-section (RCS) prediction of complex target with electronically large size, which is a combination of geometrical optics and physical optics (GO–PO) method. The method taking the multiple reflections into account is applied to the electromagnetic scattering analysis of a satellite model. Then RCS curves of entire satellite model and the model without antenna structure are figured out. Based on the simulated echoes, the traditional inverse synthetic aperture radar (ISAR) images are discussed. Moreover, an application of motion compensation technique based on the joint time-frequency analysis is presented for ISAR imaging of the moving satellite that has both translational and rotational movements. Numerical results show good performance of GO–PO method in accuracy and efficiency and the great influence of the antenna with corner structures on the scattering characteristic of the satellite.