In this paper, two compact quad-channel and six-channel diplexer are designed and fabricated using Defected Microstrip Structure (DMS). This Structure is designed for the desired frequency based on the literature reviews. The proposed configuration is composed of a conventional T-junction divider with two pairs of open bended stubs and dual/tri-band filters. In designing dual band filters, a loop resonator loaded with two stepped-impedance resonator and Defected Microstrip Structure. In addition, by adding a pair of open stubs, triband responses easily achieved without increasing the circuit size. The operating mechanism in resonance frequencies by surface current density is obtained. As a result, the multi-channel diplexer occupies a compact size of 0. 13λ g by 0. 13λ g. The measured results are fully in agreement with the simulated predictions indicating that an isolation between channels is more than 29 dB.

A low profile fractal Defected ground Structure (DGS) antenna is presented for super-wideband (SWB) wireless communication applications. The designed antenna covers a very wide frequency range from 1 to 27.4 GHz (impedance bandwidth of 186%) with |S11|<-10 dB. Moreover, In spite of small electrical dimension of the proposed antenna (0.11 λ× 0.11 λ), a large bandwidth dimension ratio of 15372 is resulted. The SWB operation is achieved by using fractal DGS on the ground plane to improve the impedance characteristics between adjacent resonant frequencies. The antenna consists of a 34×34×1.6 mm3 FR4 substrate with a dielectric constant of 4.4 and a narrow rectangular radiator. A multi-frequency resonance characteristic is obtained by increasing the fractal slot iterations on the ground plane. The simulation results are verified by experimental measurements. Measured data are in good agreement with the simulated results. The frequency- and time-domain characteristics of the antenna including impedance matching, far-field patterns, gain, radiation efficiency, group delay, and fidelity factor are presented and discussed. The results indicate that the antenna has good performance over the entire operating bandwidth which make it very potential candidate for integration in SWB wireless communication systems.

A novel geometry of polarization and frequency reconfigurable antenna is proposed in this paper. Proposed antenna consists of an L shaped patch antenna, where arms are separated using PIN-diode. Two parasitic elements, shorted back element and edge tapered Defected ground Structure with slot are used for achieving wide impedance and axial ratio bandwidth. It acts as circular polarized antenna with 1.183 GHz axial ratio band width and 3.09 GHz impedance bandwidth in ON state of both diodes and act as linear polarized frequency reconfigurable antenna at remaining states of diodes. Proposed antenna can be used in C band wireless applications like RADAR, satellite communication etc.

In this paper, a generalized method for accurate full-wave analysis of shielded MIC's and the three-layer Microstrip Structure enclosed in a rectangular cavity based on Mixed Potential Integral Equation (MPIE) derived in real space have been developed. Method of moments (MoM) with Galerkin technique has been used for the solution of the integral equation to obtain the surface electric currents distribution on the conductors. An accurate de-embedding procedure for the characterizing electric currents distribution and extracting S parameters based on pencil of matrix technique are employed. A new numerical technique for fast convergence of the double infinite series expansion of the MoM solution has been considered. A computer program implementing the analysis has been written in Fortran on a personal computer. Several types of Microstrip discontinuities such as Open-end, bend, collinear Broadside Coupled Line (BCL) and crossover is analyzed and numerical results are presented and compared with both previously published data and the results found by HP-HFSS software.

The hexagonal shaped slotted Wine glass shaped Co Planar Waveguide (CPW) fed antenna for wireless applications is proposed in this paper. The Woodpile based Electronic Bandgap (EBG) Structure is used as linked ground surface for bandwidth and gain enhancement. The performance characteristics of different sized strip widths of woodpile Structures with wine glass shaped antenna have carried out; the antenna resonates in the band of 2GHz, 5 GHz, and 7 GHz. The band width enhancement of 43 % and gain of 9 dB at 1. 9910 GHz for 1mm strip width of woodpile has observed. In addition, the group delay variation and E – plane co and cross polarization radiation patterns for various strip widths of woodpile Structure have obtained. The group delay is maintained less than 5 nanosecond and there is a significant difference between co and cross polarization for E-plane radiation patterns for 1mm strip width of woodpile Structure. The antenna is fabricated with hexagonal slot and 1mm strip width woodpile Structure and tested for return loss and radiation pattern.

Background and Objectives: Microstrip patch antennas are widely used due to their advantages of compact size and easy fabrication compared to other types. However, they have low-performance parameters. As a result, several techniques are used to improve performance parameters in newly designed Microstrip antennas. In this study, a novel miniaturized Microstrip antenna with circular polarization (CP) is proposed for GNSS applications.Methods: In the design process, the semi-fractal Structure is used to reduce the antenna size. Circular polarization is generated using a three-feed configuration with 120◦ phase shift. The CP value is increased by use of perturbing slots and also removing the corners. The novel design of the feeding network and also considering the ground size same as the patch layer, keep the antenna size small. The co-axial probe is used in the feeding network and it is printed on Taconic RF-43 substrate with a low loss tangent of 0.0033. Numerical simulation is applied via CST commercial software to evaluate the antenna performance. The simulations are repeated in two other software, HFSS and FEKO, to validate the study. Results: The proposed antenna has a compact size of 17.56 cm2. The single-layer Structure of the designed antenna leads to easy fabrication feature. The proposed antenna has a bandwidth of 55 MHz (1.558-1.614 GHz). It can operate at GPS L1 (1575 MHz), GLONASS G1 (1602 MHz), Galileo E1 (1589 MHz), and E2 (1561 MHz) bands. Results show a high front-to-back ratio (FBR) of 40 dB, RHCP gain of 3.45 dB, and pure CP with axial ratio (AR) beamwidth of 108⸰. Furthermore, the phase center variation (PCV) is less than 0.16 mm.Conclusion: Key features of the proposed antenna are its novel fractal Structure that leads to compact size, high front-to-back ratio, wide RHCP beamwidth with desirable bandwidth, and axial ratio beamwidth.