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This article consists of the design of single band bandpass filter, multiband bandpass filter, and multiband bandstop filter based on a substrate integrated waveguide technique. First, proposed structure of single band bandpass filter has been designed with the combination of inductive and capacitive metallic posts at 14.8 GHz center frequency of Ku band application. Moreover, the tuning scheme for frequency has been also demonstrated for the same band. Similar concept has been applied for the design of multiband bandpass filter keeping distance between posts as a function of guided wavelength. In addition to above, multiband bandstop filter has been proposed by providing E‐plane discontinuities with the use of the metallic edge (by putting multiple cylinder posts). The effect of position of the metallic edge on the performance has been observed and analyzed. All the proposed structures have been simulated by Ansoft High frequency structural simulator and its equivalent models by Ansoft system designer (which compared and shows its performance parameters are equal and they are sensitive to parameter variations). © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1409–1417, 2015

Interconnected three-element and four-element wideband MIMO antennas have been proposed for millimeter-wave 5G applications by performing numerical computations and carrying out experimental measurements. The antenna structure is realized using Rogers 5880 substrate (εr = 2.2, tan δ = 0.0009), where the radiating element has the shape of an inverted L with a partial ground. The unit element is carefully designed and positioned (by orthogonally rotating the elements) to form three-element (case 1) and four-element (case 2) MIMO antennas. The interconnected ground for both cases is ascertained to increase the practical utilization of the resonator. The proposed MIMO antenna size is (0.95λ × 3λ) for case 1 and (2.01λ × 1.95λ) for case 2 (at the lowest functional frequency). Both the designs give an impedance bandwidth of approximately 26–40 GHz (43%). Moreover, they achieve greater than 15 dB isolation and more than 6 dBi gain with an ECC value lower than 0.02, which meets the MIMO diversity performance thus making the three-element and four-element MIMO antennas the best choice for millimeter-wave 5G applications.

This article represents microstrip low-pass filter using defected ground structure (DGS) for the wireless communication application. DGS is used as the basic building block for the realisation of a low-pass filter. A low-Pass filter with a 23 dB cutoff frequency of 3.5 GHz has been designed and simulated using high frequency structure simulator. Tuning of frequency is carried out by changing the dimension of DGS. An equivalent LC circuit of proposed structure is derived and simulated it with advanced design system software. Proposed low-pass filter has been fabricated and provides better performance with compact size; it can be used in wireless communication application such as PCS-1900, UMTS, Bluetooth, WLAN, Wi-max, IMS, and RFID etc. V C 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:993-996, 2017; View this article online at wileyonlinelibrary.com.ABSTRACT: The aim of this work is to design a low-profile Circularly Polarized Dielectric Resonator Antenna for the X-band frequency applications. With optimized design the proposed Cylindrical DRA (CDRA) fed by off-centered L shaped slot is showing characteristics of Circular Polarization in the proposed band. Two orthogonal arms of off-centered L shaped slot having different dimension excite the two TM 01d modes at 9.5 and 10.5 GHz, in addition both slots itself produce resonances nearly at 8.6 GHz. Combination of all these resonances is generating the nature of circular polarization near 9.5 GHz. Parametric study on designed antenna has been done in order to determine the effect of design parameters on the circular polarization. Axial Ratio bandwidth of 10.5% (1 GHz) and impedance bandwidth of 25% (2.3 GHz) at 9.5 GHz has been shown for single and simple feed low-profile CDRA. Prototype of optimized design has been fabricated for the validation and measured results have shown good agreement with simulated ones.

A bandpass filter using substrate integrated waveguide technology is proposed in this paper for ISM band frequency (5.7–5.9 GHz) application. Metallic inductive posts are used for the realization of the filter. The proposed structure provides pass band from the frequency range of 5.72 GHz to 5.84 GHz with the insertion loss of 0.7 dB and return loss more than 25 dB. Frequency tuning is carried out from the frequency range of 5.65 GHz to 6.06 GHz with the variation of pass band bandwidth from 88 MHz to 222 MHz. All the simulations are carried out by high frequency structure simulator based on FEM method software. Proposed bandpass filter is fabricated and measured result indicates better performance. It will be utilized in the system developed at CSRTC for the suppression of higher order harmonics in frequency modulated continuous wave radar at the frequency from 5.725 GHz to 5.875 GHz.