Foundations For Microwave Engineering

A compact microstrip lowpass filter with sharp selectivity and wide stopband designed on the basis of dual-plane, is presented. Initially, a basic one pole defected ground structure (DGS) filter is modified so as to achieve sharp selectivity as well as compact size. The modified DGS reduces the circuit size of the filter by 68.8%. To suppress the higher order harmonics, mirrored symmetrical uniform impedance stubs are designed in the top surface of the substrate, thereby wide stopband up to 20 GHz is achieved. The stopband suppression level of the filter is improved by incorporating a spurline resonator which acts as a defected microstrip structure (DMS) in the top microstrip line. The designed filter has 3 dB cutoff frequency of 2.11 GHz with high relative stopband bandwidth of 159.2% within the rejection level of 18 dB. The wide passband frequency range of the proposed filter covers the GSM, GPS, Wi-Fi communications and various L-band applications such as aircraft surveillance etc.

Compact microstrip lowpass filter with high harmonics suppression using defected structures

A novel perturbation approach using additional metalized via-holes for implementation of the dual-band or wide-band dual-mode substrate integrated waveguide (SIW) filters is proposed in this paper. The independent perturbation on the first resonant mode TE101 can be constructed by applying the proposed perturbation approach, whereas the second resonant mode TE102 is not affected. Thus, new kinds of dual-band or wide-band dual-mode SIW filters with a fixed or an independently reconfigurable low-frequency band have been directly achieved. In order to experimentally verify the proposed design method, four two-cavity dual-band SIW filters, which have different numbers of perturbation via-holes in each cavity, and a two-cavity dual-band SIW filter, which includes four via-holes and eight reconfigurable states in each cavity, are designed and experimentally assessed. The measured results indicate that the available frequency-ratio range from 1 to 1.3 can be realized by using four two-cavity dual-band SIW filters. The center frequency of the first band can be tuned from 4.61 GHz to 5.24 GHz, whereas the center frequency of the second one is fixed at around 6.18 GHz for the two-cavity dual-band SIW filter with four reconfigurable states via-holes. All the simulated and measured results show an acceptable agreement with the predicted data.

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Dual-Band Dual-Mode Substrate Integrated Waveguide Filters with Independently Reconfigurable TE101 Resonant Mode.

Design procedure of a small dual-band antenna based on composite right/left-handed (CRLH) transmission line is proposed in this article. The conventional microstrip patch is assumed as a primary antenna and then, Minkowski-like fractal geometry is applied. The antenna has a compact size of 20 × 20 mm2, and operates efficiently at 4.4 GHz and 6.1 GHz. The antenna provides high gain of 3.8 dB and 6.2 dB in the two operating bands, respectively. It also has an omnidirectional radiation pattern with low cross-polarization level. The effect of the fractal structure along with CRLH transmission line concepton the miniaturization and multiband performance of the antenna have been studied. The related results show the accuracy of the theoretical studies and good agreement between simulated and measured results, which verify that the antenna is a suitable candidate for wireless communication applications.

Compact and miniaturized metamaterial-based microstrip fractal antenna with reconfigurable qualification

The mode converter is a key component in a gyrotron traveling-wave tube (gyro-TWT) application system, which can transform the output circular TE $_{0n}$ modes (in a gyro-TWT loaded with lossy ceramic dielectric or photonic bandgap interaction structure, the output mode is normally a TE $_{0n}$ mode) into a mode conducive to transmission and emission (linearly polarized Gaussian-like HE11 mode). In particular, the bandwidth of the TE01–TE11 mode converter is the most important challenge in the conversion sequence. In this paper, based on the deformation of the transverse cross section and the modified multi-frequency iteration synthesis technique along the longitudinal propagation axis, a novel method for synthesis of a broad bandwidth mode converter is proposed. Then, an application of the method to a wideband serpentine TE01–TE11 mode converter with an elliptical section is given. This novel mode converter including transitional waveguides achieves a 19.18% relative bandwidth (conversion efficiency over 95%) at center frequency 30.5 GHz, which increases nearly 195% compared with the conventional circular design, and its structure length is 1151.65 mm. Overall, this method offers a novel solution to the requirement of broad bandwidth in the high-power microwave transmission system.

A Broadband TE 01 –TE 11 Mode Converter With Elliptical Section for Gyro-TWTs

The paper presents overmoded circular waveguide mode converters (TE01 into HE11 with TE11 as an intermediate mode) used in a 42 ± 0.2 GHz, 200 kW gyrotron transmission line system for plasma heatin...

Millimeter-wave TE01–TE11–HE11 mode converter using overmoded circular waveguide

This paper represents new generation of slotted antennas for satellite application where the loss can be compensated in terms of power or gain of antenna. First option is very crucial because it totally depends on size of satellite so we have proposed the high gain antenna creating number of rectangular, trapezoidal, and I shape slots in logarithm size in Substrate Integrated Waveguide (SIW) structure. The structure consists of an array of various shape slots antenna designed to operate in C and X band applications. The basic structures have been designed over a RT duroid substrate with dielectric constant of 2.2 and with a thickness of 0.508 mm. Multiple slots array and shape of slot effects have been studied and analyzed using HFSS (High Frequency Structure Simulator). The designs have been supported with its return loss, gain plot, VSWR, and radiation pattern characteristics to validate multiband operation. All the proposed antennas give gain more than 9 dB and return loss better than −10 dB. However, the proposed structures have been very sensitive to their physical dimensions.

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Logarithmic Slots Antennas Using Substrate Integrated Waveguide

Defected ground structure based wideband microstrip low-pass filter for wireless communication

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

Design and performance analysis of metallic posts coupled SIW‐based multiband bandpass and bandstop filter

The automatic creation of a repository of the building’s floor plan helps a lot to the architects to reuse them. The basic approach is to extract and recognize texts, symbols or graphics to retrieve the information of the floor plan from the images. This paper proposes a floor plan information retrieval algorithm. The proposed algorithm is based on shape extraction and room identification.
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 -shape is used for finding an accurate shape. From the detected shapes, actual areas of rooms are calculated. Later, a regression model-based binary room classification model is proposed to classify them into room-type, i.e., bedroom, drawing room, kitchen, and non-room-type, i.e., parking porch, bathroom, study room and prayer room. The proposed model is tested on the CVC-FP dataset with an average room detection accuracy of 85.71% and room recognition accuracy of 88%.

Alpesh Vala

Papers

Millimeter-wave TE01–TE11–HE11 mode converter using overmoded circular waveguide

Logarithmic Slots Antennas Using Substrate Integrated Waveguide

Defected ground structure based wideband microstrip low-pass filter for wireless communication

Design and performance analysis of metallic posts coupled SIW‐based multiband bandpass and bandstop filter

Automatic room information retrieval and classification from floor plan using linear regression model