A novel wideband dual cavity backed substrate integrated waveguide antenna is presented in this paper. The properties of dual cavity backed substrate integrated waveguide (SIW), U-iterative slot design and dumbbell shaped defected ground structure has remarkably improved the bandwidth of the proposed antenna design. The proposed antenna achieves high gain, wide bandwidth, wide beam-width, good FBR and high radiation efficiency in a compact design. A 2 & times; 2 MIMO dual cavity backed SIW antenna is proposed in this research paper. The proposed antenna element achieves a bandwidth of approximately 850 MHz and a fractional bandwidth of 8.2%. The antenna achieves a peak gain of 8.99 dBi at 10.4 GHz and an average simulated radiation efficiency of 93.59% over the bandwidth. The overall size of the proposed MIMO antenna is 2.3 lambda g & times; 2.2 lambda g & times; 0.04 lambda g where lambda g is the guided wavelength at operating frequency of 10 GHz. The MIMO performance parameters are lying within acceptable limits. These performance parameters of antenna are suitable for RADAR tracking and detection application at X-band.

This study derives analytical bit error rate (BER) expressions for the downlink multiple-input-multiple-output (MIMO) non-orthogonal multiple access (NOMA) system over the generalized α -κ -μ fading channel. The expressions are formulated using the upper bound of the Q-function and the moment generating function for two scenarios—erroneous and error-free successive interference cancellation. Simulations are conducted to validate the derived expressions, and the strong agreement between analytical and simulation-based BER curves substantiates the accuracy of the theoretical formulations. To assess the generalization capability of the α -κ -μ fading model, its simulation and empirical probability density functions (PDFs) are compared with the theoretical PDFs of standard fading distributions, namely Rayleigh and Nakagami-m. Results also demonstrate that MIMO-NOMA achieves significantly better BER performance than conventional NOMA. Overall, the findings confirm the effectiveness of the proposed α -κ -μ based MIMO-NOMA framework in accurately modeling diverse wireless environments and enhancing communication reliability.

This paper proposes the design of an ultra-wideband four-channel switched filter bank (SFB) operating in the frequency range of 10-40 GHz. First, a filter bank board consisting of four microstrip bandpass filters (BPFs) placed in parallel row is simulated, fabricated and tested for validity. The design of individual composite microstrip BPF is based on open/short stubs and spurlines using Ansoft HFSS ver. 22R1. A tuning range from 10 to 40 GHz with a fractional bandwidth of 120% is achieved with mid-band measured insertion loss ranging from 1.8 to 3 dB. Thereafter, the complete design of SFB with these four BPFs, two single-pole four-throw (SP4T) switch along with biasing control mechanism is proposed and designed using EDA tool Kicad ver. 6.0. An SFB with ultrawide bandwidth for SATCOM and 5G applications covering overall frequency range from 10 to 40 GHz is proposed for the first time.

A low-cost Substrate Integrated Waveguide (SIW) based sensor is proposed in the paper for detection of adulteration of edible oil especially mustard oil. The adulteration in mustard oil is done in variety of ways by adding low cost oil in different percentage of volume by volume. These adulterations produce multiple health hazards to the human mankind as the edible is used in daily consumption at Indian homes. The proposed sensor is based on probe techniques, where the detection of dielectric constant change is measured by dipping the one end of sensor in the liquid and may be reutilized after cleaning. The change in the dielectric constant of the liquid is expected when there is mixing of any kind oil to the pure mustard oil. This change in dielectric constant produces shift in the S-parameter which is measured through the VNA. The paper proposed a SIW based sensor with concentric rings at the end of the probe to make it sensitive to the small change if dielectric constant of the edible oil changes. The resonance of the probe is fixed to the X-band to make it cost effective due to low cost dielectric material used for fabrication.

The paper presents a novel partial ground microstrip structure with liquid coupled Multiple Input Multiple Output (MIMO) antenna working in Ku-band. The antenna structure designed to radiate at 13.13 GHz with return loss of 15.21 dB. The microstrip patch antenna radiates the electromagnetic waves with modified ground structure. A good fractional bandwidth of 5 % is achieved with band-width of 660 MHz (12.86 GHz to 13.52 GHz). The EM waves radiate from superstrate and couples with liquid to achieve reconfigurability and transparency. The two unit cell antennas are placed orthogonal to achieve 2x2 MIMO antennas. A high peak gain of 7.55 dBi is achieved at resonant frequency of 13.16 GHz. The MIMO performance parameters are simulated using Ansys HFSS software. All the parameters are within acceptable limits. The proposed antenna is useful for military and defense applications.

This paper investigates the bandwidth enhancement of a microstrip patch antenna (MPA) by incorporating a Koch fractal-based Defected Ground Structure (DGS). The antenna features a rectangular patch of 29.4 × 38 mm and a ground plane of 60 × 60 mm, designed on an FR4 epoxy substrate with a dielectric constant of 4.4 and a substrate height of 1.6 mm. The operating frequency is 2.4 GHz chiefly used for wireless LAN (WLAN) and Wi-Fi applications. The Koch fractal, with its self-similar structure involves recursive iterations that enhance the antenna’s performance improving the antenna's bandwidth. The design is simulated using HFSS, showing significant performance improvement in terms of return loss and bandwidth.

A selective substrate integrated waveguide (SIW) band pass filter (BPF) with a wide upper stop band for satellite communication (SATCOM) applications in C band is proposed in this paper. The design consists of comb-shaped slots engraved on half-mode SIW. Its performance is further enhanced by applying the first and second iteration of Minkowski fractal curve in the ground plane as defected ground structure (DGS). The filter is simulated on 0.062″ (1.6 mm) FR4 with dielectric constant, ɛr = 4.4 using commercial full-wave electromagnetic simulator HFSS v19. Simulated results demonstrate that BPF has resonant frequency (f0) of 4.9 GHz and possesses a wide and deep (> 22 dB) stop band.

A substrate-integrated waveguide (SIW) bandpass filter (BPF) with extraordinary selectivity and an adequate upper stopband for C-band Satellite Communication (SATCOM) applications is proposed in this paper. The design comprises comb-shaped slots engraved on a half-mode SIW (HMSIW) that constitute a multimode resonator (MMR). Its performance is further ameliorated by applying the first and second iterations of the Minkowski fractal curve in the ground plane as a defected ground structure (DGS). The Minkowski fractal has advantages in terms of better bandwidth and miniaturization. The filter is first simulated using the commercial full-wave electromagnetic simulator HFSS v19 and then fabricated on a 0.062′′ (1.6 mm) FR4 with dielectric constant εr = 4.4. The measured results are comparable with the simulated ones and demonstrate that the BPF has a resonant frequency (f0) of 4.75 GHz, a 3 dB bandwidth of 770 MHz (fractional bandwidth of 21.4%), an insertion loss of 1.05 dB, and an out-of-band rejection (in the stopband) of more than 28 dB up to 8 GHz, demonstrating a wide and deep stopband. Using the multimode resonator (MMR) technique, a wide bandwidth has been achieved, and by virtue of using half-mode SIW (HMSIW), the proposed BPF is compact in size. Also, the fractal DGS aids in better stopband performance.

The present paper proposes a novel miniaturized and selective half-mode substrate integrated waveguide (HMSIW) bandpass filter (BPF) using Hilbert fractal geometry. A non-uniform horizontal periodical DGS (HPDGS) is introduced in the ground plane to miniaturize it further and obtain wide and steep outband rejection to enhance the filter's performance. A three-pole bandpass filter (BPF) with a center frequency of 3.5 GHz is simulated, analyzed and designed on a low-cost substrate FR-4 (epsilon(r) = 4.4). The filter becomes small, shows the low insertion loss of 1.1 dB and return losses of more than 16 dB, and is appropriate for operation from 3.38 to 4.20 GHz spectrum considered for the lower band fifth-generation (5G).

Wireless devices supporting global navigation satellite systems (GNSS) services have become an essential tool in different areas of technology such as agriculture, construction, automotive, etc. Therefore the performance and reliability of such devices are important aspects that need to be addressed in the testing stage during the development of the units. The integration of the Over-the-Air (OTA) testing method with the 3D Wave Field Synthesis (3DWFS) technique offer not only the benefit of having tests under controllable and repeatable conditions but also the ability to recreate complex and realistic scenarios in a controlled environment with full polarimetric support for the testing of wireless devices. This contribution applies this technology to emulate a GNSS scenario within an anechoic chamber. For the results validation, a realistic GNSS outdoor scenario was recorded and compared with the emulated scenario where 3DWFS was applied for each individual satellite. This represents a significant step for the GNSS community and also for the future development and testing of wireless devices.

A compact and wide-stop band half mode substrate integrated waveguide (HMSIW) filter, incorporated with a hybrid fractal on the upper plane and a complementary split ring resonator (CSRR), along with a defected ground structure (DGS) etched on the bottom plane, is proposed for 5G sub-6 GHz application. A CSRR reduces the resonant frequency causing size miniaturisation by approximately 40% by augmenting the equivalent inductance and capacitance of the CSRR. Further, the low-pass characteristics of the DGS aid in suppressing out-of-band spurious harmonics. A two-pole band pass filter (BPF) is fabricated using FR4 (flame retardant) to validate the design. The results confirm that the proposed filter has a pass band from 3.75 GHz–5.12 GHz with spurious response below −20 dB > 4f0.

Microwave planar bandpass filters are indispensable in wireless communication systems in most applications. With miniaturization and limited spectrum, there is a great need for a compact, selective bandpass filter with a wide stopband performance. Substrate integrated waveguide (SIW) has become a potential technology for designing and developing microwave and millimeter-wave components, circuits, and systems. This chapter presents novel, compact metamaterial-based bandpass filters with improved stopbands. Several filters’ design methodology and performance are evaluated using broadside-coupled complementary split-ring resonators (BC-CSRR) and edge-coupled complementary split-ring resonators (EC-CSRR) techniques. A comprehensive method to evaluate negative permittivity and permeability for designing the proposed metamaterial structure is also described. These filters have not only compact size but also a wider upper stopband resulting from bandstop resonator characteristics.

In this article, a wideband bandpass filter (BPF) is designed using the comb slotted substrate integrated waveguide (SIW) cavities. The comb-shaped slots engraved on the SIW cavity are used to constitute a novel multiple-mode resonator (MMR) that accomplishes a wide passband of operation. Further, a Jerusalem cross defected ground structure (DGS) is introduced to miniaturize it and enhance filter performance in the pass band and stop band. The filter is fabricated on RT/Duroid 5880 having dielectric constant 2.2 and tested to prove the validity of design. The filter achieves 3 dB fractional bandwidth of 48%, return loss above 14 dB and insertion loss of 1.1 dB in the passband. Also, the proposed filter has steep selectivity and wide upper stopband with 25 dB attenuation from 16.7 to 24 GHz.

This paper proposes the design of a novel double folded substrate integrated waveguide (FSIW) band pass filter (BPF) based on Koch space-filling curve (SFC). The folded SIW filter is incorporated with first and second iteration levels of Koch curve on central conducting layer. A prototype of second iteration Koch fractal FSIW BPF has been fabricated using substrate having dielectric constant 2.55 and thickness 0.508 mm for each layer and then tested. The fabricated second order filter has merits of compact size (0.204 λ02), high roll off rate (82.2 dB/GHz) and low insertion loss (<0.85 dB) in the X band.

In this paper, compact substrate integrated waveguide (SIW) band pass filters (BPFs) incorporated with novel diamond shaped complementary split ring resonator (CSRR) are proposed and analyzed using simulation software HFSS. First single stage SIW BPF is analyzed with face to face orientation of outer ring. Thereafter, a two stage filter is analyzed with similar type of orientation. The filters are simulated using substrate material RT Duroid 5880 with relative permittivity of 2.2 and height 0.508 mm. The proposed two stage SIW BPF exhibits highly selective pass band with center frequency of 8.86 GHz with 3-dB bandwidth of 0.74 GHz. It also exhibits one stop band with rejection peak below -60 dB in close proximity to two transmission poles in the pass band. The two stage SIW filter has better selectivity, bandwidth and stop band performance.

This paper proposes the study and analysis of various slot loaded folded substrate integrated waveguide band pass filter for K-band applications. Three prototypes of filer are simulated and analyzed with different resonant slot lengths for enhancing the impedance bandwidth. By incorporating a slotted structure of I shape geometry at middle of central septum, the filter achieves the maximum bandwidth of 4.33 GHz (20.8–25.13 GHz) with FBW of 18.89%. Further it achieves compact size by virtue of its folded nature which reduces its width by half.

A novel substrate-integrated waveguide antenna incorporated with filter is presented in this paper. The band-pass filter is designed using substrate-integrated waveguide technology. The filter has a range from 11 to 11.5 GHz. A slot has been etched on the upper layer of SIW to work filter as an antenna. The designed antenna has a wide bandwidth with resonant frequency of 11.4 GHz. The gain at this frequency is 6.67 dBi. All the results are simulated in ANSYS HFSS software.

This paper presents the analysis of Empty Substrate-Integrated Waveguide (ESIW) H plane horn antenna for K band application. The paper also compares the ESIW with Substrate-Integrated Waveguide (SIW) technology on various parameters for making the horn antenna. For K band applications, the SIW horn antenna provides various advantages over normal microstrip horn antenna. SIW technology is easy to fabricate and test and it provides all advantage of the conventional waveguide horn antenna. The SIW horn antenna is planer in design and can be easily interfaced with planer active and passive circuits. To improve the performance of SIW, the air-filled substrate cut is made to form ESIW, which is presented in this paper. The cut in substrate allows less dependency of an ESIW horn antenna over dielectric losses. The ESIW horn antenna does not require any extra element to improve the impedance matching at the end of the aperture; hence it shows an advantage over normal SIW horn antenna. The ESIW horn antenna can be used to make low profile short-range radar working in the K band.