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In this paper, a novel mode decoupling technique of a SIW dual mode square resonator is presented. It is then utilized to design a self diplexing radiator. A single corner cut square cavity with a triangular ring slot on top is used for dual mode excitation and mode decoupling. Both the electric and magnetic mode couplings are used simultaneously to improve the port isolation. Once the single square cavity is optimized for good port isolation, two extra TE110 mode cavities are further added to improve the isolation. Finally, 37 dB port isolation is achieved. The measured gains are 4.45 dBi and 4.20 dBi at 10.5 GHz and 11.7 GHz respectively. The proposed design can be used in a transceiver system without any circulator, switch or additional bandpass filter. © 2019 IEEE.

Department of Electrical Engineering

World University root node

2019 IEEE MTT-S International Microwave and RF Conference, IMARC 2019

Mode De-coupling of a dual mode SIW resonator and its application in designing a self-diplexing radiator

This letter presents a substrate-integrated-waveguide-based compact, dual-mode self-diplexing antenna. A single square cavity with a rectangular ring slot is used for both dual-mode excitation and radiation. A prototype diplexing antenna is fabricated that radiates linear, orthogonal polarization at 9.5 and 10.5 GHz. The measured peak gains at the two frequencies are 5.75 and 5.95 dBi, respectively. Intermodal coupling between the modes provides two transmission zeros, which are utilized to achieve port isolation better than 29 dB. The proposed technique can be used for closely spaced radiating frequencies. As no external filter is used, the structure is compact. Furthermore, because of the slot loading effect, the antenna is smaller than a recently published antenna claimed as the most compact antenna. Its working principle is discussed in detail. Finally, design guidelines are suggested. © 2018 IEEE.

IEEE Antennas and Wireless Propagation Letters

Compact Self-Diplexing Antenna Using Dual-Mode SIW Square Cavity

In this letter, a highly selective narrowband bandpass filter (BPF) is presented in substrate integrated waveguide (SIW) technology. Higher order TE301 resonators are used to utilize their high unloaded Q-factors. A midline feeding scheme together with a bypass coupling provides three transmission zeros (TZs). Two of the zeros can be placed at band edges for high selectivity. A three-pole BPF with 3-dB fractional bandwidth of 1.1% at f0 = 8.25 GHz is fabricated. It provides at least 35-dB attenuation over 2 GHz above and below the passband starting from f0 ± 0.15 GHz. © 2001-2012 IEEE.

IEEE Microwave and Wireless Components Letters

Narrowband Substrate Integrated Waveguide Bandpass Filter with High Selectivity

A substrate integrated waveguide dual-mode single cavity filter with two inclined slots on top metal plane provides two transmission zeros. It is shown that the feed offset as well as the slot offset both can be used to tune the zeros over a wide range of frequencies. Leakage loss from the slot is negligibly small. Two bandpass filters are fabricated to validate the predicted zero variation. Further, tunability of the zeros is utilised to greatly improve the isolation characteristics of two X-band planar diplexers. Measurement results show that the isolation is better than 30 dB even if the channel separation is as close as 5% of the average frequency. The effect of packaging on the filter characteristics is also presented. © The Institution of Engineering and Technology.

IET Microwaves, Antennas and Propagation

Design of planar diplexers with improved isolation using the tunable transmission zeros of a dual-mode cavity filter

In this paper, a dual-band bandpass filter is proposed in substrate integrated waveguide (SIW) technology. A single cavity that supports both TE101 and TE201 resonating modes is used for the design. The two passbands are created by the two modes. To improve the selectivity, one bypass coupling path is introduced which provides additional transmission zero. The procedures to control the passband center frequencies as well as their bandwidths are presented. A prototype narrowband bandpass filter with the center frequencies of two passbands as 10 GHz and 11 GHz is fabricated for space applications. The 3 dB fractional bandwidths are 3% and 1.6%, respectively. The measured insertion losses at the passband center frequencies are 1.4 dB and 2.6 dB, respectively. © 2016 IEEE.

Asia-Pacific Microwave Conference Proceedings, APMC

Dual-band substrate integrated waveguide filter with independently controllable bandwidth

In this paper, effects of different shapes of periodic slots etched on the broad wall of a via-less substrate integrated waveguide leaky wave antennas are presented. Different shapes of the slots namely circular, elliptical, rectangular and triangular are considered. A comparative performance study based on gain, radiation efficiency and scan range of the antenna for the different shapes is studied over X-band frequency range. Several structures are fabricated. 50 ω microstrip lines are used to excite the antennas. It is observed that the rectangular shaped slot is the best choice if higher gain, radiation efficiency and wide scan range including the stopband is considered. Measured results match well with simulated results. © 2015 IEEE.

2015 IEEE Applied Electromagnetics Conference, AEMC 2015

A comparative study on substrate integrated waveguide periodic leaky wave antennas with differently shaped periodic slots

In this letter, a novel coaxial line to substrate integrated waveguide (SIW) broadband transition is presented. The transition is designed by connecting the inner conductor of a coaxial line to an open-circuited SIW. The configuration directly transforms the TEM mode of a coaxial line to the fundamental TE10 mode of the SIW. A prototype back-to-back transition is fabricated for X-band operation using a 0.508 mm thick RO 4003C substrate with dielectric constant 3.55. Comparison with other reported transitions shows that the present structure provides lower passband insertion loss, wider bandwidth and most compact. The area of each transition is 0.08λg2 where λg is the guided wavelength at passband center frequency of f0= 10.5 GHz. Measured 15 dB and 20 dB matching bandwidths are over 48% and 20%, respectively, at f0. © 2001-2012 IEEE.

A Compact Broadband Direct Coaxial Line to SIW Transition

A dual-beam substrate integrated waveguide (SIW) periodic leaky wave antenna (LWA) is designed and fabricated. The dual-beam operation is obtained by using leakage from the side walls of the SIW. The two beams are mirror image of each other. The feeding arrangement is simple and the antenna as a whole is easy to fabricate. A backward end fire to forward end fire scanning range of almost 74° is obtained by varying frequency from 8.5GHz to 13.3GHz. Side lobe level is better than 13dB in the specified frequency range. Measurement results match well with simulated results. © 2015 IEEE.

Proceedings of the 2015 International Conference on Microwave and Photonics, ICMAP 2015

Dual-beam substrate integrated waveguide periodic leaky-wave antenna

In this paper, a novel excitation technique by a commercially available SMA connector is presented for the empty substrate integrated waveguide (ESIW). The SMA connector is directly connected to one end of the ESIW. A prototype back-to-back transition is designed and fabricated for X-band operation. Measurement results show that the insertion loss of the back-to-back transition is below 1 dB over 7.15 GHz to 12.5 GHz. Losses from the transition are studied in details. The transition has a compact dimension of 22 mm × 3.5 mm. © 2015 IEEE.

IEEE MTT-S International Microwave and RF Conference 2015, IMaRC 2015

A compact and wideband SMA connector to empty substrate integrated waveguide (ESIW) transition

Electroplating on dielectric is used to realize continuous metallic side walls of a substrate integrated waveguide (SIW). Thus the complexity of fabricating chain of metallic via using precise mechanical or laser drilling used in conventional SIW fabrication is avoided. To show effectiveness of the procedure, a single cavity dual-mode bandpass filter is designed and fabricated. A modified corner cut configuration, compatible with the via less fabrication technology, is used to obtain the dual-mode operation. The bandpass filter with microstrip lines as the external feed lines offers two transmission zeroes which is symmetrically placed on both sides of the passband. The filter has a fractional bandwidth of 5% at a center frequency 10 GHz. © 2015 IEEE.

Dual-mode bandpass filter using via less substrate integrated waveguide technology

In this letter, compact substrate integrated waveguide (SIW) power dividers are presented. Both equal and unequal power divisions are considered. A quarter-wavelength long wedge shape SIW structure is used for the power division. Direct coaxial feed is used for the input port and SIW-to-microstrip transitions are used for the output ports. Four-way equal, unequal and an eight-way equal division power dividers are presented. The four-way and the eight-way power dividers provide -10 dB input matching bandwidth of 39.3% and 13%, respectively, at the design frequency f0= 2.4 GHz. The main advantage of the power dividers is their compact sizes. Including the microstrip to SIW transitions, size is reduced by at least 46% compared to other reported miniaturized SIW power dividers. © 2016 IEEE.

Miniaturized Substrate Integrated Waveguide (SIW) Power Dividers

In this paper, the variation of unloaded Quality factor QU of a substrate integrated waveguide (SIW) resonator with the substrate parameters is presented. It is observed that the QU strongly depends on substrate thickness, dielectric constant and loss tangent values. QU of a SIW resonator is also compared with that of a conventional rectangular air filled waveguide resonator and also that of a microstrip resonator. The graphical results shown in this paper can be used as a guideline to choose a proper wave guiding structure or an appropriate substrate for SIW application especially where insertion loss is an important issue. © 2013 IEEE.

2013 International Conference on Microwave and Photonics, ICMAP 2013

Unloaded quality factor of a substrate integrated waveguide resonator and its variation with the substrate parameters

The paper presents the electrical and thermo-mechanical design of single stage beam recovery system for 120 GHz, 1 MW gyrotron. The electrical study shows that the cylindrical shape single stage beam recovery system enhances the efficiency by 66.26%. The maximum power deposited to collector in depressed collector operation is 0.48 MW for electronic efficiency, 30% and 1.44 MW for DC electron beam. The thermo-mechanical analysis has been performed to evaluate the water cooling system. The cooling system has capability of accommodating a peak wall loading, 0.9 kW/cm2 at flow rate of 1500 l/min for safe operating time, 60 ms. Further, a high voltage analysis is also carried out to appraise the electric field distribution in the collector. © 2013 Elsevier B.V.