Cavity-backed circularly polarized (CP) antennas can reduce the multipath interferences, oﬀer ﬂexibility in orientation angle between receiving and transmitting terminals, have higher gain, and improve the electromagnetic compatibility/electromagnetic interference shielding and unidirectional radiation characteristic [1–4]. Hence, various waveguide cavity-backed CP antennas have been proposed for satellites, mobile communications and other wireless applications. However, the traditional waveguide cavity-backed CP antennas are also characterized by their bulky size, stringent manufacturing precision and high cost. To overcome these shortcomings, many substrate integrated waveguide (SIW) cavity- backed CP slot antennas have been proposed. The following three main radiating conﬁgurations of CP SIWcavity-backed slot antennas have been proposed in the literature: compound slots [5–9], annular, triangular or split ring slot [10–13] and patches, loop or cavity that cover the slots [14–19].
To investigate the operating principle of the proposed MIMO antenna, electric-ﬁeld distributions on the bottom plane of the SIWcavity are plotted in Figure 3. When port 1 is excited, strong ﬁeld is concentrated in the left part of the cavity while negligible ﬁeld is distributed in the right part. A similar distribution can also be observed when port 2 is excited. It can be concluded that cavity energy input by one port is little transmitted to the other port, but mainly radiated into free space through the opened edge and narrow slot.
Low-proﬁle antennas with wide bandwidth and good radiation are in great demand for modern wireless communications [1, 2]. Cavity antennas based on the substrate integrated waveguide (SIW) technique have attracted increasing attention, which exhibit some outstanding advantages, such as low cost, convenient integration, and surface wave suppression . However, due to low proﬁle and high quality factor (Q-factor), conventional SIWcavity antennas usually suﬀer from narrow bandwidth, restricting their practical applications .
In this paper, a set of new hybrid antennas including a semi-circular SIWcavity and microstrip patch providing wide impedance bandwidth is proposed. Different shaped patch including rectangular, semi-circlular and equilateral triangular are investigated numerically and experimentally. All proposed hybrid antennas are excited by an inset 50 W microstrip line, which facilitate integration with planar circuits and directly connection to a SMA connector. Also, they are implemented only on a single substrate using low cost PCB process. It is shown that placing a mircrostrip patch at an appropriate distance along the dielectric aperture of an HMSIW cavity-backed antenna, enhances antenna bandwidth and gain effectively. These hybrid antennas have been numerically investigated and results indicated fractional impedance bandwidth wider than 6% and gain higher than 7 dB. The best type of the proposed hybrid antennas, rectangular patch hybrid antenna which providing maximum impedance bandwidth is fabricated. The measured fractional impednace bandwidth of 10% with 7.5 dBi gain for is also obtained.
Ultra-wideband SIWcavity slots antenna is presented in this paper. a novel antenna design base on SIW including an intelligent slots for antennas resonating in an ultra wideband that covers from 42 GHz to 54 GHz. The designed antennas expected to support the applications of future wireless communications systems such as future WLAN and satellite systems. It is simulated in CST Microwave Studio programming and the author recommends improving the results of this study to obtaining more deep below of reflection coefficients. In future, real-time implementation, fabrication and measurements will be done.
Abstract—A substrate-integrated-waveguide (SIW) cavity multiple-input-multiple-output (MIMO) antenna using hybrid boundaries and anti-symmetric U-shaped slots is proposed. Unlike conventional SIW cavities completely shorted by metallic vias, the proposed two cavities possess opened edges. Since shorted and opened cavity edges can be regarded as electrically and magnetically conducting boundaries, respectively, hybrid resonating boundaries are achieved. Excited by coaxial ports, antenna elements can radiate cavity energy through the opened edges. Moreover, antenna isolation can be signiﬁcantly enhanced by introducing a pair of anti-symmetric U-shaped slots on the top and bottom planes. This design has been validated by experiments. With the overall size of 0.44 λ 0 × 0.44 λ 0 × 0.04 λ 0 , the
Microwave and millimeter-wave communication systems, especially airborne platforms, communication satellites, earth stations, and wireless base-stations, more and more requires filter with stringent selective, low insertion and potential integration into the circuit. The waveguide filters are widely used because of their high Q value, high power capability and outstanding selective. However, they are bulky, heavy and not suited for integration. Substrate integrated waveguide (SIW) filter provides a low-profile, low-cost, possible integration and low-weight scheme while maintaining high performance, which is satisfied with the needs perfectly, but the discontinuities in the post wall of the SIWcavity resonator are needed to generate the appropriate coupling for a small number of resonators in the filter. These discontinuities lead to poor stopband attenuation with an increasing amount of power carried across the coupling sections. Additionally substrate dissipation causes a loss to the SIW resonator Q value,
In order to verify the accuracy of the above analysis triple-mode half-mode bandpass ﬁlter using a single perturbed substrate integrated waveguide (SIW) cavity is fabricated, and the simulation and measurement results are depicted in Fig. 9. As we can see from Fig. 9(b), for the triple-mode half-mode bandpass ﬁlter, the measured results are in good agreement with the simulated ones. The measurement shows that the CF of ﬁlter is 7.43 Hz, and the 3-dB FBW is 13%. The measured minimum in-band insertion loss is nearly 1.8 dB, and passband return loss is better than 12 dB. It is also found that one transmission zero is located at 8.6 Hz above the passband, and the location of the transmission zeros can be controlled by changing the dimension of the slots, so the stopband rejection in the upper band of this ﬁlter is greatly improved.
Circularly polarized substrate integrated waveguide (SIW) cavity-backed antennas have attracted great attention due to their merits of simplicity in structure, low proﬁle, light weight, low fabrication cost, low loss, mitigating the eﬀect of the unexpected electromagnetic interference in the installment environment due to self-consistent electrical shielding, realizing unidirectional radiation with higher gain, capabilities of reducing polarization mismatch, suppressing multipath interference, and suitability for integration with microwave circuits [1–12]. Meanwhile, though the feature of broad 3-dB axial ratio (AR) bandwidth is becoming increasingly necessary due to the high data rate required by modern services, many newly published circularly polarized SIWcavity-backed antennas in [5–8] only support narrow-band applications due to the inherent high-quality factor of the backed SIW cavities. In , a planar high- gain circularly polarized element antenna with an eﬀective CP bandwidth of 0.99% is investigated for the use in array applications. Meanwhile, a dual-mode SIWcavity is utilized as the planar-backed cavity for the proposed antenna. In , a new low-proﬁle circularly polarized hybrid antenna with an eﬀective CP bandwidth of 1% is introduced. The proposed antenna consists of two resonators including semi-circular SIWcavity and patch antenna, which are coupled by proximity eﬀect. In , a compact and circularly polarized planar antenna with an eﬀective CP bandwidth of 5.8% is presented based on a quarter-mode substrate integrated waveguide sub-array. In , a single fed low-proﬁle cavity-backed planar slot antenna for right handed circular polarization (RHCP) applications is ﬁrst introduced by half mode substrate integrated waveguide (HMSIW) technique, which obtains an eﬀective CP bandwidth of 1.74%. Furthermore, in , a traditional truncated corner patch antenna using annular gap and parallel
Abstract—In this paper, two compact planar substrate integrated waveguide (SIW) cavity-backed antennas are proposed for wireless local area network (WLAN) at 5.5 GHz and wireless body area network (WBAN) at 5.8 GHz. The miniaturization is achieved with the concept of quarter-mode- topology, and the size of the cavity is reduced up to one-fourth of the circular SIWcavity. A L-shaped slot is etched on the top plane for miniaturization, and antenna-1 is realized which resonates at 5.5 GHz. A metal strip has been added in the middle section of the slot, and antenna-2 is realized, which resonates at 5.8 GHz. Both proposed antennas are tested in free space, while the performance of antenna-2 is investigated for on-body condition. In free space, the measured impedance bandwidths of the antenna are 160 MHz and 210 MHz at 5.5 GHz and 5.8 GHz, respectively. The radiation eﬃciency of the antenna is 89.4% in free space and 57% on phantom at 5.8 GHz. Both measured and simulated results are observed, and they are in a good agreement.
Simulated results presented in Figure 6 show that the dual-mode SIWcavity with tapered transitions has the 3 dB bandwidth is approximately 0.45 GHz (from 8.855 to 9.305 GHz) centered at 9.08 GHz. The insertion loss is 0.43 dB and the return loss is better than 20 dB across the band of interest. Moreover, a transmission zeros at 9.38 GHz and the Q-factor is 414.
2. Banerjee, S., S. Chatterjee, T. Mohanty, S. Ray, T. S. Sarkar, and M. Gangopadhyaya, “A compact dual-band half-mode SIW based semicircular antenna,” 2016 IEEE 7th Annual Ubiquitous Computing, Electronics & Mobile Communication Conference (UEMCON), Oct. 20–22, 2016. 3. Kumar, A. and S. Raghavan, “A design of miniaturized half-mode SIWcavity backed antenna,” A
Abstract—This paper presents a novel quintuple-mode wideband ﬁlter based on a circular Substrate Integrated Waveguide (SIW) cavity. To implement this ﬁlter, a pair of two metallic perturbation vias loaded around the diameter resonator line is used. An Elliptic Dielectric Resonator (EDR) was introduced in the middle of the cavity to shift certain resonant modes and restrain the higher-order modes. The optimal dimensions and dielectric permittivity of the EDR are investigated. A single SIW resonator ﬁlter has been designed, manufactured, and measured as an experimental example to verify the proposed design. Simulation and measurement results agree with 51.7% of fractional bandwidth at 10.1 GHz central frequency, with one transmission zero (TZ) at the lower frequency side and four TZs at the upper side.
In this paper, two linear arrays including a linear 1×4 and a planar 2×2 of microstrip patch and half- mode substrate integrated waveguide (SIW) cavity hybrid antenna are introduced and investigated. These are simply implemented using low cost single layer printed circuit board (PCB) process. The array element consists of a rectangular microstrip patch with appropriate dimensions in the vicinity of a semi-circular SIW resonator provide a wideband hysbrid antenna. In both antenna arrays a microstrip feeding network including a quarter-wave transformer matching circuit has been used to feed the array elements. The size of 1×4 linear array is 1.58λ 0 ×2.87λ 0 and planar 2×2 array size is 1.57λ 0 ×1.37λ 0 .
The substrate integrated waveguide (SIW) cavity-based CP antennas have low conduction loss and high gain, while maintaining the advantages of low proﬁle, low cost, and easy integration with planar circuits [4–8]. However, generating pure CP waves in SIW cavities is not as straightforward as that in microstrip patches. The general solutions are either to design two standalone radiating elements , or to cut slots on top (or bottom) of the SIWcavity [4–7]. The ﬁrst solution requires external feeding to provide the phase diﬀerence. For the second one, though widely used, the performance of the antennas is highly dependent on the shape, size, and location of the slots. Therefore, the design procedure typically involves heavy optimization in full-wave simulators, which takes a lot of time and computation.
The objectives of this project are to produce a filter design that utilize substrate integrated waveguide band pass filter. The SIWcavity has higher Q factor than conventional microstrip resonator, and as result it will produce high performance filters. It also has the advantage of easy connection to other MIC or MMIC devices via a simple transition.
This paper presents the designs of Substrate Integrated Waveguide (SIW) bandstop filter. In order to give the bandstop response, this network comprises a Substrate Integrated Waveguide (SIW) cavity resonator which is coupled to a strip line. SIW are high performance broadband interconnects with excellent immunity to electromagnetic interference and suitable for use in microwave and millimeter-wave electronics, as well as wideband systems. They are very low-cost in comparison to the classic milled metallic waveguides as they may be developed using inexpensive printed circuit board (PCB) fabrication techniques. With the advent of SIW technology in microwave area, many circuits are designed based on these structures. SIW is synthesized by placing two rows of metallic via-holes in a substrate. The field distribution in an SIW is similar to that in a conventional rectangular waveguide. Hence, it takes the advantages of low cost, high Q-factor and can easily be integrated into microwave and millimeter wave integrated circuits. The transmission loss of the on substrate transitions may be much lower than that of the transitions or coupling sections made between the conventional waveguide and planar circuits. Whilst many researches using this technology are being carried out, this project proposes that instead of designing bandstop filter based on a SIW rectangular or square resonator. In order to develop a bandstop filter base on the SIW rectangular resonator, cavity resonator coupled to a strip line to give bandstop response. The microstrip probe was positioned in the middle of SIW resonator to ensure only the TE 10 mode was excited. The size of
was firstly proposed in literature  to facilitate integration of bulky waveguide with planar circuits. In recent years, the applications of SIW have been widely developed in designing and implementing microwave components and antennas [8, 9]. The cavity-backed slot antenna based on the SIW technology is proposed in . Although using these antennas, the size of the radiating structure is significantly reduced, but they provide narrow bandwidths, especially while thin substrates are used. In literature , three crossed slot antennas backed by the SIWcavity for dual frequency, dual linear polarization and CP antennas are presented. The CP antennas proposed in literature  produce RHCP and LHCP waves and for both antennas the achieved AR bandwidth is nearly 0.8%. In literature , two low profile cavity-backed slot antennas are introduced using Half Mode SIW (HMSIW) resonator providing RHCP and LHCP waves. It is shown that the measured impedance and AR bandwidth are 8.8% and 1% respectively.
by two metallic vias with diameters of 0.5 mm. To enhance the AR bandwidth, two ring slots with widths of 0.2 mm are loaded around the circular patch radiator’s two feeding points. Meanwhile, four identical rectangular slots with widths of 0.5 mm are symmetrically loaded on the circular patch radiator, which facilitates the proposed antenna’s miniaturization. Moreover, a parasitic ring slot with width of 0.5 mm is etched on the upper metal layer of the SIWcavity to further improve the AR performance. Furthermore, since the two SMA connectors are soldered from the back side of the proposed antenna, two blind vias with size of Φ 3 mm × 2 mm is designed in the upper substrate above the two feeding points of the quadrature hybrid coupler for solder joint avoidance. Finally, a set of air vias with radii of 1.5 mm are symmetrically loaded on the proposed double-layered stacked antenna acting as locating structures, which facilitate the proposed antenna’s installation and welding. Detailed geometry and dimensions of the proposed antenna are given in Figure 1 and Table 1 after optimization using ANSYS HFSS.
Based on the discussion above, a modified SIW BC-CSRR resonator pair is proposed to improve the spurious suppression by removing the middle metal strip line between the two rings of the BC-CSRR on the bottom broadwall of the SIW. Fig. 4 shows the configuration of the new unit cell, where the middle metal strip line between the two rings on the bottom of the SIW is removed and these two rings are united along the common side. The simulated transmission response of the modified unit cell is shown in Fig. 4(c). Like the frequency response of the original unit cell, a passband is observed, now with the center frequency at 4.2 GHz. As expected, the spurious passband of the original unit cell at 9.37 GHz is suppressed and a broad stopband with an enhanced out-of- band rejection is achieved for the modified unit cell.