Stripline-fed cylindrical slot antennas

A rigorous method of moments solutions for a stripline-fed cylindrical slot antenna is presented. The effects of the feeding parameters on the input impedance and far-field pattern are discussed. It is found that a cylindrical slot antenna can be matched to a 50-Ω stripline by displacing the slot from the axis of the feedline. © 1998 John Wiley & Sons, Inc. Int J RF and Microwave CAE 8: 33–41, 1998.     

Two‐dimensional beam‐scanning using tapered slot antennas and piezoelectric transducers

A wideband phased array is demonstrated using antipodal exponentially‐tapered slot‐antenna (ATSA) arrays operated by piezoelectric transducer (PET)‐controlled phase shifters. A 4 × 4 ATSA array is designed to scan two‐dimensionally across the entire X‐band. The phase shifters for 2D scanning consist of two sets of multiline phase shifters controlled by the PET for scanning in both planes. The 2D phased array has an antenna gain greater than 8 dBi, including all losses due to the phase shifters and transitions, and shows a wide beam‐scanning capability greater than 30° in both the E‐plane and the H‐plane. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.     

Wideband slot antenna using a new feeding technique for wireless applications

This article presents a new wideband slot antenna for wireless applications at 5.8 GHz. To improve the antenna bandwidth, a new feeding mechanism based on a capacitively‐ and inductively‐coupled slot is proposed. To demonstrate this approach, an experimental antenna prototype operating at the 5.8‐GHz band was designed, fabricated, and measured. The obtained results indicate very good agreement between the numerical and experimental results. The proposed antenna achieves a 28.5% bandwidth, a 5.7‐dBi gain, and a ?15‐dB front‐to‐back ratio, which are very sufficient for broadband wireless applications. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.     

A compact slot antenna configuration for ultrawideband (UWB) terminals and mobile phones

A novel technique to design a mobile phone antenna by using an ultrawideband (UWB) antenna configuration is proposed. The technique is validated with a novel printed slot antenna configuration. The slot is composed of a circle connected to a trapezoid and fed by means of a 50 Ω microstrip line connected to a patch with similar shape to the slot. An UWB antenna with size of 19 mm × 24 mm and measured ?10 dB bandwidth of 2.97‐11.32 GHz is developed based on the configuration. When the configuration is applied in a system circuit board of 60 mm × 115 mm to design a mobile phone antenna, the simulated ?6 dB bandwidths are 1.0‐1.2 GHz and 2.25‐15 GHz. To enhance antenna bandwidth, another slot with rectangular shape is etched in the ground plane, and the microstrip line is moved to the center of the circuit board and folded to distribute along the rectangular slot. The measured ?6 dB bandwidths of the mobile phone antenna are 0.69‐1.09, 1.68‐2.75, 3.45‐3.52, and 3.62‐15 GHz.     

A novel virtually centered broad wall longitudinal slot for antenna application

A virtually centered broad‐wall longitudinal slot antenna have been designed and studied using commercial Electromagnetic Simulation Software (CST Microwave Studio). The result obtained for the S₂₁ of such an antenna has been compared with the measured data to find the accuracy of the software. Also the results obtained for the slot have been compared with the more common offset broad‐wall longitudinal slot. Different slot characteristics also have been studied by varying different slot parameters. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.     

A broadband coplanar waveguide to rectangular waveguide power divider using a slot

In this article, a broadband coplanar waveguide (CPW) to rectangular waveguide power divider using the dipole slot is proposed. The power divider consists of an input CPW port and two output rectangular waveguide ports. The CPW to rectangular waveguide power divider using the dipole slot has a return loss larger than 15 dB and an insertion loss equal to 3.08–3.27 dB in the whole X‐band (8.2–12.4 GHz). Furthermore, to broaden the bandwidth, the dipole slot is replaced by the bow‐tie slot. The CPW to rectangular waveguide power divider using the bow‐tie slot yields a return loss larger than 16 dB and an insertion loss equal to 3.05–3.29 dB from 8 to 13 GHz, which exceeds the X‐band. To verify our design, power dividers that use the dipole slot or the bow‐tie slot are fabricated and measured. The measurement results of both power dividers are in good agreement with the simulation results. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

Ultra‐wideband slot antenna for wireless communication systems

In this article, a new ultra‐wideband rectangular‐slot antenna is proposed and developed for multiband wireless communication systems. The radiating slot is fed by a microstrip line with a microstrip fork‐shaped tuning stub. The frequency characteristic and radiation performance of the proposed antenna are successfully optimized, and a prototype is fabricated and tested. The measured results show that the impedance bandwidth can cover the band from 1.85 to 6.1 GHz with return loss of better than 10 dB, and the corresponding radiation displays omnidirectional patterns across the interested bands. With these frequencies, the proposed structure is especially suitable for applications in wireless communication systems, where a single antenna is needed to operate simultaneously at different bands, such as PCS (1.85–1.99 GHz), UMTS (1.92–2.17 GHz) and all WLAN bands (2.4–2.48 GHz and IEEE802.11a WLAN applications at 5.15–5.35 GHz and 5.725–5.825 GHz). © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.     

Low‐cost broadband microstrip antenna array for 24 GHz FMCW radar applications

Two designs of microstrip antenna arrays consisting of eight radiating elements and operating within a broad frequency range having the center frequency of 24 GHz are presented. One of the proposed antenna arrays uses a single laminate layer with a ground plane on one side and radiating elements on the other side, the other one is a double layer structure, where the radiating elements with beam‐forming network are placed on the top layer and are fed with the use of the slot coupler. The application of U‐slot radiating elements with enlarged inner parasitic patch allows us to achieve reflection coefficient better than 10 dB within the assumed bandwidth of currently developed FMCW radars, which is 23–25 GHz frequency range. The theoretical analysis as well as experimental results of the manufactured 2 × 4 antenna arrays is shown. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

Printed slot antennas for various wideband applications using shape blending

This article presents a novel design of wide slot antenna for various wideband applications created using a shape‐blending algorithm. The proposed printed antenna consists of a wide rectangular slot and a tuning stub, which is formed by blending the shapes of from a cross and a square. Various bandwidths can be obtained based on the structure with different blended shapes. The impact of the antenna geometry on the antenna performance has been investigated and analyzed in detail. To verify the proposed designs, six prototypes of slot antennas with various tuning stub shapes are designed, fabricated, and measured. The simulated results are compared with the measured performance and show good agreement. A bandwidth range from 38.5 to 126.4% for voltage standing wave ratio (VSWR) less than 2 is exhibited by selecting different blended shapes, which can be served as an antenna design guideline. Moreover, the proposed type of antenna has a compact size and a simple structure, which make it an excellent candidate for wideband applications. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:3–12, 2016.     

Employing irises and septums to excite the centreline longitudinal slot antennas

A suitable method is introduced to excite the centreline longitudinal slot antennas. For each slot, an iris and a rectangular septum are employed at the opposite sides of the slot such that they have offset from the waveguide centreline. It is shown that to form a high performance slotted array antenna consists of the centreline longitudinal antennas, employing antenna elements where each of them is excited only by an iris or a septum is not advisable. So, employing an iris and a septum all together is proposed to excite the centreline longitudinal slot antennas. This enables one to have a better control over the characteristics of the proposed slot antennas. The performed study indicates that the proposed slot antennas can be modelled as a shunt admittance on a transmission line. In order to demonstrate the effectiveness of the proposed slot antennas, a two‐by‐three planar array is designed, constructed and tested. The efficacy of the proposed slot antennas is verified by the simulation and the measurement results.     

Position synchronization of multiple motion axes with adaptive coupling control

A new control approach to position synchronization of multiple motion axes is developed, by incorporating cross-coupling technology into adaptive control architecture. The control strategy is to stabilize position tracking of each axis while synchronizing its motion with other axes’ motions so that differential position errors amongst axes converge to zero. The proposed adaptive controller and parameter estimator employ coupling control by feeding back position errors and differential position errors, and have been realized to guarantee asymptotic convergence to zero of both position and synchronization errors. Simulations conducted on a multi-axis motion control system demonstrate the effectiveness of the method.     

Design and analysis of wideband U‐slot patch antenna with U‐shaped parasitic elements

A single layer single probe‐fed wideband microstrip antenna is presented and investigated. By cutting a U‐slot in the rectangular patch, and by incorporating two identical U‐shaped parasitic patches around both the radiating edges and the nonradiating edges of the rectangular patch, three resonant frequencies are excited to form the wideband performance. Details of the antenna design is presented. The measured and simulated results are in good agreement, the measured impedance bandwidth is GHz ( GHz), or centered at GHz, which covers WLAN GHz ( GHz), WLAN GHz ( GHz), and WIMAX GHz ( GHz) bands. The measured peak gains at the three resonant frequencies are dB, dB, and dB, respectively. An equivalent circuit model which is based on the transmission line theory, the asymmetric coupled microstrip lines theory, and the π‐network theory is established. This equivalent circuit model is used to give an insight into the wideband mechanism of the proposed antenna, and is also used to explain why the three resonant frequencies shift at the variations of different parameters from a physical point of view. The error analysis is given to demonstrate the validity of the equivalent circuit model.     

CPW‐fed C‐shaped slot antenna for broadband circularly polarized radiation

A novel broadband circularly polarized (CP) C‐shaped slot antenna fed by a coplanar waveguide is presented. The broadband CP operation can be achieved simply using a C‐shaped slot in the ground to produce orthogonal surface currents for left‐hand circular polarization. Using the semicircle‐shaped radiator patch, wide impedance bandwidth and broad axial‐ratio (AR) bandwidth can be obtained simultaneously. The measured results show that the proposed antenna can provide a 10‐dB impedance bandwidth of 105% from 2.78 to 8.92 GHz, and a 3‐dB AR bandwidth of 70.4% from 2.9 to 6.05 GHz. Finally, an antenna prototype with a reflector for unidirectional pattern applications is also developed. The proposed antenna has broader impedance and CP bandwidths but with a more compact size compared with the previous designs. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:739–746, 2015.     

基于HFSS的漏波长槽波导天线的口径场诊断

介绍HFSS在漏波长槽波导天线口径场诊断中的应用,通过合理的子网格设置仿真得到辐射长槽上精确的口径场。采用提取的口径场分布反演得到天线远场方向图,将其与仿真得到的方向图相比,非常吻合,证明这种诊断方法正确有效。根据口径场诊断结果,对天线结构进行调整优化,达到明显的优化效果,天线副瓣明显降低,负载吸收率与理论设计非常吻合。     

Composite corporate traveling‐wave power dividers for slot array waveguide antennas

A composite corporate traveling‐wave power divider is presented. The single‐layer structure is composed of three parts: two interdigital traveling‐wave subsections combined with a power splitter. An iterative design technique is described in which the divider is split into a number of basic blocks. Large‐scaled networks are then easily designed because the whole structure does not need to be simulated. A method to take into account the insertion losses is also proposed and bandwidth enhancement is discussed, which is done by increasing the number of corporate layers. Experimental results are also shown for a 1:4 subsection. It provides equal output power with 0.5 dB of insertion loss. The phase‐shift between output ports is close to the specifications of ?150° at 30 GHz, with an error of less than 2°. It is also shown that this topology is well suited for frequency scanning antenna. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

A computer‐aided approach for designing dielectric‐covered planar array antennas consisting of longitudinal slots

A straightforward design approach is proposed to design arrays of longitudinal slots covered with dielectric slabs. The design of the arrays is accomplished via linking the slotted array antennas fed by the waveguides to a corresponding array of the loaded slots cut in an infinite ground plane and covered with dielectric slab. In this regard, the Elliott's design equations are modified for the dielectric‐covered longitudinal slotted array antennas. The introduced design equations are employed to find the final dimensions of the slot antennas while the updated mutual admittances of the corresponding array of the loaded slots are used iteratively in the design equations. Employing the introduced design equations, a two by three slotted array antenna was designed, simulated and tested. The proposed design approach is verified by the simulation and the measurement results.     

Antipodal tapered slot antenna array using broadband decoupling structure for mutual coupling reduction

In this article, an effective method to reduce the mutual coupling between the antipodal tapered slot antenna (ATSA) array is proposed. This method is mainly implemented by loading a set of decoupling structures (DS) perpendicular to the dielectric substrate between two antenna elements. The proposed DS can provide transmission forbidden band which can effectively prevent leaked electromagnetic waves. DS can operate in most frequency bands within 4 to 17.5 GHz. It can enhance about 23 dB isolation between the ATSA array without affecting bandwidth and radiation characteristics. The proposed ATSA arrays are fabricated and tested. The measured results can verify its excellent properties. The proposed broadband decoupling method is a suitable candidate for restrain mutual coupling of ultra‐wideband planar end‐fire antennas. This design sheds new light on broadband decoupling.     

A cavity‐backed quad‐slot antenna with novel aperture‐coupled feed for circular polarization

This article describes a novel aperture‐coupled feed, for the excitation of a cavity‐backed quad‐slot antenna with circular polarization. Firstly, a quad‐slot cavity‐backed antenna with linear polarization (LP) is proposed. Then, a novel aperture‐coupled feed, which is composed of a cross‐shaped coupling aperture and a T‐shaped feeding microstrip line, will be applied to this LP antenna. By differing the lengths of the four radiation slots together with the novel aperture‐coupled feed, 90° phase difference and equal magnitude between the radiations from the two pairs of slots can be generated. As a result, a good performance of axial ratio will be achieved for the proposed antenna. A prototype is fabricated at Ka band for a demonstration. Investigations show that the antenna can present a minimum axial ratio (AR) of only about 0.37 dB, as well as a fractional AR bandwidth of about 0.94%. A relative high gain of 6.9 dBic at 32.1 GHz is also achieved for the prototype. The proposed substrate integrated cavity backed antenna with circularly polarization has great potential to be integrated into millimeter‐wave transceiver modules. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:588–594, 2016.     

A WiMAX circularly polarized antenna array using slot‐coupling feeding technique

In this letter, we present a circular polarization antenna array using the novel slot‐coupling feeding technique. This antenna includes eight elements which are installed in line, each array element is fed by means of two microstrip lines with equal amplitude and phase rotation of 90°. The feeding microstrip lines are coupled to a square patch through a square‐ring slot realized in the feeding network ground plane. With the presence of the slots, this antenna array is able to cover the range of frequency of 3 GHz to 4 GHz. The size of the proposed antenna array is 7λ × 1.8λ × 0.4λ. The measured gain is 15.2 dBi and the bandwidth of S11< ?10 dB is 1 GHz (3–4 GHz, 28%). The antenna array is suited for the WiMAX applications. With the use of slot‐coupling feeding technique, the measured bandwidth for axial ratio < 3 dB is about 24% in the WiMAX frequency band (3.3–3.8GHz). The measured HPBW of the y–z planes is larger than 62°. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:567–574, 2016.     

Neural models for coplanar waveguides with a finite dielectric thickness

This article presents a new approach based on artificial neural networks (ANNs) to determine the characteristic parameters of symmetric and asymmetric coplanar waveguides with a finite dielectric thickness. ANNs are trained with the use of five training algorithms. The results obtained from neural models are in very good agreement with the theoritical and experimental results available in the literature. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13: 438–446, 2003.