Compact dual‐ and triband bandpass filter using frequency selecting coupling structure loaded stepped‐impedance resonator

This article presents two novel resonators, that is, frequency selecting coupling structure loaded stepped‐impedance resonator (FSCSLSIR) and π‐section loaded FSCSLSIR. The resonator behaviors and guidelines are given to design FSCSLSIR dual‐band bandpass filter (BPF) and π‐section loaded FSCSLSIR triband BPF. The proposed dual‐ and triband BPF have very compact sizes of 0.13 λ_gd × 0.06 λ_gd and 0.115 λ_gt × 0.074 λ_gt, respectively. Moreover, good return loss, low insertion loss, and high band‐to‐band isolation can be observed, and the proposed FSCSLSIR dual‐band BPF has an ultrawide stopband from 5.79 to 36 GHz. The experimental results are in good agreement with the simulations. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:427–435, 2015.     

A thin‐layer dielectric and metamaterial unit‐cell stack loaded miniaturized SRR‐based antenna for triple narrow band 4G‐LTE applications

This article presents the design of a miniaturized dual‐band antenna for long‐term evolution (LTE) application is presented. In the basic antenna design, split ring resonator was loaded in the radiating plane of the patch and frequency of resonance was further modified with the help of E‐shaped stub. The antenna has been fabricated using FR‐4 substrate and the measured dual bands at 2.11 and 2.665 GHz are found in a close match with the simulated data. By placing a thin dielectric resonator of permittivity ε _r = 10.2 and thickness of 1.27 mm, two closely spaced narrow bands are obtained at 2.217 and 2.28 GHz. A novel metamaterial unit‐cell having near‐zero refractive index is designed and mounted above the dielectric resonator. This stack configuration generates triple narrow frequency band in the LTE 2 GHz spectrum range. The overall size of the proposed antenna is 20 × 25 mm².     

Compact tri‐band BPF applying novel multi‐mode microstrip resonator

This article presents a novel multi‐mode microstrip resonator. Using the even‐odd‐mode method, its resonance characteristics are analyzed and the design graphs are given. Each mode equivalent circuit is a λ/4 stepped impedance resonator (SIR), so the proposed resonator has a compact size and the higher harmonics can be tuned in a wide range. Stub–stub coupling is introduced to split two identical modes and produce two transmission zeros (TZs). Then a tri‐band filter operating at 1.5, 2.4, and 3.8 GHz is designed using the proposed resonator. The three center frequencies and bandwidths can be independently controlled. By tuning the impedance and length ratios of the stubs, wide upper stopband is achieved. Finally, the designed filter is fabricated and measured, and the measured results agree well with the simulated ones. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:559–564, 2016.     

Dual‐band rotary standing‐wave voltage‐controlled oscillator

In this article, a dual‐band rotary standing‐wave oscillator (RSWO) is introduced that generates sinusoidal signals by the formation of a standing wave on a ring (closed‐loop)‐distributed composite right/left‐handed (CRL) Inductor‐Capacitor (LC) transmission line network. The LC network consists of four unit cells of CRL LC resonator stacked in series, and two pairs of cross‐coupled transistors are used to compensate for the loss of LC resonator. Varactors are used as the control to switch on/off the high‐ or low‐frequency bands. In the fundamental mode, the RSWO operates at the high‐frequency band. In the harmonic mode, the oscillator provides low‐frequency band outputs. The dual‐band function exploits the multiple oscillation modes of the CRL RSWO. The proposed RSWO has been implemented with the Taiwan Semiconductor Manufacturing Company, Limited (TSMC) 0.18‐μm SiGe BiCMOS technology. It can generate differential signals in the high‐band frequency range of 6.73–8.60 GHz and in the low‐band frequency range of 3.68–3.73 GHz. The die area of the RSWO is 1.123 × 1.123 mm². © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:536–543, 2014.     

A novel millimeter‐wave dual‐band circularly polarized dielectric resonator antenna

In this article, a novel dual‐band circularly polarized (CP) dielectric resonator antenna (DRA) for millimeter‐wave (MMW) band is presented. The rectangular dielectric resonator with layered truncated corners is excited by a microstrip‐coupled cross‐slot. CP radiations in the lower band are realized by utilizing two quasi‐TE₁₁₁ modes operating at 21.7 GHz and 23.8 GHz, while CP radiations in the upper band are obtained by exciting a quasi‐TE₁₁₃ mode at 28.2 GHz. The dual‐band DRA is fabricated and measured. Due to the higher order mode, the average gain of the DRA in the upper band is about 3 dB higher than that in the lower band. The measured impedance bandwidths (|S₁₁| < ?10 dB) are 17.0% (20.5‐24.3 GHz) and 15.2% (26.1‐30.4 GHz), while the measured axial ratio (AR) bandwidths (AR < 3 dB) are 12.8% (21.2‐24.1 GHz) and 5% (27.4‐28.8 GHz). In addition, the peak gain values are 5 and 8 dBic.     

A compact dual‐band zeroth‐order resonator antenna loaded with meander line inductor

A novel zeroth‐order resonator (ZOR) meta‐material (MTM) antenna with dual‐band is suggested using compound right/left handed transmission line as MTM. In this article, suggested antenna consists of patch through series gap, two meander line inductors, and two circular stubs. The MTM antenna is compact in size which shows dual‐band properties with first band centered at 2.47 GHz (2.05‐2.89 GHz) and second band is centered at 5.9 GHz (3.70‐8.10 GHz) with impedance bandwidth of (S₁₁ < ? 10 dB) 34.69% and 72.45%, respectively. At ZOR mode (2.35 GHz), the suggested antenna has overall dimension of 0.197λ_o × 0.07λ_o × 0.011λ_o with gain of 1.65 dB for ZOR band and 3.35 dB for first positive order resonator band which covers the applications like Bluetooth (2.4 GHZ), TV/Radio/Data (3.700‐6.425 GHz), WLAN (5‐5.16 GHz), C band frequencies (5.15‐5.35, 5.47‐5.725, or 5.725‐5.875 GHz) and satellite communication (7.25‐7.9 GHz). The radiation patterns of suggested structure are steady during the operating band for which sample antenna has been fabricated and confirmed experimentally. It exhibits novel omnidirectional radiation characteristics in phi = 0° plane with lower cross‐polarization values.     

A novel 3D cavity diplexer with compact size using LTCC technologies for V‐band wireless communication systems

In this article, a novel concept of 3D integrated V‐band diplexer, which permits the realization of compact size using a dual‐mode cavity and four single‐mode cavities, has been realized in low‐temperature cofired ceramic technologies. The dual‐mode cavity resonator acting as one resonator for both Rx and Tx filters is developed to generate two resonant modes (TE₁₀₂ and TE₁₀₃) at the center frequency of Rx (56.5–58.5 GHz) and Tx (64–66 GHz) channels, separately. Meanwhile, this dual‐mode cavity becomes the interconnect between Rx/Tx channels and help to realize good isolation without using conventional T‐junction. In the measurement, each filter designed for Rx and Tx channels exhibits excellent performance. Channel‐to‐channel isolations better than 35 dB across the Rx band and better than 32.5 dB across the Tx band are also obtained. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:141–145, 2015.     

A novel compact planar ultra‐wideband antenna with dual band‐notched characteristics

A novel planar ultrawideband monopole antenna with dual notched bands is presented. The antenna mainly consists of a radiation patch and a modified ground plane. To realize dual band‐notched characteristics, a U‐shaped stub embedded in the rectangular slot of the radiation patch and a novel coupled open‐/shorted‐circuit stub resonator are used on the backside of the substrate. The bandwidth of the dual notched bands can be controllable by adjusting some key parameters. The simulated and measured results indicate that the proposed antenna offers a very wide bandwidth from 2.6 to 18 GHz with Voltage Standing Wave Ratio (VSWR) < 2, except the dual notched bands of 3.3–3.7 GHz (World Interoperability for Microwave Access [WiMAX]) and 5.15–5.825 GHz (Wireless Local Area Network [WLAN]). Furthermore, good group delay and stable gains can be achieved over the operating frequencies. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:48–55, 2015.     

CPW fed miniaturized dual‐band short‐ended metamaterial antenna using modified split‐ring resonator for wireless application

A miniaturized dual‐band metamaterial (MTM) antenna has been designed in this article. The designed coplanar waveguide fed antenna has composed of inner split‐ring resonator and an outer open ring resonator with rectangular stub. The series parameter of the antenna is used to determine the zeroth order resonance frequency due to short‐ended boundary condition. The whole size of proposed structure is 20 × 25.5 mm². This MTM antenna exhibits dual‐band operation at 3.17 GHz (3.1–3.22 GHz) and 5.39 GHz (5.27–5.47 GHz). The proposed MTM structure achieves measured peak gain of 0.71 and 1.89 dB at 3.17 and 5.39 GHz, respectively. The proposed antenna can be used for recent radio communication in form of S‐band application and Wi‐MAX.     

Hybrid wideband dual‐cylindrical circularly polarized dielectric resonator antennas excited with S‐shaped microstrip feed for sub‐6 GHz frequency range

In this article, a hybrid microstrip fed dual‐cylindrical dielectric resonator antenna (dual‐CDRA) has been proposed for the sub‐6 GHz band application with a wide circular polarization band. The proposed hybrid microstrip feed cylindrical dielectric resonator antenna utilizes an S‐shaped microstrip feed line to excite fundamental HE_11δ like mode and hybrid mode in dual‐CDRAs. The presented antenna structures are acting as monopole antenna separately with 48.75% (3.88‐6.38 GHz) bandwidth whereas both radiators called dual‐CDRAs enhances the bandwidth up to 93.06% (2.16‐5.92 GHz) in addition with an axial ratio bandwidth of 15.2% (3.52‐4.1 GHz). The proposed antenna is applicable for WiMAX (3.4‐3.69 GHz), and WLAN application of 802.11d and 8.02.11e IEEE standard. For validation of simulated results, an antenna prototype has been fabricated and experimentally verified. A good agreement between simulation and measured results are obtained. The simulation results have been carried out by using Ansys HFSS 14.0 version software.     

Novel application of a new metamaterial complementary electric LC resonator for the design of miniaturized sharp band‐pass filters

In this article, we introduce a new metamaterial complementary electric LC resonator (CELC) and investigate its operational mechanism, characteristics, and potentialities for application in microwave components and devices, such as filters. We consider the excitation of CELC by the electric and magnetic fields of microstrip lines and its resonance characteristics by the diagrams of effective permittivity (ε_eff) and permeability (μ_eff). A circuit model is obtained by the consideration of its coupling with the loaded microstrip line. We then realize a novel left‐handed (LH) cell by the combination of the CELC resonator and a short circuited stub. It is designed by the least mean square method. We finally use the cascade connection of such LH cells for the design of a miniaturized narrow‐band band‐pass filter with high out of band rejection. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

A dual‐band dual‐polarized cubical DRA coupled with new modified cross‐shaped slot for ISM (2.4 GHz) and Wi‐MAX (3.3‐3.6 GHz) band applications

In this article, a new modified cross‐shaped coupled cubical dielectric resonator antenna (DRA) has been investigated for dual‐band dual‐polarized applications. The linearly polarized (LP) fields in DRA has been generated by using a single slot in the ground plane and kept at either 45° (S_L1) or ?45° (S_L2) from the microstrip feed line. Combining these two slots (S_L1 and S_L2) in the modified ground plane, the proposed structure able to generate circularly polarized (CP) field in DRA. But the generated CP field is not enough to cover ISM 2400 band. To achieve CP in ISM 2400 band, an extra slot (S_L3) to the existing slots and an extra strip (S_T) in the circular ring feed line have been included. This modified final antenna arrangement has been able to produce LP (due to loading effect, ie, slot and DRA) and CP fields (orthogonal modes have been generated, ie, TE ^x₁₁₁ and TE ^y₁₁₁), simultaneously. The measured CP and LP, ?10 dB impedance bandwidths are 11.85% (2.38‐2.68 GHz) and 9.11% (3.25‐3.56 GHz) in combination with the 3‐dB axial ratio bandwidth of 4.11% (2.38‐2.48 GHz). The generated CP and LP fields are used for different wireless communication bands such as ISM 2400 and Wi‐MAX (3.3‐3.7 GHz) bands.     

An equivalent circuit model for the wide‐band band‐pass filter with the modified Minkowski‐island‐based fractal patch

An equivalent circuit model for the wide‐band band‐pass filters (BPFs) using modified Minkowski‐island‐based (MIB) fractal patch are proposed in this article. The BPF is mainly formed by a square patch resonator in which a modified MIB fractal configuration with second‐order iteration is embedded in the patch. By the equivalent circuit model with diamond structure, the wide‐band responses are analyzed. The design procedure included equivalent circuit model is available for wide‐band design. For wide‐band characteristics, at 5.0 GHz central frequency, it has good measured characteristics including the wider bandwidth of 3.14–6.89 GHz (3‐dB fractional bandwidth of 75%), low insertion loss of 0.39 dB, and high rejection level (?48.5/?44.9 dB). The patch size is 7.4 λ 7.4 mm² (0.25 λ_g × 0.25 λ_g) with 14.1% reduction. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:170–176, 2014.     

A novel dual‐band bandpass filter using co‐directional split ring resonators with closely spaced passbands and wide upper stopband

In this article, interdigital capacitor loaded co‐directional split ring resonators (CDSRRs) and their dual‐band bandpass filter applications are proposed. The proposed resonator is formed by nested open loop resonators having open ends at the same place unlike conventional split ring resonators (SRRs). In addition, the inner open loop resonator has interdigital capacitor located between the open ends. The proposed resonator exhibits dual resonance behavior with a small center frequency ratio. Both of resonance frequencies can be controlled due to the changes in the interdigital capacitor and the electrical length of the outer resonator. A dual‐band microstrip bandpass filter is designed by using the proposed CDSRR. Two CDSRRs are used to obtain two poles in each passband. Overall electrical length of the designed filter is 0.23 λ_g × 0.14 λ_g (0.0329 λ_g²), where λ_g is the guided wavelength for the used substrate at the lowest passband center frequency of 1.8 GHz. A small center frequency is obtained by adjusting the second passband at 2.27 GHz. A very wide upper stopband, closely spaced passbands, low insertion losses and high selectivity at both passbands can be obtained by means of the proposed structure. The designed filter was also fabricated and tested. The measured results show a very good agreement with the predicted results.     

Realization of a VCO for WLAN applications using 0.35 μm‐siGe BICMOS technology

In this article, a 4.5–5.8 GHz, ?G_m LC voltage controlled oscillator (VCO) for IEEE 802.11a standard is presented. The circuit is designed with Austria MicroSystems 0.35 μm SiGe BiCMOS process that includes high‐speed SiGe heterojunction bipolar transistors (HBTs). According to measurement results, phase noise is ?102.3 dBc/Hz at 1 MHz offset from 5 GHz carrier frequency. A linear, 1300 MHz tuning range is obtained utilizing accumulation‐mode varactors. Phase noise is relatively low because of the advantage of differential tuning concept. Output power of the fundamental frequency changes between ?1.6 and 0.9 dBm depending on the tuning voltage. Average second and third harmonic levels are ?25 and ?41 dBm, respectively. The circuit draws 14 mA DC current from 3.3 V supply including buffer circuits leading to a total power dissipation of 46.2 mW. The prototype VCO occupies an area of 0.6 mm² on Si substrate, including DC and RF pads. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

A compact dual band short ended metamaterial antenna with extended bandwidth

A compact dual‐band CPW–fed metamaterial inspired antenna using Composite Right/Left Handed (CRLH) resonant approach is presented in this article. The antenna is designed such that it can be operated in series resonant mode where resonance behavior is characterized by series LC parameters. Proposed antenna comprises two annular ring resonators connected with the signal patch intended to excite the higher order modes. This results extension of second band from 51.4% (f_c = 6.92 GHz) to 69.2% (f_c = 7.35 GHz). In addition to that proposed antenna shows compact nature with an electrical size of 0.14 λ₀ × 0.21 λ0 × 0.01 λ₀ at f₀ = 2.18 GHz. The antenna is operating over 2.14–2.23 GHz, 4.81–9.90 GHz with simulated peak gain of 0.66 and 4.44 dB, respectively. Simulated radiation efficiencies of proposed antenna are 69.8 and 94.1% throughout first and second band, respectively. To examine the resonance and radiation characteristics prototype is fabricated and measured. Observed experimental results are in good agreement with those simulated one. These characteristics makes this antenna is a good candidate for modern wireless communication systems such as Bluetooth, WLAN/Wi‐Fi band. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:435–441, 2016.     

Inter‐digital coupled dual‐mode patch resonator with crossed‐island configuration for tri‐band filter design

The miniaturized dual‐mode tri‐band band‐pass filters (BPF) using crossed‐island patch resonator is proposed in this article. The BPF is mainly formed by a square patch resonator in which a crossed‐island configuration is embedded in the patch. The patch size reduction with 74.4% is achieved. By the perturbation and the alternative inter‐digital coupling, the tri‐band responses are obtained. The proposed filter covers the required bandwidths for WLAN band (2.26–3.11 GHz and 5.02–6.0 GHz) and X‐band (7.58–8.41 GHz) applications. Five transmission zeros are placed between three pass‐bands and resulted in a good isolation. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:457–463, 2014.     

Design,analysis, and measurement of a new dual‐band compact hybrid resonator antenna

A new dual‐band compact hybrid resonator antenna is proposed in this article. The analysis is based on electric‐field and magnetic‐field integral equations. In the proposed design, the structure uses a combination of a thin circular disk dielectric resonator (DR) and a microstrip‐fed dog‐bone slot. This dog‐bone slot works as a half‐wavelength radiator and as a feed circuit for the DR. By optimizing the structure's parameters, the hybrid structure allows not only the DR to resonate at one frequency band but also the dog‐bone slot to resonate at the other one with the required frequency separation. Based on the above design concept, an antenna prototype for wireless communication applications centered at 1.9 and 2.45 GHz is successfully designed, fabricated, and tested. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.     

Design and its state‐of‐the‐art of different shaped dielectric resonator antennas at millimeter‐wave frequency band

This review article provides an extensive literature survey on the research progress of dielectric resonator antenna (DRA) at millimeter‐wave frequency band that includes concepts of DRAs, their empirical formulae and design methodologies for different shaped DRAs at 60 GHz frequency band. The different shaped DRAs such as cylindrical, rectangular, hexagonal, and octagonal at 60 GHz are designed, simulated and analyzed using CST microwave studio solver. The ?10 dB impedance bandwidth of cylindrical, rectangular, hexagonal, and octagonal DRAs are 52.7 to 62.8 GHz, 57 to 62.2 GHz, 55.8 to 64.2 GHz, and 54.2 to 63.5 GHz, respectively. The idea behind getting broad impedance bandwidth is due to use of double‐layer substrate with different permittivity (ε_r1 = 4 and ε_r2 = 11.9). Empirical formulae are deduced for hexagonal and octagonal DRA, by studying the analogy of dielectric resonator geometry. Consequently, the mode of different shaped DRAs, that is, HEM₁₁₁ and TE₁₁₁ are investigated by the electric field and magnetic field distribution. With these analysis, a comprehensive research review over the period of the last two decades is carried for investigating various techniques, targeted to realized gain, circular polarization, and impedance bandwidth. Along with these analysis the state‐of‐the‐art at different shaped DRAs at mm‐wave frequency band are also reported.     

Design of novel compact dual‐band filtering power divider using stepped‐impedance resonators with high selectivity

A novel compact dual‐band power divider with filtering responses is presented in this article. The proposed circuit utilizes coupled quarter‐wavelength stepped‐impedance resonators. By controlling these resonators, dual‐band operation can be realized. Furthermore, a resistor is connected between the two open ends of the input feed line to obtain good isolation at two bands. Source load coupling is utilized to enhance the selectivity. To verify the proposed idea, a filtering power divider with the operating frequencies of 2.4 and 5.8 GHz is implemented. Good agreement between the simulated and measured results validates the proposed idea. The total size of the circuit is 0.23λ_g × 0.28λ_g, where λ_g is the guide wavelength of 2.4 GHz. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:262–267, 2016.