A miniaturized Vivaldi antenna by loading with parasitic patch and lumped resistor

A miniaturized Vivaldi antenna is presented in the paper. On the basis of original antenna, the miniaturized Vivaldi antenna applies parasitic patch and lumped resistor to improve impedance characteristics. The proposed load can expand the lower operating frequency to 1.96 GHz without changing antenna dimensions. The size of antenna is set as 43 × 40 mm². This size is about 0.28λ_L × 0.26λ_L, where λ_L is the free space wavelength at 1.96 GHz. The loaded Vivaldi antenna is fabricated and measured. The simulated and measured results clarify the viability and effectiveness of the proposed design. The measured impedance bandwidth (VSWR ≤ 2) is from 2 GHz to more than 18 GHz. In addition, the measured radiation patterns and a peak gain between −1 and 9 dB can be obtained in the band of 2–18 GHz.     

Multiband monopole antenna loaded with Complementary Split Ring Resonator and C-shaped slots

This paper presents a compact semi circular monopole antenna loaded with Complementary Split Ring Resonator (CSRR) and two C-shaped slots is proposed for Global System for Mobile Communication (GSM), Worldwide Interoperability for Microwave Access (WiMAX) and C-band applications. The size of the proposed antenna is 20 × 20 × 0.5 mm³. The resonance frequency of WiMAX (3.73 GHz) is achieved by introducing CSRR slots on the ground plane. To realize multiband characteristics for GSM (1.77 GHz), WiMAX (2.6 GHz) and C-band (4.15 GHz), two C-shaped slots of quarter wavelength are introduced in radiating element. The extraction procedure of negative permittivity for the proposed CSRR is discussed in detail. The proposed antenna is fabricated and measured. Simulated and measured results are in good agreement. Omni directional radiation pattern is obtained in H-plane and bi directional radiation pattern is obtained in E-plane. Parametric study of CSRR and C-shaped slot are examined to obtain best results. The proposed antenna has significant advantages, including low profile, miniaturization ability, and good impedance matching.     

Wheel shaped modified fractal antenna realization for wireless communications

A compact, low profile circular fractal patch antenna with low latency, low cost, high speed and multiband is presented. With the help of CST Microwave Studio Suite TM the proposed structure has been designed and analyzed. The simulated results are fixed experimentally. The suggested antenna has dimension of 32 × 36 mm² (W × L) and operating from 2.93 GHz–9.53 GHz with VSWR ≤ 2. The aerial is assembled on FR-4 (ε_r = 4.4) substrate with a thickness of substrate 1.25 mm. Detailed parametric studies of the antennas have been carried out. This microstrip fed antenna is suitable for ultra wideband (UWB), S, C and part of the X band applications.     

A compact double-sided MIMO antenna with an improved isolation for UWB applications

This paper presents compact size 4 × 4 cm² MIMO antenna for UWB applications. The proposed antenna consists of four symmetric circular elements printed on low cost FR4 substrate with partial slotted ground plane. The two sides of the substrate are symmetric and each side is consisting of two radiators with the partial ground planes associated to the two other elements mounted on the other side. The two elements of the front side are orthogonal to the two other elements of the back side in order to increase the isolation between elements. For further reduction in the mutual coupling between elements, decoupling structures are presented in the top and bottom layers of the substrate. The simulated and measured results are investigated to study the effectiveness of the MIMO-UWB antenna. The results demonstrate the satisfactory performance of MIMO-UWB antenna, which has a return loss less than −10 dB from approximately 3.1 GHz to more than 11 GHz with an insertion loss lower than −20 dB through the achieved frequency band, and a correlation less than 0.002. Moreover, the proposed MIMO model exhibits a nearly omni-directional radiation pattern with almost constant gain of average value 3.28 dBi.     

Corrugated SIW K band horn antenna

In the recent years, the strong demand for high performance, low cost and high gain antennas for telecommunication, surveillance, and imaging applications has rapidly grown at microwave and higher frequencies. High speed wireless links require modular, compact size and high directivity with low cross polarization antennas. To demonstrate the proposed concepts and design features, in this paper, a substrate integrated waveguide (SIW) feeding technique has been created having well behaved gain and suitable −10 dB bandwidth from 23.8 GHz to 25.7 GHz (roughly 2 GHz bandwidth), while the impedance bandwidth for VSWR < 2.5 is nearly 3 GHz. The simulated antenna attains 12.5 ± 1 dB gain over majority of K band with an occupied size of 82 mm × 40 mm × 2.54 mm and has roughly 95% radiation efficiency. The proposed antenna is an excellent candidate for integrated low cost K band and even higher frequency systems. The simulations are done by two full wave packages i.e. ANSYS HFSS and CST MWS that associated with finite element method (FEM) and finite difference time domain (FDTD), respectively. The results show good agreements between these two methods.     

A novel 5.8 GHz quasi-lumped element resonator antenna

In this paper, a novel quasi-lumped element resonator antenna is presented. The proposed antenna consists of the interdigital capacitor in parallel with a straight line inductor and is fabricated on Duroid RC4003C circuit board. The entire arrangement was fed by a coaxial feed at a frequency of 5.8 GHz. The size, bandwidth and radiation patterns were studied. The proposed antenna exhibits better impedance bandwidth and significant size reduction in comparison with similar results obtained from the conventional microstrip patch antenna with similar feeding technique and resonant frequency. The size of the proposed antenna structure is 5.8 × 5.6 mm² and experimental results are shown to be in good agreement with the design simulation.     

A printed monopole ellipzoidal UWB antenna with four band rejection characteristics

An antenna design with four band rejection characteristics for UWB application is demonstrated. The proposed unique UWB antenna has shape of an embedded ellipse at top of trapezoidal patch (named as ellipzoidal), 50 Ω impedance microstrip line feed and a truncated beveled ground plane. To realize four band stop characteristics, three inverted U-shaped and a single I-shaped slots each of half guided wavelength are utilized on radiating element. The fabricated antenna has dimensions of 27 mm × 36 mm × 1.6 mm. This four band notched ellipzoidal UWB antenna has measured frequency bandwidth 2.8–14 GHz for magnitude of S₁₁ < −10 dB level. The measured ellipzoidal antenna exhibits four band rejection characteristics for magnitude of S₁₁ > −10 dB at 3.55 GHz for WiMAX band (3.26–3.9 GHz), 4.55 GHz for ARN band (4.35–5.05 GHz), 5.7 GHz for WLAN band (5.5–6.65 GHz) and 8.8 GHz for ITU-8 band (7.95–9.35 GHz). The proposed ellipzoidal UWB antenna maintains omnidirectional radiation pattern, gain, linear phase response, <1 ns group delay, and transfer function in the whole UWB operating bandwidth except at notched frequency bands.     

A compact broadband MMIC sub-harmonic mixer using quasi-lumped transmission lines

A compact broadband monolithic microwave integrated circuit (MMIC) sub-harmonic mixer using an OMMIC 70 nm GaAs mHEMT technology is demonstrated for 60 GHz down-converter applications. The present mixer employs an anti-parallel diode pair (APDP) to fulfill a sub-harmonic mixing mechanism. Quasi-lumped components are employed to broaden the operational bandwidth and minimize the chip size to 1.5×0.77 mm². The conversion gain is optimized by a quasi-lumped 90° phase shift stub. Experimental results show that from 50 GHz to 70 GHz, the conversion gain varies between −12.1 dB and −15.2 dB with a LO power level of 10 dBm and 1 GHz IF. The LO-to-RF, LO-to-IF and RF-to-IF isolations are found to be greater than 19.5 dB, 21.3 dB and 25.8 dB, respectively. The second harmonic component of the LO signal is suppressed. The proposed mixer has an input 1 dB compression point of -2 dBm and exhibits outstanding figure-of-merits.     

A compact low-profile dual-band antenna for WLAN and WAVE applications

A compact and low-profile patch antenna with a simple structure is presented for the wireless local-area network (WLAN) and the wireless access in the vehicular environment (WAVE) applications. The proposed antenna with an overall size of only 23 mm × 25 mm is fed by a coplanar waveguide (CPW), and yields 10-dB impedance bandwidths of about 250 MHz centered at 2.44 GHz and of about 22% ranging from 5.13 to 6.38 GHz suitable for the WLAN 2.4/5.2/5.8 GHz and the WAVE 5.9 GHz (IEEE 802.11p) applications. Also, good dipole-like patterns and high average antenna gain of ≥2.3 dBi over the operating bands have been obtained. In this design, resonance can be effectively controlled by simply tuning the shaped slots on the patch. Mechanism of mode excitations and effect of the added slot's length on resonance for the proposed antenna are examined and discussed in detail. The experimental results have validated the proposed design as useful for modern mobile communication.     

Offset-fed complementary split ring resonators loaded monopole antenna for multiband operations

A miniaturized multiband monopole antenna based on rectangular-shaped Complementary Split Ring Resonators (CSRRs) with offset-fed microstrip line is proposed for Global System for Mobile Communication (GSM) and Wireless Local Area Network (WLAN) applications. The proposed antenna is fabricated on a FR-4 substrate having a dielectric constant (ɛ_r) of 4.4 within a small size of 19.18 × 22.64 × 1.6 mm³. CSRRs in the monopole antenna create a multiband characteristics and bandwidth improvement, which is analyzed by use of the precise quasi-static design equations and electromagnetic simulation software (HFSS version 13). By selecting a proper offset-fed microstrip line, it is capable to achieve 50 Ω characteristic impedance and good impedance matching. The parameter extraction procedure of the metamaterial property of the CSRRs is enlightened in detail, by which the negative permittivity existence and the new resonance frequencies are verified. Simulated and measured result coincides with each other. The measured H-Plane (azimuthal plane) exhibits omnidirectional radiation pattern and E-plane (elevation plane) shows a dipole like bidirectional radiation pattern. The proposed antenna has adequate advantages, including simple design, small size, lower return loss and capable of multiband operations.     

Design of a compact U-shaped slot triple band antenna for WLAN/WiMAX applications

This article presents a small, low-profile planar microstrip antenna that is applicable for both WLAN and WiMAX applications. The goal of this paper is to design an antenna which can excite triple-band operation with appreciable impedance bandwidth to combine WLAN/WiMAX communication specifications simultaneously in one device. The designed antenna has a compact size of 10 × 26 mm². The proposed antenna consists of an inverted U-shaped slot radiator and a defected ground plane. Overall the design method and parametric study found appropriate dimensions, which provides three distinct bands I from 2.40 to 2.52, II from 3.40 to 3.60 and III from 5.00 to 6.00 GHz that covers entire WLAN (2.4/5.2/5.8 GHz) and WiMAX (2.5/3.5/5.5) bands. Finally, a prototype antenna was fabricated and experimentally characterized to verify the design concept as well as to validate the simulation results. Thus the simulation results along with the measurements show that the antenna can simultaneously operate over WLAN and WiMAX frequency bands.     

Hexagonal boundary Sierpinski carpet fractal shaped compact ultrawideband antenna with band rejection functionality

In this paper a second iteration Sierpinski carpet fractal shape UWB antenna with hexagonal boundary is presented. The antenna covers the frequency band from 3 GHz to 12 GHz (VSWR ≤ 2). The proposed antenna has the capability to reject 5.15–5.825 GHz band assigned for IEEE802.11a and HIPERLAN/2 which is achieved by embedding a ‘Y’ shaped slot in the radiator that extends to the central conductor of the CPW feed as well. A fabricated prototype is developed where the simulation and experimental results are in good agreement. Measured peak antenna gain varies from 1.25 dBi to 6 dBi within the band. The proposed antenna has a compact size of 33 mm × 32 mm that includes the substrate around the radiating element. Time domain characteristic reveal that the antenna is non-dispersive with a variation of measured group delay within 0.5 ns over the entire band.     

Design,fabrication and measurement of triple band frequency reconfigurable antennas for portable wireless communications

In this paper two triple-band monopole antennas are proposed for portable wireless applications such as WiFi, WiMAX and WLAN. Two different geometrical structures are used for the radiating elements of these antennas, each printed on a low cost FR-4 substrate. Truncated metallic copper ground is used to attain optimum radiation pattern and better radiation efficiency. The frequency of the antennas is reconfigured using a lumped-element switch. The proposed antennas covers three frequency bands 2.45, 3.50 and 5.20 GHz depending upon the switching conditions. Both antennas works with an optimum gain (1.7–3.4 dB), bandwidth (6–35%), VSWR (<1.5) and radiation efficiency (85–90%). Due to its affordable size (1.6 × 35 × 53 mm³), the antennas can be used in modern and portable communication devices such as laptops, iPads and mobile phones. The prototype of the antennas are fabricated and the measurements and simulations are found in close agreement.     

UWB Metamaterial-based miniaturized planar monopole antennas

In this paper, ultra wide band (UWB) metamterial based compact planar antennas have been designed and experimentally verified. Four novel unit cells have been realized and each unit cell dispersion characteristics are numerically calculated which follows CRLH-TL properties. These four CRLH-TL unit cells are loaded into monopole antennas which result, four open-ended MTM antennas respectively. Further, a novel via free version of CRLH-TL unit cells have been designed, which increases the fabrication flexibility. The compactness has been achieved by realizing ZOR (zeroth order resonance) mode and its bandwidth is increased by realizing small shunt capacitance and large shunt inductance. Further, by optimizing CRLH-TL unit cells, two closely spaced zeroth-order and first-order resonance modes are merged into a single pass band, which gives wide bandwidth. The each proposed antenna has a compact dimension of 0.27 λ₀ × 0.19 λ₀ × 0.02 λ₀ (22 × 15 × 1.6 mm³), where λ₀ is a free space wavelength at 3.8 GHz. The four proposed antennas have S₁₁ < −10 dB impedance bandwidths of 8.4 GHz, 8.5 GHz, 8.2 GHz and 8.3 GHz respectively. The optimum gain, good efficiency, desired radiation characteristics in frequency domain analysis and less distortion of waves in time domain analysis have been achieved for proposed antennas, which are most suitable for UWB applications. The CST-MWS has been used for the parametric study of the proposed antennas. A good agreement has been observed between simulated and experimental results.     

Dual band monopole antenna based on metamaterial structure with narrowband and UWB resonances with reconfigurable quality

In this article, an Ultra Wide Band (UWB) monopole antenna based on Metamaterial (MTM) unit cell with reconfigurable feature has been developed. The proposed antenna covers 3.1–10.6 GHz for UWB applications and it has a reconfigurable narrow-band for L-band (1.27 GHz) and wireless applications. The gaps in Split Rings Resonator (SRR) element are made for the Left-hand capacitance and Ω-shape strip layer by four via junctions are used for Left-hand inductance. The antenna is printed on FR-4 low cost substrate with relative permittivity of 4.4 and thickness of 1.6 mm. The total size of the antenna is 40 mm × 40 mm. The simulation is carried out using HFSS commercial full-wave software. In addition, the experimental results are presented and compared with simulated results. The antenna gives a maximum peak gain of 6 dBi with Omni-Directional radiation pattern and high efficiency of more than 70%. By embedding four switches in Ω-shape strip layer, a reconfigurable antenna has been successfully designed for wireless applications with sufficient qualification. The monopole part covers the UWB spectrum and the CRLH is responsible for the controllable narrowband resonance. The simulation and experimental results are confirmed by the numerical results.     

Low power high gain CMOS LNA based on inverter cell and self-body bias for UWB receivers

A low-power low-noise amplifier (LNA) utilized a resistive inverter configuration feedback amplifier to achieve the broadband input matching purposes. To achieve low power consumption and high gain, the proposed LNA utilizes a current-reused technique and a splitting-load inductive peaking technique of a resistive-feedback inverter for input matching. Two wideband LNAs are implemented by TSMC 0.18 μm CMOS technology. The first LNA operates at 2–6 GHz. The minimum noise figure is 3.6 dB. The amplifier provides a maximum gain (S₂₁) of 18.5 dB while drawing 10.3 mW from a 1.5-V supply. This chip area is 1.028×0.921 mm². The second LNA operates at 3.1–10.6 GHz. By using self-forward body bias, it can reduce supply voltage as well as save bias current. The minimum noise figure is 4.8 dB. The amplifier provides a maximum gain (S₂₁) of 17.8 dB while drawing 9.67 mW from a 1.2-V supply. This chip area is 1.274×0.771 mm².     

A 1 V, 69–73 GHz CMOS power amplifier based on improved Wilkinson power combiner

A 1 V, 69–73 GHz CMOS power amplifier based on improved Wilkinson power combiner is presented. Compared with the traditional one, the proposed Wilkinson power combiner could lower down the insertion loss and reduce the die area by eliminating the quarter-wavelength transmission lines while preserving the characteristics of Wilkinson power combining and good port isolation. The presented power amplifier has been implemented in 65 nm CMOS process and achieves a measured saturated output power of 10.61 dBm and a peak power added efficiency of 8.13% at 73 GHz with only 1 V power supply. The die area including pads is 1.23×0.45 mm², while the power combiner only occupies 200×80 μm².     

Miniaturized active stepped impedance planar inverted-F antenna using common ground

This paper presents a compact active integrated antenna (AIA) comprising of class-A power amplifier (PA) and stepped impedance planar inverted-F antenna (PIFA). In the proposed design, a common ground is used for both PA and PIFA, resulting a compact antenna of size 0.14λ₀ × 0.11λ₀ × 0.01λ₀ (λ₀ is free space wavelength at 0.85 GHz). Moreover, it is demonstrated that by using the stepped impedance radiator the operating frequency of the active PIFA is shifted down from its natural resonant frequency of 1.36 GHz to 0.85 GHz, offering an extensive size reduction of 80%. This active integration increases the passive antenna gain through the effective loading of the antenna to the power amplifier. The measured result indicates that the active and passive antennas achieved the gain of 15.7 dB and 3.81 dBi, respectively after the integration. In addition, the maximum SAR value of antenna is found to be 0.64 W/kg.     

Utility of RF MEMS miniature switched capacitors in phase shifting applications

This paper demonstrates research carried out towards the development of switched capacitors having miniature dimensions. Such devices are based on the Radio Frequency Micro Electro Mechanical Systems (RF MEMS) technique which has gained prominence in implementing a wide variety of microwave and millimetre devices till date. Switched capacitors having standard or conventional dimensions are prone to several limitations which are addressed by scaling down the standard dimensions by 150× times (in terms of area requirement). Such switched capacitors are employed to develop phase shifters working in K-band (22 GHz) frequency range to yield appreciable performance both in terms of electromechanical and RF characterizations. Such switched capacitors are utilized to develop phase shifters which find immense applications in the design of Phased Array RADARs. Switched capacitors fabricated on 500 µm thick quartz substrates, result in 30° phase shift (0.66 mm × 1 mm in dimension) with associated minimum −0.18 dB insertion loss and better than −21 dB reflection coefficient at 22 GHz frequency. Electromechanical characterization reports an actuation voltage of 14.6 V, mechanical vibration frequency of 2.5 MHz and a switching time of 620 ns respectively. Demonstrations showing complete realization of 180° phase shifter (4 mm × 1 mm) employing a cascaded arrangement of six similar 30° unit cells are also included in this paper.     

A tunable CMOS Wilkinson power divider using active inductors

This paper presents the design and implementation of a tunable CMOS Wilkinson power divider using active inductors. Compared to a conventional active inductor topology, the proposed active inductor features higher inductance tuning range, higher self-resonant frequency, and lower power consumption by introducing two additional transistors. Benefitting from the superior inductor, the low-loss Wilkinson power divider is practical while maintaining a wide tuning range. The design consuming 10.2 mW demonstrates an insertion loss of 0.67 dB, a return loss of 27 dB, and an isolation of 22.6 dB at 8 GHz. Moreover, the tuning range of the circuit is between 5.8 GHz and 10.4 GHz, rendering a 4.6 GHz bandwidth. The active chip size of the lumped design is merely 0.25 mm × 0.15 mm.