Frequency Tunable Microstrip Patch Antenna Using RF MEMS Technology

A novel reconfigurable microstrip patch antenna is presented that is monolithically integrated with RF microelectromechanical systems (MEMS) capacitors for tuning the resonant frequency. Reconfigurability of the operating frequency of the microstrip patch antenna is achieved by loading it with a coplanar waveguide (CPW) stub on which variable MEMS capacitors are placed periodically. MEMS capacitors are implemented with surface micromachining technology, where a 1-mum thick aluminum structural layer is placed on a glass substrate with a capacitive gap of 1.5 mum. MEMS capacitors are electrostatically actuated with a low tuning voltage in the range of 0-11.9 V. The antenna resonant frequency can continuously be shifted from 16.05 GHz down to 15.75 GHz as the actuation voltage is increased from 0 to 11.9 V. These measurement results are in good agreement with the simulation results obtained with Ansoft HFSS. The radiation pattern is not affected from the bias voltage. This is the first monolithic frequency tunable microstrip patch antenna where a CPW stub loaded with MEMS capacitors is used as a variable load operating at low dc voltages     

Double MOS Loaded Circular Microstrip Antenna with Airgap for Mobile Communication

A novel model of a wide frequency range double MOS loaded circular microstrip patch antenna with airgap between ground plane and substrate is proposed. In this structure two metal oxide semiconductor (MOS) devices are loaded on the patch to enhance the operating frequency range of antenna. To investigate the antenna, different parameters such as resonance frequency, input impedance, frequency agility, VSWR, radiation pattern etc. are calculated and simulated. The resonant frequency of proposed 10 mm radius patch is upward shifted from 5.2 to 6.8 GHz using 1 mm airgap and by loading MOS, antenna can be tuned down to 1.27 GHz operating frequency, which leads to compactness and tunability of antenna. Proposed antenna can be tuned between 1.27 and 6.8 GHz frequency of operation which makes the antenna highly suitable for wide frequency range of mobile communication. The proposed double MOS loaded antenna possessed 82.94 % frequency agility. The antenna is worth for GPS, WLAN, UMTS, and WiMAX operations.     

Frequency agile slot-fed patch antenna

The authors present an original application of a slot-fed patch antenna. Voltage controlled tuning varactors are connected across the radiating edges of the patch antenna and the resonant frequency can be adjusted in a large frequency band (up to 1 GHz) while the impedance matching remains good. Results based on the transmission line model are compared with measurements     

Antenna design strategy and demonstration for software-defined radio (SDR)

Antennas are a key enabling technology for software-defined radio (SDR). Although software is extremely flexible, SDR??s potential is limited by antenna size and performance. In this paper, we review typical antenna miniaturization techniques and fundamental theories that limit antenna size and performance including operational bandwidth, gain (or range), and radiation pattern. Possible antenna design strategies are discussed to meet the desired specifications in SDR based on observations from the limit theories. The application of strategies to enable multiband (resonant), continuous multiband (frequency independent), and instantaneous, ultra-wideband antennas are discussed qualitatively. Advantages, disadvantages, and design trade-off strategies for different types of antennas are compared from a system-level perspective. A design example for a compact ultra-wideband (UWB) antenna is presented for a software-defined platform. The example involves a direct-conversion radio developed in Wireless@VT that uses a Motorola RFIC having a 100 MHz?C6 GHz operational frequency range with a 9 kHz?C20 MHz channel bandwidth. The example antenna covers frequencies from 450 MHz to 6 GHz instantaneously with approximately 5-dBi realized gain over a finite-size ground plane, including return loss and omni-directional coverage.     

A Rectangular SRR Switched Slotted Microstrip Patch for Frequency Diversity Application

Planar antenna with a specific resonant mode is essential to meet the diversity demand for wireless communication. This paper presents modeling and experimental validation of a microstrip antenna design in which multiple resonant frequencies are excited based on different negative permeability response of the rectangular split ring resonator (SRR). The antenna geometry consists of a slotted patch with split ring resonator loaded between its two arms. The patch was fabricated on FR-substrate of relative permittivity ε_r?=?4.4, and has a size of 30.5 mm?×?34 mm. In the antenna desing, PIN diodes connect the outer ring and inner ring resonator of the SRR to the adjacent arms of the patch. Under various bias conditions, quad-band resonance was observed at 2.07 GHz, 2.11 GHz, 2.31 GHz, and 2.46 GHz. The measured S₁₁ results are found comparable to the simulated data, and demonstrate proper functioning of the proposed antenna with stable gain and radiation patterns.     

Design of an Ultra-Wideband Microstrip Patch Antenna Suspended by Shorting Pins

Designing a compact wideband microstrip patch antenna which is composed of a folded-patch feed, a symmetric E-shaped edge and shorting pins is presented in this paper. One pin is applied in order to expand the impedance bandwidth. Two other pins are utilized to miniaturize the size of patch as well. The measured impedance bandwidth ( $\text{ VSWR}\le 2$ ) of the fabricated antenna is more than 90 % in the frequency range 3.92–10.67 GHz for ultra-wideband (UWB) applications. The antenna size is $0.438\lambda _{0}\times 0.365\lambda _{0}\times 0.170\lambda _{0}$ at its center operating frequency. Also, radiation patterns with acceptable stability within the bandwidth are obtained. In addition, the effects of some key parameters are investigated to describe the performance of the proposed design.     

BST Varactor Loaded Frequency Agile Stacked Circular Microstrip Radiator

A new frequency agile BST varactor loaded stacked circular microstrip antenna is presented. The antenna is analysed using extended cavity model. One of two bands of antenna is tunable with the help of BST varactor. The upper band is useful for WiMAX and lower band for other wireless communication systems. Various antenna parameters like return loss, resonant frequency, frequency agility etc. have been investigated. The simulated results agree well with the numerical data. A frequency agility of 60.64 % is achieved, which is better than simple Varactor diode loaded antenna. Lowest resonant frequency of 0.866 GHz is obtainable that shows a significant physical area reduction. The group delay of S $_{11}$ remains constant for entire band of operation.     

Shorting pin loaded dual-band compact rectangular microstrip antenna

Theoretical and experimental investigations carried out on shorted microstrip patch antenna for dual band operation. The investigations were carried out by varying the shorting-pin position from the edge to the centre of the patch; such an antenna provides a frequency tunability range from 0.88?GHz to 1.08?GHz for first resonance and from 2.20?GHz to 2.59?GHz for second resonance. A frequency ratio of about 2.91 to 2.2 for the two operating frequencies is observed. When the shorting-pin position is close to centre or at the centre of the patch, a single resonant frequency is observed. It is also observed that the resonant frequency of the antenna heavily depends upon the thickness of the substrate, dielectric constant of the substrate and radius of the shorting-pin.     

一种新型小尺寸三陷波超宽带天线设计

文中提出了一种新型小尺寸具有三陷波特性的UWB天线。所设计的天线基本几何结构由50 Ω馈电线、圆形辐射贴片、缺陷地和一对开口谐振环组成,通过在天线的圆形辐射贴片上内嵌一对Y型贴片、地板上蚀刻出U型贴片和一对开口谐振环实现三陷波特性,天线的尺寸为30 mm×30 mm×16 mm。仿真和测试结果表明,该天线29~107 GHz的频段内回波损耗＜-10 dB,在37~42 GHz、515~5825 GHz和79~84 GHz3个频段内具有陷波特性,分别有效抑制了C频段的卫星系统、WLAN系统和X频段卫星系统对超宽带系统的干扰。在除3个阻带频段外的其余UWB工作频段范围内,有着良好的辐射方向特性和稳定的增益。仿真结果和实验结果表现出了良好的一致性。     

Integrated amateur band and ultra-wide band monopole antenna with multiple band-notched

This paper presents the integrated amateur band and ultra-wide band (UWB) monopole antenna with integrated multiple band–notched characteristics. It is designed for avoiding the potential interference of frequencies 3.99 GHz (3.83 GHz–4.34 GHz), 4.86 GHz (4.48 GHz–5.63 GHz), 7.20 GHz (6.10 GHz–7.55 GHz) and 8.0 GHz (7.62 GHz–8.47 GHz) with VSWR 4.9, 11.5, 6.4 and 5.3, respectively. Equivalent parallel resonant circuits have been presented for each band-notched frequencies of the antenna. Antenna operates in amateur band 1.2 GHz (1.05 GHz–1.3 GHz) and UWB band from 3.2 GHz–13.9 GHz. Different substrates are used to verify the working of the proposed antenna. Integrated GSM band from 0.6 GHz to 1.8 GHz can also be achieved by changing the radius of the radiating patch. Antenna gain varied from 1.4 dBi to 9.8 dBi. Measured results are presented to validate the antenna performances.     

Compact UWB monopole antenna with quadruple band notched characteristics

ABSTRACT

A compact planar Ultrawideband (UWB) monopole antenna with quadruple band notch characteristics is proposed. The proposed antenna consists of a notched rectangular radiating patch with a 50 Ω microstrip feed line, and a defected ground plane. The quadruple band notched functions are achieved by utilising two inverted U-shaped slots, a symmetrical split ring resonator pair (SSRRP) and a via hole. The fabricated antenna has a compact size of 24 mm × 30 mm × 1.6 mm with an impedance bandwidth ranging from 2.86 to 12.2 GHz for magnitude of S₁₁ < ?10 dB. The four band notched characteristics of proposed antenna are in the WiMAX (worldwide interoperability for microwave access) band (3.25–3.55 GHz), C band (3.7–4.2 GHz), WLAN (wireless local area network) band (5.2–5.9 GHz) and the downlink frequency band of X band (7–7.8 GHz) for satellite communication are obtained. The measured and simulation results of proposed antenna are in good agreement to achieve impedance matching, stable radiation patterns, constant gain and group delay over the operating bandwidth.     

Characterization of a photonic active integrated antenna using a direct off-air transmission technique

This article presents a characterization study of a state-of-the-art 40 GHz mode-locked laser using a hybrid integrated microstrip patch antenna and bias-T circuit. A passive mode-locking range of 300 MHz is measured using this technique by tuning the gain and saturable absorber bias values for a maximum wireless distance of 15 cm. The passive mode-locking signal is detected by a direct off-air method from a photonic active integrated antenna. This signal can be used as a remote local oscillator to downconvert incoming signals as part of a bidirectional system for in-building/campus wide remote antenna units in next generation millimetre-wave radio-over-fibre systems.     

A High-gain Wideband Antenna with Double Fabry-perot Cavities

A high-gain wideband antenna, using the electromagnetic resonances of double Fabry-Perot (F-P) cavities, is proposed. The two cavities are excited by a patch antenna placed in the cavities on top of the ground plane. One of the double F-P cavities is formed by a ground plane and a single metallic strips array, and the other consists of the patch and the metallic strips array. The two F-P cavities have different resonance points which yield the frequency bandwidth of 7% between 13.0 and 14 GHz with S₁₁?≤?10 dB, meanwhile, in this frequency region high gain is also obtained. Moreover, the center frequency and bandwidth could be adjusted by changing the cavity length. The high-gain wideband antenna was manufactured and measured. The measured VSWR is less than 2 from 13.3 GHz to 15.2 GHz, the measured gain is 13.5 dB at 13.5 GHz. In addition to that, a considerable improvement of 7 dB in terms of gain is obtained when compared to the same antenna without metallic strips.     

Equivalent circuit model-based design and analysis of microstrip line fed electrically small patch antenna for sub-6 GHz 5G applications

In this paper, an equivalent circuit model-based electrically small patch antenna is designed for sub-6 GHz 5G application (3.5 GHz) using 50-Ω microstrip line feed. The overall size of the proposed antenna is 0.33λ₀ × 0.4λ₀ × 0.019λ₀ (28 × 34 × 1.6 mm³) at 3.50 GHz frequency. The proposed antenna has a tilted Y-shape slot, two rectangular shape slots, and two rectangular shape notches in the radiating patch. The proposed antenna is resonating from 3.21 to 3.74 GHz covering the entire sub-6 GHz 5G band (3.3–3.8 GHz). The impedance bandwidth (simulated) of the proposed antenna has been obtained 530 MHz resonating at 3.50 GHz frequency. The good return loss of −23.62 dB is also obtained at 3.50 GHz resonant frequency. The simulation results and geometry of the proposed antenna are validated with equivalent circuit model and experimental measurement of prototype antenna using vector network analyzer (VNA) and anechoic chamber. In the whole operating frequency range, the measured findings show reasonable agreement with the simulated ones. The measured impedance bandwidth of the proposed antenna has been obtained 480 MHz (3.21–3.69 GHz) resonating at 3.48 GHz frequency with a return loss of −21.61 dB, while the theoretical impedance bandwidth of the proposed antenna has been obtained 720 MHz (3.18–3.90 GHz) resonating at 3.58 GHz frequency with a return loss of −21.5 dB. The peak gain of 3.39 (simulated) and 3.2 dB (measured) is obtained at 3.50 GHz frequency. Moreover, the antenna shows 97% (simulated) and 95% (measured) efficiency at 3.50 GHz frequency.     

Asymmetrical mirror imaged monopole antenna with modified ground structure for DBDP radiations

ABSTRACT

In this article, asymmetrical mirror-imaged monopole antenna comprises a rectangular patch with tuneable stub and supported with modified ground structure (MGS) is investigated. The proposed antenna is characterised for dual band dual polarised (DBDP) radiations and can operate at 2.45 GHz for Wi-Fi and WLAN systems (2.4–2.485 GHz) and 5.45 GHz for WLAN band (WLAN band: 5.2–5.8 GHz) with the corresponding polarisations. A rectangular patch integrated with tuneable stub and a pair of asymmetrical inverted L-shaped slots positioned at ground plane is responsible for circularly polarised higher band; while a parasitic patch is created due to slotting of a mirror-imaged stub from the extended ground plane which is accountable for lower frequency band. The fabricated prototype shows that the measured Impedance bandwidths (VSWR < 2) are 350 and 1770 MHz for lower and higher frequency bands, respectively. The measured axial ratio bandwidth (AR < 3 dB) is yielded as 1450 MHz centred at 5.44 GHz for higher frequency band. The peak gains are measured as 4.3 and 4.15 dB for lower and higher frequency band, respectively. For the prototype antenna, substantial 3-dB beamwidth is found along with good cross polarisation suppression.     

Dual Band-Notched Small Monopole Antenna with Enhanced Bandwidth for UWB Applications

This article proposes a novel printed monopole antenna for ultra wideband applications with dual band-notch function. The antenna consists of a disc-shaped radiating patch with a pair of folded strips arms, and a ground plane with a two L-shaped conductor backed plane, which provides a wide usable fractional bandwidth of more than 140 % (2.6–14.43 GHz). In order to generate single band-notch characteristics, we use a modified disc-shaped radiating patch with a pair of folded strips arms also by using this modified radiating patch, additional resonance is excited and hence much wider impedance bandwidth can be produced, especially at the higher band. By adding two L-shaped conductor backed plane in the ground plane a dual band notch function is achieved. The measured results reveal that the presented dual band-notch monopole antenna offers a very wide bandwidth with two notched bands, covering all the 5.2/5.8 GHz WLAN, 3.5/5.5 GHz WiMAX and 4 GHz C bands. The designed antenna has a small size of $12\times 18\,\hbox {mm}^{2}$ .     

Small H-shaped antennas for MMIC applications

A small short-circuited H-shaped GaAs monolithic microwave integrated circuits (MMICs) patch antenna is presented. Resonant at 5.98 GHz, it is the lowest frequency MMIC patch antenna reported that we are aware of and is intended for short-range communications (e.g., vehicular). Initial experimental and theoretical characterization of the proposed structure has been carried out on soft microstrip substrates. It has been shown that the size of an H-shaped patch antenna can be reduced to as low as one tenth of that of a half wavelength patch antenna resonant at the same frequency, saving valuable substrate space. The resonance frequency, radiation patterns and gain have been investigated. Ground plane truncation effects, which are important for MMIC applications, have been examined using the finite-difference time-domain (FDTD) method     

适于毫米波应用的新型MEMS实时延时线(英文)

介绍了两种适于毫米波应用的RF MEMS实时延时线的设计。首先,在设计中采用了一种新颖的RF MEMS拓宽调节范围的变容器结构,得到了最大变容比为5.39的在片测试结果。其工艺设计基于表面微机械工艺,采用了由5个掩模版组成的工艺流程。然后,在RF MEMS变容器设计的基础上,完成了用于原理论证的Ka波段RF MEMS实时延时线的仿真设计、工艺流片和在片测试。Ka波段RF MEMS实时延时线的在片测试结果显示,在28GHz时处于下降状态的插入损耗为-2.36dB;两端口在28GHz时的回波损耗都小于-15dB,而在5～40GHz的整个测试频率范围内的回波损耗都小于-10dB。在Ka波段RF MEMS实时延时线设计基础上,60GHz RF MEMS实时延时线的仿真设计已经完成并准备投片。     

Design and Analysis of Triple-Band Rectangular Microstrip Antenna Loaded with Notches and Slots for Wireless Applications

In this paper, a rectangular triple-band microstrip antenna has been designed for Bluetooth application by successively loading notches and slots of different dimension in radiating patch. The conventional microstrip antenna suffers with narrow impedance bandwidth. The current work affords an alternate option to enhance the bandwidth of antenna that resonates in triple-band operation. Initially, the antenna is resonating in single-band but after loading slots, the bandwidth of microstrip antenna has been obtained 1.97% (lower band), 10.35% (middle band) and 33.16% (upper band) resonating in triple-band with three resonant frequency at 1.422 GHz (lower resonant frequency), 1.791 GHz (middle resonant frequency) and 2.467 GHz (higher resonant frequency). The suggested antenna has upper frequency band in the range of 2.045–2.858 GHz resonating at 2.467 GHz frequency and it is appropriate for Bluetooth applications (2.40–2.48 GHz) and both lower band useful for other wireless (L-band) applications. The return loss of upper band is ??34.52 dB at 2.467 GHz. The suggested microstrip antenna is directly fed by 50 ohm microstrip line feed. The suggested antenna has been designed, simulated and analyzed by IE3D simulation software.

     

微波化学谐振腔的模式抑制研究

对一种微波化学反应腔及其中的圆柱腔如何实现单模谐振和调谐进行了研究,得到了不会因为置入材料的不同而产生失配的新型系统结构。在腔体和系统设计中,谐振腔由谐振腔主体、谐振腔上盖和谐振腔下盖组成,谐振腔下盖通过电机升降实现上下移动,由此改变腔体的谐振频率,实现了2.2~2.6 GHz 的调谐范围。利用标量函数法分析扇形腔的场结构,根据目标模式的分布特点提出了多种干扰模式净化技术,最后得到了频率范围为2.2~2.6 GHz 的单模谐振腔。