The paper presents a study of coplanar waveguide (CPW) fed circular disc monopole antenna for ultra-wideband (UWB) applications. A circular disc monopole printed on a dielectric substrate and fed by a 50 /spl Omega/ CPW on the same layer can yield an ultra-wide -10 dB return loss bandwidth with satisfactory radiation patterns. The performance and characteristics of the antenna are investigated in order to understand its operation. Good agreement has been obtained between the simulation and experiment.

http://ap-s.ei.tuat.ac.jp/isapx/2004/pdf/1B2_4.pdf

Study of CPW-fed circular disc monopole antenna for ultra wideband applications

Looking to increase the functionality of current wireless platforms and to improve their quality of service, we have explored the merits of using frequency-reconfigurable antennas as an alternative for multiband antennas. Our study included an analysis of various reconfigurable and multiband structures such as patches, wires, and combinations. Switches, such as radio-frequency microelectromechanical systems (RFMEMS) and p-i-n diodes, were also studied and directly incorporated onto antenna structures to successfully form frequency-reconfigurable antennas.

Frequency-reconfigurable antennas for multiradio wireless platforms

Nowadays synthetic aperture radar (SAR) and multiple-input-multiple-output (MIMO) antenna systems with the capability to radiate waves in more than one pattern and polarization are playing a key role in modern telecommunication and radar systems. This is possible with the use of antenna arrays as they offer advantages of high gain and beamforming capability, which can be utilized for controlling radiation pattern for electromagnetic (EM) interference immunity in wireless systems. However, with the growing demand for compact array antennas, the physical footprint of the arrays needs to be smaller and the consequent of this is severe degradation in the performance of the array resulting from strong mutual-coupling and crosstalk effects between adjacent radiating elements. This review presents a detailed systematic and theoretical study of various mutual-coupling suppression (decoupling) techniques with a strong focus on metamaterial (MTM) and metasurface (MTS) approaches. While the performance of systems employing antenna arrays can be enhanced by calibrating out the interferences digitally, however it is more efficient to apply decoupling techniques at the antenna itself. Previously various simple and cost-effective approaches have been demonstrated to effectively suppress unwanted mutual-coupling in arrays. Such techniques include the use of defected ground structure (DGS), parasitic or slot element, dielectric resonator antenna (DRA), complementary split-ring resonators (CSRR), decoupling networks, P.I.N or varactor diodes, electromagnetic bandgap (EBG) structures, etc. In this review, it is shown that the mutual-coupling reduction methods inspired By MTM and MTS concepts can provide a higher level of isolation between neighbouring radiating elements using easily realizable and cost-effective decoupling configurations that have negligible consequence on the array’s characteristics such as bandwidth, gain and radiation efficiency, and physical footprint.

/pdf/a-comprehensive-survey-on-various-decoupling-mechanisms-with-8ltuxavmy7.pdf

A Comprehensive Survey on “Various Decoupling Mechanisms With Focus on Metamaterial and Metasurface Principles Applicable to SAR and MIMO Antenna Systems”

This expanded and thoroughly revised edition of Thomas H. Lee's acclaimed guide to the design of gigahertz RF integrated circuits features a completely new chapter on the principles of wireless systems. The chapters on low-noise amplifiers, oscillators and phase noise have been significantly expanded as well. The chapter on architectures now contains several examples of complete chip designs that bring together all the various theoretical and practical elements involved in producing a prototype chip. First Edition Hb (1998): 0-521-63061-4 First Edition Pb (1998); 0-521-63922-0

The Design of CMOS Radio-Frequency Integrated Circuits: RF CIRCUITS THROUGH THE AGES

A novel and compact ultra-wideband (UWB) microstrip-fed monopole antenna having frequency band notch function is presented. To increase the impedance bandwidth of an antenna, a narrow slit is used. By inserting a modified inverted U-slot on the proposed antenna, the frequency band notch characteristic is obtained. The designed antenna satisfies the voltage standing wave ratio requirement of less than 2.0 in the frequency band between 3 and 11 GHz while showing the band rejection performance in the frequency band of 5.0 to 5.9 GHz.

Wideband microstrip-fed monopole antenna having frequency band-notch function

A reconfigurable planar inverted-F antenna using a switchable PIN-diode and a fine-tuning varactor is presented for mobile communication applications. Selection of operating modes is achieved by switching the PIN-diode between radiators and tuning the varactor on an antenna's shorting line. Mode I, with the PIN-diode off and tuning the varactor, operates for USPCS (1.85-1.99 GHz), WCDMA (1.92-2.18 GHz), and WLAN (5.15-5.825 GHz). As a result, the varactor used to achieve frequency fine-tuning does not need a DC bias circuit and can expand the bandwidth without increasing the physical size. Mode II, with the PIN diode on and the fixed 0-V varactor, operates for USPCS and m-WiMAX (3.4-3.6 GHz). To optimize the antenna structure, a parametric analysis is performed by sweeping the length and width of the radiators. Furthermore, equivalent models of a PIN diode and a varactor are presented for accurate prediction of antenna performances which are also analyzed by varying diode parameters. All simulated results are confirmed with measured data. The peak gains show 2.84, 2.81, 1.25, and 1.49 dBi at USPCS, WCDMA, m-WiMAX, and WLAN, respectively.

A Reconfigurable PIFA Using a Switchable PIN-Diode and a Fine-Tuning Varactor for USPCS/WCDMA/m-WiMAX/WLAN

A novel reconfigurable microstrip patch antenna with frequency and polarization diversities is proposed. A U-slot is incorporated into a square patch, and a PIN diode is utilized to switch the slot on and off, which realizes the frequency diversity characteristic. The polarization diversities among linear polarization (LP), right-hand circular polarization (RHCP), and left-hand circular polarization (LHCP) are also obtained by switching three PIN diodes on the slot and the truncating corners of a square patch on and off. The antenna design and experimental results are presented. The reconfigurable microstrip antenna in (6) was capable of making polarization diversity among LP, RHCP, and LHCP. In this letter, we propose a novel reconfigurable microstrip patch antenna having frequency and polarization diversities simultaneously. A U-slot is incorporated into the square patch. The frequency diversity characteristic of the antenna is realized by switching a PIN diode on a U-slot of a microstrip patch on and off. The polarization diversity is also obtained by turning three PIN diodes on the slot and the truncating corners of a square patch on and off. The proposed antenna is designed to operate at 2415 MHz in wireless local area network (WLAN) systems or at 2650 MHz in digital multimedia broadcasting (DMB) systems. The design has been successfully implemented and the experimental results are presented.

Reconfigurable microstrip patch antenna with switchable polarization

A novel compact and wideband coplanar waveguide(CPW)-fed monopole antenna is proposed To increase the impedance bandwidth, two parasitic elements and three slots are added, which structures are optimised by a parametric analysis The antenna operates over 31 to 11 GHz for the return loss of less than −10 dB Radiation patterns also show very well omnidirectional performance of the proposed antenna

Wideband CPW-fed monopole antenna with parasitic elements and slots

A planar, compact, dual-band antenna on a semiflexible substrate is proposed for 2.45/5.85 GHz wireless body-area network applications. The proposed antenna is comprised of an I-shaped monopole embedded with an inverted L-shaped slit and an inductive meander line on the front side of the substrate, which excites the higher resonant mode at 5.85 GHz. On the backside, an inverted U-shaped stripline embedded with another inductive meander line is attached to the ground plane to excite the lower resonant mode at 2.45 GHz. The key to the miniaturization procedure is increasing the inductance and the capacitance by loading the inductive meander lines and slit line. The overall size of the proposed antenna is 0.15λ × 0.1λ × 0.004λ at 2.45 GHz. The measured results of the proposed antenna show the impedance bandwidths of 5.7% (2.4–2.54 GHz) and 3.78% (5.72–5.94 GHz) and the maximum peak gains of 2.1 dBi and 3.5 dBi, respectively. The simulated specific absorption rate values satisfy both the U.S. and EUR standards of under 1 g average and under 10 g average, respectively.

Miniaturization of a Dual-Band Wearable Antenna for WBAN Applications

A reconfigurable multiple input multiple output (MIMO) planar inverted-F antenna (PIFA) is presented for three worldwide m-WiMAX bands: 2.3-2.4 GHz, 2.5-2.7 GHz, and 3.4-3.6 GHz. In order to achieve low mutual coupling, i.e., high isolation, a band-notched quarter-wave slot line on the ground plane is used between the two reconfigurable antennas. Two PIN-diodes are appropriately located on the slot line in order to electrically control the slot length. By adjusting both the PIN-diode biases for the reconfigurable antennas and the reconfigurable isolation slot, the proposed antenna simultaneously obtains the operating frequency and isolation reconfigurability for the three operating bands. A parametric analysis is performed to investigate optimized slot lengths for the three operation modes. All of the simulated results are confirmed with measurements. Measured isolation performance of greater than 30 dB improves the radiation efficiency, diversity gain, and channel capacity for all operating frequencies.

Tae-Yeoul Yun

Papers

A Reconfigurable PIFA Using a Switchable PIN-Diode and a Fine-Tuning Varactor for USPCS/WCDMA/m-WiMAX/WLAN

Reconfigurable microstrip patch antenna with switchable polarization

Wideband CPW-fed monopole antenna with parasitic elements and slots

Miniaturization of a Dual-Band Wearable Antenna for WBAN Applications

Simultaneous Frequency and Isolation Reconfigurable MIMO PIFA Using PIN Diodes