Three patch antennas suitable for integration and operation in a compact 24 GHz wireless sensor node with radar and communication functions are designed, characterized, and compared. The antennas are manufactured on a low loss glass wafer using thin film (BCB/Cu) wafer level processing (WLP) technologies. This process is well suited for 3D stacking. The antennas are fed through a microstrip line underneath a ground plane coupling into the patch resonator through a slot aperture. Linear polarization (LP), dual mode (DM) operation, and circular polarization (CP) are achieved through the layout of the slot aperture and rectangular patch dimensions. Antenna gain values of ∼5.5 dBi are obtained in addition to the  10 dB impedance bandwidths of 900 MHz and 1.3 GHz as well as 500 MHz CP bandwidth with a 3 dB axial ratio for the LP, DM, and CP patch antennas, respectively.

Florian Ohnimus

Uwe Maaß

Gerhard Fotheringham

Brian Curran

Ivan Ndip

Thomas Fritzsch

Jürgen Wolf

Stephan Guttowski

Klaus-Dieter Lang

Design and Comparison of 24 GHz Patch Antennas on Glass Substrates for Compact Wireless Sensor Nodes

An effective solution to reduce both the mutual coupling and return loss of a microstrip array antenna consisting of rectangular patches is proposed. The patch is made concave in both horizontal and vertical sides. Applying the proposed structure to a microstrip array antenna having two elements, the effects of patch concavity on the mutual coupling and return loss are simulated and studied. To obtain a concave rectangular patch array antenna having low amounts of mutual coupling and return loss, the patch length and width as well as the amounts of concavities are optimized using an enhanced genetic algorithm. To verify the simulation results, then, the optimal array antenna is fabricated. The simulation and experimental results confirm that the optimal concave rectangular array antenna has low amounts of mutual coupling and return loss.

Shahram Mohanna

Ali Farahbakhsh

Saeed Tavakoli

Nasser Ghassemi

Reduction of Mutual Coupling and Return Loss in Microstrip Array Antennas Using Concave Rectangular Patches

This paper reports a wide bandwidth planar bandstop filter with improved RF characteristics. The proposed filter on alumina is realized incorporating tapped open stub along with spurline topology. Further, stepped impedance resonator (SIR) approach has been introduced in the tapped stubs to achieve wider band performance with improved selectivity. The proposed topology effectively controls the transmission poles. Fabrication of this BSF has been carried out on glass substrate showing minimal effect of permittivity variation on bandwidth performance.  This validates the applied approach with achievable bandwidth of more than 100&#x25; ranging from S- to Ku-band. Close agreement with simulation and practical results have been demonstrated with measured insertion loss of less than 1&#x2009;dB and attenuation loss better than 30&#x2009;dB at C-band.

Kamaljeet Singh

K. Nagachenchaiah

Very Wideband, Compact Microstrip Bandstop Filter  Covering S-Band to Ku-Band

A novel technological method to improve the quality factor (<i  >Q</i>) of RF-integrated inductors for wireless applications is presented in this paper. A serious reduction of substrate losses caused by capacitive coupling is provided. This is realised by removing the oxide layers below the coils with optimized underetching techniques. This special etching procedure is used to establish an environment in the inductor substructure with very low permittivity. A set of solid oxide-metal-columns placed below the metal windings stabilize the coil and prevent the hollowed out structure from mechanical collapse. The oxide capacitance is lowered significantly by the reduction of the permittivity <svg style="vertical-align:-3.13504pt;width:11.95px;" id="M1" height="10.925" version="1.1" viewBox="0 0 11.95 10.925" width="11.95"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,10.925)">
		<g transform="translate(72,-63.26)">
			<text transform="matrix(1,0,0,-1,-71.95,66.44)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝜀</tspan>
			</text>

			<text transform="matrix(1,0,0,-1,-65.9,63.31)">
				<tspan style="font-size: 8.75px; " x="0" y="0">r</tspan>
			</text>

		</g>
	</g>
</svg> from values around 4 to nearly 1. Capacitive coupling losses into substrate are decreasing in the same ratio. The resulting maximum <i  >Q</i>-factors of the new designs are up to 100&#x25; higher compared to the same devices including the oxide layers but shifted significantly to higher frequencies. Improvements of <i  >Q</i> from 10 up to 15 have been obtained at a frequency of 3&#x2009;GHz for a 2.2&#x2009;nH inductor with an outer diameter of 213&#x2009;<svg style="vertical-align:-2.29482pt;width:9.6374998px;" id="M2" height="9.6750002" version="1.1" viewBox="0 0 9.6374998 9.6750002" width="9.6374998"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,9.675)">
		<g transform="translate(72,-64.26)">
			<text transform="matrix(1,0,0,-1,-71.95,66.6)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝜇</tspan>
			</text>

		</g>
	</g>
</svg>m. The resonance frequency (<svg style="vertical-align:-3.22281pt;width:22.15px;" id="M3" height="14.5875" version="1.1" viewBox="0 0 22.15 14.5875" width="22.15"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,14.5875)">
		<g transform="translate(72,-60.33)">
			<text transform="matrix(1,0,0,-1,-71.95,63.6)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝑓</tspan>
			</text>

			<text transform="matrix(1,0,0,-1,-65.01,60.47)">
				<tspan style="font-size: 8.75px; " x="0" y="0">r</tspan>
				<tspan style="font-size: 8.75px; " x="2.8969121" y="0">e</tspan>
				<tspan style="font-size: 8.75px; " x="6.7828002" y="0">s</tspan>
			</text>

		</g>
	</g>
</svg>) and frequency at maximum <i  >Q</i> (<svg style="vertical-align:-4.68874pt;width:44.087502px;" id="M4" height="16.4125" version="1.1" viewBox="0 0 44.087502 16.4125" width="44.087502"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,16.4125)">
		<g transform="translate(72,-58.87)">
			<text transform="matrix(1,0,0,-1,-71.95,63.6)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝑓</tspan>
			</text>

			<text transform="matrix(1,0,0,-1,-65.01,60.47)">
				<tspan style="font-size: 8.75px; " x="0" y="0">(</tspan>
				<tspan style="font-size: 8.75px; " x="2.9144161" y="0">𝑄</tspan>
			</text>

			<text transform="matrix(1,0,0,-1,-55.26,60.47)">
				<tspan style="font-size: 8.75px; " x="0" y="0">m</tspan>
				<tspan style="font-size: 8.75px; " x="6.8090558" y="0">a</tspan>
				<tspan style="font-size: 8.75px; " x="10.694944" y="0">x</tspan>
			</text>

			<text transform="matrix(1,0,0,-1,-40.19,60.47)">
				<tspan style="font-size: 8.75px; " x="0" y="0">)</tspan>
			</text>

		</g>
	</g>
</svg>) are shifted to higher frequencies, caused by the shrunk total capacitance of the structure. This enables the circuit designer to use the inductors for applications working at higher frequencies. Coils with different layouts and values for inductance (<i  >L</i>) were verified and showed similar results.

Kevni B&#252;y&#252;ktas

Klaus Koller

Karl-Heinz M&#252;ller

Angelika Geiselbrechtinger

A New Process for On-Chip Inductors with High <i>Q</i>-Factor Performance

The effects of adaptive genetic algorithms (AGAs) and defected ground structures (DGSs) on performance optimization of tapered microstrip filter are investigated. The proposed structure achieves an ultra wide stopband with high attenuation within a small surface area, as well as 45&#37; smaller size, in comparison with conventional filters. The parameters of the filter are optimized using in-home AGA code. In the proposed AGA algorithm, the crossover and mutation probabilities are adaptively changed according to the value of individual fitness. Then by utilizing the proposed DGS, a compact S-band lowpass filter with ultra-wide spurious free window is obtained. The proposed filter achieves an insertion loss of 0.8&#x2009;dB from DC up to 4&#x2009;GHz and 21&#x2009;dB rejection in the stopband from 4.3 up to 60&#x2009;GHz. The fabricated and measured results exhibit good agreement with the simulated results. They demonstrate that combining AGA and DGS yields best possible response for this group of filters.

Amir Reza Dastkhosh

Gholamreza Dadashzadeh

Mohammad Hossein Sedaaghi

New Design Method of UWB Microstrip Filters Using Adaptive Genetic Algorithms with Defected Ground Structures

Radio Frequency (RF) modules have been miniaturized to meet the demand for smaller and more enhanced handsets for wireless applications such as cellular phones. However, area for passive devices used in RF modules has made further miniaturization difficult. Passives embedded in substrates are now being studied intensively. In addition, circuit simulation technology has been developed that enables efficient designing of RF module circuits. Circuit designers, however, have limited database of organic substrates and embedded passives. Further, optimized thermal designs are required to prevent thermal resistance increase due to miniaturization of substrates.
 In this paper, we describe the high-frequency properties of the capacitors embedded in the organic substrates and present the equivalent circuit models of the embedded capacitors. We also present the thermal design of organic substrates applicable to RF modules.

Yusuke Kondo

Yasushi Shimada

Yoshitaka Hirata

Kazunori Yamamoto

Etsuo Watanabe

Akira Kuriyama

High-Frequency Properties of Embedded Passives and Thermal Resistance in Organic Substrates for RF Module

A CMOS active inductor with thermal noise cancelling is proposed. The noise of the transistor in the feed-forward stage of the proposed architecture is cancelled by using a feedback stage with a degeneration resistor to reduce the noise contribution to the input. Simulation results using 90 nm CMOS process show that noise reduction by 80% has been achieved. The maximum resonant frequency and the quality factor obtained are 3.8 GHz and 405, respectively. An RF band-pass filter has been designed based on the proposed noise cancelling active inductor. Tuned at 3.46 GHz, the filter features total power consumption of 1.4 mW, low noise figure of 5 dB, and IIP3 of −10.29 dBm.

Santosh Vema Krishnamurthy

Kamal El-Sankary

Ezz El-Masry

Noise-Cancelling CMOS Active Inductor and Its Application in RF Band-Pass Filter Design

RFIC integration has seen dramatic progress since the early 1990s. For example, Si-based single-chip products for GSM, WLAN, Bluetooth, and DECT applications have become commercially available. However, RF power amplifiers (PAs) and switches tend to remain off-chip in the context of single-chip CMOS/BiCMOS transceiver ICs for handset applications. More recently, several WLAN/Bluetooth vendors have successfully integrated less demanding PAs onto the transceivers. This paper will focus on single-chip RF-system-on-a-chip (i.e., &#8220;RF-SoC&#8221;) implementations that include a high-power PA. An analysis of all tradeoffs inherent to integrating higher power PAs is provided. The analysis includes the development cost, time-to-market, power efficiency, yield, reliability, and performance issues. Recent design trends on highly integrated CMOS WiFi transceivers in the literature will be briefly reviewed with emphasis on the RF-SoC product design tradeoffs impacted by the choice between integrated versus external PAs.

D. Y. C. Lie

&#8220;RF-SoC&#8221;: Integration Trends of On-Chip CMOS Power Amplifier: Benefits of External PA versus Integrated PA for Portable Wireless Communications

About this journal

Journal profile

Meet the editorial board

Editor spotlight

Submit your proposal

Do you think there is an emerging area of research that really needs to be highlighted? Or an existing research area that has been overlooked or would benefit from deeper investigation? Raise the profile of a research area by leading a Special Issue.

Special Issues

International Journal of Microwave Science and Technology - Table of contents 2010

International Journal of Microwave Science and Technology | Hindawi

title

International Journal of Microwave Science and Technology

https://images.hindawi.com/journals/ijmst/ijmst.banner.jpg

twitter:card

twitter:site

twitter:title

twitter:url

twitter:image