Ramanan Bairavasubramanian

Pattern and frequency reconfigurable annular slot antenna using PIN diodes

This paper presents the use of pin diodes to reconfigure the impedance match and modify the radiation pattern of an annular slot antenna (ASA). The planar antenna is fabricated on one side of a Duroid substrate and the microstrip feeding line with the matching network is fabricated on the opposite side of the board. The central frequency is 5.8 GHz and, by reconfiguring the matching circuit, the antenna was also designed to operate at 5.2 and 6.4 GHz. Pin diodes are also used to short the ASA in preselected positions along the circumference, thereby changing the direction of the null in the plane defined by the circular slot changes. As a proof of concept, two pin diodes are placed 45/spl deg/ on both sides of the feeding line along the ASA and the direction of the null is shown to align with the direction defined by the circular slot center and the diode. Consequently, a design that is reconfigurable in both frequency and radiation pattern is accomplished. Return loss and radiation pattern measurements and simulations are presented, which are in very good agreement.

Fractal-shaped microstrip coupled-line bandpass filters for suppression of second harmonic

In this paper, microstrip coupled-line bandpass filters using a Koch fractal shape are proposed for the first time. These filters are fabricated on a liquid crystal polymer (LCP) substrate for Ku-band. Conventional microstrip coupled-line filters are very popular for RF front ends because they can be fabricated easily. However, their large second harmonic causes the shape of the passband to be asymmetric in the upper band and it worsens the skirt properties. By proper design, the second harmonic of fractal filters can be significantly suppressed through the use of fractal shapes. In this paper, using LCP, the maximum harmonic suppression was almost 42 dB. This type of filter can be used to suppress the second harmonic without any additional devices and regardless of the substrate.

3-D-integrated RF and millimeter-wave functions and modules using liquid crystal polymer (LCP) system-on-package technology

Electronics packaging evolution involves system, technology, and material considerations. In this paper, we present a novel three-dimensional (3-D) integration approach for system-on-package (SOP)-based solutions for wireless communication applications. This concept is proposed for the 3-D integration of RF and millimeter (mm) wave embedded functions in front-end modules by means of stacking substrates using liquid crystal polymer (LCP) multilayer and /spl mu/BGA technologies. Characterization and modeling of high-Q RF inductors using LCP is described. A single-input-single-output (SISO) dual-band filter operating at ISM 2.4-2.5 GHz and UNII 5.15-5.85 GHz frequency bands, two dual-polarization 2/spl times/1 antenna arrays operating at 14 and 35 GHz, and a WLAN IEEE 802.11a-compliant compact module (volume of 75/spl times/35/spl times/0.2 mm/sup 3/) have been fabricated on LCP substrate, showing the great potential of the SOP approach for 3-D-integrated RF and mm wave functions and modules.

Modified Wilkinson Power Dividers for Millimeter-Wave Integrated Circuits

A modification of the Wilkinson power divider is presented that eases planar implementation while maintaining performance. By adding transmission lines between the resistor and the quarter-wave transformers of the traditional design, a range of valid solutions exists that meet the conditions of being reciprocal, isolated between the output ports, and matched at all ports. The proposed design is particularly useful at millimeter-wave frequencies where reduced physical dimensions make a circuit configuration suitable for low-cost package-level implementation difficult using traditional methods. Two frequency bands are demonstrated. At V-band, the circuit gives 0.3-dB excess insertion loss, 19-dB isolation, and 50% bandwidth. At the W-band, the circuit gives 0.75-dB excess insertion loss, 24-dB isolation, and 39% bandwidth.

Compact planar and vialess composite low-pass filters using folded stepped-impedance resonator on liquid-Crystal-polymer substrate

A compact composite low-pass filter, designed by the image parameter method and semilumped component approach, will be described and results for cutoff frequency ranging from C- to V-band will be presented. This composite design combines four filter sections and the presence of a strong attenuation pole near the cutoff frequency provides an extremely sharp attenuation response, while ensuring good matching properties in the passband, making this filter design very attractive for harmonic spurious response suppression or diplexing. The lumped-element schematic of the filter has been implemented using a combination of a stepped-impedance filter and folded stepped-impedance resonators. The overall folded layout has been optimized using full-wave simulation and occupies an ultra-compact area of only 5/spl times/5 mm/sup 2/ for a C-band filter. Measured results exhibit rejection of the attenuated pole greater than 40 dB. Similar filter designs have been realized for C- and V-bands. These filters have been fabricated on a liquid-crystal-polymer substrate demonstrating a high performance, ultra-compact, and very low-cost solution for RF and millimeter-wave applications.

Wide band, high rejection and miniaturized fifth order bandpass filter on LCP low cost organic substrate

This paper deals with miniaturized and wide band bandpass filter. This filter is based on an original topology based on series and parallel resonators. Series resonators are realized using open-ended coupled lines and parallel resonator is implemented using an open-ended stub. This hybrid topology based on two kinds of stub leads to a twice more compact 5th order design compared to the conventional 5th order approach. Moreover, the use of resonators presenting different periodic behaviors implies additional transmission zeros and so, enhances the rejection of the filter. Liquid crystal polymer (LCP) is chosen by considering its low cost, good and stable RF performance over the frequency of interest and its ability to act both as a substrate and a package to obtain wide band filter. So, the combined use of this technology and this topology leads to a filter that presents very good electrical performances in a reduced occupied area. A compact wideband filter (2.38-4.2 GHz) with insertion loss of 1.2 dB and rejection has been designed by using a full-wave analysis and measurements are presented.

Multi-band RF and mm-wave design solutions for integrated RF functions in liquid crystal polymer system-on-package technology

Electronic packaging evolution involves systems, technology and material considerations. In this paper, we present a liquid crystal polymer (LCP) based multilayer packaging technology that is rapidly emerging as an ideal platform for low cost, multi-band and reconfigurable RF front-end module integration. LCPs very low water absorption (0.04%), low cost and high electrical performance makes it very appealing for RF applications. Here we describe main characteristics and real performance of LCP substrate, by means of several design examples. A Single-Input-Single-Output (SISO) dual-band filter operating at ISM 2.4-2.5 GHz and UNII 5.15-5.85 GHz frequency bands, a dual polarization, dual frequency 2/spl times/1 antenna operating at 14 and 35 GHz, and a WLAN IEEE 802.11a compliant compact module (volume of 75/spl times/35/spl times/0.2 mm/sup 3/) have been fabricated on LCP substrate, showing the great potential of the System-On-Package approach for 3D compact, multi-band and reconfigurable integrated RF and millimeter waves functions and modules.

Compact 60-GHz bandpass filters and duplexers on liquid crystal polymer technology

Planar and via-less bandpass filters and duplexers, operating in the V-Band, have been designed and measured. Filters with both symmetric and asymmetric characteristics have been developed that are then combined to realize a duplexer. All these filters have been implemented on low cost liquid crystal polymer technology. The filters exhibit a low insertion loss of 2.5 dB and the isolation between the duplexer ports is better than 25 dB. This is the first report of a V-Band duplexer on organic technology, authenticated with measured results.

Fully Canonical Pseudo-Elliptic Bandpass Filters on Multilayer Liquid Crystal Polymer Technology

Microstrip pseudo-elliptic bandpass filters, operating in the X-band, have been designed and implemented on multilayer liquid crystal polymer (LCP) technology for the first time. Folded open loop resonators printed on different dielectric surfaces and sharing the same ground plane are coupled through slots etched in the ground plane. Fully canonical filtering and modularity have been achieved through introduction of internal nonresonant nodes. Multilayer configuration is realized through thermocompression bonding of thin sheets of LCP. The designed fourth-order filter exhibits a low insertion loss of 3.2 dB at 9.9 GHz

Development of mm-wave dual-frequency multilayer antenna arrays on liquid crystal polymer (LCP) substrate

The development of mm-wave dual frequency antenna arrays has been presented in multilayer LCP technology. Two 2times2 arrays operating at 14 and 35 GHz respectively have been designed and their impedance characteristics have been validated with measurements. These arrays can be integrated with 3D modules containing integrated circuits, filters and embedded passives to realize a complete system-on-package (SOP) based RF front end