Farzaneh Taringou

Broadband CPW Feed for Millimeter-Wave SIW-Based Antipodal Linearly Tapered Slot Antennas

To achieve broadband performances in the millimeter-wave range, antipodal linearly tapered slot antenna (ALTSA) designs with new combined substrate integrated waveguide (SIW) and regular coplanar waveguide (CPW) feeds are presented and studied. This feed structure eliminates the fabrication of air bridges in direct CPW-fed tapered slot antennas (TSAs). Two millimeter-wave design techniques are introduced for the selected 41–61 GHz and 90–120 GHz frequency ranges, demonstrating very good impedance match and nearly constant gain, beamwidth, and cross-polarization levels over bandwidths of 39% and 28%, respectively. The design procedure is validated by comparing simulated results with measurements performed on a 21–31 GHz (38% bandwidth) prototype. Very good agreement between measured and calculated performance characteristics is obtained with only cross-polarization levels slightly higher than predicted. The structural design parameters and dimensions of all three designs are given.

Substrate-integrated waveguide transitions to planar transmission-line technologies

For the purpose of integrating active, nonlinear and surface-mount components in substrate-integrated waveguide (SIW) technology, this paper presents a variety of new and modified transitions from SIW to other planar transmission lines. Typical performances are shown involving connections to microstrip, coplanar waveguide (both conductor-backed and regular), coplanar strip line and slot line technologies. Both modified and new transition examples in the 18 – 27 GHz range demonstrate the feasibility of such interfaces for bandwidths in the order of 40 percent. Measurements and full-wave simulations validate the proposed designs.

A Mode-matching Approach for the Analysis and Design of Substrate-integrated Waveguide Components

Abstract A mode-matching approach is presented that allows a fast and accurate analysis of substrate-integrated wave-guide components with rectangular/square via holes. Models for several discontinuities are discussed which include microstrip as well as all-dielectric wave-guide feeds. The numerical technique is verified by comparison with commercially available field solvers. An example of a four-pole dual-mode filter in substrate-integrated wave-guide technology illustrates the capabilities of the approach.

Return-loss investigation of the equivalent width of substrate-integrated waveguide circuits

Five different models to determine the equivalent width of substrate-integrated waveguide (SIW) circuits are investigated. The reflection coefficients between all-dielectric waveguides of equivalent width and SIW circuits are analyzed by full-wave techniques. It is found that one of the models yields consistently inferior results while the others depend on the ratio of the via-hole diameter and the center-to-center spacing of the via holes. Moreover, the influence of the substrates permittivity with respect to the via-hole diameter and spacing is demonstrated. Recommendations are derived as to the use of respective models for different via diameters and spacings.

A dual branch Hammerstein-Wiener architecture for behavior modeling of wideband RF transmitters

This paper proposes a dual branch Hammerstein-Wiener system suitable for behavioral modeling of dynamic nonlinear RF power amplifiers and transmitters. The model consists of a Hammerstein system in parallel with a Wiener system. The model performances in time and frequency domains are experimentally evaluated for a 3G high power Doherty amplifier driven by multi-carrier WCDMA signals. For various orders, the performances of the proposed dual branch Hammerstein-Wiener model are benchmarked against those of the Hammerstein model, Wiener model, and the well established memory polynomial model. The proposed dual branch model achieves better performance than single branch Wiener and Hammerstein models with higher number of coefficients. Furthermore, it leads to normalized mean square error performance comparable to that of the memory polynomial model while requiring 30% to 40% less coefficients.

Mode-matching analysis of substrate-integrated waveguide circuits

A mode-matching approach is presented for the analysis of substrate-integrated waveguide (SIW) circuits. The numerical technique takes advantage of recently developed fabrication techniques employing rectangular-shaped via holes. Discontinuity models involving all-dielectric waveguides and sections with arbitrary numbers of vias are presented and combined into a powerful analysis tool which can be used straightforwardly for the design of SIW components. The influence of the overall substrate width on the circuit performance is investigated. It is found that the computational domain can be significantly reduced without impacting on the computed performances. A design example involving a back-to-back impedance transformer is presented. The results are verified by comparison with the commercially available field solver CST Microwave Studio.

Experimental verification of coplanar-to-substrate-integrated-waveguide interconnect on low-permittivity substrate

An interconnect between coplanar waveguide (CPW) and substrate integrated waveguide (SIW) is designed and experimentally verified. Common to regular SIW circuits is a low-permittivity substrate, whereas design formulas CPW usually assume a high permittivity. Therefore, commercially available field solvers are used in a parametric study to optimize the interconnect over a wide bandwidth between 18 GHz and 28 GHz. Cross-sectional field plots demonstrate its basic operation. The individual interconnect achieves return and insertion losses better than 20 dB and 0.5 dB, respectively, over the entire frequency range. The respective values for a measured back-to-back transition are 17 dB and 1.45 dB which are in good agreement with simulations.

Broadband interconnects between coplanar waveguide and substrate integrated waveguide for dense packaging and integration

Two new interconnects between coplanar waveguide (CPW) and substrate integrated waveguide (SIW) are introduced and studied. Contrary to previously published interconnects, the new ones are shorter and require less space on the printed-circuit board. Thus they are ideally suited for dense packaging and integration. The first one is a regular interconnect that runs the slots of the CPW directly into the SIW. It is straightforwardly designed and achieves 26 dB return loss over a 10 GHz bandwidth centered at 23 GHz. The second interconnect is of the inverted type. It is 43 percent shorter than the first one over the same frequency range and at the same return loss level. Experimental results conducted at back-to-back transitions agree well with theoretical predictions. The shortest inverted interconnect achieves a measured back-to-back return loss of better than 18.5 dB over the entire frequency range with a maximum insertion loss of 1.28 dB. The comparative values of the regular back-to-back CPW-to-SIW prototype are 23 dB and 1.0 dB, respectively.

Wideband transitions from Substrate-Integrated Waveguide to Coupled Microstrip lines and their applications to power dividers

Three wideband transitions from Substrate-Integrated Waveguide (SIW) to Coupled Microstrip (CMS) lines are presented. It is demonstrated that a transition from the fundamental SIW mode to the even quasi-TEM mode of the CMS is straightforward, whereas dominant coupling to the odd mode is only realizable by removing parts of the ground plane. Asymmetric transitions maintaining the ground plane excite a hybrid mode which includes both quasi-TEM modes of the CMS. For this hybrid mode, the excitation ratios between the even- and odd-mode components can be varied, and an unequal power divider is obtained. Performances of the individual transitions and power divider are verified by commercially available field solvers. Dimensional parameters are provided.

Polynomial-Based Pre-distortion for Wideband RF Transmitters Using Single Frequency Signal

In this paper a polynomial-based pre-distorter for RF transmitters is proposed which compensates for the static nonlinear behavior of the transmitter at the first step and once the inverse static model is found linear identification techniques are used for linear distortion. The signal under which the pre-distortion procedure is performed is a sinusoidal signal. The linear distortion of the system on a sinusoidal signal is merely phase shift and additive gain, the goal is to find the inverse model of the static nonlinear behavior of the transmitter by sending a sinusoidal wave through the dynamic nonlinear system and receiving a sinusoidal wave of the same frequency.