@article{fathelbab_steer_2007, title={Design of bandstop filters utilising circuit prototypes}, volume={1}, ISSN={["1751-8725"]}, DOI={10.1049/iet-map:20060147}, abstractNote={A systematic circuit-oriented approach to the design of bandstop filters with pre-defined upper passband characteristics is presented. An experimental filter is built with a fundamental stopband centred at 1.085 GHz and a first spurious stopband centred at 5.4 GHz.}, number={2}, journal={IET MICROWAVES ANTENNAS & PROPAGATION}, author={Fathelbab, W. M. and Steer, M. B.}, year={2007}, month={Apr}, pages={523–526} }
 @article{fathelbab_steer_2007, title={Filter prototypes comprising singlet and/or in-line sections}, volume={94}, ISSN={["0020-7217"]}, DOI={10.1080/00207210701682888}, abstractNote={A synthesis procedure for the design of filter prototypes comprising singlet and/or in-line sections is presented. Each singlet section realizes a finite-frequency transmission zero without requiring frequency-invariant elements at its non-resonating nodes. Prototypes comprised entirely of singlet sections realize either a lowpass or highpass response. These prototypes can also be easily transformed to in-line prototypes through the usage of simple mathematical expressions. The characteristics of an experimental bandpass filter centered at 915 MHz are reported.}, number={10}, journal={INTERNATIONAL JOURNAL OF ELECTRONICS}, author={Fathelbab, W. M. and Steer, M. B.}, year={2007}, pages={925–934} }
 @article{nath_fathelbab_lam_ghosh_aygun_gard_maria_kingon_steer_2006, title={Discrete Barium Strontium Titanate (BST) thin-film interdigital varactors on alumina: Design, fabrication, characterization, and applications}, ISBN={["978-0-7803-9541-1"]}, ISSN={["2576-7216"]}, DOI={10.1109/mwsym.2006.249652}, abstractNote={Discrete barium strontium titanate (BST) thin-film capacitors in industry standard 0603 footprint are introduced and characterized. BST capacitors have a voltage-dependent permittivity, enabling BST thin-film capacitors to be used as tuning elements in frequency agile devices. The capacitance changed by 1.5:1 at 35 V (116 kV/cm) bias. The temperature dependence of the capacitance was measured to be less than plusmn 20 % from -100 degC to +100 degC. A 2nd-order tunable combline bandpass filter on FR4 substrate has been implemented using the discrete BST varactors. The filter showed a center frequency tuning of 22% from 2.14 GHz to 2.61 GHz upon application of 130 V (433 kV/cm) bias. The zero-bias insertion loss was 4.9 dB which decreased to 2.9 dB at the high bias state. The return loss was better than 11 dB over the tuning range. Nonlinear characterization of the filter using two-tone test and a digitally-modulated CDMA 2000 signal showed an IP3 of +32 dBm and an ACPR of better than -50 dBc up to 26 dBm of input power, respectively}, journal={2006 IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST, VOLS 1-5}, author={Nath, Jayesh and Fathelbab, Wael M. and Lam, Peter G. and Ghosh, Dipankar and Aygun, Seymen and Gard, Kevin G. and Maria, J. -P. and Kingon, Angus I. and Steer, Michael B.}, year={2006}, pages={552–555} }
 @article{fathelbab_steer_2006, title={Tapped marchand baluns for matching applications}, volume={54}, ISSN={["1557-9670"]}, DOI={10.1109/TMTT.2006.875821}, abstractNote={Compact three-terminal structures with integrated matching and balun functionality are presented. The structures are in the form of tapped Marchand baluns and possess prescribed immittance profiles at either their single-ended or balanced ports. These prescribed profiles are important in ensuring stability of active circuits. Tapping the balanced resonators of the baluns enables the realization of an extremely wide range of load-to-source impedance or admittance ratios at no increase in overall size. Designs and implementations of two tapped Marchand baluns with octave bandwidths centered at 500 MHz are presented}, number={6}, journal={IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES}, author={Fathelbab, Wael M. and Steer, Michael B.}, year={2006}, month={Jun}, pages={2543–2551} }
 @article{fathelbab_steer_2005, title={A reconfigurable bandpass filter for RF/microwave multifunctional systems}, volume={53}, ISSN={["1557-9670"]}, DOI={10.1109/TMTT.2005.843502}, abstractNote={A network prototype suitable for reconfigurable filters with imaginary-axis transmission zeros is presented. The prototype is synthesized using classical cascade synthesis. Reconfiguration of the transmission zeros is implemented entirely by tunable capacitors. The measured performance of a narrow-band reconfigurable bandpass filter realized in a planar combline using varactor diodes demonstrates the principle.}, number={3}, journal={IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES}, author={Fathelbab, WM and Steer, MB}, year={2005}, month={Mar}, pages={1111–1116} }
 @article{nath_ghosh_fathelbab_maria_kingon_franzon_steer_2005, title={A tunable combline bandpass filter using Barium Strontium Titanate interdigital varactors on an alumina substrate}, ISBN={["0-7803-8845-3"]}, ISSN={["2576-7216"]}, DOI={10.1109/mwsym.2005.1516670}, abstractNote={Barium strontium titanate (BST) has a field-dependent permittivity that enables it to be used as a dielectric in a voltage-tunable capacitor or varactor. A tunable combline bandpass filter was designed and characterized using BST varactors fabricated on a polycrystalline alumina substrate with copper metallization and is 14 mm /spl times/ 14 mm in size. The center frequency of the filter varies from 1.6 to 2.0 GHz with the application of 200 V tuning voltage. A 25% tuning range was achieved using tuning field strength of 300 kV/cm. The zero bias insertion loss was 6.6 dB and this decreased to 4.3 dB at the high bias state. The return loss was better than 10 dB.}, journal={2005 IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM, VOLS 1-4}, publisher={Piscataway, NJ: IEEE}, author={Nath, J and Ghosh, D and Fathelbab, W and Maria, JP and Kingon, AI and Franzon, PD and Steer, MB}, year={2005}, pages={595–598} }
 @article{nath_ghosh_maria_kingon_fathelbab_franzon_steer_2005, title={An electronically tunable microstrip bandpass filter using thin-film barium-strontium-titanate (BST) varactors}, volume={53}, ISSN={["1557-9670"]}, DOI={10.1109/TMTT.2005.854196}, abstractNote={A tunable third-order combline bandpass filter using thin-film barium-strontium-titanate varactors and fabricated on a sapphire substrate is reported. Application of 0-200-V bias varied the center frequency of the filter from 2.44 to 2.88 GHz (16% tuning) while achieving a 1-dB bandwidth of 400 MHz. The insertion loss varied from 5.1 dB at zero bias to 3.3 dB at full bias, while the return loss exceeded 13 dB over the range. The third-order intercept of the filter was found to be 41 dBm.}, number={9}, journal={IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES}, author={Nath, J and Ghosh, D and Maria, JP and Kingon, AI and Fathelbab, W and Franzon, PD and Steer, MB}, year={2005}, month={Sep}, pages={2707–2712} }
 @article{fathelbab_steer_2005, title={Four-port microwave networks with intrinsic broad-band suppression of common-mode signals}, volume={53}, DOI={10.1108/TMTT.2005.847046}, number={5}, journal={IEEE Transactions on Microwave Theory and Techniques}, author={Fathelbab, W. M. and Steer, M. B.}, year={2005}, pages={1569–1575} }
 @article{fathelbab_steer_2005, title={New classes of miniaturized planar Marchand baluns}, volume={53}, ISSN={["1557-9670"]}, DOI={10.1109/TMTT.2005.845707}, abstractNote={Three new classes of miniaturized Marchand balun are defined based on the synthesis of filter prototypes. They are suitable for mixed lumped-distributed planar realizations with small size resulting from transmission-line resonators being a quarter-wavelength long at frequencies higher than the passband center frequency. Each class corresponds to an S-plane bandpass prototype derived from the specification of transmission zero locations. A tunable 50:100-/spl Omega/ balun is realized at 1 GHz to demonstrate the advantages of the approach presented here.}, number={4}, journal={IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES}, author={Fathelbab, WM and Steer, MB}, year={2005}, month={Apr}, pages={1211–1220} }
 @article{fathelbab_steer_2005, title={Parallel-coupled line filters with enhanced stopband performances}, volume={53}, ISSN={["1557-9670"]}, DOI={10.1109/TMTT.2005.859871}, abstractNote={A new class of parallel-coupled line filters with broad stopband response is introduced. The design is based on the synthesis of bandpass prototypes with pre-defined upper stopband characteristics. The new filters have uniform- and stepped-impedance resonators, some of which are loaded by open-circuited stubs at their open-circuited ends. A seventh-order filter implementation is presented with a fundamental passband centered at 1 GHz. The measured wide-band transmission characteristic of the filter demonstrated a broad upper stopband and was in agreement with simulations. The performance of the new filter is also compared with the characteristic of a conventionally designed filter to highlight the advantages of the proposed design method.}, number={12}, journal={IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES}, author={Fathelbab, WM and Steer, MB}, year={2005}, month={Dec}, pages={3774–3781} }