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Papers by Nima Azadi-Tinat
IEEE Access, 2023
A compact asymmetric coplanar strip (ACS)-fed monopole antenna is presented, which operates withi... more A compact asymmetric coplanar strip (ACS)-fed monopole antenna is presented, which operates within the Bluetooth and UWB frequency bands with the capability to simultaneously reject the lower WLAN interfering band. The antenna consists of an inverted right triangle patch monopole loaded by open-ended L-shaped slits not only to produce the additional 2.4 GHz passband to the UWB design but also to achieve stopband characteristics around 5.2 GHz. The conceptual equivalent circuit model as well as characteristic mode analyses are carried out in the design evolution process. The proposed antenna has an overall size of only 20 mm × 10 mm, having the smallest area among the so far developed designs, which can be easily integrated within any wireless gadgets. A prototype is fabricated and measured to validate the design, demonstrating the predicted behavior fairly achieved by full-wave analysis. The antenna −10 dB operating bandwidth ranges from 2.38 to 2.42 GHz and from 3.35 to 11 GHz while rejecting from 4.69 to 5.2 GHz. Unlike the unwanted stopband, where the radiation characteristics are adequately deteriorated, the proposed antenna fairly provides stable omni-directional radiation patterns in the H-plane, and has an average efficiency (gain) of 87.3% (2.6 dBi) in the desired passband. As far as the antenna transient behavior is concerned, an adequate measured (simulated) system fidelity factor of 0.7 (0.68) is achieved for the transmission of impulse-type UWB signals in the face-to-face configuration. INDEX TERMS ACS-fed, compact, monopole, Bluetooth, UWB, band-notch. I. INTRODUCTION With the exponential pace of technology, portable wireless gadgets with low power consumption, large bandwidth, and more importantly, small dimensions are very attractive in today's competitive market. The two widely-used license-free Bluetooth (2.4-2.48 GHz, 40 channels with 2 MHz spacing) and UWB (3.1-10.6 GHz, over 100% fractional bandwidth) technologies are key enablers for mobile and short-range communications [1], [2]. The evolution of such systems The associate editor coordinating the review of this manuscript and approving it for publication was Sotirios Goudos .
IEEE Access
A compact asymmetric coplanar strip (ACS)-fed monopole antenna is presented, which operates withi... more A compact asymmetric coplanar strip (ACS)-fed monopole antenna is presented, which operates within the Bluetooth and UWB frequency bands with the capability to simultaneously reject the lower WLAN interfering band. The antenna consists of an inverted right triangle patch monopole loaded by open-ended L-shaped slits not only to produce the additional 2.4 GHz passband to the UWB design but also to achieve stopband characteristics around 5.2 GHz. The conceptual equivalent circuit model as well as characteristic mode analyses are carried out in the design evolution process. The proposed antenna has an overall size of only 20 mm × 10 mm, having the smallest area among the so far developed designs, which can be easily integrated within any wireless gadgets. A prototype is fabricated and measured to validate the design, demonstrating the predicted behavior fairly achieved by full-wave analysis. The antenna −10 dB operating bandwidth ranges from 2.38 to 2.42 GHz and from 3.35 to 11 GHz while rejecting from 4.69 to 5.2 GHz. Unlike the unwanted stopband, where the radiation characteristics are adequately deteriorated, the proposed antenna fairly provides stable omni-directional radiation patterns in the H-plane, and has an average efficiency (gain) of 87.3% (2.6 dBi) in the desired passband. As far as the antenna transient behavior is concerned, an adequate measured (simulated) system fidelity factor of 0.7 (0.68) is achieved for the transmission of impulse-type UWB signals in the face-to-face configuration. INDEX TERMS ACS-fed, compact, monopole, Bluetooth, UWB, band-notch. I. INTRODUCTION With the exponential pace of technology, portable wireless gadgets with low power consumption, large bandwidth, and more importantly, small dimensions are very attractive in today's competitive market. The two widely-used license-free Bluetooth (2.4-2.48 GHz, 40 channels with 2 MHz spacing) and UWB (3.1-10.6 GHz, over 100% fractional bandwidth) technologies are key enablers for mobile and short-range communications [1], [2]. The evolution of such systems The associate editor coordinating the review of this manuscript and approving it for publication was Sotirios Goudos .
Aeu-international Journal of Electronics and Communications, Feb 1, 2019
In this paper, an Electromagnetic Band-Gap (EBG) structure that consists of the two type square p... more In this paper, an Electromagnetic Band-Gap (EBG) structure that consists of the two type square patch located on the FR4 substrate is proposed. The equivalent circuit model of the unit cell is presented and analyzed. The reflection phases of the proposed structure validates the feature of radar cross section reduction. The results show the wide operation frequency band of 6.65 GHz to 12.95 GHz, where the bandwidth of 64% is achieved for this structure compared to Perfect Electric Conductor (PEC). The proposed EBG structure is studied for different radiation angles and different polarization.
Wireless Personal Communications, 2019
A reconfigurable antenna is proposed for aircraft communication application in the frequency band... more A reconfigurable antenna is proposed for aircraft communication application in the frequency bands of VHF/UHF/L. The aim of this design is to miniaturize the size of antenna to the extent possible and also to enhance its bandwidth. The semi-DGS technique is used to improve the antenna VSWR subsequent to size reduction. The proposed antenna is fabricated on FR4 substrate with dielectric constant 4.4 and thickness of 3.2 mm. One PIN diode is used for reconfiguration capability of antenna. When the PIN-diode is on (ON state), the operating frequency band is 30-230 MHz with gain of 1.5 dBi and when the diode is off (OFF state), the operating frequency band is 420-1560 MHz with the gain of 3 dBi. The VSWR in all the bands is less than two. The measurement results show a good agreement with the simulation results obtained by the fullwave software CST.
2006 European Microwave Conference, 2006
A novel least square based method is developed for the microstrip multi-section bandpass combline... more A novel least square based method is developed for the microstrip multi-section bandpass combline filter. First, the overall transmission matrix of the filter is obtained in terms of its various geometrical dimensions. The effects of couplings among adjacent and nonadjacent coupled conducting strips and also the dispersion relations of coupled lines on microstrips are considered. Then, the filter scattering parameters and its insertion loss is determined. Subsequently, an error function is constructed based on the optimization of specified insertion losses in the passband, transition bands and stopbands. The performance of the proposed least square method for the combline filter design and optimization is verified by the available electromagnetic software packages, which highlights its several advantages (such as simultaneous input and output impedance matching) compared with the available design procedures
Design of compact UWB multilayered microstrip filter with E-shape resonator is presented, which p... more Design of compact UWB multilayered microstrip filter with E-shape resonator is presented, which provides wide stopband up to 20 GHz and arbitrary impedance matching. The design procedure is developed based on the method of least squares and theory of N-coupled transmission lines. The dimensions of designed filter are about 11 mm × 11 mm and the three E-shape resonators are placed among four dielectric layers. The average insertion loss in the passband is less than 1 dB and in the stopband is about 30 dB up to 20 GHz. Its group delay in the UWB region is about 0.5 ns. The performance of the optimized filter design perfectly agrees with the microwave simulation softwares.
International Journal of Antennas and Propagation, 2012
Optimum design of a novel ultra-wideband multilayer microstrip hairpin filter is presented, provi... more Optimum design of a novel ultra-wideband multilayer microstrip hairpin filter is presented, providing for harmonic suppression and impedance matching between source and load impedances. The theory of N-coupled transmission lines is employed to obtain an equivalent circuit for development of a design procedure based on the method of least squares. A prototype model of proposed two-layer filter of order 5 is fabricated for 3.1–10.6 GHz. The dimensions of designed filter are 23 mm × 7 mm. The insertion loss in the passband varies from 0.3 dB to 3 dB (in the worst case at the edge of passband) and in the stopband is about 30 dB up to 20 GHz. Its group delay in the UWB region is about 0.5 ns. Close agreement among the filter frequency responses as obtained by the proposed method, full-wave computer simulation softwares, and measurement data verify the effectiveness of the proposed filter structure and design methods.
IEEE Access, 2023
A compact asymmetric coplanar strip (ACS)-fed monopole antenna is presented, which operates withi... more A compact asymmetric coplanar strip (ACS)-fed monopole antenna is presented, which operates within the Bluetooth and UWB frequency bands with the capability to simultaneously reject the lower WLAN interfering band. The antenna consists of an inverted right triangle patch monopole loaded by open-ended L-shaped slits not only to produce the additional 2.4 GHz passband to the UWB design but also to achieve stopband characteristics around 5.2 GHz. The conceptual equivalent circuit model as well as characteristic mode analyses are carried out in the design evolution process. The proposed antenna has an overall size of only 20 mm × 10 mm, having the smallest area among the so far developed designs, which can be easily integrated within any wireless gadgets. A prototype is fabricated and measured to validate the design, demonstrating the predicted behavior fairly achieved by full-wave analysis. The antenna −10 dB operating bandwidth ranges from 2.38 to 2.42 GHz and from 3.35 to 11 GHz while rejecting from 4.69 to 5.2 GHz. Unlike the unwanted stopband, where the radiation characteristics are adequately deteriorated, the proposed antenna fairly provides stable omni-directional radiation patterns in the H-plane, and has an average efficiency (gain) of 87.3% (2.6 dBi) in the desired passband. As far as the antenna transient behavior is concerned, an adequate measured (simulated) system fidelity factor of 0.7 (0.68) is achieved for the transmission of impulse-type UWB signals in the face-to-face configuration. INDEX TERMS ACS-fed, compact, monopole, Bluetooth, UWB, band-notch. I. INTRODUCTION With the exponential pace of technology, portable wireless gadgets with low power consumption, large bandwidth, and more importantly, small dimensions are very attractive in today's competitive market. The two widely-used license-free Bluetooth (2.4-2.48 GHz, 40 channels with 2 MHz spacing) and UWB (3.1-10.6 GHz, over 100% fractional bandwidth) technologies are key enablers for mobile and short-range communications [1], [2]. The evolution of such systems The associate editor coordinating the review of this manuscript and approving it for publication was Sotirios Goudos .
IEEE Access
A compact asymmetric coplanar strip (ACS)-fed monopole antenna is presented, which operates withi... more A compact asymmetric coplanar strip (ACS)-fed monopole antenna is presented, which operates within the Bluetooth and UWB frequency bands with the capability to simultaneously reject the lower WLAN interfering band. The antenna consists of an inverted right triangle patch monopole loaded by open-ended L-shaped slits not only to produce the additional 2.4 GHz passband to the UWB design but also to achieve stopband characteristics around 5.2 GHz. The conceptual equivalent circuit model as well as characteristic mode analyses are carried out in the design evolution process. The proposed antenna has an overall size of only 20 mm × 10 mm, having the smallest area among the so far developed designs, which can be easily integrated within any wireless gadgets. A prototype is fabricated and measured to validate the design, demonstrating the predicted behavior fairly achieved by full-wave analysis. The antenna −10 dB operating bandwidth ranges from 2.38 to 2.42 GHz and from 3.35 to 11 GHz while rejecting from 4.69 to 5.2 GHz. Unlike the unwanted stopband, where the radiation characteristics are adequately deteriorated, the proposed antenna fairly provides stable omni-directional radiation patterns in the H-plane, and has an average efficiency (gain) of 87.3% (2.6 dBi) in the desired passband. As far as the antenna transient behavior is concerned, an adequate measured (simulated) system fidelity factor of 0.7 (0.68) is achieved for the transmission of impulse-type UWB signals in the face-to-face configuration. INDEX TERMS ACS-fed, compact, monopole, Bluetooth, UWB, band-notch. I. INTRODUCTION With the exponential pace of technology, portable wireless gadgets with low power consumption, large bandwidth, and more importantly, small dimensions are very attractive in today's competitive market. The two widely-used license-free Bluetooth (2.4-2.48 GHz, 40 channels with 2 MHz spacing) and UWB (3.1-10.6 GHz, over 100% fractional bandwidth) technologies are key enablers for mobile and short-range communications [1], [2]. The evolution of such systems The associate editor coordinating the review of this manuscript and approving it for publication was Sotirios Goudos .
Aeu-international Journal of Electronics and Communications, Feb 1, 2019
In this paper, an Electromagnetic Band-Gap (EBG) structure that consists of the two type square p... more In this paper, an Electromagnetic Band-Gap (EBG) structure that consists of the two type square patch located on the FR4 substrate is proposed. The equivalent circuit model of the unit cell is presented and analyzed. The reflection phases of the proposed structure validates the feature of radar cross section reduction. The results show the wide operation frequency band of 6.65 GHz to 12.95 GHz, where the bandwidth of 64% is achieved for this structure compared to Perfect Electric Conductor (PEC). The proposed EBG structure is studied for different radiation angles and different polarization.
Wireless Personal Communications, 2019
A reconfigurable antenna is proposed for aircraft communication application in the frequency band... more A reconfigurable antenna is proposed for aircraft communication application in the frequency bands of VHF/UHF/L. The aim of this design is to miniaturize the size of antenna to the extent possible and also to enhance its bandwidth. The semi-DGS technique is used to improve the antenna VSWR subsequent to size reduction. The proposed antenna is fabricated on FR4 substrate with dielectric constant 4.4 and thickness of 3.2 mm. One PIN diode is used for reconfiguration capability of antenna. When the PIN-diode is on (ON state), the operating frequency band is 30-230 MHz with gain of 1.5 dBi and when the diode is off (OFF state), the operating frequency band is 420-1560 MHz with the gain of 3 dBi. The VSWR in all the bands is less than two. The measurement results show a good agreement with the simulation results obtained by the fullwave software CST.
2006 European Microwave Conference, 2006
A novel least square based method is developed for the microstrip multi-section bandpass combline... more A novel least square based method is developed for the microstrip multi-section bandpass combline filter. First, the overall transmission matrix of the filter is obtained in terms of its various geometrical dimensions. The effects of couplings among adjacent and nonadjacent coupled conducting strips and also the dispersion relations of coupled lines on microstrips are considered. Then, the filter scattering parameters and its insertion loss is determined. Subsequently, an error function is constructed based on the optimization of specified insertion losses in the passband, transition bands and stopbands. The performance of the proposed least square method for the combline filter design and optimization is verified by the available electromagnetic software packages, which highlights its several advantages (such as simultaneous input and output impedance matching) compared with the available design procedures
Design of compact UWB multilayered microstrip filter with E-shape resonator is presented, which p... more Design of compact UWB multilayered microstrip filter with E-shape resonator is presented, which provides wide stopband up to 20 GHz and arbitrary impedance matching. The design procedure is developed based on the method of least squares and theory of N-coupled transmission lines. The dimensions of designed filter are about 11 mm × 11 mm and the three E-shape resonators are placed among four dielectric layers. The average insertion loss in the passband is less than 1 dB and in the stopband is about 30 dB up to 20 GHz. Its group delay in the UWB region is about 0.5 ns. The performance of the optimized filter design perfectly agrees with the microwave simulation softwares.
International Journal of Antennas and Propagation, 2012
Optimum design of a novel ultra-wideband multilayer microstrip hairpin filter is presented, provi... more Optimum design of a novel ultra-wideband multilayer microstrip hairpin filter is presented, providing for harmonic suppression and impedance matching between source and load impedances. The theory of N-coupled transmission lines is employed to obtain an equivalent circuit for development of a design procedure based on the method of least squares. A prototype model of proposed two-layer filter of order 5 is fabricated for 3.1–10.6 GHz. The dimensions of designed filter are 23 mm × 7 mm. The insertion loss in the passband varies from 0.3 dB to 3 dB (in the worst case at the edge of passband) and in the stopband is about 30 dB up to 20 GHz. Its group delay in the UWB region is about 0.5 ns. Close agreement among the filter frequency responses as obtained by the proposed method, full-wave computer simulation softwares, and measurement data verify the effectiveness of the proposed filter structure and design methods.