UC-PBG substrate has over 9.2% wider impedance bandwidth than the same antenna etched on a ground... more UC-PBG substrate has over 9.2% wider impedance bandwidth than the same antenna etched on a grounded dielectric slab with same the same characteristics, due to in-phase reflection phase of UC-PBG structure. Compared with the reference antenna at 7.2 GHz, the back lobe is reduced by 7.86 dB in E plane and 7.68 dB in H plane. Cross-polarization level remains below -10 dB in both E and H planes.
This article presents a very compact coplanar waveguidefed planar monopole antenna for ultrawideb... more This article presents a very compact coplanar waveguidefed planar monopole antenna for ultrawideband (UWB) applications. The antenna consists of a palmate leaf-shaped radiator with a modified shaped ground plane on the same side of the substrate. The measured impedance bandwidth of the proposed antenna is from 3.08 to over 14 GHz with a ratio of about 4.6:1 for VSWR 2. Experimental results show that the proposed antenna has stably omnidirectional H-plane radiation patterns with low cross-polarization level and average peak gain of 3 dBi across the UWB. The antenna dimensions are restricted to 13.5 3 14.8 3 0.8 mm 3 .
The 8th European Conference on Antennas and Propagation (EuCAP 2014), 2014
In this paper, a novel reflectarray antenna based on the folded stepped impedance resonator (SIR)... more In this paper, a novel reflectarray antenna based on the folded stepped impedance resonator (SIR) patch-slot configuration with variable size is presented. For the modified parametrics, the proposed structure shows an almost linear behavior, while the phase range is in excess of 400°. Then, a prime-focus 15 × 15 element reflectarray has been designed and simulated. A high gain of 24.3 dB with half-power beamwidth of 6.7° is obtained at the designed frequency of 11.5 GHz.
Progress In Electromagnetics Research Letters, 2014
In this letter, a reflectarray antenna based on the folded stepped impedance resonator (SIR) patc... more In this letter, a reflectarray antenna based on the folded stepped impedance resonator (SIR) patch-slot configuration with variable size is presented. A novel frequency selective surface (FSS) in the reflectarray as a ground plane for reducing radar cross section (RCS) level is applied. The FSS is based on the folded SIR configuration. Two prime-focus 15×15 reflectarray antennas backed on the folded SIR FSS ground and a conventional ground are designed and manufactured. The radiation performance of a reflectarray element backed either by a solid ground plane or a band-stop FSS structure is compared. The measured results demonstrate that the radiation pattern and gain of the FSS-backed reflectarray are almost same to its counterpart backed by a conventional ground plane at the operating band of 11.5 GHz. The RCS is effectively reduced in the out of this band when compared with the reflectarray with a solid metal ground plane of the same dimension.
This paper presents a novel radiation pattern reconfigurable antenna using a central circular pat... more This paper presents a novel radiation pattern reconfigurable antenna using a central circular patch and four parasitic stub. Then by designing a DNG's structure and using it as superstratum of aforesaid antenna, we improve gain about 4 dB. The radiation pattern of the proposed antenna can changed into three modes. Changing the mode of antenna is done by four pin diode switches that are located in gaps of circular patch and parasitic stub. The antenna has been designed for operating in 3.56 GHz frequency, which is suitable for WiMAX applications.
2014 IEEE Antennas and Propagation Society International Symposium (APSURSI), 2014
This paper is reported the design of a novel Compact frequency Reconfigurable Antenna with using ... more This paper is reported the design of a novel Compact frequency Reconfigurable Antenna with using Defected Ground structure (DGS). The bandwidth of the proposed antenna is increased by using DGS. The resonances frequency of the proposed antenna can be reconfigured into four different modes. The designed antenna is able to cover the frequency band 3-22 GHz, and perform the operation of removal frequency band in different modes. Changing the mode of antenna is done by three pin diode switches that are located in ground plane.
International Journal of Microwave and Wireless Technologies, 2014
ABSTRACT In this paper, a switchable antenna with capability to operate in ultrawideband (UWB) fr... more ABSTRACT In this paper, a switchable antenna with capability to operate in ultrawideband (UWB) frequency from 3 to 10.7 GHz with two switchable notch bands of 3.3–3.7 and 3.7–4.2 GHz, is presented for cognitive radio (CR) and multiband orthogonal frequency-division multiplexing (MB-OFDM) applications. The proposed antenna has a simple structure and compact size of 17 × 24 mm2. The antenna in the UWB characteristics is obtained using a circular radiator patch with an embedded T-slot on the patch and a rectangular parasitic element that is attached to the patch. The reconfigurability is also achieved by two L-shaped parasitic elements placed in the left and right of the patch that two ideal switches is inserted over the these elements and the circular patch. The function of the antenna can be changed by tuning status of the switches that make the notch bands in application frequencies. The measurement and simulation results show that the antenna has good characteristics for CR application and MB-OFDM, where the UWB antenna is required for spectrum sensing and the switchable band rejection antenna is used for reconfigurable operation.
ABSTRACT In this study, a compact ultra-wideband (UWB) bandpass filter (BPF) with sharp roll-off,... more ABSTRACT In this study, a compact ultra-wideband (UWB) bandpass filter (BPF) with sharp roll-off, improved out-of-band performance and dual-band-notch operation is presented and its design procedure is discussed. In the proposed structure, in order to reject the unwanted harmonic pass bands, a pair of modified cross-shaped coupled lines (CCLs) is implemented along the ports of the filter. Moreover, a pair of half-circle-shaped stubs and a stepped-impedance stub are loaded on the main resonator in order to obtain additional transmission zeros (TZs) which are controllable separately. Implementation of the CCLs and the stub loaded resonator (SLR) reduce the total size of the presented microstrip BPF. Besides, by extending and folding the upper coupled line of each CCLs and also through an open stub which is protruded inside a slot on the main resonator, dual-band-notch operation is added to the performance of the presented filter. The fabricated prototype has a small size and is capable to cover frequency band of 2.8–10.69 GHz with two band-notch functions at 4.9–5.4 and 7.83–8.25 GHz which suppresses the interference between UWB spectrum with wireless local area network (WLAN) and satellite communication frequency bands, respectively. The proposed filter has a compact size while showing good return loss and insertion loss characteristic in the frequency band of interest.
In this paper, a novel planar ultrawideband bat-shaped monopole antenna with dual band rejections... more In this paper, a novel planar ultrawideband bat-shaped monopole antenna with dual band rejections is proposed. The dual band-notched functions are achieved by etching two C-shaped slots with circular-arcs on the radiation patch. A single band-notched antenna is firstly presented, and then an improved dual band-notched antenna is designed and analyzed. The effects of the width and length of the slots on the center frequency and bandwidth of the notched bands are parametrically studied. The measured results show that the monopole antenna could operate from 2.75 to 13.98 GHz with 10 dB return loss bandwidth, except two stop-bands at 3.21-4.02 and 4.99-6 GHz for rejecting the WiMAX, WLAN, and DSRC signals. The antenna shows nearly omnidirectional radiation patterns in E-plane and quasi omnidirectional radiation patterns in the H-plane.
2013 IEEE Antennas and Propagation Society International Symposium (APSURSI), 2013
A microstrip antenna with reconfigurable Dumbbellshaped defected ground plane (DGS) is designed a... more A microstrip antenna with reconfigurable Dumbbellshaped defected ground plane (DGS) is designed and simulated. In the proposed structure, in order to generate frequency diversity at 1.8GHz and 1.9GHz, a DGS with a p-i-n diode is etched on the ground plane. The simulated results by HFSS and CST softwares show the effectiveness of the proposed antenna configuration.
Abstract: the problematic reduction of civic engagement in local communities of Khuzistan provinc... more Abstract: the problematic reduction of civic engagement in local communities of Khuzistan province in the southwest of Iran has became a serious issue for research in social planning and policy making. It has occasioned an attempt to search for risk factors as deterrents to ...
This paper presents a simple and innovative method for designing and optimizing a quadrifilar hel... more This paper presents a simple and innovative method for designing and optimizing a quadrifilar helix antenna (QHA) for dual-band operation. The main feature is the use of a very simple impedance matching network at two narrow frequency bands, which makes the optimization simpler. This antenna may be implemented on a low Earth orbit (LEO) small satellite operative in the UHF band.
UC-PBG substrate has over 9.2% wider impedance bandwidth than the same antenna etched on a ground... more UC-PBG substrate has over 9.2% wider impedance bandwidth than the same antenna etched on a grounded dielectric slab with same the same characteristics, due to in-phase reflection phase of UC-PBG structure. Compared with the reference antenna at 7.2 GHz, the back lobe is reduced by 7.86 dB in E plane and 7.68 dB in H plane. Cross-polarization level remains below -10 dB in both E and H planes.
This article presents a very compact coplanar waveguidefed planar monopole antenna for ultrawideb... more This article presents a very compact coplanar waveguidefed planar monopole antenna for ultrawideband (UWB) applications. The antenna consists of a palmate leaf-shaped radiator with a modified shaped ground plane on the same side of the substrate. The measured impedance bandwidth of the proposed antenna is from 3.08 to over 14 GHz with a ratio of about 4.6:1 for VSWR 2. Experimental results show that the proposed antenna has stably omnidirectional H-plane radiation patterns with low cross-polarization level and average peak gain of 3 dBi across the UWB. The antenna dimensions are restricted to 13.5 3 14.8 3 0.8 mm 3 .
The 8th European Conference on Antennas and Propagation (EuCAP 2014), 2014
In this paper, a novel reflectarray antenna based on the folded stepped impedance resonator (SIR)... more In this paper, a novel reflectarray antenna based on the folded stepped impedance resonator (SIR) patch-slot configuration with variable size is presented. For the modified parametrics, the proposed structure shows an almost linear behavior, while the phase range is in excess of 400°. Then, a prime-focus 15 × 15 element reflectarray has been designed and simulated. A high gain of 24.3 dB with half-power beamwidth of 6.7° is obtained at the designed frequency of 11.5 GHz.
Progress In Electromagnetics Research Letters, 2014
In this letter, a reflectarray antenna based on the folded stepped impedance resonator (SIR) patc... more In this letter, a reflectarray antenna based on the folded stepped impedance resonator (SIR) patch-slot configuration with variable size is presented. A novel frequency selective surface (FSS) in the reflectarray as a ground plane for reducing radar cross section (RCS) level is applied. The FSS is based on the folded SIR configuration. Two prime-focus 15×15 reflectarray antennas backed on the folded SIR FSS ground and a conventional ground are designed and manufactured. The radiation performance of a reflectarray element backed either by a solid ground plane or a band-stop FSS structure is compared. The measured results demonstrate that the radiation pattern and gain of the FSS-backed reflectarray are almost same to its counterpart backed by a conventional ground plane at the operating band of 11.5 GHz. The RCS is effectively reduced in the out of this band when compared with the reflectarray with a solid metal ground plane of the same dimension.
This paper presents a novel radiation pattern reconfigurable antenna using a central circular pat... more This paper presents a novel radiation pattern reconfigurable antenna using a central circular patch and four parasitic stub. Then by designing a DNG's structure and using it as superstratum of aforesaid antenna, we improve gain about 4 dB. The radiation pattern of the proposed antenna can changed into three modes. Changing the mode of antenna is done by four pin diode switches that are located in gaps of circular patch and parasitic stub. The antenna has been designed for operating in 3.56 GHz frequency, which is suitable for WiMAX applications.
2014 IEEE Antennas and Propagation Society International Symposium (APSURSI), 2014
This paper is reported the design of a novel Compact frequency Reconfigurable Antenna with using ... more This paper is reported the design of a novel Compact frequency Reconfigurable Antenna with using Defected Ground structure (DGS). The bandwidth of the proposed antenna is increased by using DGS. The resonances frequency of the proposed antenna can be reconfigured into four different modes. The designed antenna is able to cover the frequency band 3-22 GHz, and perform the operation of removal frequency band in different modes. Changing the mode of antenna is done by three pin diode switches that are located in ground plane.
International Journal of Microwave and Wireless Technologies, 2014
ABSTRACT In this paper, a switchable antenna with capability to operate in ultrawideband (UWB) fr... more ABSTRACT In this paper, a switchable antenna with capability to operate in ultrawideband (UWB) frequency from 3 to 10.7 GHz with two switchable notch bands of 3.3–3.7 and 3.7–4.2 GHz, is presented for cognitive radio (CR) and multiband orthogonal frequency-division multiplexing (MB-OFDM) applications. The proposed antenna has a simple structure and compact size of 17 × 24 mm2. The antenna in the UWB characteristics is obtained using a circular radiator patch with an embedded T-slot on the patch and a rectangular parasitic element that is attached to the patch. The reconfigurability is also achieved by two L-shaped parasitic elements placed in the left and right of the patch that two ideal switches is inserted over the these elements and the circular patch. The function of the antenna can be changed by tuning status of the switches that make the notch bands in application frequencies. The measurement and simulation results show that the antenna has good characteristics for CR application and MB-OFDM, where the UWB antenna is required for spectrum sensing and the switchable band rejection antenna is used for reconfigurable operation.
ABSTRACT In this study, a compact ultra-wideband (UWB) bandpass filter (BPF) with sharp roll-off,... more ABSTRACT In this study, a compact ultra-wideband (UWB) bandpass filter (BPF) with sharp roll-off, improved out-of-band performance and dual-band-notch operation is presented and its design procedure is discussed. In the proposed structure, in order to reject the unwanted harmonic pass bands, a pair of modified cross-shaped coupled lines (CCLs) is implemented along the ports of the filter. Moreover, a pair of half-circle-shaped stubs and a stepped-impedance stub are loaded on the main resonator in order to obtain additional transmission zeros (TZs) which are controllable separately. Implementation of the CCLs and the stub loaded resonator (SLR) reduce the total size of the presented microstrip BPF. Besides, by extending and folding the upper coupled line of each CCLs and also through an open stub which is protruded inside a slot on the main resonator, dual-band-notch operation is added to the performance of the presented filter. The fabricated prototype has a small size and is capable to cover frequency band of 2.8–10.69 GHz with two band-notch functions at 4.9–5.4 and 7.83–8.25 GHz which suppresses the interference between UWB spectrum with wireless local area network (WLAN) and satellite communication frequency bands, respectively. The proposed filter has a compact size while showing good return loss and insertion loss characteristic in the frequency band of interest.
In this paper, a novel planar ultrawideband bat-shaped monopole antenna with dual band rejections... more In this paper, a novel planar ultrawideband bat-shaped monopole antenna with dual band rejections is proposed. The dual band-notched functions are achieved by etching two C-shaped slots with circular-arcs on the radiation patch. A single band-notched antenna is firstly presented, and then an improved dual band-notched antenna is designed and analyzed. The effects of the width and length of the slots on the center frequency and bandwidth of the notched bands are parametrically studied. The measured results show that the monopole antenna could operate from 2.75 to 13.98 GHz with 10 dB return loss bandwidth, except two stop-bands at 3.21-4.02 and 4.99-6 GHz for rejecting the WiMAX, WLAN, and DSRC signals. The antenna shows nearly omnidirectional radiation patterns in E-plane and quasi omnidirectional radiation patterns in the H-plane.
2013 IEEE Antennas and Propagation Society International Symposium (APSURSI), 2013
A microstrip antenna with reconfigurable Dumbbellshaped defected ground plane (DGS) is designed a... more A microstrip antenna with reconfigurable Dumbbellshaped defected ground plane (DGS) is designed and simulated. In the proposed structure, in order to generate frequency diversity at 1.8GHz and 1.9GHz, a DGS with a p-i-n diode is etched on the ground plane. The simulated results by HFSS and CST softwares show the effectiveness of the proposed antenna configuration.
Abstract: the problematic reduction of civic engagement in local communities of Khuzistan provinc... more Abstract: the problematic reduction of civic engagement in local communities of Khuzistan province in the southwest of Iran has became a serious issue for research in social planning and policy making. It has occasioned an attempt to search for risk factors as deterrents to ...
This paper presents a simple and innovative method for designing and optimizing a quadrifilar hel... more This paper presents a simple and innovative method for designing and optimizing a quadrifilar helix antenna (QHA) for dual-band operation. The main feature is the use of a very simple impedance matching network at two narrow frequency bands, which makes the optimization simpler. This antenna may be implemented on a low Earth orbit (LEO) small satellite operative in the UHF band.
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Papers by P. Rezaei