Hany A. Atallah

Design of dual band-notched CPW-fed UWB planar monopole antenna using microstrip resonators

In this letter, a new coplanar waveguide (CPW) fed ultra-wideband (UWB) planar monopole antenna with dual band-reject characteristics is proposed. Two resonators of different lengths are employed at the bottom layer to create two notches at the frequency of interest. The proposed fabricated antenna works from 2.8 to 11.34 GHz with two notched bands which cover the WLAN (5.725– 5.825GHz) and ITU (8.025–8.4 GHz) bands. The proposed antenna is fabricated and measured for verification purposes. Good agreement between the measurement and simulation is found.

Radiation pattern improvement of RDRA using LHM flat lens composed of CSRR

In this paper, the performance of a rectangular dielectric resonator antenna (RDRA) is improved using CSRRs-based MTM flat lens. A RDRA as a multilayer EM structure is fed by a coaxial probe and is integrated with the LHM flat lens, which is placed above the dielectric resonator. Based on the negative refractive index of the LHM flat lens, the radiated electromagnetic beam is focused, and the beam area is reduced and hence the radiation efficiency increases and great improvement in the gain and the directivity is observed. To optimize the radiation properties of the proposed antenna, a parametric analysis using finite element-based electromagnetic simulator was carried out. A CSRRs-based LHM flat lens with NRI in a specific frequency band matched with the original RDRA bandwidth is designed and optimized. To validate the concept, the RDRA is integrated with the MTM flat lens composed of CSRR 2-D periodic structure and then intensive EM simulations has been done for optimization purpose. The simulation results showed a significant enhancement in the radiation properties such as gain and directivity by about 4 dB.

Tunable Band-Notched CPW-Fed UWB Monopole Antenna Using Capacitively Loaded Microstrip Resonator for Cognitive Radio Applications

In this paper, a new compact coplanar waveguide (CPW) ultrawideband (UWB) antenna with an electronically tunable notched band is proposed for an overlay onto cognitive radio (CR) systems. The proposed antenna utilized a rectangular microstrip resonator in the bottom layer to create a single notched band and to realize tunability and miniaturization using varactors. The center frequency of the notched band can be electronically tuned by changing the effective electrical length of the microstrip resonator, which is achieved by employing two varactor diodes at the resonator edges. Moreover, the simple biasing of the varactor diodes has a small effect on the antenna performance. Experimental results show that the proposed antenna can selectively have a band notch over a continuous operating band about 1.44 GHz from 4.77 to 6.21 GHz to prevent the interference to the primary users that are operating in this band such as the WLAN (5.15-5.35 GHz; 5.725-5.825 GHz) and the WiMAX (5.25- 5.825 GHz). Good agreement is found between the simulated and the measured data.

Novel compact UWB monopole RDRA for cognitive radio spectrum sensing applications

In this paper, a novel compact UWB, low-profile monopole rectangular dielectric resonator antenna (RDRA) is proposed using relatively low dielectric constant substrate material (Rogers RT/Duroid 3010 εr = 10.2) and developed for cognitive radio (CR) spectrum sensing wireless communications applications. The rectangular DRA is fed with a modified stepped microstrip feed to ensure efficient coupling between the RDR and the feeder. UWB operation is achieved by converting RDRA to monopole RDRA by finite ground plane which leads to a wider operating bandwidth. The proposed UWB monopole RDRA with finite ground plane produced an impedance bandwidth about 141 % covering a huge band for CR spectrum sensing. The proposed antenna is designed to operate over a frequency range from 3.1 to 18 GHz and the radiation patterns are stable over the operating frequency range. The frequency characteristics and radiation performance of the proposed antenna are successfully optimized with numerical experimentation techniques using 3D full-wave electromagnetic simulator Ansoft HFSS. Moreover, the proposed design is implemented using three dimensional finite difference time domain (FDTD) method for verification purposes. The obtained FDTD and simulation results are in good agreement.

Compact wideband low permittivity RDR antenna using double parasitic metallic strips for Ku-band applications

In this paper, a compact broadband, low-profile rectangular dielectric resonator antenna (RDRA) is presented using relatively low dielectric constant material. The rectangular DRA is fed with a modified stepped microstrip feed to ensure efficient coupling between the RDR and the feeder. The performance of the proposed antenna has been significantly improved by loading the RDR with two narrow conducting metallic strips of suitable widths, which results in dual-resonance excitation and leads to a wider operating bandwidth (up to 24 %). Parametric investigations of some geometrical variables have been carried out. The frequency characteristics and radiation performance of the proposed antenna are successfully optimized and experimentally verified. Measurements and simulation results are in excellent agreement.

Design of frequency tunable CPW-Fed UWB antenna using varactor diodes for cognitive radio and future software defined radio

In this paper, a novel compact coplanar waveguide (CPW) ultra-wideband (UWB) antenna with an electronically reconfigurable band is developed for interweave cognitive radio (CR) system and future software defined radio (SDR). The center frequency of the tunable band can be electronically altered by adjusting the electrical length of the microstrip resonator at the bottom layer, which is accomplished by incorporating two varactor diodes at the resonator edges. Simulation results show that the proposed design is capable of tuning over a continuous wide operating band of 1.15 GHz covering a wide band for interweave CR communication from 4.54 to 5.69 GHz. Furthermore, the radiation patterns are steady over the interesting frequency bands. The proposed antenna is fabricated and measured at a fixed capacitance for verification purposes. Good agreement is found between the simulated and the measured results.

Compact frequency tunable filtenna with wide continuous tuning range using capacitively loaded folded arms open loop resonator for interweave cognitive radio applications

In this paper, a compact microstrip planar monopole antenna with a wide tunable frequency band is proposed and developed for interweave cognitive radio (CR) communication applications. Tunability is achieved by integrating a tunable folded arms open loop resonator bandpass filter with an ultra-widband (UWB) microstrip monopole antenna. The technique depends on centrally loading the folded arms open loop resonator with a single lumped varactor diode, decreasing the varactor capacitance results in increasing the miniaturized even resonant mode of the folded arms open loop resonator while keeping the odd-mode fixed. The filter-antenna is adaptable and compact in terms of the availability of several tunable bands. Moreover, the simple biasing of the varactor diode does not have a significant effect on the filtenna performance. Simulation results show that the proposed design is capable of tuning over a continuous wide operating band of 3.18 GHz covering a large band for interweave CR communication with a 52 % frequency tuning range from 4.6 to 7.8 GHz. Furthermore, the normalized radiation patterns are steady over the operating frequency bands. The frequency parameters and radiation patterns of the proposed filter-antenna are successfully optimized with numerical experimentation approaches using 3D full-wave electromagnetic simulator.

New compact tunable filter-antenna using varactor loaded ring resonator for cognitive radio front end system

In this paper, a novel compact filter-antenna with tunable frequency band is proposed and developed for interweave cognitive radio (CR) system. The antenna is fed by a microstrip line integrated with a ring resonator bandpass filter. Reconfiguration is achieved by centrally loading the ring resonator with only a single varactor diode. Furthermore, the simple biasing of the varactor diode has a small effect on the filter-antenna performance. The proposed design is fabricated and measured for verification purposes. Experimental results show that the proposed filter-antenna is capable of tuning over a wide operating band of 1.43 GHz covering continuous bands for interweave CR from 4.65 to 6.08 GHz. Moreover, the radiation patterns are stable over the operating frequency range. Good agreement is found between simulated and measured results.

Reconfigurable Band-Notched Slot Antenna Using Short Circuited Quarter Wavelength Microstrip Resonators

Abstract—In this paper, a CPW feed ultrawideband (UWB) slot antenna with a single reconfigurable notched band is proposed for overlay cognitive radio (CR) systems. The proposed antenna utilizes two symmetrical short circuited quarter wavelength resonators at the top layer and close to the ground to create a single notch. The switching reconfiguration is achieved by changing the length of resonators to prevent the interference to the primary users that are operating in the wireless local area network (WLAN) band at 5.725–5.825 GHz and the international telecommunication union (ITU) band at 8.05– 8.4 GHz. The center frequency of the notched band can be tuned by selecting the length of the resonators, which is achieved by employing two ideal switches. Moreover, the proposed antenna has been fabricated and tested. The experimental data confirmed that the proposed design can selectively have a band notch over the two existent desired bands.

Design of miniaturized reconfigurable slot antenna using varactor diodes for cognitive radio systems

In this paper, a new compact tunable microstrip-line fed slot antenna is proposed for interweave cognitive radio (CR) front end systems. The proposed antenna utilized four varactor diodes to control the antenna resonant frequency. The resonant frequency of the antenna can be electronically tuned by changing the effective electrical length of the resonant slot, which is accomplished by employing the varactor diodes inside the slot. Moreover, the simple biasing of the varactor diodes has a small effect on the antenna performance. Simulation results show that the proposed antenna is capable of frequency switching over a tuning range of 0.93 GHz from 1.83 to 2.76 GHz with 40.5 % frequency tuning range. The proposed antenna has a miniaturized size of 25 × 30 × 0.762 mm3.