Saeid Karamzadeh

Compact and Broadband 4

A novel two-layer 4 × 4 Butler matrix by feeding substrate integrated waveguide is designed and realized. The proposed Butler matrix has broadband operation frequency range of over 8.5 to 10.6 GHz with excellent phase and amplitude performance. The proposed design in this letter prevents the loss of amplitude and phase shifts in Butler matrix and decreases amplitude imbalance to less than 0.6 dB. This is achieved by reducing the size of Butler matrix and avoiding the use of a line length which causes a phase shift.

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Wireless technology can eliminate dense wire ropes from hospitals and far access to medical devices. The bandwidth scarcity is the biggest issue in this technology. In order to overcome this issue, cognitive radio driven hospitals are introduced and devices are divided in two categories. Primary devices are the ones with very high priority and their communication is vital for the patients and hospital, so that no interference should be made with such devices. Secondary devices are the ones which has lower priority and they can wait until the primary devices finish their communication and then, they begin to use the allocated spectrum. One of the key functions to assure that there will be no interference is a reliable spectrum sensing method. This method should be a simple one to be able to implement it in the secondary devices. Among all the sensing methods, energy detection based spectrum sensing is the most popular and easy to implement one. Memory based energy detection method is a new algorithm that we introduce in this paper by using memory sticks to improve the energy detection sensing method without making the sensing procedure more complex by only the cost of delay in secondary devices communication.

4 SIW Butler Matrix With Phase and Magnitude Error Reduction

By attention to price of microwave components and need to use of them in many applications, the creation of an integrated component which can incorporate the performances of several components in one structure is a necessity. Therefore, in this paper a novel symmetric six-ports multifunctional microwave component is designed and realized. The proposed component consists of two modified half mode substrates integrated waveguide couplers which are joined and a slot which is attained from joined two mentioned couplers. Despite the slot prevents the exciting of higher order modes in proposed component, it divides signal in two parts by exciting middle SIW ports. By exciting each of the ports as input, the component can act as an equal and an unequal 90-degree couplers or power dividers. The proposed component with mentioned conditions covers 23.5% frequency bandwidth with maximum magnitude and phase error of ±0.7 dB and ±0.63 degree, respectively.

Memory based energy detection spectrum sensing method in cognitive radio driven hospitals

Cognitive radio is the key technology to overcome the lack of available spectrum in the world that the demand for it is rapidly increasing while people use more wireless services and need higher speeds. One of the key functions of cognitive radio is to ensure that there will be no interference between the primary users and secondary ones by detecting the transmission channel occupation reliably. Because of low computational complexity, energy detection-based (ED) spectrum sensing is very popular. Double threshold energy detection-based (DTED) spectrum sensing is introduced to increase the reliability of normal ED method. In this paper, the performance of DTED spectrum sensing method with the parameters effecting in low SNRs over Nakagami-m fading channels with and without noise uncertainty will be analyzed.

A NEW MULTI-FUNCTIONAL HALF MODE SUBSTRATE INTEGRATED WAVEGUIDE SIX-PORT MICROWAVE COMPONENT

A compact CPW-fed printed monopole slot antenna is presented for ultra-wideband (UWB) applications. The antenna comprises of a dome-shaped radiating element in which embedded is an open-loop inverted triangular-shaped slot (TSS). The antenna is fed through a coplanar waveguide to provide an ultra-wide impedance bandwidth of 8.95 GHz (2.58–11.53 GHz) which corresponds to a bandwidth ratio of 1:4.46 for VSWR <2. The antenna possesses a notch band functionality to filter out interfering C-band signals like wireless local-area network (WLAN). The notch band frequency is determined by physical parameters defining the TSS that allows fine control of the notchs location. The proposed antenna also possesses a flat gain response expect at the notched band and occupies a relatively small volume of 25 × 25 × 0.8 mm3 for ease of system integration.

Performance analysis of double threshold energy detection-based spectrum sensing in low SNRs over Nakagami-m fading channels with noise uncertainty

ABSTRACT A novel symmetric two layer six ports multi-functional microwave component was designed and presented in the present study. The proposed component consists of two 90-degree broadband double layer substrate integrated waveguide couplers and two T-shape power dividers. By exciting each port, the component could act as a −6 dB equal power divider, an unequal −3/−6 dB 90-degree coupler, as well as a −3 dB equal coupler. This component with mentioned conditions covers 23% frequency bandwidth with maximum magnitude and phase error of ±0.5 dB and ±0.6 degree in all bandwidths, respectively.

CPW-fed printed UWB antenna with open-loop inverted triangular-shaped slot for WLAN band filtering

Todays, Ground Penetrating Radar (GPR) System is used for civil applications such as detection of buried pipes, mine and military fields. One of the recent applications of GPR in civil and defense industry is detection of human vital signs through obstacles such as wall, rubble etc. In this study, we aim to set ultra-wideband ground penetrating radar system for detection human vital signs. For this purpose, system parameters will be designed and data acquisition will be performed successfully. For signal extraction of respiratory motion, Fast Fourier Transform will be applied on radar data.