Browsing by Subject "Phased array antennas"

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Open Access
Design and analysis of slotted sectoral waveguide array antennas embedded in cylindrically stratified media
(IEEE, 2014-07) Kalfa, Mert; Ertürk Vakur B.
Slotted waveguide antennas are being widely used in military and commercial applications for many decades. Low cross-polarization, high power capacity, ease of fabrication in microwave bands, and the ability to form arrays make them excellent candidates for phased array antennas in radar applications. However, due to slots being highly resonant (narrow-band, high Q) radiators, their design parameters are very sensitive; hence, accurate design and analysis methods are required for a successful antenna design. Moreover, slotted waveguide array antennas are low-profile structures, which makes them suitable candidates for conformal and structure-integrated applications. Conformal and structure-integrated system solutions are especially required for air platforms, where aerodynamics, radar cross-section (RCS) and efficient use of real estate are of utmost importance. Although the accurate and efficient design and analysis of low-profile conformal slotted waveguide arrays are of great interest, available solution methods in the literature usually suffer in terms of efficiency and memory requirements. Among the available solution methods, one of the widely used solvers are integral equation (IE) based ones that utilize the method of moments (MoM). However, IE solvers suffer from long matrix fill times, especially for matrix entries related to the cylindrically stratified media. © 2014 IEEE.
Open Access
Phase-only beam synthesis by iterative semidefinite relaxations with rank refinement
(IEEE, 2013) Alp, Yaşar Kemal; Arıkan, Orhan; Bayri, A.
In phased array antennas, by varying the complex element weights beam patterns with desired shapes can be synthesized and/or steered to desired directions. These complex weights can be implemented by using amplitude controllers and phase shifters at the system level. Since controlling the phase of an RF signal is much easier than controlling its power, many systems do not have an individual amplitude controller for each element. Hence, beamshaping and steering are to be achieved by varying only the element phases. In this work, a new approach is proposed for phase-only beam synthesis problem. In this approach, the phase-only beam synthesis is formulated as a non-convex quadratically constrained quadratic problem (QCQP). Then, it is relaxed to a convex semidefinite problem (SDP), which generally provides an undesired high rank solution. An iterative technique is developed to obtain a rank-1 solution to the relaxed convex SDP. Conducted experiments show that, proposedmethod can successfully synthesize beam shapes with desired characteristics and steering directions by using only the element phases. © 2013 EURASIP.