A Wideband Widebeam Tapered Slot Array Antenna for Active Electronically Scanned Array Antenna

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www.seipub.org/ijc

International Journal on Communications (IJC) Volume 4, 2015 Doi: 10.14355/ijc.2015.04.002

A Wideband Widebeam Tapered Slot Array Antenna for Active Electronically Scanned Array Antenna Babu Saraswathi K.Lekshmi*1, I.Jacob Raglend2 Research scholar, Electrical and Electronics Engineering, Noorul Islam University, Tamilnadu, India

*1

Professor, Electrical and Electronics Engineering, Noorul Islam University, Tamilnadu, India

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kavitha20012@gmail.com; 2jacobraglend@rediffmail.com

*1

Abstract Phased arrays when mounted on aircraft and missiles will be capable of allowing only the desired signals to be received and simultaneously suppress all other unwanted ones incident from hostile sources. This in turn will make them invisible for the radars at the enemy base or on their aircraft. This paper discusses about the design of Phased array antenna for military airborne radar applications. A milllimeter wave active phased array antenna has been developed that is capable of wide scanning angle in both Eand H-planes. In order to achieve wide angle scanning over X-band frequency, a linear tapered slot antenna (LTSA) element has been designed and the resulting element is capable of scanning out to 60o from broadside in all scan planes for a bandwidth of 11-14GHz and an active reflection coefficient less than -10 dB. Beam scanning angles of above ±45 degrees in the E-plane and ±60 degrees in the H-plane were obtained for an isolated element. An end fire array pattern with half power beamwidth of 14 degrees in E-plane is achieved over 11-14GHz frequency. This design was implemented on linear array antenna consisting of 7-elements and planar array antenna consisting of 49 (7x7) elements. The predicted performance of the antenna was verified by simulation of element patterns, array radiation patterns and S-parameter plot using commercially available electromagnetic simulator HFSS. Since the radar antenna is intended for applications where stealth is important. The antenna aperture consists many radiating elements used for beam-forming and hence through the adjustment of elemental phases steer the beam efficiently. Moreover, they are capable of rejecting all the unwanted components of the received signals while maintaining at the same time sufficient pattern gain in the desired directions. These characteristics can be implemented for stealth applications. Keywords Radar; Stealth; Tapered Slot Antenna; Phased Array Antenna; Scan Angle; Beam Width; Radiation Pattern

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Introduction A phased array is a directive antenna made up of a number of individual antennas or radiating elements. Its radiation pattern is determined by the amplitude and phase of the current at each of its elements [Balanis]. The phased array antenna has the advantage of being able to have its beam electronically steered in angle by changing the phase of the current at each element. The beam of a large fixed phased array antenna therefore can be rapidly steered from one direction to another without the need for mechanically positioning a large and heavy antenna [Skolnik]. A typical phased array antenna for microwave radar might have several thousand individual radiating elements that allow the beam to be switched from one direction to another in several microseconds or less [Babu et al]. Phased array elements that are considered mainly as broadband elements may be suitable for wide angle scanning if the bandwidth is reduced; the tapered-slot element is such an element. The average reflected power over the scan range normalized to unit input power was a good measure to evaluate wide-angle scanning performance [Ellgardt et al]. This paper discuss about Tapered slot antennas, Doubly layered linear tapered slot antenna, Vivaldi notch elements and a design of array antenna. Tapered slot antennas has a slotline flare from a small gap (50Ω) to a large opening, matching to free space's wave impedance of 377Ω and is usually parasitically fed by a "hockey-stick" balun at the base of the element. A tapered slot antenna uses a slot line etched on a dielectric material, which is widening through its


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