Abstract
This paper proposes the design of a gain enhanced single circular patch radiator (SCPR) with a cavity-backed structure using multiple substrate integrated waveguide (SIW) feeders for monopulse systems. We derive the equations of a radiation pattern for the multi-feed SCPR and compare it with the full EM simulation results. Based on the theoretical results, the proposed SCPR with multiple feeds is designed by adding the cavity-backed structure to obtain high gain characteristics. In the feeding network, four SIW structures are designed and circularly arranged, which can reduce loss and mutual coupling. Each pair of the SIW feeders can provide sum ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Sigma$ </tex-math></inline-formula> ) and difference ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta$ </tex-math></inline-formula> ) patterns to achieve the monopulse direction finding (DF) properties in both elevation and azimuth directions. To verify the feasibility, the proposed antenna is fabricated, and the antenna characteristics are measured. The measured reflection coefficient is −14.5 dB at 5.8 GHz, and the maximum gains are 4.9 dBi and 4.8 dBi in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">zy</i> -plane. To observe the monopulse DF, the estimated direction of arrival (DOA) results are examined in both elevation and azimuth directions. In the whole estimated angle range, the estimation error is lower than 0.49, and the average error is 0.26.
Highlights
A monopulse system is one of the accurate and rapid direction finding (DF) systems for target tracking in radar and satellite technologies [1]−[5]
The results demonstrate that the proposed single circular patch radiator (SCPR) with multiple substrate integrated waveguide (SIW) feed structures is suitable for small monopulse DF applications
In this paper, the high-gain SCPR with a cavity-backed structure using multiple SIW feeders was proposed for monopulse DF applications
Summary
A monopulse system is one of the accurate and rapid direction finding (DF) systems for target tracking in radar and satellite technologies [1]−[5]. To obtain a high gain property, many studies on various radiator designs of monopulse system have been conducted by employing a horn antenna structure [11], [12], a slotted antenna structure [13]-[16], and a printed Yagi-Uda structure [17], [18]. Multiple radiators with complicated feeding structures and expensive fabrication costs are still required for the monopulse array antenna to estimate both azimuth and elevation angles. We propose a high-gain single circular patch radiator (SCPR) with a cavity-backed structure using multiple substrate integrated waveguide (SIW) feeders for monopulse direction finding (DF) applications. Based on the cavity model results, the proposed SCPR is designed with the multiple SIW feeding network to minimize the distortion of the radiation patterns [24], [25]. The results demonstrate that the proposed SCPR with multiple SIW feed structures is suitable for small monopulse DF applications
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