In the present study, ultra‐wide band antenna attachable on unmanned aerial vehicle (UAV) surfaces usable as signal detection antenna in various bands was designed, and the practicality of the developed antenna was verified by attaching the antenna to a UAV and measuring the performance. The antenna suggested in this article was manufactured by forming a hemispheric conductor having the shape of a baseball seam on the ground and satisfying a self‐complementary through an image theory. This Hemispheric shape can reduce a drag and risk of breakage. The diameter of the antenna is 400 mm (0.4λL and λL is 0.3 GHz.), the height is 200 mm (0.2λL), and the ground size is 800 mm (0.8λL) × 800 mm (0.8λL). The designed antenna showed an ultra‐wide band property as it was matched to a band from 300 MHz to 10 GHz. After being attached to the bottom of a 7.3:1 scale UAV, the antenna showed matching properties from 1.85 to 10 GHz above and maintained a monopole pattern in all directions and in a bandwidth. To author's knowledge, the antenna was proper to using as a signal detection antenna which need wide bandwidth, conical pattern, drag reduction and reduced risk of breakage.

In this study, the structure of a circular four-array antenna was designed for a monopulse radar attached to a conical small missile warhead with a diameter of 29 mm and a lateral length of 63 mm. A printed monopole Yagi-Uda antenna was adopted as the basic model for the antenna to decrease production cost and reduce weight. The director structure of the printed monopole Yagi-Uda antenna that we proposed was modified to λ/2 to improve the beam direction. Unlike the existing structure, the proposed director was made to be separated from the ground, so that it could act as a director. The antenna was expanded to a four-array structure for the detection of vertical and horizontal planes. As a result of the design, the S₁₁ had excellent matching characteristics at the center frequency of 9.375 GHz, and the beam pattern also had directivity in the same direction as the missile travel direction. In the case of gain, it showed more than 6 dBi performance. Finally, the proposed four-array structure antenna was fabricated to verify that the S₁₁ and radiation patterns were maintained.

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