High gain CPW‐fed UWB planar monopole antenna‐based compact uniplanar frequency selective surface for microwave imaging

Abstract

In this article, a novel uniplanar ultra‐wideband (UWB) stop frequency selective surface (FSS) was miniaturized to maximize the gain of a compact UWB monopole antenna for microwave imaging applications. The single‐plane FSS unit cell size was only 0.095λ × 0.095λ for a lower‐operating frequency had been introduced, which was miniaturized by combining a square‐loop with a cross‐dipole on FR4 substrate. The proposed hexagonal antenna was printed on FR4 substrate with coplanar waveguide feed, which was further backed at 21.6 mm by 3 × 3 FSS array. The unit cell was modeled with an equivalent circuit, while the measured characteristics of fabricated FSS array and the antenna prototypes were validated with the simulation outcomes. The FSS displayed transmission magnitude below −10 dB and linear reflection phase over the bandwidth of 2.6 to 11.1 GHz. The proposed antenna prototype achieved excellent gain improvement about 3.5 dBi, unidirectional radiation, and bandwidth of 3.8 to 10.6 GHz. Exceptional agreements were observed between the simulation and the measured outcomes. Hence, a new UWB baggage scanner system was developed to assess the short distance imaging of simulated small metallic objects in handbag model. The system based on the proposed antenna displayed a higher resolution image than the antenna without FSS.

A new type of compact ultra‐wideband planar fractal antenna with WLAN band rejection

“…The pulse handling capability is described by the transmission loss (|S 21 |). In the case of the proposed design, |S 21 | is seen to be below −35 dB for both configurations. The phase angle of S 21 (known as "isolation phase") shows a linear variation with frequency.…”

A compact uniplanar ultra‐wideband frequency selective surface for antenna gain improvement and ground penetrating radar application

“…The proposed FSS can be analyzed very simply and accurately from the ECM. As per the design methodology, initially a conventional square ring loop is formed along the peripheral of unit cell that can be modeled as series‐shunt LC resonator 21 . The inductance L s is created because of the metallic square ring loop and the capacitance C g is created due to the gap between the adjacent unit cells of FSS.…”

“…Owing to its diverse merits, several researches are going on now a days to design and develop application specific FSS to fulfill its applicability in various modern applications such as electromagnetic shielding, 2 polarizers, 3 absorbers, 4 RFID, 5 cloaking, 6 radomes, 7 reduction of radar cross section 8 and satellite communication 9 . One more modern use of FSS can be noted as antenna gain augmentation when it is integrated to the antenna 10‐21 . Design of wideband FSS 11‐21 finds special research attention as broadband and ultra‐wideband (UWB) antennas offer usually low gain profile 22 .…”

“…One more modern use of FSS can be noted as antenna gain augmentation when it is integrated to the antenna 10‐21 . Design of wideband FSS 11‐21 finds special research attention as broadband and ultra‐wideband (UWB) antennas offer usually low gain profile 22 . An exceptional gain enhancement of 8 to 10 dBi is realized in the frequency band of 4.5 to 6.5 GHz in Reference 10 using FSS based corner reflector.…”

“…Das and Mandal proposed UWB FSS whose unit cell contains multiple non‐symmetric rectangular patches with circular slots to offer gain augmentation of UWB antenna in a wide bandwidth of 4.7 to 14.9 GHz 20 . Abdulhasan et al proposed a compact single layered UWB FSS that offers 3.2 to 11.3 GHz bandwidth and UWB antenna gain improvement by 3.5 dBi on an average 21 . Apart from FSS, recently artificial magnetic conductor (AMC) is also considered for radiation improvement of UWB antenna.…”