Optically transparent sea‐water monopole antenna with high radiation efficiency for WLAN applications

Abstract

A high efficiency and transparent seawater monopole antenna operating at 2.4 GHz for wireless local area network (WLAN) applications is proposed in this Letter. The antenna has high transparency (>85%) achieved by using seawater as its conductive medium contained within a clear acrylic tube. To improve the radiation efficiency of the antenna, a short metal tube with a metal disk at the base was loaded into a feeding probe to achieve greater excitation. The antenna is simulated and its properties are verified through this experiment. Measurement results show a −10 dB bandwidth of 1.1 GHz (2.1-3.2 GHz) and a high radiation efficiency (>71%) over the entire WLAN band (2.4-2.5 GHz). These results demonstrate the proposed antenna as an attractive alternative to conventional metal monopoles for WLAN applications.

Liquid Antennas: Past, Present and Future

“…They are suitable for a DRA or a hybrid antenna formed by a metal antenna loaded with the liquid (mainly to increase the bandwidth and reduce the antenna size), In addition to the flexibility and reconfigurability, they offer other benefits which metallic liquid antennas do not have, such as: a) cost-effective, eco-friendly and readily accessible (hence the myriad of antennas in this category); b) compact size because the antenna size could be reduced by a factor of √ ; c) a small radar cross section (RCS) if the liquid is drained when not in operation; d) transparency -this is attractive for the application that the antenna should be invisible or not obvious. Two types of water-based liquid antennas have been investigated: saline water antennas [12,14,[50][51][52][53][54][55][56][57][58][59] and pure water antennas [15][16][17][60][61][62][63][64][65][66][67][68][69][70] which are discussed in the coming two sub-sections.…”

“…It has certainly inspired a lot of interesting research in water-based antennas. Major progresses were made in bandwidth enhancement [50,51], reconfigurability exploration [52][53][54][55][56] and radiation efficiency improvement [14,[57][58][59]. A common concern on saline water antennas is the low efficiency which is resulted from the liquid loss tangent or conductivity.…”

“…7(b). Various techniques have been reported to improve the radiation efficiency of saline water antennas by such as adding a circular disk at the top of feeding probe [57], using a conducting tube and shunt-excited feeding arm [14], employing cylindrical metal rods surrounding the feeding probe [58], and utilizing short metal tube at the base of the water holder [59]. The main idea of these designs is to add metallic element to the antenna to improve the radiation efficiency of the saline water antenna accordingly.…”

Transparent Saltwater in Glass Structure: Simultaneous Tunable UHF Antenna and EMI Shielding Window

“…Due to its great optical transparency (OT) (> 95% at a salinity level of 40 ppt), low cost, and ready availability, saltwater has recently been explored as a potential candidate for developing a new class of high-transparent antennas [8]. For transparent antennas, saltwater as the conductive part conducts electric charges in the form of ions.…”

Transparent Electromagnetic-Wave Shielding Using Liquid Saltwater

“…salinity 35 ppt)와 비교적 낮은 재료 가격, 안전성 등으로 인하여 잠재적인 액체 투명전극으로 고려되고 있다 [2] . 이 온(ion) 형태의 전하입자를 가지는 소금물은 높은 OT를 가지며, 증류수에 비해 높은 전도도를 갖는 도체로써의 역할을 하며, 이로 인한 투명 안테나 및 전자파 차폐로써 의 활용가능성이 있으며 [2] , 본 논문에서는 평면형 소금물 의 광학적, 전기적 특성을 분석하였고, 소금물의 투명 전 자파 차폐 활용 가능성을 조사하였다.…”