## 1 Introduction  
The application scenario of antennas becomes more and more diverse in form with the continuous development of mobile communication technology, which brings new requirements and challenges to antenna designs in terms of appearance and performance. In terms of performance, antennas are required to have large bandwidth, high gain, easy integration and other characteristics. In 2020, a wideband circular cavity-backed slot antenna with conical radiation patterns was shown to have a \(-10\) dB impedance bandwidth of 16.35%, extending from 9.26 to 11.02 GHz with flat gain and conical radiation characteristics [1]. In addition, there are some other meaningful studies about antenna analysis and designs [2; 3; 4]. For instance, a substrate integrated waveguide planar cavity slotted antenna array was realized, and it can be excited in TE33 higher mode, which operates at X-band (10.4-10.8 GHz). This antenna array has the features of low cost and easy integration [3]. In addition to the performance of today's antennas with a variety of features, there are also new requirements in terms of appearance. In the fields of aerospace, satellite communication, vehicle radar, etc., glass dielectric substrate-based antennas are becoming increasingly important, as it can be integrated in buildings, cars and other scenes where glass exists. Moreover, glass dielectric substrates were frequently employed as parts of the structure in human-machine interaction (HMI) systems, and the most common one is touch screen applications [5; 6]. There is no doubt that the realization of communication devices (such as antennas) on glass substrates would endow these HMI systems with more functions and potentials. One of the early attempts at using glass dielectric substrate for antenna designs was reported by scientists at the National Aeronautics and Space Administration (NASA) in 1997, and they initially verified the realizability of glass antennas in an experiment [7]. With the continuous advancement of research on glass antennas, the methods of implementing metallization on glass substrates are becoming more diverse, such as nano carbon, transparent conductive oxides, metallic nanostructures, etc. [8]. In previous studies on nano carbon based antennas, [PERSON] et al. implemented a 2.4 GHz glass antenna for wireless local area network (WLAN) applications using onion-like carbon (OLC) and multi wall carbon nanotubes (MWCNT) [9]. Transparent conductive oxides (TCO) are another popular method for the realization of glass antennas, and it has been widely used in the industrial sector. Based on the used TCO structure, TCO based glass antennas can be classified as mono-layer and multilayer. In 2017, a series of glass antennas working at 28 GHz was implemented by applying four types of mono-layer TCOs, which include indium tin oxide (ITO), fluorine-doped tin oxide (FTO) and silver-coated polyester films (AgHT-4, AgHT-8) [10], respectively. These antennas can be employed on solar panels for the field of satellite communication. In a different example, multilayer TCO material was demonstrated for the use of optically transparent antenna [11]. The proposed 2.45 GHz antenna was fabricated with IZTO/Ag/IZTO multi-layer thin films, and the performance of this antenna was compared with that of antennas making a metal grid, showing acceptable characteristics [11]. Metallic nanostructure is considered as another effective technology for accomplishing glass antennas. Metallic nanostructure can be mainly divided into three forms, which are nanowire, ultra-thin metal films and patterned metal grid [8]. In 2017, a research group at Leibniz University of Hannover has successfully fabricated a glass antenna operating at 24 GHz and 61 GHz with the help of silver nanowire (AgNW) on a glass substrate [12].