## 2 Theoretical Background and Literature Review
### The Core of 5G Networks: Advanced Ceramic Antenna Technologies
#### 2.1.2 Advantages of 5G Ceramic Antennas and Comparison with PCB Antennas  
The advancement of 5G technology has brought to the forefront the critical role of antenna technologies in shaping the future of telecommunications. Among these, 5G ceramic antennas have emerged as a significant improvement over the traditional Printed Circuit Board (PCB) antennas, offering a range of benefits that are pivotal in the advancement of 5G networks [33, 34, 35, 36, 37, 38]. One of the primary advantages of 5G ceramic antennas lies in their compact and efficient design. These antennas are designed to support higher bandwidths and data transmission rates, which directly translates to enhanced flexibility and directivity. This improvement is crucial for expanding coverage and improving signal quality within 5G networks, aspects that are fundamental to the reliability and effectiveness of these advanced communication systems. Additionally, the use of ceramic materials in these antennas brings about an improvement in durability, making them more robust and suitable for diverse environmental conditions. This enhancement in durability not only extends the lifespan of the antennas but also contributes to increased manufacturing efficiency. The inherent characteristics of ceramic antennas, therefore, are vital in driving the progress and adoption of 5G communication technologies and are expected to become a cornerstone in future 5G network infrastructures [39,40]. A technical aspect that highlights the superiority of ceramic antennas is their physical construction and the principles governing their design. The length of a 5G antenna, denoted as \(L\), is intrinsically linked to its effective wavelength, \(\lambda_{\text{eff}}\), a relationship that is definedby specific equations in antenna design theory. The effective wavelength is influenced by various factors, including the wavelength in a vacuum (\(\lambda_{0}\)), the relative permeability (\(\mu_{\text{r}}\)), and, most importantly, the relative permittivity (\(\epsilon_{\text{r}}\)). In the realm of antenna materials, the relative permittivity is a key determinant of antenna size and performance. The physical length \(L\) of a 5G antenna is determined by Equation (1), which is half the effective wavelength \(\lambda_{\text{eff}}\). The effective wavelength \(\lambda_{\text{eff}}\) is given by Equation (2) [41; 42; 43]. \[L=\frac{\lambda_{\text{eff}}}{2} \tag{1}\]  
\[\lambda_{\text{eff}}=\frac{\lambda_{0}}{\sqrt{H\cdot\epsilon_{\text{r}}}} \tag{2}\]  
Since the permeability of conventional dielectric materials is typically unity, the length of the antenna is closely related to the permittivity. Comparing the materials used in traditional PCB antennas and the proposed ceramic antennas reveals a stark difference in their relative permittivities. PCB antennas typically have a relative permittivity of around 3.47, whereas the ceramic material proposed for 5G antennas boasts a much higher permittivity of 9.45 [44]. This higher permittivity of ceramic materials implies a significant reduction in the physical size of the antenna, by as much as 39.4%, when calculated using the fundamental antenna design equations. This reduction in size does not come at the cost of performance; in fact, ceramic antennas maintain, or even enhance, their efficiency and effectiveness. This attribute of ceramic antennas, to significantly reduce size while maintaining high performance, positions them as a highly desirable choice for 5G networks, offering an optimal balance between physical footprint and technological capability. As exemplified in Figure 1, an integrated 5G ceramic chip antenna array manifests this advantage by featuring a combination of low-band and high-band units, specifically tailored for 24.25 GHz to 29.5 GHz and 37 GHz to 40 GHz frequency ranges, respectively. These units are arranged in a 1 \(\times\) 5 configuration, culminating in a comprehensive 5G antenna system module.