Image data provided by the real-time processing tool chain were transmitted to a ground control station 80 km away. In this research, the authors showed that the redundancy optimized image data enable seamless real-time mapping of the recorded area at an average data link rate of about 1-10 Mbit/s. Satellite images acquired on the day of the mission are generally not available to rescuers. Therefore, the use of fixed-wing drones, due to their longer autonomy and higher cruising speed compared to rotary wing copters, could be a solution for land surveying and searching for lost or injured persons. The goal of providing reliable throughput for transfer of high-resolution images from UAV to GS can be tackled from two perspectives: hardware and software. Hardware perspective comprises improvements in datalinks and antenna systems while software mostly focuses on image compression algorithms. Compact multi-frequency antennas have received substantial attention in recent years [17; 18]. They offer the additional benefit of being easily mounted on a small UAV. Wavelet-based antenna systems as well as fractal antennas show promise of providing the small antennas and unifying design, analysis, and optimization. Recent progress in the study of fractal antennas [19; 20; 21] suggests some attractive solutions for using a single small antenna operating in several frequency bands. Fractal-wavelet modelling has prominent application in image compression which allow significant reductions in amount of data that must be transmitted from UAV [22; 23; 24; 25; 26; 27]. Different flight plans can be adopted depending on the search area (Figure 2). An actual search mission usually starts from the IPP and then spreads outwards towards the defined statistical limits (based on the ISRID database information). Because of this fact, in addition to standard flight plans, a circular flight plan has been proposed. Standard handbooks for rescuers [2] use statistical search areas with up to a 5-km radius (distance from the IPP), although that distance may be shorter. Figure 2: Different flight plan solutions. Standard path—**left**. Circular path—**right**. A comparison of the two paths is given in Table 1. An approximate estimation of the UAV flight length (only 2D) for a circular flight plan is given in Equation (1):  
\[S\ =\ D\cdot\sum_{i\ =\ 0}^{n-1}[1+2\cdot\pi(1+i)] \tag{1}\]  
where \(D\) is the difference between two successive trajectory radii (Figure 2) and n is the number of circles around the IPP (\(n=(R\ -\ D/2)/D\)). In the case of steep terrain, UAV flight altitudes might change during the mission, so flight length calculation is more complicated [28]. Depending on the available camera sensor resolution, flight altitude and the UAV velocity, the time needed to acquire images of the area of interest can be calculated. This aspect is not the focus of the current paper, but for the desired resolution (-5 cm/pixel) and flight altitude (-200 m), the flight time needed to survey a search area can take a few hours (around 200 min for a 3.8-km search radius from the IPP for v = 20 m/s). Since time is a critical factor for a search and rescue mission, the real-time transfer of images acquired from the UAV to the ground station (GS) is necessary. The acquired images can then be used to update maps (Figure 3) with Structure from Motion software, such as Agisoft [29], Pix4D [30] and ArcGIS Drone2 Map [31] (or other approaches to 2D image stitching), and imported into the GIS as a new layer [32].