# A Novel High-Precision Imaging Radar for Quality Inspection of Building Insulation Layers
## 5 Conclusions  
The main reason for the detachment of the insulation layer is an insufficient amount of mortar used during construction. In the insulation layer inspection standard, the proportion of the bonding area of the mortar is used to measure the sticking quality of the insulation layer. Generally, in the dot-frame sticking method, the sticking area should be no less than 40%. Traditional inspection methods either cannot penetrate the external medium to detect the internal structure of the mortar or have insufficient resolution to distinguish the internal structure of the mortar. Generally speaking, traditional methods are unable to provide reliable data for the quantitative evaluation of the sticking area.  
To address this issue, a new type of high-precision imaging radar specially used for quality inspection of the external insulation system of buildings is designed by analyzing the relevant technical parameters of the bonded mortar structure determination radar of the insulation system in this paper. The radar can realize high-precision imaging of the bonded mortar structure, which provides data support for the subsequent quantitative calculation of the laying density and the area of the bonded mortar structure, which is of great significance to the quantitative detection of the bonded mortar layer.  
The ultra-wideband high-bunching antenna equipped with the radar combines the advantages of the high gain and high directionality of the lens antenna with the ultra-wideband characteristics of the sinusoidal antenna, which effectively reduces the antenna azimuth angle. In conjunction with the high-frequency radar design, the high-precision imaging radar system can penetrate through a 120 mm insulation layer for high-precision imaging. In addition, affected by the edge-diffracted waves, the imaging results of this radar are slightly larger than the actual area of the mortar. To avoid missing the situation of insufficient mortar usage, the imaging algorithm will be continuously improved in the follow-up to increase imaging accuracy.  
At present, the radar collects data by laying out multiple survey lines and then stitching the data to achieve high-precision imaging, which can intuitively obtain the distribution of bonding mortar. In the future, a multi-channel imaging radar can be designed to increase the data acquisition rate.  
Currently, the radar is carried by a wall-climbing robot, and cables are used to connect the radar system and the remote display control terminal, which greatly limits the radar's crawling range and speed. In the future, wireless connection can be considered and a more stable carrying platform can be replaced.  
Investigation, methodology, software, validation, visualization, writing--original draft, D.C.; conceptualization, project administration, Z.Z.; formal analysis, supervision, writing--review and editing, W.G.; resources, test designing, data collection, Y.Y.; investigation, validation, writing--review and editing, C.W.; antenna designing and manufacturing, S.L. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
The authors wish to thank The 22 nd Research Institute of the China Electronics Technology Group Corporation for providing the multi-channel radar system and raw data.  
**Conflicts of Interest:** Authors [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] were employed by the company The 22 nd Research Institute of the China Electronics Technology Group Corporation. The remaining author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.