The development of copper clad laminate horn antennas for drone interferometric synthetic aperture radar

Interferometric synthetic aperture radar (InSAR) is an active remote sensing technique that typically utilises satellite data to quantify Earth surface and structural deformation. Drone InSAR should provide improved spatial-temporal data resolutions and operational flexibility. This necessitates the development of custom radar hardware for drone deployment, including antennas for the transmission and reception of microwave electromagnetic signals. We present the design, simulation, fabrication, and testing of two lightweight and inexpensive copper clad laminate (CCL)/printed circuit board (PCB) horn antennas for C-band radar deployed on the DJI Matrice 600 Pro drone. This is the first demonstration of horn antennas fabricated from CCL, and the first complete overview of antenna development for drone radar applications. The dimensions are optimised for the desired gain and centre frequency of 19 dBi and 5.4 GHz, respectively. The S11, directivity/gain, and half power beam widths (HPBW) are simulated in MATLAB, with the antennas tested in a radio frequency (RF) electromagnetic anechoic chamber using a calibrated vector network analyser (VNA) for comparison. The antennas are highly directive with gains of 15.80 and 16.25 dBi, respectively. The reduction in gain compared to the simulated value is attributed to a resonant frequency shift caused by the brass input feed increasing the electrical dimensions. The measured S11 and azimuth HPBW either meet or exceed the simulated results. A slight performance disparity between the two antennas is attributed to minor artefacts of the manufacturing and testing processes. The incorporation of the antennas into the drone payload is presented. Overall, both antennas satisfy our performance criteria and highlight the potential for CCL/PCB/FR-4 as a lightweight and inexpensive material for custom antenna production in drone radar and other antenna applications

Performance Comparison of Simple and Low Cost Metallization Techniques for 3D Printed Antennas at 10 GHz and 30 GHz

We investigate the performance of several metallization techniques for 3-D printed antennas at 10 and 30 GHz. The investigated techniques reduce the complexity and the overall cost of the metallization process. The first investigated technique is called Jet Metal Process which is a direct plating of silver ions through spray coating. The second and third techniques are through spray coating of the antennas using electromagnetic interference or radio frequency interference conductive aerosol paint consists of either copper or nickel particles. The final investigated technique is by brush painting the antennas using electrolube silver conductive paint. Simulation and measurement results show that the proposed techniques have a reasonable performance in both bands which qualifies them to be simple and low cost possible alternative of the electro-less plating for some antenna applications

Design and Evaluation of Microwave Antennas for Abdominal Fat Measurement Systems

PhDAvailability of accurate, low cost and non-invasive devices for the measurement of abdominal fat is an important factor for early diagnosis of the obesity-related diseases. To achieve this, a wideband (WB) system was developed that includes the advantages of high range resolution due to the wide bandwidth (BW 0.5 GHz) and acceptable penetration depth due to the low centre frequency (1 – 3.5 GHz). For the pulse transmission, double-ridged horn (DRH) antennas were proposed because of their wide bandwidth, high gain, and impedance matching capability. Simulation studies suggested that optimal pulse focus and minimal interference to be introduced into the system by pyramidal- and elliptical-DRH, especially when extended to locate the antenna in the far-field region. Since these shapes are complex to manufacture, 3D printing was employed to fabricate low-cost antennas with high resolution. A further improvement in system performance as well as a reduction in system size was achieved by embedding the antenna in a high dielectric material, which further reduced the reflections caused by impedance differences. Previously proposed high dielectric materials such as Barium Titanate-based ceramics and canola oil were characterised during this study and combined with different percentages of Titanium Oxide to increase their dielectric constant, while retaining good conductivity. In addition, Paraffin was preferred over oil, as it has the same dielectric properties but solidifies at room temperature. Analyses were conducted based on a three-layer dielectric tissue model mimicking human tissue thicknesses. To measure the extent of the fat layer, a parameterised WB pulse was transmitted through the tissue model and its reflections were recorded. Evaluation metrics including the reflection coefficient were employed to investigate the pulse magnitude reduction and time of arrival at the fat layer. Results indicate that the proposed system is able to measure fat thickness with the accuracy within ±1 mm