Antenna Impedance Matching Using Deep Learning

We propose a deep neural network (DNN) to determine the matching circuit parameters for antenna impedance matching. The DNN determines the element values of the matching circuit without requiring a mathematical description of matching methods, and it approximates feasible solutions even for unimplementable inputs. For matching, the magnitude and phase of impedance should be known in general. In contrast, the element values of the matching circuit can be determined only using the impedance magnitude using the proposed DNN. A gamma-matching circuit consisting of a series capacitor and a parallel capacitor was applied to a conventional inverted-F antenna for impedance matching. For learning, the magnitude of input impedance S11 of the antenna was extracted according to the element values of the matching circuit. A total of 377 training samples and 66 validation samples were obtained. The DNN was then constructed considering the magnitude of impedance S11 as the input and the element values of the matching circuit as the output. During training, the loss converged as the number of epochs increased. In addition, the desired matching values for unlearned square and triangular waves were obtained during testing.

A 2.45 GHz FSS Loaded Rectifying Antenna

In this paper the development of a rectenna system has been presented for 2.45 GHz wireless power transfer application. The receiving element of the rectenna (or the antenna) has been designed to possess spurious free response at least up to 10 GHz to improve the RF-DC conversion efficiency. It was found that the gain of the antenna is not sufficient for rectenna application. Therefore, to improve the gain of the antenna, it has been loaded with an angle and polarization insensitive FSS. The FSS loaded antenna achieved 7.7 dB gain, 85% radiation efficiency, and single operating band at 2.45 GHz; which is suitable for developing a rectenna for wireless power transfer. To convert the received RF energy into DC voltage a 2.45 GHz matched rectifier circuit has been designed. L-type matching network has been used to match the complex rectifier impedance with the 50 Ω antenna impedance. 1.52 V output voltage was obtained for 7 dBm input power and 3 kΩ load. Achieved maximum efficiency is 66.13% for 1.1 mW received power. It has been shown that the FSS loading of the antenna has the capacity of drastically improve the efficiency of the rectenna system.

Impedance Matching Simulation for Microstrip Antenna on Frequency 3.4-3.7 GHz Using Double Stub

Impedance matching is an attempt to adjust the antenna impedance with the characteristic impedance of the transmission line. Impedance matching has functions to avoid reflected power from the antenna so that power cannot be received by the receiver. In this study, impedance matching was used double stub. The voltage standing wave ratio (VSWR) indicates how well the impedance matching is made. Simulation of this impedance matching will use to microstrip antenna on frequency 3.4 – 3.7 GHz. CST Studio Suite is used to simulating the antenna microstrip with double stub. Based on the result, this research shows that VSWR and return loss in single and double rectangular microstrip antenna have a better value if use impedance matching than without using impedance matching.