Fig. 1. Structure block diagram of multi-layer perceptron and hidden neurons

Fig. 2. Adam optimizer algorithm framework flow

Fig. 3. DMLP neural network architecture

Fig. 4. Structure diagram of ultra-wideband stepped microstrip monopole antenna. (a) Front antenna; (b) back antenna

Fig. 5. HFSS simulation result of S11 characteristic curve of ultra-wideband stepped microstrip monopole antenna

Fig. 6. Flow chart of DMLP neural network

Fig. 7. Optimization process of DMLP network, RBF network, and MLP network

Fig. 8. Prediction curves of three kinds of networks and their HFSS simulation curves fitting in original data

Fig. 9. Prediction curves of three kinds of networks and their HFSS simulation curves fitting in interpolation data