Redundancy Elimination of the Classic Log-Periodic Dipole Array Antenna by Resonance Point Optimization for a Miniaturized Structure

To axially miniaturize the microstrip log-periodic dipole array (LPDA) antenna, a new design method is proposed. The proposed method redistributes the LPDA’s resonance points, meanwhile reducing the number of dipoles required for a designated bandwidth. The length of each dipole is adjusted according to the proposed design formula to redistribute the resonance points while keeping the bandwidth unaffected. The proposed design method can achieve a considerable size reduction. Two LPDAs with 19 and 15 pairs of dipoles are designed, and they both work at 1–10 GHz. They achieve an axial size reduction rate of 18% and 28%, respectively, compared with the classic LPDA. The versatility of the method is verified in a different band of 2–20 GHz, in which the proposed PRO LPDA with fewer dipoles achieves an axial size reduction rate of 44% compared with the classic LPDA. The proposed design method not only provides mathematical and physical insight into the mechanism of the LPDA but also has directive guidance for antenna engineers.