A Compact Tri-band Miniaturized Antenna with Parasitic Elements Loading

A compact tri-band miniaturized antenna with parasitic element loading is proposed for small form factor devices. Firstly, the dual-band antenna is proposed. Based on the theory of characteristic mode (TCM), the resonant of the metal loop decreases by adding three identical square monopole on the other side of the substrate. By exciting one of three square monopoles, the other two monopole treating as parasitic units, can lower the Q factor of the monopole and enhance the bandwidth of the antenna. Then, the tri-band antenna is proposed. By adding metal patches on the side of the parasitic elements, the higher order of the metal loop is excited and the new resonant point is created. With the adoption of the TCM, two degenerate modes are separated by adding metal strips on the metal loop to enhance the bandwidth of the low band. Also, the same way is carried out to decrease the electric size of the antenna and the size of the proposed structure meets the requirement of the electric small antenna. To verify the performance, the proposed antenna is fabricated and tested. The measured results are in agreement with simulated results.