A novel spiral high impedance surface structure for size reduction

Abstract

ASE or satellite pulses. Increasing the modulation frequency makes the energy extraction more efficient-and thus leaves less energy to cause instability. Figure 4 also shows that the pulse repetition rate of the laser can be adjusted from few Hz up to 25 kHz. CONCLUSIONWe have demonstrated a high efficiency, all fiber AQ EYDF laser that uses a MZI as the Q-switch. The laser formed a narrow linewidth, stable Q-switched pulse with the peak power of 2.2 W, pulse width of 1.2 s, and 3-dB line width of ϳ0.06 nm. The pulse repetition rate of the laser can be adjusted from few Hz up to 25 kHz. In the experiment, we also found that different pump power needs different modulation frequency to generate the stable Qswitched pulses. INTRODUCTIONIn recent years, there has been growing interests in investigating electromagnetic band gap (EBG) structures, and diversified kinds of EBG structures have been suggested for the applications in the electromagnetic and antenna community [1][2][3][4][5][6][7]. Because the period of EBG lattices has to be a half-wavelength at the band-gap frequency, practical application of EBG structures usually has difficulty in accommodating its physical size, and realizing compact size for EBG structure is one of the most important issues to be solved. Recently high impedance surfaces (HIS), as a successful compact EBG structure consisted of small metal pads with grounding vias, have been exclusively investigated [5][6][7]. However, in some practical applications, such as in antenna array, the spacing of neighboring antenna element has to be less than a half wavelength of operating frequency, the Sievenpiper HIS structure is still too large to be fixed on the antenna. In this study, we proposed a novel EBG structure, which can be considered as a distorted HIS structure in spiral shape, so it is named as Spiral HIS, while it becomes extremely compact in size. DESIGNThe scheme of the novel EBG structure was inspired during the numerical process of conventional HIS using Method of Lines (MoL). For the conventional mushroom-like HIS structure, the geometry of the problem is shown in Figure 1. According to the Floquent theorem, one cell of the periodic structure is taken as calculated object, as shown in Figure 1(a). Now the cell is seen as a two-storied structure. First, the upper unilateral immitance matrix in the air region is readily obtained using MoL with periodic boundary. Second, the nether unilateral immitance matrix in the slab region can also be gained using MoL after combining PEC surface of the grounding vias at the four corners with periodic boundary at the rims. In this way, when the unilateral immitance matrices have been decided, the characteristic equation will rest with the magnetic currents distribution in the aperture of the cell, as shown in Figure 1(b).For the conventional HIS, the magnetic currents distribution is just in the cross aperture as a simple format, as shown in Figure 2(a). At this time, we found that when the magnetic currents are lengthened in a spiral shape, as s...

Optimization of Electromangnetic Band Gap Structure for Mutual Coupling Reduction in Antenna Arrays-A Comparative Study

“…In [12] MEBG is proposed and applied to improve the isolation of radiating elements in an array by suppressing the surface wave propagation. Various EBG architectures were designed [13][14][15][16][17][18][19] and applied to antenna arrays for mutual coupling reduction. In this paper, MEBG surface have been chosen as a base of designing new SEBG and PSEBG surfaces.…”

Miniature Electromagnetic Band-Gap Structure Using Spiral Ground Plane

“…Miniature EBG structures are desired for these array antennas, which have gained broad attention from EBG researchers. Most previous works are changing EBG patches such as complementary geometries, spiral shape structures, and Hilbert curve [4][5][6][7][8].…”