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TABLE 8: 1-X-5 ELEMENT LINEAR ARRAY a. 1-x-5 Linear Array with Amplitude Taper During a sequence of simulations, the width of each element was adjusted to reduce the sidelobe levels to acceptable limits; in this case, -20 dB. b. Conductor Current Distribution The conductor current distribution illustrates amplitude taper and near 0° phase progression. The slight difference in the excitation phase contributes asymmetry to the radiation pattern. c. 1-x-5 Array Radiation Patterns The azimuth and elevation radiation patterns exhibit a perceptible asymmetry due to minor unequal phase excitation. Ideally, the on- boresight gain would be 14 dB; however, conductor losses have modestly reduced the gain to 13.7 dB. d. 1-x-5 Array Input Impedance The input impedance at 5.8 GHz is 50 Ohms. The slight tail on the fifth element of the array provided a convenient adjustment and is at times used to improve the input impedance without a significant impact to the radiation patterns. SERIES/PARALLEL FEED FOR MICROSTRIP ARRAY ANTENNAS 24 As the final example of microstrip antenna arrays, the combination of series and parallel feed techniques will be examined. The series/parallel feed is quite common due to flexibility in the ability to provide amplitude taper and phase progression. The 1-x-5 series feed array of the previous section is repeated four times to form a 4-x-5 array with amplitude taper in azimuth, and no amplitude taper in elevation. The results are graphically summarized in Table 9. 24 The series fed array is also referred to as a traveling wave antenna. 1 0 -10 -20 -30 -40 -50 -60 -70 -80 - 9 0 -100 -110 -120 -130 -140 -150 -160 -170 180 170 160 150 140 130 120 110 100 9 0 80 70 60 50 40 30 20 10 Azimuth and Elevation Patterns Mag Max 20 dB Mag Min -30 dB 10 dB Per Div p2 p1 Mag 13.7 Ang 0 DB(|PPC_EPhi(0,1,90,2,1)|)[1] 1_x_5_SF_Array_A.$FSAMP DB(|PPC_ETheta(0,1,0,2,1)|)[1] 1_x_5_SF_Array_A.$FSAMP p1: FREQ = 5.8 GHz p2: FREQ = 5.8 GHz 0 1.0 1.0 -1.0 10.0 10.0 -10.0 5.0 5.0 -5.0 2.0 2.0 -2.0 3.0 3.0 -3.0 4.0 4.0 -4.0 0.2 0.2 -0.2 0.4 0.4 -0.4 0.6 0.6 -0.6 0.8 0.8 -0.8 Input Impedance Swp Max 5.9GHz Swp Min 5.7GHz 5.8 GHz r 0.954835 x 0.0310346 S(1,1) 1_x_5_SF_Array_A Microstrip Antenna Design 21 www.cadence.com/go/awr