The Stellar Labs 30-2460 is a four-element Yagi with folded dipole and integral 300Ω balun. The boom length is 1.63 m (64″). The red dot marks the feedpoint.
I modeled the antenna with the AO 9.67 Antenna Optimizer. Calculated performance is for 28 analysis segments per conductor halfwave. Forward gain includes mismatch and conductor losses. F/R is the ratio of forward power to that of the worst backlobe in the rear half-plane.
Frequency Impedance SWR Mismatch Conductor Forward F/R MHz ohms Loss dB Loss dB Gain dBd dB 88 130-j94 2.58 0.94 0.01 4.47 8.33 89 146-j62 2.17 0.63 0.01 4.81 10.38 90 162-j34 1.88 0.43 0.01 4.98 12.17 91 178-j10 1.69 0.30 0.01 5.04 13.38 92 192+j13 1.57 0.22 0.01 5.05 13.94 93 205+j34 1.50 0.18 0.01 5.04 13.90 94 218+j55 1.47 0.16 0.01 5.01 13.50 95 230+j75 1.47 0.16 0.01 4.98 12.93 96 242+j96 1.51 0.18 0.01 4.95 12.32 97 256+j115 1.55 0.21 0.01 4.92 11.71 98 270+j137 1.63 0.26 0.01 4.89 11.15 99 285+j159 1.72 0.31 0.01 4.86 10.64 100 301+j181 1.81 0.38 0.01 4.83 10.16 101 319+j205 1.92 0.45 0.01 4.79 9.72 102 340+j228 2.03 0.54 0.01 4.76 9.32 103 366+j251 2.15 0.62 0.01 4.72 8.94 104 394+j274 2.27 0.71 0.01 4.68 8.61 105 426+j295 2.39 0.80 0.01 4.65 8.30 106 464+j313 2.50 0.88 0.01 4.61 8.05 107 507+j326 2.59 0.95 0.01 4.58 7.84 108 554+j329 2.67 1.00 0.01 4.58 7.71
Stellar Labs 4-Element Yagi Free Space Symmetric 98 MHz 7 6063-T832 wires, mm ab = 46 ; DE distance above boom bb = 37 ; DE distance below boom dep = 629 ; element positions d1p = 1113 d2p = 1630 r = 808 ; element half-lengths de = 705 d1 = 589 d2 = 589 1 0 -r 0 0 r 0 10 1 dep -de -bb dep de -bb 10 1 dep -de ab dep de ab 10 1 dep -de ab dep -de -bb 10 1 dep de ab dep de -bb 10 1 d1p -d1 0 d1p d1 0 10 1 d2p -d2 0 d2p d2 0 10 1 source Wire 2, center
You can improve forward gain somewhat by extending the boom and adding an element. Use one 96″ length of 6063-T5 aluminum angle. Cut a 49¾″ piece for the element. Use the remainder, doubled up side by side, to support it 22″ in front of the last director. Use the same dimensions for ⅜″ or 10 mm tubing.
Joe Comer, AD3P, in Severna Park, Maryland, modified his antenna. The modification improved reception of a favorite but weak station at the low end of the band.
George S. Martins modified this antenna in Sobral, Ceará, Brazil. He has received 600 km aircraft scatter with it.