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ANTENTOP- 03- 2003, # 004

Half-Loop Antennas


impedances at various frequencies on the Smith charts, with computed values (in full line) and measured values (in doted lines). These charts underscore the performances of a resonating cavity like a R, L, C parallel device, and confirm the impedance values computed by the method of moments.



Figure 4


Figure 5


The calculated and measured values are compared at various frequencies (FIG 6, FIG7) The bandwidth is measured at VSWR ý 2.5:1 , when the real and the imaginary terms of the impedance are equal.


Figure 6



Figure 7


The results have validated the antenna equivalent circuit.

This sheme helped to optimize the dimensions of the radiating element, considering the efficiency and bandwidth requirements. The approximative values are, from 2 to 12 MHz:

Rr = 0,5m to 3 with a 2,2m2 antenna surface

Rp= 0.01 to 0.02

C= 3500 to 60 pF

Rc= 0.05 to 2

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