QEX

windshield corner post. Nonetheless, the main lobe is horizontal and in this intuitively "impossible" direction. It is obvious that things are not as simple as they appear at first glance—other parts of the car must affect the situation in some complex way. This main lobe shows a gain of over 10 dBi and the majority of the radiated power is in this single lobe.

Center of Trunk—My unenlightened thoughts—before starting this study—led me to think that the trunk was not an especially good location. After all, the main roof appears to shield the antenna from the front of the car. Not so; the main lobe is arguably the most nearly circular of the four locations studied and shows gains between 9 and 6 dBi in almost all directions. Isn't this worthy of more careful study?

Input Impedances

Table 1 shows how the input impedance of a 19.6 inch vertical whip depends on its location. The high feed-point impedances for locations at the roof edge seem to result from the glass windshield and left-front window pre-

Table 1—Feedpoint Impedances for Several Antenna Locations

Location

Center Roof Front Roof Corner Roof Center Trunk

Resistive Reactive

0 0

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