![]() It can be argued that the bi-conical antenna positioning and proximity means it is not behaving as an antenna as is commonly understood (no longer a doughnut shaped radiation pattern, etc), and therefore can simply be regarded as an arrangement of vertical conducting rods, unevenly loaded, and unevenly illuminated. We shall regard these as supporting components only, and concentrate on the parts to the right of the dotted line. Auxiliary components such as LISNs and representative loads required by the test are shown to the left of the dotted line. This will be referred to as the Field Emanating Structure (FEF). The figures show the 2m long EUT cable harness (in yellow) held 5cm above the copper sheet by insulated pillars. Simplified schematic showing renamed parts.Ī much simplified layout of the test set-up highlighting the cable harness/copper sheet arrangement is shown in Figures 1(a) and 1(b). We start by renaming the parts of interest. Also, to allow the exercise to fit within an article of reasonable length, we will 1) limit the review to the transmitter and receiver parts of the test system, and 2) frame the review with rules and assumptions. To make for an open mind generally, and in an effort to discourage the surfacing of long-held reader prejudices, we shall name parts by their function. E-field sensor close to fixture and chamber floor. After the examination it then suggests possible improvements, particularly as regards symmetry of field emanation and thereby symmetry of antenna illumination. In the guise of a design review 1, this article examines the working of the harness/antenna pair design. Simplified field emanating fixture seen from front. Simplified field emanating fixture seen from above.įrom a cold, dispassionate RF engineering perspective, the automotive radiated test set-up is a strange looking transmit/receive arrangement, with the cable harness of the equipment under test (EUT) suspended above a large copper sheet acting as the transmitter, and a huge antenna close to the chamber floor, and partly in the shadow of the copper sheet, acting as the receiver.
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