| 摘要 |
<p>The invention relates to a passive band-pass filter constructed by means of microstrips on a dielectric substrate (4). This filter is composed of at least three microstrips (6,7,8), which are parallel to one another and one end of which is grounded (5). At least two microstrips (6,8) which are not adjacent are coupled by a coupling impedance Z (12). The distances x1, x2, x3, x4 of fixings on the microstrips of the input (10), coupling impedance Z (12) and output (11) regulate the impedances and the characteristics of the filter. A first improvement permits the narrowing of the pass band, by means of a high impedance (17) in parallel on the input (E) of the filter. A second impedance (18), in series on the input, corrects the input impedance modification. A second improvement consists in folding the filter back on itself, in order to reduce its space requirement. Continuity of the microstrip lines (6,7,8) is ensured by metallised coatings (20) on the flanks of the substrate (4), and jumper links (21) provide the channels for access to the filter and its fixing means.</p> |
