Procedure arrangement and sensor for testing of the H-F tightness of the junction between two adjacent parts

#The present application claims priority of EP application no. 01108668.9, filed Apr. 6, 2001, which is incorporated herein by reference.

#The invention concerns a method and structures for the testing of the electromagnetic leakage of a junction between two adjacent, electrically conductive parts, especially the cover parts of a high frequency (HF)-shielded case for the electromagnetic alternating fields. However, electronic equipment itself often generates electromagnetic waves. To ensure the electromagnetic tolerance, (EMC), the cases for the installation of electronic equipment must therefore be shielded against irradiation and emission of electromagnetic waves.

#The tightness of a case against high-frequency electromagnetic oscillation is based on the shielding effect of the metallic walls. Essentially, two physical effects are responsible for this. First, the incident waves induce high-frequency currents in the parts, which generate opposite arranged electromagnetic waves. Thereby the incident electromagnetic wave is reflected. On the other hand, the skin effect that occurs with high frequencies has the result that the currents caused by the high frequency only flow on the surface of the part facing the incoming wave. The penetration depth of the HF current decreases with increasing frequency and already remains clearly below the thickness of a common case wall at relatively low frequencies. This has the result that the electromagnetic waves hitting the surface cannot reach the inside of the case trough the metallic wall.

#The invention is explained in the following in more detail with the help of the enclosed drawings.

#FIG. 1 an arrangement for testing a junction between two plane parts, in an extremely simplified schematic diagram;

#FIG. 2 an electrical equivalent circuit diagram of the arrangement in FIG. 1;

#The drawings show the same elements with the same reference numbers.

#The schematic arrangement illustrated in FIG. 1 serves to test the HF tightness of a junction 1 between two adjacent flat parts 2a and 2b of a case for the installation of electronic equipment. HF tightness refers to the ability opaqueness of the junction to electromagnetic radiation. It is desirable to provide a junction that prevents HF signals from entering the case and/or prevents HF signal from exiting the case. A HF seal 3 of electrically highly conducting material is inserted between both parts 2a and 2b. In an embodiment, parts 2a and 2b are planar cover parts made of metal. An HF generator generates a series of electromagnetic sine-oscillations between 30 and 1,000 MHz. A first wave guide 5a sends the HF signal from HF generator 4 to junction 1. Wave guide 5a is designed as a coaxial cable and has an inner conductor 6a and an outer conductor 7a, which carry the HF signal. The first electrode 8a is electrically conductive and connected with the outer conductor 7a of the first wave guide 5a. The electrode 8a is formed flat and is positioned on the top of part 2a. That way, the HF signal generated by the HF generator is capacitively coupled in the first of the two adjacent parts 2a on the left side of the junction 1.

#The HF signal is decoupled from the second part 2b on the other side of the junction 1. A second wave guide 5b is intended for this purpose, which is also designed as a coaxial cable and which contains an inner conductor 6b and an outer conductor 7b. The outer conductor 7b of the second wave guide 5b is electrically conductive and connected with a second electrode 8b. The second electrode 8b capacitively decouples the HF signal from the second part 2b on the right side of junction 1.