In a previous post the introduction to RADAR technology in embedded systems was discussed. With the key physical and technical elaborations, an Infineon’s development kit ‘Distance2Go’ was mentioned. It would be of great advantage for any interested party to carefully examine the Documentation web page. The application notes, datasheet, user manuals, source code in C, and GUI test tool can be found there and downloaded for free use. Developing this kind of technology requires well based prior knowledge on the topic.
Microwave frequency range
Without further ado, it’s time to present a new way of looking at the electrical schematic and electronic elements. This is, of course, because a microwave (MW) frequency range has some specifics regarding the behavior of electrical energy. To elaborate, in an MW frequency range, one must consider that the propagation of electoral energy is in the form of an electromagnetic wave, rather than in the form of a moving stream of electrons. If this sounds like science fiction, it is warmly advised to do some reading on the topics of electromagnetic wave propagation and transmission line theory at this point. With this new consideration in mind, it is easier to comprehend that the elements used in MW domain have a bit peculiar schematic representation.
As the name depicts, a DC block is a part of an electric circuit that makes a galvanic separation between two parts of the circuit. This is especially important for the isolation of the flow of direct current. Since the useful signal is in the MW frequency domain, an energy flow is uninterrupted. This also means that the path of information flow is uninterrupted, too. Next, there is a 2nd Harmonic filter, a dual-sided comb-looking element.
This microstrip filter provides attenuation greater than 20 dB for frequencies in a margin of about 48 GHz. Last but not the least, in this part of the MW circuit analysis, we deal with the Wilkinson power combiner. The Wilkinson power combiner combines the differential signals from the IC into single-ended ones and it is used for many RF applications. Some of its key advantages: low level of loss and its high level of isolation between the output ports, which means that the Wilkinson power divider is an excellent choice. A very cheap implementation, since the transmission line elements can be printed on the circuit board, is an additional advantage in the MW frequencies domain. This means that the only physical component required for the Wilkinson divider is a resistor, although additional board space is required. The Wilkinson power combiner is widely used in many areas and can provide excellent performance.
This is the second blog post in series about an in-depth analysis of the basic operations for the selected RADAR IC.