Читать книгу Handbook of Microwave Component Measurements - Joel P. Dunsmore - Страница 47

The 2.92 mm connector is scaled down from the 3.5 mm connector and can be mechanically mated to both the 3.5 mm and the SMA connectors. The smaller diameter outer conductor means that its mode‐free operation extends proportionally higher, to 40 GHz, and is usable to perhaps 46 GHz. The female connector has a two‐slot collet that provides sufficient compliance to mate with the center pin of the larger 3.5 mm and SMA connectors but that makes it less suitable for precision measurements due to increased uncertainty of the contact point on the center pin radius, which now depends upon the radius of the pin that is inserted. A further point is that the metal wall of the female collet on the 2.92 connector is quite thin and prone to damage if the mating pin is not well aligned or oversize. It's not uncommon to find 2.92 female adapters missing one of the collet fingers. The 2.92 mm connector was popularized by the Anristu company (formally Wiltron), which introduced it as the K connector, and it is common to hear any 2.92 mm connectors referred to by that name.

Figure 1.25 shows some examples of 2.92 connectors. The key difference is in the diameter of the inside of the outer conductor. Figure 1.26 shows the insertion loss of a mated pair of 2.92 mm female‐to‐female adapters with a 2.92 male‐to‐male adapter, along with an example of a 3.5 mm mated adapter pair. The moding of the 3.5 mm pair is clearly seen above 30 GHz, but the connector is generally usable up to 38 GHz as the first small modes are bead modes and are able to be calibrated out as they generally don't propagate through the cable.

Figure 1.25 A 3.5 mm connector compared with 2.92 mm female (upper) and male (lower).

Figure 1.26 Performance of a mated pair, 2.92 compared with 3.5 mm.