Peculiarities of "delta" to "star" equivalent impedances conversion in P- and T-shaped filter structures

The peculiarities of «delta» to «star» equivalent impedances conversion are noted in p- and T-shaped filter structures. They are taken into consideration for design filters and oscillators resonators. The physical limitations are determined for structures parameters, which lead to these peculiarities. The conversion frequencies are obtained for π- and T-shaped filter structures, where «delta» to «star» equivalent impedances transformation is fulfilled.