Design of triangular slot The basic structure of the proposed microstrap artificial model transmission lines (ATL) with triangular slot is illustrated in Fig. 1(a). The equivalent circuit model of designed triangular slot patch BLC as illustrate in Fig. 1(b). The circuit model consists of combination inductors and capacitors both in series and parallel. We included an inductor and capacitors for the splits for the metal strip. The overall area of the triangular slot patch was approximated to that of the low impedance line in this case. The related parameters can be expressed as follows[30]:
TATL = \(\left(\frac{L}{2}\right)^{2}\) (1)\(\frac{L}{2}\) =\(\sqrt{{2W}_{\text{TL}}L_{\text{TL}}}\ \) (2)
Where TATL, L, WTL, and LTL, the width and length of the base line were ATL and TTL, respectively. In order to miniaturise the common 3-dB BLC, we proposed a triangular slot -type artificial model transmission lines with modified slots. This ATL was an isosceles triangular slot formed by folding a stepped impedance line (SIL) into a right angle, as shown in Fig.2 (a) Sex triangular slot BLC.