A Novel Coupled Line Directional Coupler Design For L-Band Wireless Applications

Abstract

Directional couplers are commonly used in microwave circuit design. Therefore, miniaturization of these components is very important. This paper presents the miniaturized microstrip coupled line directional coupler (CLDC) for L-band wireless applications. The coupled line directional coupler presented in the article was designed and simulated. In this paper coupler line directional coupler has been proposed with a low coupling factor. The proposed CLDC operates at the L-band and it is designed for use in mostly wireless applications. High and low impedance transmission lines are used to miniaturize the CLDC. The CLDC has been designed using a substrate material of FR-4 with a dielectric constant of 4.3 and substrate thickness of 1.57 mm. The size of the designed CLDC is 33.4 x15.05 〖mm〗^2. This is 58 % less than are of the conventional coupled line directional couplers. Also, The reflection coefficient and isolation level are in the permissible level in order for the proposed CLDC to be utilized in L-band wireless applications. The coupling factor of the designed coupled line directional coupler is between 28 dB and 21 dB at the L-band. The measured return loss value is better than 19 dB. Same time the isolation value is better than 23 dB at L-band.