Title :
Uniplanar hybrid couplers using asymmetrical coplanar striplines
Author :
Heimer, Brad Ryan ; Fan, Lu ; Chang, Kai
Author_Institution :
Dept. of Electr. Eng., Texas A&M Univ., College Station, TX, USA
fDate :
12/1/1997 12:00:00 AM
Abstract :
This paper presents four new uniplanar 3-dB hybrid couplers using asymmetrical coplanar strips (ACPSs) for microwave integrated circuit (MIC) and monolithic MIC (MMIC) applications. Experimental results show that the standard (1.5 λg circumference) uniplanar 180° hybrid-ring coupler has 3.5± 0.4 dB coupling, greater than 21-dB isolation, and greater than 23.4-dB return loss over a 25% bandwidth centered at 3 GHz. The 180° reverse-phase hybrid-ring coupler (1.0 λg circumference) provides better performance as compared to conventional microstrip hybrid couplers. This circuit has a bandwidth of more than one octave from 2 to 4 GHz with ±0.4-dB power dividing imbalance and ±4° phase imbalance. The 180° reduced-size reverse-phase hybrid-ring coupler (0.8 λg circumference) maintains the performance of the 180° reverse-phase hybrid coupler with the advantage of smaller size. This circuit also has a bandwidth of more than one octave from 2 to 4 GHz with ±0.3-dB power dividing imbalance and ±3.1° phase imbalance. A new 90° 3-dB branch-line hybrid coupler is also introduced. Experimental results show the insertion loss of this component to be 0.5 dB at 3 GHz, and also greater than 15.3-dB isolation and 17.1-dB return loss over a 10% bandwidth centered at 3 GHz. The circuits were designed and simulated with Sonnet electromagnetic-circuit solver software. The measured results agree well with the simulations
Keywords :
coplanar waveguides; strip line couplers; 0.5 dB; 17.1 to 23.4 dB; 2 to 4 GHz; MMIC; Sonnet electromagnetic-circuit solver software; asymmetrical coplanar stripline; bandwidth; branch-line hybrid coupler; circuit simulation; hybrid-ring coupler; insertion loss; isolation; microwave integrated circuit; phase imbalance; power dividing imbalance; reduced-size reverse-phase hybrid-ring coupler; return loss; reverse-phase hybrid-ring coupler; uniplanar hybrid coupler; Application specific integrated circuits; Bandwidth; Circuit simulation; Couplers; Hybrid integrated circuits; MMICs; Microwave integrated circuits; Monolithic integrated circuits; Stripline; Strips;
Journal_Title :
Microwave Theory and Techniques, IEEE Transactions on