Compact planar microstrip-slotline symmetrical ring eight-port comparator circuits

• Published in: IEEE transactions on microwave theory and techniques 1990-10, Vol.38 (10), p.1421-1426
• Main Author: Riblet, G.P.
• Format: Article
• Language: English
• Subjects: Applied sciences; Circuit properties; Distributed parameter circuits; Electric, optical and optoelectronic circuits; Electronics; Exact sciences and technology; Microstrip; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; Planar transmission lines; Printed circuits; Radar; Reflection; Slotline; Symmetric matrices; Transmission line matrix methods
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/22.58680

It is shown that the common eight-port comparator circuit may be constructed starting from a fully symmetrical eight-port device. The conditions for a lossless symmetrical eight-port circuit to be a symmetrical eight-port comparator are derived. These are used to design several versions of a planar ring microstrip-slotline comparator. Two experimental versions of such an eight-port circuit have been constructed using a planar microstrip-slotline technique. In the case of the second version, the ring circumference is only a wavelength at midband. This is the same circumference as the common 180 degrees magic T ring circuit, four of which are frequently used to build a conventional comparator. The bandwidth of these eight-port planar ring circuits can be as much as 30% for a return loss better than 20 dB. A quasi-optic eight-port symmetrical comparator circuit based on a single wire grid is discussed. It has no bandwidth limitation.< >