Stripline Hybrid Research Articles

A stripline hybrid dual‐capacitively loaded SIW resonator and its filter implementation

AbstractA stripline hybrid dual‐capacitively loaded (DCL) substrate integrated waveguide (SIW) resonator is proposed and analyzed in this letter. First, the fundamental mode (TE101) and two higher order modes (TE102 and TE201) are shifted lower through the capacitive perturbation effect. Extra Striplines are then integrated with the proposed DCL triple‐mode resonator to generate transmission zeros both below and above the passband. Subsequently, the proposed stripline hybrid DCL SIW resonator is used to design an example fourth‐order filter with three transmission zeros. A step‐by‐step design guideline is then summarized under specified filter performance. Finally, to verify the proposed design method, an example fourth‐order bandpass filter at 5.5 GHz with an improved lower rejection band is designed, fabricated, and measured. The measured results indicate that this filter has the advantages of compact size, good selectivity, and easy three‐dimensional integration.

Compact wideband stripline hybrid coupler with an imbedded ground strip

ABSTRACTIn this paper, a compact and wideband stripline 180° hybrid coupler with a simple design structure is proposed. For wideband capability and a size reduction, the long branch of the conventional ring hybrid coupler is substituted with a coupled line with two quarter‐wavelength short‐circuited stubs having a narrow gap and a rectangular ground strip. The ground strip is embedded in a dielectric substrate between the coupled line and a ground plane, and the operating bandwidth can be widened in the ground strip design to control the parasitic capacitance and inductance. The proposed coupler has a 71% wide operating bandwidth at the center frequency with a ±0.5 dB power split error and a high isolation of below 20 dB. The phase difference between two output signals is within ±5°, and the reflection coefficient for all ports is less than −10 dB in the operating bandwidth. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2433–2437, 2016

COMPACT FOUR-ELEMENT ANTENNA ARRAY DESIGN FOR BEIDOU NAVIGATION SATELLITE SYSTEM APPLICATIONS

In this letter, a compact four-element microstrip patch antenna array for BeiDou navigation satellite system (BDS) operation at the B3 (1268MHz) band is proposed. High permittivity dielectric substrate and slit-loaded microstrip patch are used to reduce the antenna element size down to 40mm × 40mm which implies an aperture size of only λ0/6 × λ0/6 at the B3 band. The right-handed circularly polarized (RHCP) radiation is achieved by connecting two coaxial probes to a 0◦–90◦ stripline hybrid. Four identical antenna elements are distributed with the same polarity and an inter-element separation of 80mm (λ0/3 at the B3 band). The overall size of the antenna array, including the stripline feeding network and supporting ground plane, is only 140mm × 140mm × 5.5mm. A prototype was fabricated and measured to verify the design concept. Simulated and measured results will be presented and discussed, showing that the proposed BDS antenna array is suitable for BDS applications.

Cryogenic Hybrid Coupler for Ultra-Low-Noise Radio Astronomy Balanced Amplifiers

Modern heterodyne ultra low noise receivers used for radio astronomy have evolved to provide very wide instantaneous bandwidth. Some of the configurations used in present cryogenic front-ends, such as sideband separating mixers and balanced amplifiers, require 90° hybrids as a part of the intermediate frequency (IF) circuitry. A very common choice for the band of operation of these hybrids is 4-12-GHz band. There are devices commercially available covering this band with good ambient temperature characteristics, but their cryogenic performance degrades to unacceptable levels. This paper describes the design, construction and measurement of a multioctave stripline hybrid for the 4-12 GHz band specially conceived to operate satisfactorily when cooled down to 15 K (-258°C). The materials and mechanical construction have been carefully selected and the result is a very compact, reliable and low thermal mass device, capable to withstand extreme thermal cycling. The coupling and reflection characteristics of the prototype show very low temperature dependence. The utility of the hybrid developed is demonstrated in a cryogenic balanced amplifier. The noise temperature obtained using this configuration (6 K) shows clear advantage (about 33%) over the classical isolator-amplifier combination normally used in heterodyne radio astronomy receivers. Besides, a superior insensitivity of the amplifier's noise performance to the input termination mismatch is obtained.

Circularly polarised circular ring slot antenna fed by stripline hybrid coupler

A novel circular ring slot antenna which has a stripline hybrid coupler feed network is proposed for generating broadband circular polarisation performance. A broad impedance bandwidth (VSWR 2:1) at 20.5% and a CP bandwidth at 9% for a <3 dB axial ratio have been achieved.

Miniaturization of stripline hybrid coupled diode phase and shifter and its wavebanding method

AbstractThis paper describes miniaturization of a hybrid coupled diode phase shifter made of striplines and its widebanding. An impedance transformer setting the phase shift of a single‐bit phase shifter is fabricated with a coupled line with two open ends having a bias blocking capability. This makes the size of the phase shifter about one‐half of the conventional one. It is pointed out that a wideband characteristic of this phase shifter is possible by choosing a large ratio of the even‐mode impedance to the odd‐mode impedance in the coupled line. An S‐band hybrid coupled phase shifter fabricated based on the present design method has a phase error less than 7.4 (RMS value) in the relative bandwidth of 26%, a loss of less than 1.4 dB and a VSWR of less than 1.6.

An Eigenadmittance Condition Applicable to Symmetrical Four-Port Circulators and Hybrids

Recently, an expression for the equivalent admittance of symmetrical three-port circulators has been derived on the basis of symmetry considerations. In this paper, the same technique is extended to the symmetrical four-port circulator. It is shown that a simple relationship must be satisfied by the eigenadmittances jY/sub 0/, jY/sub -1/, jY/sub 1/, and jY/sub 2/ if perfect circulation is to be obtainable by matching alone. This relationship also applies to recriprocal four-port devices with 2-fold symmetry about two perpendicular axes which are required to be 90/spl deg/ hybrids upon matching, provided that the eigenadmittances jY/sub 1/, jY/sub 2/, jY/sub 3/, and jY/sub 4/ are used. An interesting application of this relation to the construction of a compact stripline hybrid is given.

Strip Line Hybrid Junction

The equivalent circuit of a strip line network is shown to display the properties of a hybrid junction. An application is illustrated by design of a balanced mixer and the presentation of the resultant measured data.