Before the emergence of ultra-wideband (UWB) radios, widely used wireless communications were based on sinusoidal carriers, and impulse technologies were employed only in specific applications (e.g. radar). In 2002, the Federal Communication Commission (FCC) allowed unlicensed operation between 3.1–10.6 GHz for UWB communication, using a wideband signal format with a low EIRP level (−41.3dBm/MHz). UWB communication systems then emerged as an alternative to narrowband systems and significant effort in this area has been invested at the regulatory, commercial, and research levels.

IEEE Transactions on Microwave Theory and Techniques and Antennas and Propagation Announce a Joint Special Issue on Ultra-Wideband (UWB) Technology

Three novel wideband balanced-to-unbalanced filtering power dividers based on coupled lines are proposed in this paper. Multifunctional power dividers can replace various cascaded single devices to decrease integration mismatching loss and circuit size. The wideband response can be easily realized by the coupled lines structures. To further improve the differential-mode passband selectivity, open/shorted coupled lines and half-wavelength open stubs are applied to introduce two transmission zeros near the passband, respectively. In addition, a resistor in the middle of two single-ended ports can be used to realize isolation between out ports. To verify the proposed concepts, three prototypes of wideband balanced-to-unbalanced filtering power dividers operating at 2 GHz are designed and fabricated with the 4-dB differential-mode bandwidths of 80.5%, 71.5%, and 80%. All the structures show good performances for differential-mode out-of-band suppression, common-mode suppression, and isolation.

Wideband Balanced-to-Unbalanced Filtering Power Dividers Based on Coupled Lines

Thank you very much for reading microwave differential circuit design using mixed mode s parameters. Maybe you have knowledge that, people have look numerous times for their chosen books like this microwave differential circuit design using mixed mode s parameters, but end up in malicious downloads. Rather than reading a good book with a cup of tea in the afternoon, instead they cope with some infectious virus inside their desktop computer.

Microwave Differential Circuit Design Using Mixed Mode S Parameters

A wideband circularly polarized (CP) dielectric resonator antenna (DRA) with filtering response was proposed in this communication. To combine additional filtering and harmonic suppression functions within an antenna while realizing circular polarization, a new wideband filtering quadrature coupler was implemented to feed a hollow DRA. The filtering quadrature coupler was based on a snowflake shaped patch, whose operating modes can be flexibly controlled by the loading slots. Quarter wavelength coupled line sections were introduced to the coupler, realizing simultaneously wide bandwidth, excellent bandpass filtering, and wide harmonics suppression characteristics. For demonstration, a filtering CP antenna operating at 1.8 GHz was designed, fabricated, and measured. Reasonable agreement between simulated and measured results was observed. The prototype exhibited excellent bandpass filtering characteristics together with a wide overlapping bandwidth of 27.8%, within which the axial ratio value was less than 3 dB, and return loss was better than 12.4 dB. Over the same band, an average gain of 6 dBic with a variation less than 1 dB was achieved. A rejection level larger than 19 dB was found within the suppression band up to the third harmonic.

Wideband Circularly Polarized Dielectric Resonator Antenna With Bandpass Filtering and Wide Harmonics Suppression Response

A compact wideband balanced-to-unbalanced (BTU) out-of-phase power divider (PD) is proposed in this letter. This novel circuit essentially consists of three pairs of cascaded coupled lines and a grounded resistor for output isolation. By using the even- (odd-) mode method analysis and the traditional transmission-line theory, closed-form design equations for equal power division with out of phase from one differential input to two unbalanced outputs, high output isolation and good common-mode suppression are obtained, simultaneously. In addition, an experimental PD is designed and fabricated. The good performance and the consistency between the simulated and measured results verify our design theory.

A Wideband Balanced-to-Unbalanced Coupled-Line Power Divider

In this paper, a balanced-to-unbalanced microstrip power divider based on branch lines with several stubs and one resistor is proposed. The functions of power dividing, frequency selectivity, isolation between output ports, and common-mode suppression can be realized at the same time. The even–odd-mode equivalent circuits combining with the standard S-parameters and the mixed-mode S-parameters are adopted to derive the analytical equations at the center frequency. One or two transmission zeros can be achieved to enhance the out-of-band suppression. The center frequency, bandwidth, isolation, common-mode suppression, and the frequencies of transmission zeros can be controlled by the design procedure. To verify the theoretical prediction, two fabricated prototypes are designed and compared. One gets 7.7% 1-dB bandwidth with 0.6-dB insertion loss and one transmission zero. The other gets 1-dB bandwidth of 5% with 0.7-dB insertion loss and two transmission zeros. The isolation and common-mode suppression for both prototypes are better than 15 and 20 dB within the whole passband, respectively.

A Balanced-to-Unbalanced Microstrip Power Divider With Filtering Function

In this letter, a balanced-to-balanced power divider (PD) is proposed By etching both slot and aperture on the common ground of the back-to-back microstrip Wilkinson PD, the proposed balanced-to-balanced PD can achieve wide and high common-mode (CM) suppression while keeping the PD function for differential-mode signals Compared with previous technologies of CM suppression for back-to-back microstrip balanced circuits, the proposed one has the advantage of compact size Furthermore, the proposed PD shows enhanced bandwidth for matching and isolation A prototype is realized with the size of $035 \lambda_{\rm g} \times 04 \lambda_{\rm g}$  The measured results show relative frequency bandwidth for $\vert S_{dd11}\vert dB of 85% The fractional bandwidths for $\vert S_{dd32}\vert, \vert S_{cc21}\vert$ and $\vert S_{cc32}\vert$ under ${-}20$ dB are 44%, 44% and 55%, respectively

A Balanced-to-Balanced Power Divider With Wide Bandwidth

In this paper, a coupled-line balanced-to-single-ended out-of-phase power divider is proposed. Configured by three quarter-wavelength coupled lines, the proposed power divider is compact and able to enhance the bandwidth of differential-mode power dividing, isolation, common-mode suppression, and phase difference between the output ports. Furthermore, enhancing the bandwidth for common-mode suppression using additional quarter-wavelength open stubs is discussed. Analytical solution of the parameters for specified bandwidth can be achieved using odd- and even-mode analysis. Analytical and practical bandwidth limitation has been analyzed, and it is shown that the bandwidths can be controlled by the odd- and even-mode impedance of the coupled lines. For demonstration, a prototype of size 15 mm $\times95$ mm ( $0.15~\lambda _{g} \times 0.95~\lambda _{g}$ ) achieves an operating bandwidth ( $\vert S_{ddAA}\vert dB) of 30% with the minimum insertion loss of 0.1 dB.

A Coupled-Line Balanced-to-Single-Ended Out-of-Phase Power Divider With Enhanced Bandwidth

In this paper, a balanced branch-line coupler with an arbitrary power division ratio is proposed. Configured by four quarter- and half-wavelength microstrip lines, the proposed design achieved desired functions of branch-line coupler for differential-mode signal and common-mode suppression with the merits of wide bandwidth, a simple configuration and a design method, low insertion loss, and low cost. The even-and odd-mode equivalent circuits combining with the standard and mixed-mode S-parameters are adopted to derive the analytical equations. Three prototypes with the power division ratios of 1:1, 2:1, and 4:1 are designed to verify the theoretical prediction. The prototypes with the size of 0.52 λg X 0.5 λg (λ
 g
 is the guided wavelength at 1.86 GHz) exhibits the operating bandwidths (IS
 ddAA
/DA|, |S
 ccDA
| <; -15 dB) of 4.3%, 7.3%, and 10.2% and the minimum insertion losses of 0.45, 0.25, and 0.1 dB, respectively, while the isolation and common-mode suppression are higher than 20 dB within the whole passband.

A Balanced Branch-Line Coupler With Arbitrary Power Division Ratio

A balanced filtering branch-line coupler is proposed for the first time. The proposed design is realized by coupled microstrip lines and coupled-line-fed coupling structures. Based on this, the proposed design not only exhibits the functions of power dividing and filtering for differential-mode signals, but also can suppress the common-mode noise/signal and be easily connected with other balanced circuits. The dimension of the proposed design is similar to that of the traditional single-ended design. A prototype of the balanced filtering branch-line coupler centered at 1.87 GHz with the size of 0.33 $\lambda_\mathrm{g}\times 0.42\ \lambda_\mathrm{g}$ is fabricated, where $\lambda_\mathrm{g}$ is the guided wavelength at the center frequency. The measured results exhibit the maximum insertion loss of 1.4 dB with a 3-dB fractional bandwidth of 3.5%.

Kai Xu

Papers

A Balanced-to-Unbalanced Microstrip Power Divider With Filtering Function

A Balanced-to-Balanced Power Divider With Wide Bandwidth

A Coupled-Line Balanced-to-Single-Ended Out-of-Phase Power Divider With Enhanced Bandwidth

A Balanced Branch-Line Coupler With Arbitrary Power Division Ratio

A Balanced Filtering Branch-Line Coupler