WDCoupler (Wilkinson Divider)

Symbol

Parameters

Name	Description	Unit	Default
Subst	Microstrip substrate name	None	MSub1
F	Center frequency	GHz	1
DeltaF	Frequency bandwidth	GHz	0.5
Zo	Characteristic impedance	Ohm	50
ResponseType	Type of frequency response	None	Uniform
N	Number of quarter-wave sections; set N=0 to compute N	None	0
Rmax	Maximum voltage reflection coefficient on input port	None	0.1
K	Ratio of power out port 2 to power out port 3	None	1.0
Wgap	Width of gap for resistor	mil	50
Delta	Length added to quarter-wave branches for tuning performance	mil	0

Notes

1. A Wilkinson power divider splits the power at the input (pin 1) between the two outputs (pins 2 and 3). Unequal or equal power splits can be realized. The signals at the outputs are in phase. All three ports will be matched, and ports 2 and 3 will in general be well isolated from each other.
2. For broadband performance, the divider can have multiple quarter-wave sections. If the number of sections N is set to zero, the Design Assistant chooses N such that such that the reflection coefficient is less than Rmax over the bandwidth DeltaF (centered at the design center frequency). the resulting bandwidth can be broader than that specified. Otherwise, Rmax and DeltaF are ignored.
3. ResponseType specifies the distribution of the partial reflection coefficients seen at each section interface - Uniform, Binomial, and Chebyshev distributions are available. These in turn specify the shape of the reflection coefficient versus frequency.
4. For a single section divider (N=1), the value of K can be set to realize the desired power split out of ports 2 and 3. Be aware that choosing K larger than 3 to 4 (or smaller than 1/3 to 1/4) is likely to cause difficulties in the design.
5. Pozar specifies K ² = P3/P2, while the DesignGuide uses K ² = P2/P3. Therefore, if you use the equations in Pozar to verify everything, you must substitute 1/K for K. The DesignGuide automatically puts quarter-wave matching sections on ports 2 and 3, so all ports are matched to the characteristic impedance. If you remove these matching segments, the output impedances are those specified by Pozar.
6. The optimization minimizes the input reflection coefficient (S11) at the design center frequency by changing the length of the quarter wave branches forming the divider.
7. A SmartComponent subnetwork is empty until the Design Assistant is used to generate the design. Refer to Design Assistant.

For a more detailed discussion of this device, see: D. M. Pozar, Microwave Engineering, 2nd Edition, John Wiley & Sons: New York, 1998, pp. 363-368.

Example

A single-section Wilkinson power divider (N=1) was designed for a center frequency of 5 GHz with an equal power split (K=1) and a gap width for the resistor of 50 mil. Tuning using the Optimization Assistant yielded a value of Delta = 58.03 mil.

Passive Circuit DG - Filters