Difference between revisions of "Application Note 3: Designing A Slot-Coupled Patch Antenna Array With A Corporate Feed Network Using EM.Picasso"
Kazem Sabet (Talk | contribs) (→Designing the Wilkinson Power Divider) |
Kazem Sabet (Talk | contribs) (→Designing the Wilkinson Power Divider) |
||
| Line 91: | Line 91: | ||
== Designing the Wilkinson Power Divider == | == Designing the Wilkinson Power Divider == | ||
| − | The input signal power must be divided equally among 16 patch radiating elements. In other words, a 1:16 power distribution network is needed for this project. The design of a Wilkinson power divider is described in detail in [[EM.Picasso Tutorial Lesson 9: Designing a Microstrip Wilkinson Power Divider]]. An Ω-shaped microstrip ring is used to create a three-port network. The input and output microstrip lines all have a width of 2.4mm with Z<sub>0</sub> = 50Ω. The microstrip partial ring has a width of √2Z<sub>0</sub> = 70.7Ω. It is determined that if a lumped 100Ω resistor is connected between the two output arms of this divider, better return loss and isolation levels are achieved. | + | The input signal power must be divided equally among 16 patch radiating elements. In other words, a 1:16 power distribution network is needed for this project. The design of a Wilkinson power divider is described in detail in [[EM.Picasso Tutorial Lesson 9: Designing a Microstrip Wilkinson Power Divider]]. An Ω-shaped microstrip ring is used to create a three-port network. The input and output microstrip lines all have a width of 2.4mm with Z<sub>0</sub> = 50Ω. The microstrip partial ring has a width of √2Z<sub>0</sub> = 70.7Ω and serves as the two quarter-wave arms of the Wilkinson power divider. It is determined that if a lumped 100Ω resistor is connected between the two output arms of this divider, better return loss and isolation levels are achieved. The figure below shows the geometry of the optimized 1:2 Wilkinson power divider. |
<table> | <table> | ||
Revision as of 00:26, 17 October 2016
Contents
Introduction
EM.Picasso can be used to analyze large and fairly complex multilayer planar structures. In this application note, we will show how to use EM.Picasso to design a 4 × 4 slot-coupled patch antenna array with a microstrip corporate feed network. The design process involves three steps: design of the slot-couple patch element, design of the power divider, and finally, construction of the 16-element array. The first two steps are the subject of two of EM.Picasso's tutorial lessons.
Designing the Patch Radiating Element
The operating frequency of the patch array is f = 2.4GHz. At this frequency, the free-space wavelength is λ0 = 125mm. The patch radiators will be spaced at half free-space wavelength: Sx = Sy = λ0/2 = 62.5mm. The design of the slot-coupled patch antenna is described in detail in EM.Picasso Tutorial Lesson 7: Designing A Slot-Coupled Patch Antenna. The substrate consists of two finite-thickness dielectric layers with εr = 3.38, σ = 0, separated by a perfect electric conductor (PEC) ground plane of infinite lateral extents. The table below summarizes the substrate stackup's layer hierarchy:
| Substrate Object Label | Substrate Object Type | Function | Material | Thickness |
|---|---|---|---|---|
| THS | Half-Space Medium | Top Substrate Termination | Vacuum | Infinite |
| PEC_1 | PEC Trace | Patch Plane | PEC | 0 |
| Layer_1 | Substrate Layer | Patch Substrate | ROGER RO4003C | 2mm |
| PMC_1 | Slot Trace | Slot Plane | PMC | 0 |
| Layer_2 | Substrate Layer | Feed Substrate | ROGER RO4003C | 0.787mm |
| PEC_2 | PEC Trace | Microstrip Feed Plane | PEC | 0 |
| BHS | Half-Space Medium | Bottom Substrate Termination | Vacuum | Infinite |
The design variables in this problem include the side dimensions of the square patch radiator, length and width of the coupling slot and the length of the open microstrip stub extended beyond the coupling slot. The width of the mircostrip feed line is chosen to be wf = 2.4mm to yield a characteristic impedance of Z0 = 50Ω.
| Design Variable Name | Optimal value |
|---|---|
| patch_len | 39.5mm |
| slot_len | 12mm |
| slot_wid | 1.5mm |
| stub_len | 21mm |
Designing the Wilkinson Power Divider
The input signal power must be divided equally among 16 patch radiating elements. In other words, a 1:16 power distribution network is needed for this project. The design of a Wilkinson power divider is described in detail in EM.Picasso Tutorial Lesson 9: Designing a Microstrip Wilkinson Power Divider. An Ω-shaped microstrip ring is used to create a three-port network. The input and output microstrip lines all have a width of 2.4mm with Z0 = 50Ω. The microstrip partial ring has a width of √2Z0 = 70.7Ω and serves as the two quarter-wave arms of the Wilkinson power divider. It is determined that if a lumped 100Ω resistor is connected between the two output arms of this divider, better return loss and isolation levels are achieved. The figure below shows the geometry of the optimized 1:2 Wilkinson power divider.
 |
Building the Array Structure
The corporate feed network on the microstrip trace plane (PEC_1) consists entirely of rectangle and circle strip objects. For the Wilkinson power dividers, circle strips with unequal outer and inner radii and incomplete start and end angles are used just as you saw in Tutorial Lesson 7. A 50Ω microstrip line on the lower thin substrate has a width of 2.4mm. Small circle strips of (outer) radius 2.4mm are used to provide a round bend junctions between two perpendicular microstrip line segments. Rather than a quarter-circle, a 3/4-circle shape is used to have some good overlap area over the conjoining line objects. This helps with a smoother and more consistent mesh in such junction areas.
Draw the following 9 circle strip objects, all on PEC_2 trace plane, with the given coordinates and dimensions:
|
