ArbitraryFiniteGapFeed

R2026b

Create arbitrary finite gap feed

Since R2024b

Description

Use the ArbitraryFiniteGapFeed object to specify the FeedDefinitions property in a parent pcbComponent object.

The ArbitraryFiniteGapFeed object defines a lumped feed across arbitrarily shaped finite gaps between multiple metal regions, enabling the specification of potential relationships among the conductors.

Creation

Syntax

f1 = ArbitraryFiniteGapFeed

f1 = ArbitraryFiniteGapFeed(PropertyName=Value)

Description

f1 = ArbitraryFiniteGapFeed creates a default ArbitraryFiniteGapFeed object.

f1 = ArbitraryFiniteGapFeed(PropertyName=Value) sets object Properties using one or more name-value arguments. PropertyName is the property name, and Value is the corresponding value. You can specify several name-value arguments in any order as PropertyName1=Value1,...,PropertyNameN=ValueN. Properties that you do not specify retain their default values.

Properties

SignalLocations — Locations to apply positive excitation

[-0.01,0] (default) | N-by-2 matrix

Locations to apply positive excitation, specified as an N-by-2 matrix in meters. N is the number of positive excitation sites.

The first and the second columns correspond to the X- and Y-coordinates in meters, respectively. Each location must lie on an edge of a metal layer.

Example: [-0.2 0]

Data Types: double

GroundLocations — Locations to apply negative excitation

[-0.01,0] (default) | N-by-2 matrix

Locations to apply negative excitation, specified as an N-by-2 matrix in meters. N is the number of negative excitation sites.

The first and the second columns correspond to the X and Y coordinates in meters, respectively. Each location must lie on an edge of a metal layer.

Example: [-0.2 0]

Data Types: double

SignalWidths — Width of each positive excitation site

0.005 (default) | N-by-1 vector

Width of each positive excitation site in SignalLocations, specified as an N-by-1 vector in meters. N is the number of positive excitation sites.

The metal edge on which SignalLocations(n,:) lies must be at least as long as SignalWidths(n).

Example: f1=ArbitraryFiniteGapFeed;f1.SignalWidths=.007

Data Types: double

GroundWidths — Width of each negative excitation site

0.005 (default) | N-by-1 vector

Width of each negative excitation site in GroundLocations, specified as an N-by-1 vector in meters. N is the number of negative excitation sites.

The metal edge on which GroundLocations(n,:) lies must be at least as long as GroundWidths(n).

Example: f1=ArbitraryFiniteGapFeed;f1.GroundWidths=0.007

Data Types: double

SignalLayers — Layer indices for all positive excitation sites

1 (default) | N-by-1 vector

Layer indices for all positive excitation sites, specified as an N-by-1 vector. N is the number of positive excitation sites. SignalLayers(n) is the layer index into the pcbComponent layer stack for the site at SignalLocations(n,:). The referenced layer must be a metal layer, and SignalLocations(n,:) must lie on an edge of that metal.

Example: f1=ArbitraryFiniteGapFeed;f1.SignalLayers=2

Data Types: double

GroundLayers — Layer indices for all negative excitation sites

3 (default) | N-by1 vector

Layer indices for all negative excitation sites, specified as an N-by-1 vector. N is the number of negative excitation sites. GroundLayers(n) is the layer index into the pcbComponent layer stack for the site at GroundLocations(n,:). The referenced layer must be a metal layer, and GroundLocations(n,:) must lie on an edge of that metal.

Example: f1=ArbitraryFiniteGapFeed;f1.GroundLayers=4

Data Types: double

Examples

Arbitrary Finite Gap Feed Setup for a Coplanar Port

This example shows how to configure an ArbitraryFiniteGapFeed to excite a coplanar waveguide with no conductor backing implemented as a pcbComponent object.

Set up three rectangles in a coplanar waveguide configuration.

w = 3e-3;           % width of the strip (m)
s = 0.2e-3;         % spacing from strip to ground planes (m)
t = 1e-3;           % substrate thickness
boardWidth = 4*w;   % Total width of the board (m)
boardLength = 10*w; % Length of the trace and all GPs (m)

d = dielectric('Teflon');
d.Thickness = t;

rect1 = traceRectangular('Length', boardLength, 'Width', boardWidth);
rectCut1 = traceRectangular('Length', boardLength, 'Width', s, 'Center', [0, (s/2+w/2)]);
rectCut2 = copy(rectCut1); rectCut2.Center = -rectCut1.Center;

p = pcbComponent;
p.BoardShape = rect1;
p.BoardThickness = t;
p.Layers = {rect1 - rectCut1 - rectCut2, d};

To expose its FeedDefinitions property set the pcbComponent.FeedFormat property to FeedDefinitions. Configure one ArbitraryFiniteGapFeed at each end of the coplanar waveguide. In this example every property of the requires two rows. The combined first rows define the first +/- excitation pair - the excitation of the strip against the right ground plane. The combined second rows define the second +/- excitation pair - the strip against the left ground plane.

p.FeedFormat = 'FeedDefinitions';
f1 = ArbitraryFiniteGapFeed('SignalLocations', [-boardLength/2 0; -boardLength/2 0], ...
    'GroundLocations', [-boardLength/2, (w+s); -boardLength/2, -(w+s)], ...
    'SignalWidths', [w;w], 'GroundWidths', [w; w], 'SignalLayers', [1; 1], 'GroundLayers', [1, 1]);
f2 = copy(f1); f2.SignalLocations = -f1.SignalLocations; f2.GroundLocations = -f1.GroundLocations;
p.FeedDefinitions = [f1; f2];
figure; show(p)

Compute and plot S-parameters for the waveguide.

s = sparameters(p, linspace(1e9, 5e9, 51));
figure; rfplot(s)

Version History

Introduced in R2024b