FiniteGapFeed

R2026b

Create a finite gap feed

Since R2024b

Description

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

The FiniteGapFeed object represents a coplanar multi-ground edge feed across a physically finite gap between conductors. This feed excites the finite gap directly, modeling the structure more realistically. A delta-gap feed, by contrast, would require you to make the gap infinitesimally small by adding more metal, which can introduce undesirable parasitic effects.

Creation

Syntax

f1 = FiniteGapFeed

f1 = FiniteGapFeed(PropertyName=Value)

Description

f1 = FiniteGapFeed creates a default FiniteGapFeed object.

f1 = FiniteGapFeed(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

[0.001,0] (default) | N-by-2 matrix

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

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

Example: [0.002,0]

Data Types: double

GroundLocations — Locations to apply negative excitation

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

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

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

Example: [-0.02,0]

Data Types: double

SignalLayers — Layer index for positive and negative excitation site

1 (default) | positive integer scalar

Layer index for positive and negative excitation site, specified as a positive integer scalar. SignalLayers is the layer index into the pcbComponent layer stack.

Example: 2

Data Types: double

SignalWidths — Width of each excitation site

0.002 (default) | N-by-1 vector

Width of each excitation site, specified as an N-by-1 vector in meters. N is the number of excitation sites. The metal edges on which SignalLocations(n,:) and GroundLocations(n,:) lie must be at least as long as SignalWidths(n). Each negative excitation site has the same width as its corresponding positive excitation site.

Example: 0.003

Data Types: double

Examples

Finite Gap Feed Setup for an Internal Port

This example shows how to use a FiniteGapFeed object to define an internal port on a pcbComponent object.

Start with the Wilkinson splitter catalog element and convert it to a pcbComponent. Save its resistor length.

w = wilkinsonSplitter;
rL = w.ResistorLength;
p = pcbComponent(w);

The catalog element has a lumped load bridging the two output terminals. Save its location, replace it by the placeholder lumpedElement, and delete the leftover metal strip.

internalPortLocation = p.Load.Location;
p.Load = lumpedElement;
rectangleCut = traceRectangular('Center', internalPortLocation(1:2), 'Length', 0.5e-3, 'Width', rL);
p.Layers{1} = p.Layers{1} - rectangleCut;

To expose the FeedDefinitions property switch the pcbComponent object's FeedFormat property to FeedDefinitions. Instantiate a FiniteGapFeed at the saved lumped load site and add it to the list of feeds.

p.FeedFormat = 'FeedDefinitions';
f = FiniteGapFeed('SignalLocations', internalPortLocation(1:2) + [0 rL/2], 'GroundLocations', internalPortLocation(1:2) + [0 -rL/2], 'SignalLayers', 1, 'SignalWidths', 0.5e-3);
p.FeedDefinitions(end+1) = f;
figure; show(p);

Calculate 4-port S-parameters for the splitter. Terminate the internal port into a 100-ohm resistance and plot the result.

s = sparameters(p, linspace(1e9, 5e9, 51));
s100 = snp2smp(s, 1:3, 100);
figure; rfplot(s100)

Version History

Introduced in R2024b