ArbitraryFiniteGapFeed

R2026b

Create arbitrary finite gap feed

Since R2026b

Description

Use the ArbitraryFiniteGapFeed object to specify the FeedDefinitions property in a parent pcbStack 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 pcbStack 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 pcbStack 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

Coplanar Waveguide-fed Monopole Antenna

Define the strip width, the strip-to-ground spacing, and the substrate thickness. Derive the board and ground-plane dimensions from the strip width so that the geometry scales consistently. The ground planes occupy only the lower feed region; the strip continues past them to form the monopole.

w = 3e-3;
s = 0.2e-3;
t = 1e-3;   
boardWidth = 4*w;
boardLength = 10*w;
Lg = 4*w;
Wg = boardWidth/2 - (w/2 + s);

Define the substrate as a Teflon dielectric and set its thickness to match the board.

d = dielectric("Teflon");
d.Thickness = t;

Create the conductor layer from three rectangles. The central strip spans the full board length: its lower portion is the CPW signal line, and the upper portion, which extends beyond the ground planes, is the radiating monopole. Place a coplanar ground plane on each side of the strip, confined to the feed region so the strip radiates freely where the ground planes end. Combine the three shapes with to form a single conductor layer.

strip = antenna.Rectangle(Length=boardLength, Width=w);
yG = (w/2 + s) + Wg/2;
xG = -boardLength/2 + Lg/2;
gndR = antenna.Rectangle(Length=Lg, Width=Wg, Center=[xG,  yG]);
gndL = antenna.Rectangle(Length=Lg, Width=Wg, Center=[xG, -yG]);
conductor = strip + gndR + gndL;

Create the pcbStack object, set its board outline and thickness, and assign the conductor and dielectric as the layer stack.

p = pcbStack;
p.BoardShape = antenna.Rectangle(Length=boardLength, Width=boardWidth);
p.BoardThickness = t;
p.Layers = {conductor, d};

To enable the FeedDefinitions property, set the FeedFormat property to FeedDefinitions. Define a single ArbitraryFiniteGapFeed at the bottom edge of the board. The feed uses two rows: the first row references the signal strip against the right ground plane, and the second references it against the left ground plane. Assigning a single feed object, rather than an array of feeds, produces a single port.

p.FeedFormat = 'FeedDefinitions';
xf = -boardLength/2;
f1 = ArbitraryFiniteGapFeed(SignalLocations=[xf 0; xf 0], ...
    GroundLocations=[xf, (w/2+s+Wg/2); xf, -(w/2+s+Wg/2)], ...
    SignalWidths=[w; w], GroundWidths=[Wg; Wg], ...
    SignalLayers=[1; 1], GroundLayers=[1; 1]);
p.FeedDefinitions = f1;
figure
show(p)
title("Coplanar Waveguide-fed Monopole Antenna")

Compute and plot the reflection coefficient. The monopole resonates near 3.8 GHz.

s = sparameters(p, linspace(2e9, 8e9, 61));
figure
rfplot(s)

Version History

Introduced in R2026b