A UWB Bidirectional Rectangular Ring Antenna Fed by CDM with a Rod and Ridges for Constant Beam Direction

<table>The upper resonant frequency for various <svg height="16.637501" id="M35" style="vertical-align:-4.77652pt" version="1.1" viewbox="0 0 24.7875 16.637501" width="24.7875" xmlns="http://www.w3.org/2000/svg">
<g transform="matrix(1.25,0,0,-1.25,0,16.6375)">
<g transform="translate(72,-58.69)">
<text transform="matrix(1,0,0,-1,-71.95,63.5)">
<tspan style="font-size: 12.50px; " x="0" y="0">𝑙</tspan>
</text>
<text transform="matrix(1,0,0,-1,-67.97,60.37)">
<tspan style="font-size: 8.75px; " x="0" y="0">𝑓</tspan>
</text>
<text transform="matrix(1,0,0,-1,-61.57,63.5)">
<tspan style="font-size: 12.50px; " x="0" y="0">/</tspan>
<tspan style="font-size: 12.50px; " x="3.4758339" y="0">𝑏</tspan>
</text>
</g>
</g>
</svg> (<i>a</i> = 5 cm and <i>c</i> = 1.5 cm).</table>

International Journal of Microwave Science and Technology

fig5

Figure 5

Figure 5: A UWB Bidirectional Rectangular Ring Antenna Fed by CDM with a Rod and Ridges for Constant Beam Direction 