Techniques, devices and systems use pseudo-conductor materials as antennas to receive or radiate electromagnetic energy for communications and other applications. Methods of configuring an antenna can include, in some implementations, selecting a pseudo-conductor material having an electromagnetic constitutive property, wherein the electromagnetic constitutive property comprises a real part of the electromagnetic constitutive property that is greater than a corresponding imaginary part of the electromagnetic constitutive property; and forming the pseudo-conductor material into an antenna shape configured, upon being excited, to radiate emissions that satisfy a predefined antenna performance, such that the pseudo-conductor material formed in the antenna shape weakly guides an electromagnetic wave on the pseudo-conductor material using a leaky mode that is below cutoff to establish a field structure to radiate the emissions from the pseudo-conductor material that satisfy the antenna performance.