, photo mixers, photoconductive antennas, the plasmonic effect can be involved where the device dimensions are comparable to the operating wavelength. Han Sang-Pil, et al. [Han et al. (2011)] proposed a gold nano-island array in the antenna gap between the electrodes to improve the photocurrent and absorption coefficient of THz PCA. 12.8 METHODS OF THZ DETECTION The growth of the THz detection devices over time is faster than the growth of the THz generation devices. The issue in detecting the terahertz is the photon energy of 0.41-41 meV at this THz frequency region [Khiabani (2013)]. The THz energy is very Terahertz Antenna in Future Healthcare Informatics close to the background thermal noise energy, whereas it can be mitigated by cryo- genic cooling. Coherent detection techniques can be used to determine the amplitude and phase of the received signal however when using the incoherent technique, only intensity can be measured. Both narrowband and broadband signals can be detected using terahertz detectors. Heterodyne circuits, electro-optic sampling technique and THz PCA can be used in the coherent type of detection to detect the terahertz signal. In the incoherent detection, lenses and mirrors are always used to focus and guide the THz beam onto the detector. The unwanted signals can be removed from the THz signal through a coherent detection process. Some of the direct THz power measurement detectors where phase cannot be measured, are Golay cells, pyroelec- tric detectors, and bolometers, which can be used at room temperature. For a lower response time, the THz can be measured by a cryogenically cooled semiconductor detector. 12.8.1 ELECTRO-OPTIC SAMPLING METHOD Electro-optic sampling is also known as Pockels effect in nonlinear crystals. Figure 12.11. shows a representation of the electro-optic sampling method. The polarization rotation of the optical beam is detected by the balanced photodiode in the presence of the THz beam in the electro-optic (and nonlinear crystal) medium. The terahertz pulse from the