本研究主旨為，「以零階共振器實現低成本全向性圓極化自振式主動集成天線」，其主要優勢為引用超穎物質使振盪器擁有高度之直流-射頻轉換效率，並且為了簡化天線設計之複雜度，吾人專注於設計自振式主動天線之接地平面，使自振式主動天線產生全向性圓極化之輻射。
設計之基礎為以零階共振器運用於交叉耦合對中，並且使兩顆電晶體之閘極、汲極間零相位差的特性滿足起振條件，使主動天線於零階模態時產生振盪，並且交叉耦合對能夠提供一組穩定的相位差可用於激發天線，因此以此基礎下設計全向性圓極化自振式主動集成天線。
本論文共提出兩款設計，首款為以基於零階共振器自振式主動天線之基礎下巧妙的設計接地平面之形狀，使兩線性極化天線以物理空間正交結合並且引入90度相位差進而產生圓極化之輻射，其中xz平面提供-40⁰至+50⁰以及yz平面提供-40⁰至+40⁰為可接受之圓極化角度。
第二款與首款相同以零階共振器自振式主動天線之基礎下，於接地平面周圍設計寄生元件，周圍之寄生元件命名為十字形螺旋單元(cross-shaped spiral elements ，CSA)，並且十字形螺旋單元透過中心之自振式主動天線當作其激發源，可實現全向性圓極化之輻射，其中xz平面提供-40⁰至+50⁰與yz平面提供-40⁰至+40⁰之可接受圓極化角度，最後為Ө=30⁰之平面提供全向性圓極化之輻射。

The main purpose of this study is, "Achieving an omnidirectional circularly polarized self-oscillating active integrated antenna using zero-order resonator". Its innovation is to focus on the design of the ground plane, and thus to generate omnidirectional circular polarization of the self-oscillating active antenna.
The design is based on the use of zero-order resonators integrated with cross-coupled pair such that zero phase shift between the gate and drain terminals of the two transistors is achieved to meet the Barkhausen condition. On this basis, we can design an omnidirectional circularly polarized self-oscillating active integrated antenna.
This paper proposes two designs. The first one is to manipulate the shape of the ground plane of the self-oscillating active antenna with zeroth-order resonators, so that the two linearly polarized field components are orthogonally combined in physical space and introduce a 90-degree phase difference then produces circularly polarized radiation.
The second design is the similar to the first model. Based on the self-oscillating active antenna, parasitic elements are designed around the ground plane, thereby changing the original current distribution and generating omnidirectional circularly polarized radiation.

[1] M. Zorzi, A. Gluhak, S. Lange, and A. Bassi, “From today's intranet of things to a future internet of things: a wireless- and mobility-related view,” IEEE Wireless Communications, vol. 17, pp. 44–51, 2010.
[2] M. Zhang, F. Sun, and X. Cheng, “Architecture of internet of things and its key technology integration based-on RFID, ” in Proc. Int. Symp. on Computational Intelligence Design, 2012, pp. 294–297.
[3] M.-H. Lee, C.-Y. Yao, and H.-C. Liu, “Passive tag for multi-carrier RFID systems,” in Proc. IEEE 17th Int. Conf. on Parallel and Distributed Systems, 2011, pp. 872–876.
[4] P. V. Nikitin, S. Ramamurthy, R. Martinez, and K. V. S. Rao, “Passive tag-to-tag communication,” in Proc. IEEE Int. Conf. on RFID, 2012, pp. 177–184.
[5] Z. Popović, E. A. Falkenstein, D. Costinett, and R. Zane, “Low-power far-field wireless powering for wireless sensors, ” Proc. IEEE, vol. 101, no. 6, pp. 1397–1409, Jun. 2013.
[6] J. Masuch, M. Delgado-Restituto, D. Milosevic, and P. Baltus, “Co-integration of an RF energy harvester into a 2.4 GHz transceiver,” IEEE J. Solid-State Circuits, vol. 48, no. 7, pp. 1565–1574, Jul. 2013. Circuits, vol. 46, no. 7, pp. 1728–1741, Jul. 2011.
[7] H. Reinisch et al., “An electro-magnetic energy harvesting system with 190 nW idle mode power consumption for a BAW based wireless sensor node,” IEEE J. Solid-State,vol. 46, no. 7, pp. 1728–1741, Jul. 2011.
[8] C. H. P. Lorenz et al., “Breaking the efficiency barrier for ambient microwave power harvesting with heterojunction backward tunnel diodes,” IEEE Trans. Microw. Theory Techn., vol. 63, no. 12, pp. 4544–4555, Dec. 2015.
[9] D. H. Choi and S. O. Park, “A varactor-tuned active-integrated antenna using slot antenna,” IEEE Antennas Wireless Propag. Lett., vol. 4, pp. 191–193, 2005.
[10] H. P. Moyer and R. A. York, “Active cavity-backed slot antenna using MESFETs,” IEEE Microw. Guided Wave Lett., vol. 3, pp. 95–97, 1993.
[11] E. H. Lim and K. W. Leung, “Novel utilization of the dielectric resonator antenna as an oscillator load,” IEEE Trans. Antenna Propag., vol. 55, no. 10, pp. 2686–2691, 2007.
[12] J. Shi, J. X. Chen, and Q. Xue, “A differential voltage-controlled integrated antenna oscillator based on double-sided parallel-strip line,” IEEE Trans. Microw. Theory Techn., vol. 56, pp. 2207–2212, Oct. 2008.
[13] F. Giuppi, A. Georgiadis, A. Collado, and M. Bozzi, “A compact, single-layer substrate integrated waveguide (SIW) cavity-backed active antenna oscillator,” IEEE Antennas Wireless Propag. Lett., vol. 11, pp. 431–433, 2012.
[14] J. W. Andrews and P. S. Hall, “Phase-locked-loop control of active microstrip patch antennas,” IEEE Trans. Microw. Theory Techn., vol. 50, no. 1, pp. 201–206, Jan. 2002.
[15] S. Yang, V.F. Fusco and D.E.J. Humphrey, “Ring-coupled-oscillator sequentially rotated active antenna”, IEEE Trans. Microw. Theory Techn., vol. 49, no. 8, pp.1492-1497, Aug. 2001.
[16] J. Bartolic, D. Bonefacic, and Z. Sipus, “Modified rectangular patches for self-oscillating active-antenna applications,” IEEE Antennas Propag. Mag., vol. 38, pp. 13–21, Aug. 1996.
[17] P. Liao and R. A. York, “A varactor tuned patch oscillator for active arrays,” IEEE Microw. Guided Wave Lett., vol. 4, no. 10, pp. 335–337, Oct. 1994.
[18] W. J. Tseng and S. J. Chung, “Analysis and application of a two-port aperture-coupled microstrip antenna,” IEEE Trans. Microw. Theory Techn., vol. 46, no. 5, pp. 530–535, May 1998.
[19] K. H. Y. Ip, T. M. Y. Kan, and G. V. Eleftheriades, “A single-layer CPW-fed active patch antenna,” IEEE Microw. Guided Wave Lett., vol. 10, no. 2, pp. 64–66, Feb. 2000.
[20] C. H. Mueller, R. Q. Lee, R. R. Romanofsky, C. L. Kory, K. M. Lambert, F. W. V. Keuls, and F.A.Miranda, “Small-size X-band active integrated antenna with feedback loop,” IEEE Trans. Antennas Propag., vol. 56, no. 5, pp. 1236–1241, May 2008.
[21] Y.-Y. Lin, C.-H. Wu, and T.-G. Ma, “Miniaturized self-oscillating annular ring active integrated antennas,” IEEE Trans. Antennas Propag.,vol. 59, no. 10, pp. 3597–3606, Oct. 2011.
[22] C.-H. Wu, and T.-G. Ma, “Self-oscillating dual-ring active integrated antenna” IEEE Int. Symp. on Antennas and Propagation Digest, 2011, pp. 2457-2460.
[23] C.-H. Wu and T.-G. Ma, “Miniaturized self-oscillating active integrated antenna with quasi-isotropic radiation,” IEEE Trans. Antennas Propag, vol.62 ,no.2 , pp.933-936 , Feb. 2014.
[24] C.-H. Wu and T.-G. Ma, “Self-oscillating semi-ring active integrated antenna with frequency reconfigurability and voltage-controllability,” IEEE Trans. Antennas Propag, vol.61 ,no.7 , pp.3880-3885 , Jul. 2013.
[25] C.-H. Wu and T.-G. Ma, “Pattern-reconfigurable self-oscillating active integrated antenna with frequency agility,” IEEE Trans. Antennas Propag, vol.62 ,no.12 , pp.5992-5998 , Dec. 2014.
[26] A. Lai, C. Carloz, and T. Itoh, “Composite right/left-handed transmission line metamaterials,” IEEE Microw. Mag., vol. 5, no. 3, pp. 34-50, Sep. 2004D. M. Pozar, Microwave Engineering, 3rd ed. Wiley, 2005.
[27] G. V. Eleftheriades, “Enabling RF/microwave devices using negative refractive-index transmission-line (NRI-TL) metamaterials,” IEEE Antennas Propag. Mag., vol. 49, no. 2, pp. 34–51, Apr. 2007
[28] C.-J. Lee, H. Wei, A. Gummalla, and M. Achour, “Small antenna based on CRLH structures: Concept, design, application,” IEEE Antennas Propag. Mag., vol. 53, no. 2, pp. 10–25, Apr. 2011.
[29] Y. Dong and T. Itoh, “Miniaturized substrate integrated waveguide slot antennas based on negative order resonance,” IEEE Trans. Antennas Propag., vol. 58, no. 12, pp. 3856–3864, 2010
[30] M. A. Antoniades and G. V. Eleftheriades, “A folded-monopole model for electrically small NRI-TL metamaterial antennas,” IEEE Antennas Wireless Propag. Lett., vol. 7, pp. 425–428, Oct. 2008.
[31] A. Sanada, C. Carloz, and T. Itoh, “Novel zeroth-order resonator composite right/left handed transmission line resonators” in IEEE Asia Pacific Conf., Seoul, Korea, Dec. 2003, pp. 1588-1591
[32] Y.-W. Chang and T.-G. Ma, "Zeroth-order self-oscillating active integrated antenna using cross-coupled pair", IEEE Trans. Antennas Propag., vol. 65, no. 10, pp. 5011-5018, Oct. 2017.
[33] Bonefacic, D., Kastela, M., Skokic, S. "Circularly polarized active integrated antenna", ICECom ,pp. 205–208, 2003
[34] Y. Qin, S. Gao, and A. Sambell, “Broadband high-efficiency circularly polarized active antenna and array for RF front-end application,” IEEE Trans. Microw. Theory Techn., vol. 54, no. 7, pp. 2910–2916, Jul. 2006.
[35] R. K. Singh, A. Basu and S. K. Koul, " Asymmetric coupled polarization switchable oscillating active integrated antenna ", Proc. Asia–Pacific Microw. Conf. (APMC), pp. 1-4, 2016.
[36] Z.-H. Liu, Y.-W. Chang and T.-G. Ma, "High-efficiency self-oscillating active integrated antenna using metamaterial resonators and its application to multicarrier radio frequency identification systems", IEEE Trans. Antennas Propag., vol. 64, no. 9, pp. 3803-3810, Sep. 2016.
[37] W.-S. Yoon, S.-M. Han, J.-W Baik, S. Pyo, J. Lee and Y.-S. Kim, "Crossed dipole antenna with switchable circular polarisation sense", Electron. Lett., vol. 45, no. 14, pp. 717-718, 2009.
[38] Mayumi Matsunaga, "A Wideband Omnidirectional Circularly PolarizedSpiral Antenna", 2016 10th European Conference on Antennas and ropagation (EuCAP), 2016.
[39] J. Birkland and T. Itoh, “A circularly polarized FET oscillator active radiating element,” in IEEE MTT-S Int. Microw. Symp. Dig., Jun. 1991, pp. 1265–1268.
[40] L. Dussopt and J. M. Laheurte, “Coupled oscillator array generating circular polarization,” IEEE Microw. Guided Wave Lett., vol. 9, pp. 160–162, Apr. 1999.
[41] H. N. Chu, Y.-Y. Chen, Y.-L. Tsai, and T.-G. Ma, “Low-cost polarization sensing system for self-oscillating circularly-polarized active integrated antenna” IEEE Access, vol. 7, pp. 170534-170544, 2019.
[42] H. N. Chu, , Y.-L. Tsai, and T.-G. Ma, “Self-oscillating Circularly-Polarized Active Integrated Monopole Antenna Using Cross-Coupled Pair and Inverted-L Strip” IEEE Antennas and Wireless Propagation Letters., Apr. 2020.