Ultracompact Retrodirective Antenna Arrays With Superdirective Radiation Patterns

It is shown that the direction-of-arrival (DoA) information carried by an incident electromagnetic (EM) wave can be encoded into the evanescent near field of an electrically small resonance antenna array with a spatial rate higher than that of the incident field oscillation rate in free space. Phase conjugation of the received signal leads to the retrodirection of the near field in the antenna array environment, which in turn generates a retrodirected far-field beam toward the original DoA. This EM phenomenon enables electrically small retrodirective antenna arrays with superdirective, angular super-resolution, auto-pointing properties for an arbitrary DoA. A theoretical explanation of the phenomenon based on first principal observations is given and full-wave simulations demonstrate a realizability route for the proposed retrodirective terminal that is comprised of resonance dipole antenna elements. Specifically, it is shown that a three-element disk-loaded retrodirective dipole array with 0.15\lambda spacings can achieve a 3.4-dBi maximal gain, 3-dBi front-to-back ratio, and 13% return loss fractional bandwidth (at the 10-dB level). Then, it is demonstrated that the radiation gain of a three-element array can be improved to approximately 6 dBi at the expense of the return loss fractional bandwidth reduction (2%).

Broadband Dual-Polarized Antenna with High Port Isolation and Polarization Purity

This paper presents a novel high symmetry balun which significantly improves the performance of dipole-based dual-polarized antennas. The new balun structure provides enhanced differential capability leading to high performance in terms of port-to-port isolation and far-field cross polarization. An example antenna using this balun is proposed. The simulated results show 53.5% of fractional bandwidth within the band 1.71−2.96 GHz (VSWR<1.5) and port-to-port isolation >59 dB. The radiation characteristic shows around 9 dBi of gain and far-field cross polarization <−48 dBi over the entire bandwidth. The detailed balun functioning and full antenna measurements will be presented during the conference. Performance comparison with similar structures will be also provided.

From brown envelopes to community benefits: the co-option of planning gain agreements under deepening neoliberalism

The provision of physical and social infrastructure in the form of roads, green spaces and community facilities has traditionally been provided for by the state through the general taxation system. However, as the state has been transformed along more neoliberal lines, the private sector is increasingly relied upon to deliver public goods and services. Planning gain agreements have flourished within this context by offering another vehicle through which local facilities are privately funded. Whilst these agreements reflect the broader dynamics of neoliberalism, they are commonly viewed as a tool which can be employed to challenge these very dynamics by empowering local communities to secure more just planning outcomes. This paper counters such claims. Based on evidence gathered from 80 interviews with planners, councillors, developers and community groups in Ireland, the paper demonstrates how planning gain agreements have been strategically redeployed by the holders of political and economic power to serve their own ends. In seeking to understand why and how this has occurred, specific consideration is given to the changing power dynamics between the state and private capital under neoliberalism. The paper highlights how institutional arrangements have enabled developers to infiltrate the political sphere in more subtle and implicit ways than ever before. We conclude by arguing that planning gain must be understood as a mechanism which has been manipulated in ways which essentially work to preserve and enhance, rather than redress, existing power imbalances in the planning system by facilitating large scale transfers of wealth upwards in society.