Wideband Electrically Small Antennas and Array Derivatives Thereof at HF and Beyond
Abstract
Antenna miniaturization and bandwidth enhancement at the extended HF band (2-30MHz) is a difficult challenge. Narrowband and receive,-only antennas are typically integrated with a tuner that adjusts to a given HF channel a priori thus limiting multifunction and spe,ctrum coverage, which instantaneous ultrawideband (UWB) coverage allows for. For ultra-wideband (UWB) transmit coverage, the current, state-of-the-art is large log-periodic antenna. To design new electrically small UWB HF antennas, the primary challenge is the 150m, to 10m wavelengths necessitating the use of e,g the amount of reactive energy stored in the antenna sphere leads to decreased Q and thus increased bandwidth. Most often, this man,ifests in increasing the volume utilization efficiency of the antenna through broadening the structure. Additional methods for minia,turization include distributed or localized lumped-element loading, combination of lowest order TE and TM modes, non-Foster and othe,r active circuit-based matching, and/or the use of mechanical resonances or physical motion of charged/magnetized objects. In respon,se to these challenges, the University of Colorado Boulder (UCB) shall research, design, and experimentally demonstrate:(1) wideband, singly and dual-polarized ESAs,(2) conventional and tightly coupled arrays with beam-scanning,(3) design for manufacturing (DFM) to, emphasize low-cost, easy setup, and concealment,(4) energy recycling to increase ESA?s transmit compound efficiency to >80%, and(5), a low-cost, portable, and easily deployable UAV-based HF antenna measurements system.The initial ESA configuration is a combined lo,op and TEM horn usable for all three HF modes of propagation. The antenna has a structurally embedded impedance matching configurati,on that motivates research on energy recycling in the transmit mode. To achieve dual-polarized operation, two of these shall be plac,ed into an orthogonal arrangement and optimized using full-wave techniques including the impact of the real ground. Arrays of tightl,y coupled elements as well as herein developed ESAs shall also be designed. The DFM of the antennas will include easy deployment wit,h minimum compromise in RF performance. A portable UAV-based measurement system for HF antennas and arrays shall also be investigate,d and experimentally demonstrated.This project addresses several HF antenna shortfalls important for the navy, including:(1) large p,hysical sizes of communication and surveillance antennas restricting their deployment and visual as well as radar cross section conc,ealments;(2) ESA issues including:o narrow bandwidth and therefore low data rates,o low power handling and therefore short communica,tion range, ando high losses with respect to their radiation resistance and therefore low gain;(3) different grounds causing detunin,g and therefore communication blackouts;(4) diversity of the required radiation patterns limiting use for all three HF propagation m,odes;(5) irreversible power loss due to the high ohmic loss resistance of loaded ESAs;(6) phased arrays being too big and expensive,for many applications; and(7) the difficulty of in-situ measurements of HF antennas and arrays, but it being necessary to address th,e performance impact of temporal changes in the environment and/or antenna(s).Successful outcomes of this research can lead to incre,ased mission effectiveness and enhanced survivability of personnel and the naval land, sea, and airborne platforms they crew. If suc,cessful, this research will pave the way for the future low-cost fixed, mobile, and distributed RF front-end configurations at HF an
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Dec 06, 2022
- Source ID
- N000142312120
Entities
People
- Dejan S. Filipovic
Organizations
- Office of Naval Research
- Regents of the University of Colorado
- United States Navy