Low-profile steerable cardioid antenna
US5202697A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 18, 1991 |
| Grant date | Apr 13, 1993 |
| Priority date | — |
| Expiry date | Jan 18, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01Q3/24
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A multimode low-profile avionics antenna is disclosed for use in Automatic Direction Finder (ADF) systems. The low profile antenna generates a steerable cardioid radiation pattern having a minimum bandwidth of 30% and an unusual degree of independence from mutual coupling and coupling to ground-plane currents. The antenna includes two resonant cavity-backed slot antennas. The upper cavity, which backs a directional crossed-slot antenna, is the larger of the two cavities. The shallow lower cavity is actually a short-circuited radial transmission line employing a stepped inner radius and band-switching to extend the operating bandwidth to the required 30%. The crossed-slot antenna elements are configured orthogonally and the slot ends are folded over the side of the cylindrical cavity to minimize the resonant cavity diameter for the requisite slot length. The slot width is stepped open at the crossover point to enhance antenna bandwidth and to provide for greater spacing between the symmetrically-located feedpoints. The shallow circumferential slot antenna is equipped with two band-switched inductances for wider bandwidth. The two stacked cavities have a combined height of less than …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.