HF antennas for wideband signals

Details HF antennas for wideband signals HF antennas for wideband signals

1999-11-29

2001-02-20

Ho, Tan (Department: 2821)

Communications: radio wave antennas

Antennas

Loop type

C343S717000

Reexamination Certificate

active

06191752

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to radio frequency (RF) antennas and, more particularly, to high frequency (HF) antennas for wideband signals used in the tracking of railcars.
2. Description of the Prior Art
U.S. Pat. No. 5,588,005 to Ali et al. and assigned to the instant assignee describes the tracking of assets, including goods and vehicles, using the Global Positioning System (GPS). While goods are an example of assets that need to be tracked, the containers, container trucks and railcars in which the goods are shipped are themselves assets which need to be tracked, not just because of the goods they carry, but also because they represent capital assets typically of a leasing company not associated with the carrier.
The mobile tracking unit used in the Ali et al. system includes a navigation set, such as a Global Positioning System (GPS) receiver or other suitable navigation set, responsive to navigation signals transmitted by a set of navigation stations which can be either space-based or earth-based. The navigation set is capable of providing data indicative of the vehicle location, based on the received navigation signals. In addition, the mobile tracking unit can include a suitable electromagnetic emitter for transmitting to a remote location the vehicle position data and other data acquired through use of sensing elements in the vehicle.
One of the options available for tracking railcars involves transmission of a wideband HF signal from the tracked railcar. The frequency of interest and the railcar environment make the problem of efficient antenna design especially difficult. Neither a whip antenna or large erect loop antenna is deemed a viable candidate as it would be expected to suffer environmental damage and/or exceed the template limits for the railcar which are set by the railcar industry in order that the railcar may traverse rail systems of appropriate gauge without ordinarily suffering or causing damage. As the antenna is a critical element of such communications system, what is needed is a suitable antenna which is especially adapted for use on a railcar.
A primary requirement for the antenna is that it be rugged. The railcar environment is notoriously hostile. Any antenna mounted on a railcar would be subject to vibration, shock, abrasion, high humidity, extreme dryness, heat, cold and vandalism.
BRIEF SUMMARY OF THE INVENTION
Two forms of antenna for the special and unaddressed application of fitting an HF antenna underneath the carriage of a railcar are provided. One antenna is a magnetic loop composed of rugged materials such as pipes or rods. The other is an electric field antenna which is an excited, ruggedly mounted plate located just below the undercarriage, with an optional dielectric slab between the plate and the undercarriage. Optimal parameters for an antenna fitted underneath the carriage of a railcar are a function of the specific railcar type and construction. Therefore, the antennas described herein are not specified in terms of optimal parameters; rather, the approach taken in the practice of the invention is to provide a generic antenna structure adapted to being mounted underneath the carriage of a railcar. This generic structure exhibits a mitigated Q and capability of broadband tuning. This makes it easier and less costly to produce the antenna in large quantities and facilitates use of a standard mounting mechanism and installation procedure.


REFERENCES:
patent: 1484049 (1924-02-01), Zworykin
patent: 2005519 (1935-06-01), Crosley, Jr.
patent: 2020656 (1935-11-01), Renz
patent: 2055830 (1936-09-01), Vincent
patent: 3675128 (1972-07-01), Abele
patent: 5005021 (1991-04-01), Kato et al.
patent: 5588005 (1996-12-01), Ali et al.

Affiliated with

Also associated with

Rating

HF antennas for wideband signals does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with HF antennas for wideband signals, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and HF antennas for wideband signals will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2575430