US3909830A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Tactical high frequency antenna
Assignee: United States Department of the Army
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Filing: 1974-05-17
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Granted: 1975-09-30
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Expires: 1994-05-17
Abstract
Abstract An electrically short (less than lambda /4) antenna for operation in the frequency range from 2 to 30 megahertz (MHz). The antenna system contemplated by the subject invention comprises a short inductively loaded vertical radiating element having a capacitive top termination, a ground system and an automatic remote control of the tuning of the antenna which senses the state of resonance of the antenna and operates to drive a tuning reactance, e.g. a variable capacitor in series with the vertical radiator element to provide the required lambda /4 resonance at a given operating frequency.
Inventors
- 👤 Donn V Campbell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 10:21
CPC Classifications
H; H01; H01Q; H01Q9/00; H01Q9/04; H01Q9/06; H01Q9/14; H01Q9/145; H01Q5/00; H01Q9/30; H01Q9/32
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
321 words
A tunable high frequency antenna system, typically but not restricted for use in the frequency range of from 2 to 30MHz, comprising in combination: an electrically short, normally vertical radiating element having a physical length less than a quarter wavelength for the desired frequency of operation; a capacitive top termination coupled to the upper extremity of said radiating element; a first controlled electrical reactance connected in series to said radiating element comprising an inductor having a plurality of inductance taps, said first reactance being selectively adjustable in valve to provide a coarse tuning of said radiating element to a predetermined frequency band within a selected frequency range comprised of a plurality of overlapping bands; a switch means coupled to said inductance taps for selectively connecting a portion of said inductance with said radiating element; a second controlled electrical reactance connected in series with said radiating element and said first reactance wherein said second reactance comprises a variable capacitance to provide a fine tuning of said radiating element within said predetermined frequency band; first conduit means for feeding a radio frequency signal to said radiating element including a broadband transformer having a secondary winding connected in series with said radiating element and said first and second reactances; a ground system connected in series with said first and second reactances, and said secondary winding; second circuit means coupled to said first circuit means and being responsive to the resonance state of said radiating element to provide an elecTrical output signal indicative of said resonant state; and third circuit means coupled to said second circuit means and being responsive to said output signal provided thereby to generate a control signal to vary said first and second reactances in directions to effect resonance of said radiating element; means controlled from said third circuit means for remotely operating said switch means coupled to said inductance taps for selectively shortening out a selected portion of said inductor.
Claim 2
Dependent Claim
321 words
A tunable high frequency antenna system, typically but not restricted for use in the frequency range of from 2 to 30MHz, comprising in combination: an electrically short, normally vertical radiating element having a physical length less than a quarter wavelength for the desired frequency of operation; a capacitive top termination coupled to the upper extremity of said radiating element; a first controlled electrical reactance connected in series to said radiating element comprising an inductor having a plurality of inductance taps, said first reactance being selectively adjustable in valve to provide a coarse tuning of said radiating element to a predetermined frequency band within a selected frequency range comprised of a plurality of overlapping bands; a switch means coupled to said inductance taps for selectively connecting a portion of said inductance with said radiating element; a second controlled electrical reactance connected in series with said radiating element and said first reactance wherein said second reactance comprises a variable capacitance to provide a fine tuning of said radiating element within said predetermined frequency band; first conduit means for feeding a radio frequency signal to said radiating element including a broadband transformer having a secondary winding connected in series with said radiating element and said first and second reactances; a ground system connected in series with said first and second reactances, and said secondary winding; second circuit means coupled to said first circuit means and being responsive to the resonance state of said radiating element to provide an elecTrical output signal indicative of said resonant state; and third circuit means coupled to said second circuit means and being responsive to said output signal provided thereby to generate a control signal to vary said first and second reactances in directions to effect resonance of said radiating element; means controlled from said third circuit means for remotely operating said switch means coupled to said inductance taps for selectively shortening out a selected portion of said inductor.
Claim 3
Dependent Claim
25 words
The antenna system as defined by claim 1 and additionally including electrically operable driver means responsive to said control signal for mechanically varying said capacitance.
Claim 4
Dependent Claim
22 words
The antenna system as defined by claim 1 wherein said ground system comprises a counterpoise located a predetermined distance above the ground.
Claim 5
Dependent Claim
34 words
The antenna system as defined by claim 3 wherein said counterpoise comprises a plurality of radially oriented wire conductors lying substantially in a horizontal plane and being suspended a predetermined distance above the ground.
Claim 6
Dependent Claim
103 words
The antenna system as defined by claim 3 wherein said first circuit means includes an RF transmission line, a portion of which comprises a cable choke for operating in combination with said counterpoise to suppress feed line current and ground losses. 6. The antenna system as defined by claim 1 wherein said first circuit means includes an RF transmission line and a primary winding coupled to said secondary winding and said primary winding being coupled to said radio frequency signal via said transmission line; and wherein said second circuit means comprises a tuning detector coupled to said primary winding of said matching transformer.
Claim 7
Dependent Claim
64 words
The antenna system as defined by claim 1 wherein said first circuit means includes: an RF transmission line, a primary winding coupled to said secondary winding and being coupled to said radio frequency signal by means of said transmission line; and wherein said second circuit means comprises a tuning detector including circuit means for being coupled between the secondary winding and said radiating element.
Claim 8
Dependent Claim
49 words
The antenna system as defined by claim 7 wherein said ground system comprises a counterpoise located a predetermined distance above the ground; and wherein said RF transmission line includes a cable choke portion therein for operating in combination with said counterpoise to suppress feed line current and ground losses.
Claim 9
Dependent Claim
64 words
The antenna system as defined by claim 8 wherein said second conduit circuit means and said third circuit means are coupled together by means of a transmission line a portion of which is configured as a cable choke; and wherein said third circuit means and said second reactance is coupled by means of an electrical cable, a portion of which comprises a cable choke.
Claim 10
Dependent Claim
16 words
The antenna system as defined by claim 1 wherein said ground system comprises a vehicle body.
Claim 11
Dependent Claim
35 words
The antenna tuning system as defined by claim 1 wherein said second circuit means comprises phase sensor apparatus adapted to measure the phase relationship between the excitation voltage and current of said radio frequency signal.
Claim 12
Dependent Claim
34 words
The antenna system as defined by claim 1 wherein said capacitive top termination comprises a plurality of elements extending radially outward from said radiating element in a plane substantially parallel to said ground system.
Claim 13
Dependent Claim
50 words
The antenna system as defined by claim 3 further including an electrically driven rotary selector switch coupled to said taps and being operable to short a selected portion of said inductor in response to another control signal from said third circuit means to effect coarse tuning of said radiating element.
Claim 14
Dependent Claim
64 words
The antenna system as defined by claim 13 wherein said second circuit means and said third circuit means are coupled together by means of an electrical transmission line, a portion of which is configured as a cable choke; and wherein saiD third circuit means and said second reactance is coupled by means of an electrical cable, a portion of which comprises a cable choke.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-29 | 1979-03-31 | 1979-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-29 | 1983-03-31 | 1983-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-29 | 1987-03-31 | 1987-09-30 | $7700.00 | Window Closed / Lapsed |