Broadband VLF loop antenna system

• US 3,953,799 A
• Filed: 04/09/1971
• Issued: 04/27/1976
• Est. Priority Date: 10/23/1968
• Status: Expired due to Term

• Current Assignee: Amphenol Corporation
• Original Assignee: Bunker Ramo Corporation
• Inventors: Albee, Thomas K.
• Primary Examiner(s): Safourek, Benedict V.
• Application Number:
  US05/132,895
• Time in Patent Office: 1,845 Days
• Field of Search: 325/365, 325/373, 325/374, 325/376, 325/381, 325/382, 325/383, 325/385, 325/387, 325/427, 343/700, 343/722, 343/745, 343/748, 179/170 R, 179/170 G, 333/24.1, 333/80 R, 333/807
• US Class Current: 455/291
• CPC Class Codes: H01Q 23/00 Antennas with active circuits or circuit elements integrated within them or attached to them

Abstract

A loop antenna system including a negative reactance circuit and having a bandwidth of several octaves in the low frequency bands.

Claims

1. A broadband antenna system capable of operation over an operating band of a plurality of octaves in the low frequency bands ranging from approximately three kilohertz to three hundred kilohertz without requiring tuning to resonance for individual frequencies within the band, said antenna system comprising:

an antenna adapted for antenna operation in said low frequency bands, said antenna having an inherent inductance L₁ providing an inductive reactance X_L.sbsb.1 which varies with frequency f over said operating band in accordance with the equation X_L.sbsb.1 = 2π

fL₁, and

a negative inductive reactance circuit electrically coupled in parallel with said antenna and having a negative inductance -L₂ chosen to provide a negative inductive reactance X_L.sbsb.2 = 2π

f(-L₂) over said operating band which is substantially equal to the inductive reactance X_L.sbsb.1 provided by said inherent inductance.

2. The invention in accordance with claim 1, wherein said antenna is a loop antenna comprising a large number of wire turns wound around a large support so as to provide sufficient effective antenna length for operation in said low frequency bands.

3. The invention in accordance with claim 2, wherein said negative inductive reactance circuit comprises a balanced type of negative impedance converter employing a pair of transistors interconnected for cross-coupling phase inverting feedback.

4. The invention in accordance with claim 3, wherein each of said transistors has emitter, collector and base electrodes, wherein the emitter electrodes of said transistors are connected to each other through an inductor, wherein the collector electrodes of each of said transistors are transformer coupled to the base electrodes of the other of said transistors, and wherein the inductance of said inductor has an inductance substantially equal to said inherent inductance of said antenna.