US3702478A

US3702478A - Antenna and antenna coupling apparatus

Info

Publication number: US3702478A
Application number: US178865A
Authority: US
Inventors: Flefterios Georgian
Original assignee: US Air Force
Current assignee: US Air Force
Priority date: 1971-09-09
Filing date: 1971-09-09
Publication date: 1972-11-07
Anticipated expiration: 1989-11-07

Abstract

An antenna and antenna coupling apparatus is provided in which a receiving antenna is used with a super regenerative transponder receiver. The antenna comprises a coaxial cable which has the outer conductor stripped away from the inner conductor at one end and both the outer conductor and inner conductor bent so as to be at right angles. At the other end of the cable the outer conductor is also stripped away from the inner conductor and both are also bent at right angles. The coaxial cable passes through a shield enclosing the receiver and is soldered at the center of the bottom of the shield thus coupling the antenna to the receiver.

Description

United States Patent Georgian [451 Nov. 7, 1972 ANTENNA AND ANTENNA COUPLING APPARATUS Primary Examiner-Eli Lieberman Attorney-Harry A. Herbert, Jr. et al.

[72] Inventor: Flelterlm Georgian, Andover, Mass.

[73] Assignee: The United States oi America as [57] ABSTRACT "puma! by the An antenna and antenna coupling apparatus is provided in which a receiving antenna is used with a [22] Filed: Sept. 9, 1971 super regenerative transponder receiver. The antenna comprises a coaxial cable which has the outer conduc- PP'- 178,365 tor stripped away from the inner conductor at one end and both the outer conductor and inner conductor [52] US. Cl. "343/702, 343/820 bent so as to be at right angles. At the other end of the [51] m. Cl. .Jlfllq 1/24 cable the conductor is also stripped y from 5 m of Sal-ch 343/702 793 20 2 22 the inner conductor and both are also bent at right angles. The coaxial cable passes through a shield enclosing the receiver and is soldered at the center of the [56] Rah Cited bottom of the shield thus coupling the antenna to the UNITED STATES PATENTS receiver.

3,447,157 5/1969 Tranin ..343/702 2 Claims, 2 Drawing Figures Ills l l 9i un i w 2 L ,1 PM. Job

- l e o o" J PATENTEDmv 1m 3.702.478

sum 1 er 2 NVENTOR.

I LEFTER/OS .1 650A Mvv Mf /5M ANTENNA AND ANTENNA COUPLING APPARATUS BACKGROUND OF THE INVENTION This invention relates to antennas and more particularly to a coaxial fed dipole antenna and the coupling thereof to a transponder receiver by utilizing a receiver shield.

In the past, radio frequency interference has been a major problem with transponder rocketsondes. Also the signal received by the antenna was fed to the receiver which included an antenna matching network. The receiver required a resistor, capacitor and inductive coupling loop. The bandwidth as a result was wide and additional noise and interference resulted.

The present invention provides unique features so that a shield is used for both shielding and for coupling to the receiver. No antenna matching network is necessary. The antenna is a direct current short circuit to the receiver shield, but at a preselected signal frequency it provides excellent coupling, or energy transfer, to the receiver oscillator. The receiver has a narrower bandwidth and better sensitivity.

SUMMARY OF THE INVENTION A coaxial fed dipole antenna and antenna coupling apparatus therefor is provided. The antenna is coupled to a solid state super regenerative receiver. The receiver is also provided with and enclosed by a radio frequency shield which is part of the coupling apparatus. The receiver is an integral part of a meteorological transponder rocketsonde. The antenna consists of a single center coaxial cable which has the outer conductor stripped away from the inner conductor at the first end and both the outer and inner conductors bent so as to be at right angles from the trunk of the coaxial cable, so as to be at l80 to maintain quarter wave relationship to the received signal. At the second end of the coaxial cable the outer conductor is also stripped away from the inner conductor and both are also bent at right angles to the trunk of the cable. The coaxial cable prior to the bending at the second end passes through the top of the receiver shield and after bending is connected to the center of the bottom of the shield. The solid state receiver is disposed upon a receiver printed circuit board which is positioned inside the shield at a preselected distance from the bottom thereof. The receiver is provided with an input coupling loop which is located at the bottom surface of the printed circuit board. The single center coaxial cable is utilized to provide an antenna for the receiver and is also utilized in combination with the radio frequency shield to provide the coupling apparatus to the input loop to the receiver.

DESCRIPTION OF THE DRAWINGS FIG. I shows the coaxial cable with the first and second end thereof arranged on a dipole and as a portion of the coupling apparatus, respectively;

FIG. 2 shows the coaxial cable arrangement of FIG. 1 in combination with the solid state super regenerative receiver and the electromagnetic shield associated therewith.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring in detail to FIG. 1, there is shown a single center coaxial cable 10 which is conventional and may be of the RG-l 78 EN type. In this embodiment a solid state super regenerative receiver is to be fed a signal at 403 MHz. In accordance therewith, coaxial cable 10 was designed so that its original overall length was 22 It inch. Outside shield 10a is stripped back 6% inches at one end of cable 10 and bent at approximately a right angle to the trunk of cable 10. Center conductor 10b is bent back at approximately a right angle and is also 6% inches in length. Conductors 10a and 10b are approximately at a 180 angle thus providing a one fourth wavelength dipole at 403 MHz. Outside shield 10c is stripped back three-eighths inch at the other end of cable 10 and bent back at approximately a right angle to the trunk of cable 10. Center conductor 10d is also bent at approximately a right angle and is also threeeighths inch in length. Conductors 10c and 10d form about a 120 angle although this is not critical.

Now referring to FIG. 2, there is shown copper electromagnetic shield 11 which serves as a radio frequency shield. Shield 11 is comprised of cylinder Ila sealed at one end and cylinder 11b also sealed at one end. Cylinder 11a is pressure fitted to cylinder 1 lb to form shield 11. In this embodiment shield 1 1 has a diameter of approximately 1 98 inches and a depth of inch.

Solid state receiver 12 is a super regenerative receiver that is arranged on a printed circular circuit board and has a diameter slightly less than i 56 inches so that if desired it may be pressure fitted into cylinder 11b. Solid state receiver 12 is provided with coupling loop 13 at the input thereof and is part of a tuned input circuit of the receiver. Receiver 12 also is provided with signal output line 14 and power input line I5.

Prior to pressure fitting cylinder 11a to 1 1b to form shield 11 holes are drilled through the top of cylinder 1 la for coaxial cable 10 and

lines

14 and 15. A hole in receiver 12 is also provided for the passage therethrough of cable 10. Outer shield conductor 10c and inner conductor 10d are bent as hereinbefore described after passage through cylinder 11a and receiver 12. Conductors 10c and 10d are then soldered to the bottom of cylinder 1 lb and an insulating epoxy is spread over the bottom to a depth of 0.095 inches to provide a preselected critical spacing between the bottom of cylinder 11b and the bottom of receiver 12. Thereupon cylinder 11a and 11b are pressure fitted to provide shield 11 enclosing receiver 12 with the antenna assembly integrated therewith.

Thus the present invention uses a radio frequency shield not only for shielding, but also for electromagnetic coupling. The antenna coaxial cable passes through the top of the radio frequency shield and is grounded at the region of the center of the bottom of this shield. The 0.095 inch spacing is critical and is provided by a dielectric epoxy to hold the receiver electronic printed circuit board above the bottom of the radio frequency shield to maintain the proper electromagnetic coupling from dipole 10a, 10b to receive input loop 13. It is noted that the spacing may also be provided by spacers rather than by epoxy. It is emphmized that shield l 1 serves a dual purpose, it is an effective radio frequency shield and also an efficient coupling loop between fipole a, 10b and solid state super regenerative receiver 12.

What is claimed ie:

Lkcoaatiaiieddipoieantennaandcouplingapparatus therefor for rocketsonde utilization comprising a solid stare super regenerative receiver having a tuned input circuit including as input coupling loop, said super regenerative receiver be'mg tuned to a predetermined ultra llifli Frequency, a printed circuit board integrated with said solid state super regenerative receiver with input coupling loop being positioned at the bottom of said printed circuit board, an electromagnetic shield completely enclosing said solid state super remative receiver having a top and bottom, a coaxial cable of a first preselected length and havin first and second ends and single center and outside condoctors, at said first end said outer conductor being stripped may a second preselected length and bent in conjunction with the associated inner conductor at approximately a 180 angle to the trunk of said coaxial cabie to form a dipole antenna to provide a quarter wave relationship to said predetermined ultra high frequency. at said second end said outer conductor being stripped away a third lengds and bent in with the associated inner conductor at approximately a X20 angle to the trunk ofsaid coaxial cable to form an electricd connection soldered to the inner bottom of said electromagnetic shield, and means to space said printed circuit board a critical predetermineddistancefromsaid innerbottomofsaid electrornagietic shield with said input coupling loop of said solid state super regenerative receiver being adjacent to said electrical connection.

2. A coaxiai fed dipole and coupling apparatus therefor as described in claim 1 wherein said electromagnetic shield is comprised of a cylinder sealed at the bottom and top thereof, said cylinder having a preselected diameter and depth, and said printed circuit board being circular and of slightly less diameter than said cylinder for pressure fitting therein.

* i t l i

Claims

1. A coaxial fed dipole antenna and coupling apparatus therefor for rocketsonde utilization comprising a solid state super regenerative receiver having a tuned input circuit including an input coupling loop, said super regenerative receiver being tuned to a predetermined ultra high frequency, a printed circuit board integrated with said solid state super regenerative receiver with said input coupling loop being positioned at the bottom of said printed circuit board, an electromagnetic shield completely enclosing said solid state super regenerative receiver having a top and bottom, a coaxial cable of a first preselected length and having first and second ends and single center and outside conductors, at said first end said outer conductor being stripped away a second preselected length and bent in conjunction with the associated inner conductor at approximately a 180* angle to the trunk of said coaxial cable to form a dipole antenna to provide a quarter wave relationship to said predetermined ultra high frequency, at said second end said outer conductor being stripped away a third preselected length and bent in conjunction with the associated inner conductor at approximately a 120* angle to the trunk of said coaxial cable to form an electrical connection soldered to the inner bottom of said electromagnetic shield, and means to space said printed circuit board a critical predetermined distance from said inner bottom of said electromagnetic shield with said input coupling loop of said solid state super regenerative receiver being adjacent to said electrical connection.

2. A coaxial fed dipole and coupling apparatus therefor as described in claim 1 wherein said electromagnetic shield is comprised of a cylinder sealed at the bottom and top thereof, said cylinder having a preselected diameter and depth, and said printed circuit board being circular and of slightly less diameter than said cylinder for pressure fitting therein.