US3611389A

US3611389A - Vor antenna

Info

Publication number: US3611389A
Application number: US1651A
Authority: US
Inventors: Erich Coors; Kurt Tanzer
Original assignee: International Standard Electric Corp
Current assignee: Alcatel Lucent NV
Priority date: 1969-01-22
Filing date: 1970-01-09
Publication date: 1971-10-05
Anticipated expiration: 1988-10-05
Also published as: FR2033258B1; DE1902884B2; NL7000933A; GB1258656A; SE351752B; AT295603B; FR2033258A1; DE1902884A1

Abstract

A VOR antenna construction using printed circuit techniques for the radiators as well as for the balun transformers. The rotating cardioid pattern is generated by the combination of a turnstile and a loop antenna fed independent with modulated sideband energy and carrier energy, respectively. The printed circuit loop antenna includes eight arcuate sections surrounding four printed circuit half-dipoles disposed in a cross configuration to form the turnstile antenna. The arcuate sections are all fed in balance from a central feed point by printed circuit slotted transformers. The VOR antenna may be enclosed in a polarization cage.

Description

United States Patent [72] lnventors Erich Coors; 2,874,276 2/1959 Dukes et a1. 333/84 M Kurt Tanzer, both of Geisingen, Germany 3,348,228 10/ 1967 Melancon 343/ 821 X [21] Appl. No. 1,651 3,521,284 7/1970 Shelton, Jr. et a1. 343/727 X [22] Filed Jan. 9, 1970 FOREIGN PATENTS [45] Patented Oct. 5, 1971 [73] Assignee International Standard Electric 621,609 6/1961 Canada 343/727 Corporation Primary Examinerl-lerman Karl Saalbach New York, NY. Assistant Examiner-Saxfield Chatmon, Jr. [32] Priority Jan. 22, 1969 Attorneys-C. Cornell Remsen, Jr., Walter J. Baum, Paul W. [33] Germany Hemminger, Percy P. Lantzy, Philip M. Bolton, lsidore [31] P 19 02 884.3 Togut and Charles L. Johnson, Jr.

[54] VOR ANTENNA 7 Claims, 9 Drawing Figs.

[52] US. Cl 343/726, ABSTRACT: A VQR antenna canal-union using primed 343/859 343/730 333/84 343/821, 343/743 cuit techniques for the radiators as well as for the balun trans- [51] Int. Cl H0lq 9/16, f The rotating cardioid pattern is generated by the H013 7/00 combination of a turnstile and a loop antenna fed independent [50] Field of Search 343/859, with modulated b d energy d carrier energy, respec- 893, 725, 726, 727, 728, 729, 730, 797, 821, 854, tively. The printed circuit loop antenna includes eight arcuate 8953 333/84 M sections surrounding four printed circuit half-dipoles disposed 56 R (med in a cross configuration to form the turnstile antenna. The ar- 1 e erences cuate sections are all fed in balance from a central feed point UNITED STATES PATENTS by printed circuit slotted transformers. The VOR antenna may 2,493,569 l/1950 Brown, Jr. 343/821 X be enclosed in a polarization cage.

F a l. 4- l L Tr- I x I M T1; 1 F p L I F X TI C l -Tr L FUENTES hm 5am f 3.611.389

saw 2 or Fig.5 7

INVENTQRS 5121c QQ KURT TA A/ZER AGENT VOR ANTENNA I BACKGROUND OF THE INVENTION The invention relates to an antenna system for short electromagnetic waves, in particular for the VHF and UHF- ranges. It chiefly serves to radiate the VOR-signal (rotating cardioid) in conjunction with a corresponding transmitter. The antenna system, however, may also be used for other items, for example, in connection with a single-channel direction-finding receiver.

Unlike the early VOR-systems, the rotating directional pattern (cardioid) is generated by stationary antennas. Both the reception and the evaluation of the signal in the receiver may be carried out in the usual way.

In the early VOR-antenna designs, the rotating directional pattern results from a superposition of the patterns generated by two antenna systems. For instance, a disk antenna (mnidirectional pattern) and a mechanically rotating folded dipole antenna (rotating dipole pattern) together generate the cardioid pattern rotating at a frequency of Hz.

This antenna arrangement requires a considerable mechanical investment and owing to the rotating parts (bearing, rotating joint) it is subjected to wear and susceptible to interferences.

For operating the driving motor (synchronous motor) for the dipole there is required AC voltage with a frequency of 60 Hz. which, in the case of the 50 Hz. mains as customary in Europe has to be specially produced by a frequency generator. The power consumption of the entire system is rather high; it amounts to about 3 kw.

In addition to the foregoing there is another known type of design operating with stationary (loop) antennas.

In this type of embodiment four antennas are symmetrically arranged around a center antenna which is used for transmitting the omnidirectional characteristic. Each the two oppositely disposed antennas are connected together in opposite phases.

Each pair generates a figure-of-eight pattern (similar to a dipole). The two pairs are spatially shifted by 90 and receive their energy from a rotating capacitive goniometer having displaced electrodes according to a sine or cosine function respectively. The two generated partial fields form one resulting field rotating synchronously with the goniorneter rotation.

In one variant type of this system the center antenna has been omitted, and the four remaining antennas are also used for radiating the omnidirectional pattern by having all four antennas supplied in-phase with carrier energy.

In this type of system considerable errors result from the noncircular figure-of-eight characteristic owing to the distance of the loops, owing to the noncircularity of the pattern of the center antenna, as well as owing to the decentralization of the antennas.

In more recent types of systems, therefore, there is used a rotating directional antenna for generating the figure-of-eight pattern.

A further disadvantage of these systems comprising four or five stationary antennas resides in the fact that, when radiating, there exists a considerable vertical component in addition to the desired horizontal component. This vertical component is likely to cause errors when measuring the azimuth at the receiver.

By using so-called polarization cages, it is known that the radiated vertical component can be considerably reduced, thereby increasing the accuracy when measuring the azimuth at the receiver (see for instance, German Pat. Nos. 815,052; 831,419; 901,665; 917,61 1; 1,044,184). In practice, however, it is impossible in connection with stationary antennasto use a polarization cage for the purpose of reducing the vertical component. This is chiefly due to the large spatial extension of the antenna system. Up to now in VCR-beacons, in connection with polarization cages, there have only been used mechanically rotating dipoles, such as a folded dipole.

It has likewise become known to generate a cardioid-shaped radiation pattern by combining a dipole pattern (figure-ofeight pattern) with an omnidirectional pattern.

SUMMARY OF THE INVENTION It is the object of the present invention, therefore, to provide a stationary antenna which is suitable for generating a rotating cardioid pattern and which, with respect to its dimensions, is constructed in such a way that it can be built into a polarization cage having a size capable of being used in practice, i.e. having a diameter of about A12) which is small with respect to the wavelength A Generally speaking, therefore, the invention relates to a VCR-antenna system for short-electromagnetic waves, in particular for use in the VHF and UHF-ranges.

A feature of the present invention is the provision of a VCR-antenna comprising a tumstile antenna and a loop antenna symmetrically arranged around the tumstile antenna; the tumstile antenna and the loop antenna including flat printed circuit components disposed on a common baseplate of insulating material.

According to another feature of the present invention there are electrically combined a tumstile antenna including current-supplied, stretched, electrically short dipoles, and a cur.- rent-supplied loop antenna which is symmetrically arranged around the tumstile antenna.

A third feature of the present invention resides in that all elements of the antenna system consist of flat components arranged in one plane.

Accordingly, the antenna elements are of a flat design (in accordance with known printed circuit technique also known as strip-line technique) and are arranged on a common base plate.

BRIEF DESCRIPTION OF THE DRAWING The above-mentioned and other features and objects of this invention will become more apparent by reference to the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic diagram of the VCR-antenna inaccordance with the principles of the present invention;

FIG. 2 is a top plan view of the dipoles of FIG. 1 and the balun transformers employed to feed the loop antenna of FIG. I;

FIG. 3 is a cross-sectional view taken along line A--A of FIG. 2;

FIG. 4 is a schematic diagram of the loop antenna of FIG. I and balun transformers employed therewith;

FIG. 5 is a Smith Chart showing the transformation provided by the balun transformers of FIG. 4;

FIG. 6 is an exploded view of one of the balun transformers of FIG. 4;

FIG. 6ais an end viewof the balun transformer of FIG. 6; and

FIGS. 7 and 8 are schematic diagrams useful in explaining the operation of the VCR antenna in accordance with th principles of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT According to the invention the antenna system as shown schematically in FIG. 1 consists of three antenna elements which, with respect to construction, are interlinked with one another. The three antenna elements include two crossed dipoles d, and d of theturnstile antenna type, when correspondingly supplied with a modulated carrier energy, and eg. via an electronic goniorneter, serve to generate a rotating dipole. pattern; and a loop antenna R supplies the omnidirectional radiation which is independent of the azimuth. Accordingly, as a resulting pattern, there will be obtained a cardioid pattern rotating at the modulation frequency, for instance, in the case of the VCR, at 30 Hz. The rotating dipole pattern must not change its. shape during rotation, and must have a constant 3 db. bandwidth (half-power point beam width. This is only the case when the patterns of the individual dipoles d, and d which are arranged orthogonally in relation to one another, represent genuine circular functions (Hertz dipole, 3 db. bandwidth 90, 6 db. bandwidth 120).

The loop antenna R, serving as an omnidirectional radiator, is to provide an optimum circular radiation pattern ($0.25 db.), in order that the modulation factor of the VOR-signal will be extremely constant for all azimuth angles.

Provisions must be made for ensuring that the radiation centers of the three antenna elements (dipole d and d loop antenna R) coincide in order to avoid an additional error due to decentralization.

In spite of the structurally integrated arrangement, the antenna elements must be extensively decoupled from one another electrically (by more than 40 db.), and must not disturb each other mutually as regards the shape of pattern.

As extensive experiments have shown, the foregoing requirements can be met by employing the illustrated arrangement in FIG. 1 of the individual conductors forming the antenna elements.

For mechanical reasons (manufacturing tolerances), the antenna system is designed in accordance with the known printed circuit technique (strip-line technique) which, at the same time, also permits a simple and inexpensive manufacture. The individual conductors, forming the antenna elements, are manufactured in accordance with the known technique, or an almost circular common baseplate a of insulating material, see FIGS. 3, 6 and 6a, coated on either side with a copper foil. The crossed dipole systems d and d FIGS. 1, 2 are symmetrically arranged within the loop antenna R which is composed of loop R r to r,,. The loop antenna R itself, FIG. I, is supplied with carrier energy at four diametrically opposite points F along its circumference, as will still be described in detail hereinafter with respect to FIGS. 4 to 7, with the feed systems T FIGS. 3 and 4, which is also designed in accordance with the strip-line technique, FIGS. 6 and 6a, and being arranged along the axis of dipoles d, and d in recesses or cutout portions. The feed systems (not shown) for the dipoles d and d appropriately likewise designed in accordance with the strip-line technique, are attached in a metal housing serving as a shielding, not shown, on one side of the baseplate aof insulating material on which also the other antenna elements are positioned, to the bridges B, FIG. 3, conductively connecting the half-dipole portions, and are conductively connected thereto.

Since the base materialfor t heantehria cornnion baseplate a (epoxyglass fabric, 1.5 mm.) which is at present being used for stability reasons, has no particularly good rf-properties (at 100 MHz: dielectric constant e 5.2; dissipation factor tan 6=300. ID), the construction is made in such a way that the baseplate a will remain extensively field-free. For reducing the losses, it has moreover been proposed to provide the baseplate a of insulating material, at some critical points, i.e. at the respective feed-in points F or x or y, respectively, FIGS. 1, 4, 7 with recesses or cutout portions which, at the same time, effect a reduction of the capacitance between neighboring conductors. I

In the following, the individual antenna elements of the antenna system will now be described in more detail.

The two dipoles d, and d are designed as flat-shaped Hertz dipoles according to FIG. 2 (I/A=0.l7; b/ \=0.05; 1=length, b=width, -=operating wavelength), with the copper coatings forming the dipole members, being arranged on either side of the baseplate 0, FIGS. 3, 6, 6a, in an overlying relation. The conductive coating or foils forming the halves of dipoles d and d individual dipole overlying one another on both sides of the baseplate a are conductively connected through the baseplate a with the aid of connections p, FIG. 3, at least at the comers. The feeding-in of the transmitting energy is effected at the bridge B, FIG. 3, positioned on one side of the baseplate a Bridge B conductively connects two dipole halves forming dipoles d or d Thus, there will result for each dipole d and d two feed points at the bridges B, to which there is applied symmetrically the feed energy.

On the surface of plate a not coated with the'copper foil, and exactly in the center between the individual dipole halves of the dipoles d and d there are arranged the feed systems Tr, FIGS. 3, 4, for the individual loop sections r, /r r;,/r r n, and r /r,,, FIGS. 1, 7, S ot the loop antenna R. Owing to capacitive coupling to the energized dipoles d and d the feed system T, conducts current on the outside. Since the longitudinal axes thereof, however, coincide with those of the dipoles, there is not caused any adverse effect upon the radiation pattern of the dipoles.

When employing the described arrangement, the following measured values of the radiation pattern will result with respect to one dipole d or d 3 db. bandwidth: 89.5 to (theoretical limit 6 db. bandwidth: 1 l8.5 to I l9 (theoretical limit zero constrictions: 40...50 db.

squint between the zero constrictions: 03 ...0.5

The input impedance of j dipole is Re (5 j 120) ohms.

The second dipole d is arranged orthogonally to the first dipole d,. In the case of a mechanically exact construction, decoupling values ranging between 50 and 60 db. will result between the two dipoles, provided however, that unobjectionable balancing feed systems (not shown) are provided.

The loop antenna R (D/ A025; D=diameter of R, )\=operating wavelength), which is composed of eight circularly arranged loop sections r,...r,., is fed at the four points F (or x and y respectively), thus achieving a very homogenous current distribution along the circumference.

During operation there will then result a current flow which is indicated in FIG. 4 by the signs or respectively, at the individual loop sections. For matching reasons, the loop members are designed as line circuits in accordance with the stripline technique; their length I is chosen to be smaller than one quarter wavelength (I/)\ 0.25

Between the respective feedpoints x and y at F and the radiating loop sections r,...r,,, there is arranged an inductance L having a reactance X L =50 to ohms. The necessary respective value of this reactance X can be adjusted with the aid of variable short circuit slides S shown in FIGS. 4, 7, 8.

The described loop antenna R (omnidirectional radiator) generates a pattern with deviation of less than $0.2 db. from the ideal circular shape.

The feed systems Tr for the omnidirectional radiator R are designed to have the shape of slot transformers" which are designed in accordance with the known strip-line technique. They effect a balance-to-unbalance transformation, as well as a transformation of the radiator impedance, so that at the central feedpoint C, i.e. the point at which the four slot transformers Tr are connected in parallel, there will result with respect to the omnidirectional radiator R, an input resistance of approximately 50 ohms (coaxially, ground point M).

Transformation is effected as shown in FIG. 5 (Smith- Chart).

The input impedance between two adjacent radiator elements, e.g. the sections r and r of the omnidirectional radiator R, is at 2 =50 (0.05 j 2,5) ohms, balanced (point P1, FIG. 5).

By inserting in series the inductance L having reactance X (line circuits), there will result at the respective feed points x and y of the individual loop sections h/fz, r /r4, r /r and r1/r8, an impedance Z2=50 (0.06 -j0) ohms, balanced (point P2, FIG. 5).

The slot transformer Tr, as regards the charactei istic impedance and the electrical length, are so dimensioned in the conventional way, that this impedance Z; is transformed to Z =5O(5+j,,) ohms, unbalanced (point P3, FIG. 5).

By combining the inputs of the four slot transformers Tr there will result at the feed point C with respect to the ground point M an impedance Z,=50 (1.2+j0) ohms, unbalanced, serving as the input impedance for the omnidirectional radiator R (point P4, FIG. 5).

The frequency response of the matching extends in accordance with the dashlined curve in FIG. 5.

By varying the series inductance L (adjusting short circuit slide S of the line circuits), it is possible for each frequency ranging between 108 and l 18 MHz, to achieve point P4 of the pattern according to FIG. 5. The fine matching to Z=50 ohms is performed with the aid of a four-tenninal transforming network.

FIG. 6 schematically shows the construction of the slot transformers Tr. In FIG. 6, for the sake of clarity, the individual components are shown in an exploded view. In reality, however, the components are built closely together, for example, are stuck to one another.

FIG. 6A shows a cross-sectional view, looking at the face side. As may be taken from this FIG. 6a, constructions on either side of the baseplate a are alike, i.e. in a symmetrically conjugated fashion in relation to the baseplate a. For the sake of simplicity, this symmetry is not shown completely in FIG. 6.

For the purpose of keeping the losses in the slot transformers Tr, FIG. 6, as small as possible, the latter are chiefly composed of low-loss insulating material, such as polyphenylene oxide (PPO) having e-2.55 and tan8=8.l0'4(=dielectric constant; tan6=dissipation factor).

On either side of the baseplate a consisting of expoxy fiber glass, there are positioned the conically (owing to the Z-variation) extending copper coatings I constituting the inner conductor of the coaxial system, said copper coatings 1 being conductively connected to one another electrically at the beginning and at the end, hence, connected in parallel, with the aid of a connection p, FIG. 4, extending through a hole in the baseplate a. The outer conductor of the slot transformers Tr is constituted by copper coatings 2 and 3 on strips of insulating material I: or c (of PPO) on either side of the baseplate a, respectively.

On the side on which the feed-in is effected (left-hand side in FIG. 6), the coatings 2 and 3 are conductively connected to one another with the aid of a connection wl extending through the baseplate a thus forming the ground or outer conductor M (e.g. FIG. 8) of the coaxial system of the slot transformers Tr. At the (balanced) output end (right-hand side in FIG. 6), the coatings l, fonning the inner conductor of the coaxial system of the slot transformers Tr, are conductive ly connected to one another with the aid of the connection v and are conductively connected to the coating 2 with the aid of an extension of the connection v along the surface of plate b.

At the outputs of each of said slot transformers Tr (coatings 2 and 3) which are to be connected to the feed points x and y of respectively two associated loop sections, e.g. r /r (indicated by thearrows in FIG. 6), there is available a balanced voltage for feeding the radiator sections r,/r r;,/r,, ...of the omnidirectional radiator R. For the purpose of shielding the hitherto described portions of each of said slot transformers Tr, there are provided further copper coatings 4 and 5 on insulating material d or e, consisting of PFC, preventing an outward radiation, or a coupling-in of interferences from the outside. respectively. For this reason the copper coatings 4 and 5 are made somewhat wider than the copper coatings 2 and 3. The copper coatings 4 and 5, with the aid of a correspondingly extended connection W], are applied to the ground point M, forming the outer conductor of the coaxial feed system. Energy is fed in at C and M with the aid of a coaxial cable provided with a corresponding plug connector. The copper coatings 4 and 5 are conductively connected at the other end (output end, right-hand side in FIG. 6, or front end in FIG. 6a respectively with the aid of connection w2.

The individual parts or components of each of said slot transformers Tr are firmly mechanically connected to one another, for example, are stuck together with the aid of a two component epoxy-resin adhesive or cement, and care should be taken to obtain as homogeneous as possible joints (without air pockets or entrapped air).

Thanks to the partial use of good high-frequency (rf) insulating materials (e.g. PPO with t""8=8. 10"), the slot transformers Tr cause only very slight losses.

Energy is transmitted from the central feed point C, and from the ground point M of the omnidirectional radiator R to the respective feedpoints y and it via the field lying between the inner conductor 1 and the copper coatings 2 and 3. This field only extends within the low-loss PPO. The field between the coatings 2 and 3 passes through two layers of PPO and one layer of epoxy fiber glass (tan8=300.l0"). The losses, however, are low, because the voltage between the coatings 2 and 3 assumes only small values owing to the fact that the impedance Z between the respective feed-in points x and y amounts to only about 3 ohms, and because this voltage, from the output of the respective slot transformer Tr (arrows on the right-hand side in FIG. 6) towards the input (feed points C and M) on the left-hand side in FIG. 6, decreases almost linearly due to the conical shape of coating 1. When looked at from the output side (arrows on the right-hand side in FIG. 6) the coatings 2 and 3 together form a balanced strip line which is short-circuited on the input side (left-hand side in FIG. 6).

The field between the copper coatings 2 and 3 of the respec tive slot transformer Tr and the copper coatings 4 and 5 forming the respective shielding, only extends within the low-loss FPO.

When operating only the omnidirectional radiator R there will appear on the individual loop sections r,/r,,... the voltage distribution as denoted in FIGS. 4 and 7 by the signs +or respectively.

Considering now the effect of the energized loop sections r,/r upon the dipoles d, d

Owing to the balance in relation to the centrally arranged dipoles d, and d and owing to the oppositely phased excitation of loop sections disposed oppositely each other along the circumference, such as r and r,, or r, and r acting upon the dipole d these effects practically annul each other owing to the radiation coupling (indicated by the arrows in FIG. 7).

Upon the dipoles d, and d In other words, during operation of the omnidirectional radiator R, either only small or no currents at all which would be likely to affect the omnidirectional pattern, are induced in the dipoles d, and d Upon energization of one dipole only, e.g. d,, of the turnstile antenna system, and owing to the capacitive coupling or radiation coupling (indicated by the arrows in FIG. 8), there will result on the individual loop sections r,/r the voltage distribution as indicated in FIG. 8 by the sign +or respectively.

For the purpose of pennitting a comparison with the voltage distribution resulting during operation of the omnidirectional radiator R (FIGS. 4 and 7), the latter is indicated by the bracketed signs or in FIG. 8. As will be recognized, the voltage as induced by the coupling of the radiating dipole, e.g. 11,, in the loop sections, is exactly in phase opposition on the loop sections r, and r, to the voltage distribution as appearing during operation of the omnidirectional radiator. The induced voltages in oppositely lying loop sections propagate via the slot transformers Tr towards the central feed point C of the antenna (indicated by the dashlined arrows in FIG. 8) where they extinguish themselves (virtual short-circuit). Analogously the same applies to the second dipole d, (not shown in FIGS. 7 and 8) of the turnstile antenna system. Accordingly, when operating both dipoles d and d of the turnstile antenna system, no voltage will appear at the central feed point C of the omnidirectional radiator R.

The virtual short circuit transforms itself via the slot transformers Tr to the respective feed-in points x and y of the omnidirectional antenna elements (loop sections r,/r in accordance with the characteristic impedance and the electrical length of the slot transformers Tr (l/ .=0.l2) there will result between the respective feed points x and y an inductive reactance of about ohms. This is in series with the loop sections energized by radiation coupling and designed as line circuits. By connecting in parallel a cpacitor 6 (FIG. 8) of suitable value (tuned to parallel resonance) to the respective feed points x and y, it is possible to produce at this point a resistance of 5,000 to 6,000 ohms which serves to suppress parasitic currents on the omnidirectional antenna elements r r,,. Within the radiation field, therefore, only the current in the coating forming the flat dipoles d, and d of the turnstile antenna system becomes effective.

The effect as described hereinbefore is known in literature under the term tieline-effect, normally this effect is known to be utilized in connection with M4 transfonner lines A=operating wave length).

Due to the described measures for matching the omnidirectional radiator R, as well as due to the utilization of the tieline-effect for suppressing parasitic currents, of course, the antenna has only a narrow bandwidth. The antenna system, therefore, must be adjusted to the operating frequency specified for each VOR-beacon within the frequency range from 108 to H8 MHz as provided internationally for VOR- beacons. To this end, the following steps are necessary once:

I. Adjustment of the short circuit slides S on the loop sections r,...r,,, so that there will result an optimum matching of the omnidirectional radiator R.

2. Tuning of the capacitors 6 at the ends of the slot transformers Tr (feed points x and y) to parallel resonance (when the central feed point C of the antenna is in the state of a virtual short circuit).

For providing a protection against climatic influences, the antenna is coated with a corresponding protective lacquer and, during the assemblage, is additionally surrounded by a protective housing within a polarization cage.

As has already been pointed out hereinbefore, the antenna as described in the foregoing, may also be used in connection with a single-channel amplitude direction finding receiver in which, for example, direction finding is carried out by adjusting for minimum signal response. in doing so, the loop antenna R is permanently applied to the receiver input until there has been found an object which is to be subjected to direction finding (search position). The turnstile antenna ti /d is applied to the input of the direction finding receiver (track position on account of which the pattern of the antenna becomes a cardioid pattern. Thereafter, for example, with the aid of a manually rotatable goniometer, the phase of the voltages as received by the two .dipoles d, and d,, is continued to be changed-thus effecting a rotation of the cardioid about its origin-, until there is reached the minimum of the incident wave. The bearing direction can be directly read on a dial on the goniometer. Finally, it is also possible, in connection with a visual indicator, and in the manner known per se, to equip an automatic direction finder with the antenna described hereinbefore.

While I have described above the principles of my invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example.

We claim: 1. A VOR antenna comprising: a turnstile antenna; and a loop antenna symmetrically arranged around said turnstile antenna;

said turnstile antenna and said loop antenna including flat printed circuit components disposed on a common baseplate of insulating material;

said turnstile antenna including a pair of dipoles orthogonally related; and each of said pair of dipoles including two dipoles halves disposed adjacent to/and spaced from a central region on said common plate; and further including an arrangement to feed each of said dipole halves and said loop antenna simultaneously;

said loop antenna includes four pairs of printed circuit arcuate segments symmetrically disposed about said turnstile antenna, adjacent ends of said arcuate segments of each pair of arcuate segments being disposed in spaced relation and diametrically opposite said adjacent ends of said arcuate segments of another pair of arcuate segments; and

said arrangement includes printed circuit balun transformers disposed on said common plate, each of said transformers extending radially from said central region to said adjacent ends of one of said pairs of arcuate segments to feed energy to each of said pair of segments.

2. An antenna according to claim 1, wherein each of said balun transformers includes a printed circuit slot transformer.

3. An antenna according to claim I, wherein each of said dipole half includes at least a first printed circuit conductor disposed on one side of said common plate,

a second printed circuit conductor disposed on the other side of said common plate in an overlying relation with said first conductor, and

conductive elements extending through said common plate to conductively connect at least the corners of said first and second conductors; and further including a conductive bridge member to conductively connect said conductor on one side of said common plate of the two dipole halves forming each of said dipoles, said bridge members forming the feed point of said dipole halves.

4. An antenna according to claim 3, wherein each of said dipole halves includes a first printed circuit conductor disposed on one side of said common plate extending radially from said central region,

a second printed circuit conductor disposed on said one side of said common plate spaced from and parallel to said first conductor,

a third printed circuit conductor disposed on the other side of said common plate in an overlying relation with said first conductor,

a fourth printed circuit conductor disposed on said other side of said common plate in an overlying relation with said second conductor, and

conductive elements through said common plate to conductively connect at least the corners of said first and third conductors and at least the corners of said second and fourth conductors.

5. An antenna according to claim 4, wherein each of said balun transformer includes two conical conductive coatings, one of said conical coatings being disposed on one side of said common plate and the other of said conical coatings being disposed on the other side of said common plate in an overlying relation with said one of said conical coating, the input end of both said conical coatings being conductively connected to one another and the output ends of both said conical coatings being conductively connected to one another,

a first additional member of insulating material having one side thereof in contact with said one of said conical coatings,

a first additional conductive coating disposed on the other side of said first additional member in an overlying relation with said one of said conical coatings,

a second additional member of insulating material having one side thereof in contact with said other of said conical coatings,

a second additional conductive coating disposed on the other side of said second additional member in an overlying relation with said other of said conical coatings, and

a conductive member connecting the output ends of both said conical coatings to one of said first and second additional coatings.

6. An antenna according to claim 5, further including a third additional member of insulating material having one side thereof in contact with said first additional coating,

a third additional conductive coating disposed on the other side of said third additional member in an overlying relation with said first additional coating,

a fourth additional member of insulating material having ing relation with said second additional coating.

one side thereof in contact with said second additional An antenna according to Claim further including coating, d capacitive means coupled between said first and second ada f th d i i m conductive coating disposed on the ditional coatings of each of said balun transformer.

other side of said fourth additional member in an overly- 5

Claims

1. A VOR antenna comprising: a turnstile antenna; and a loop antenna symmetrically arranged around said turnstile antenna; said turnstile antenna and said loop antenna including flat printed circuit components disposed on a common baseplate of insulating material; said turnstile antenna including a pair of dipoles orthogonally related; and each of said pair of dipoles including two dipoles halves disposed adjacent to/and spaced from a central region on said coMmon plate; and further including an arrangement to feed each of said dipole halves and said loop antenna simultaneously; said loop antenna includes four pairs of printed circuit arcuate segments symmetrically disposed about said turnstile antenna, adjacent ends of said arcuate segments of each pair of arcuate segments being disposed in spaced relation and diametrically opposite said adjacent ends of said arcuate segments of another pair of arcuate segments; and said arrangement includes printed circuit balun transformers disposed on said common plate, each of said transformers extending radially from said central region to said adjacent ends of one of said pairs of arcuate segments to feed energy to each of said pair of segments.

3. An antenna according to claim 1, wherein each of said dipole half includes at least a first printed circuit conductor disposed on one side of said common plate, a second printed circuit conductor disposed on the other side of said common plate in an overlying relation with said first conductor, and conductive elements extending through said common plate to conductively connect at least the corners of said first and second conductors; and further including a conductive bridge member to conductively connect said conductor on one side of said common plate of the two dipole halves forming each of said dipoles, said bridge members forming the feed point of said dipole halves.

4. An antenna according to claim 3, wherein each of said dipole halves includes a first printed circuit conductor disposed on one side of said common plate extending radially from said central region, a second printed circuit conductor disposed on said one side of said common plate spaced from and parallel to said first conductor, a third printed circuit conductor disposed on the other side of said common plate in an overlying relation with said first conductor, a fourth printed circuit conductor disposed on said other side of said common plate in an overlying relation with said second conductor, and conductive elements through said common plate to conductively connect at least the corners of said first and third conductors and at least the corners of said second and fourth conductors.

5. An antenna according to claim 4, wherein each of said balun transformer includes two conical conductive coatings, one of said conical coatings being disposed on one side of said common plate and the other of said conical coatings being disposed on the other side of said common plate in an overlying relation with said one of said conical coating, the input end of both said conical coatings being conductively connected to one another and the output ends of both said conical coatings being conductively connected to one another, a first additional member of insulating material having one side thereof in contact with said one of said conical coatings, a first additional conductive coating disposed on the other side of said first additional member in an overlying relation with said one of said conical coatings, a second additional member of insulating material having one side thereof in contact with said other of said conical coatings, a second additional conductive coating disposed on the other side of said second additional member in an overlying relation with said other of said conical coatings, and a conductive member connecting the output ends of both said conical coatings to one of said first and second additional coatings.

6. An antenna according to claim 5, further including a third additional member of insulating material having one side thereof in contact with said first additional coating, a third additional conductive coating disposed on the other side of said third additional member in an overlying relation with said first additional coating, a fourth additional member of insulating material having one side thereof in contact with said second additional coating, and a fourth additional conductive coating disposed on the other side of said fourth additional member in an overlying relation with said second additional coating.

7. An antenna according to claim 6, further including capacitive means coupled between said first and second additional coatings of each of said balun transformer.