US 3379956 A
Description (OCR text may contain errors)
United States Patent FLOATING DIODE HARD/IONIC MULTEPLIER James W. Battles, Riverside, Delbert E. Crane, Norco,
Robert W. Yancey, Riverside, and John R. Alday, Co-
rona, Califi, assignors to the United States of America as represented by the Secretary of the Navy Filed Aug. 26, 1965, Ser. No. 576,184 6 @iaims. (ill. 32169) The invention herein described may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
The present invention relates to the generation of electromagnetic energy in millimeter wave bands, and more particularly to an improved harmonic multiplier using a crystal diode.
Previous methods employed: klystron tubes which involved difficult construction, were expensive and easily damaged, had low efficiency, short life, and high frequency limitations; backward wave oscillators and traveling wave tubes which had limited frequency range, and were expensive and required expensive power supplies; and diode harmonic multipliers which were of low efficiency and burnout power, unstable and easily damaged, and required special and difficult to replace diodes as well as external bias voltage.
The device of the present invention has: superior physical and electrical stability; is less expensive than other commercially available devices; involves simple construction and uses replaceable crystals; higher burnout powers and higher efiiciencies than heretofore; requires no external bias and has infinite shelf life. The instant device is highly useful in field environments, in any systems requiring millimeter wave sources. It has many practical uses in local oscillators in millimeter wave receivers and radiometers; communication links; high resolution radar systems; missile guidance; and, in millimeter wave research.
It is an object of the present invention therefore, to provide a new and improved harmonic multiplier for waveguides.
Another object of the invention is to provide an inexpensive harmonic multiplier for waveguides that is easy to construct and simple to adjust.
A further object of the invention is to provide a harmonic multiplier for waveguides that has very good efiiciency and stability.
Gther objects and many of the attendant advantages of this invention wiil become readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
FIG. 1 is a cross-sectional view showing in detail the construction of the waveguide junction, probes and diode.
FIG. 2 is a typical graph showing the variation of the output pover of the harmonic multiplier as a function of the input power when using a heterojunction crystal diode.
The harmonic multiplier of the instant invention consists of two sections of microwave waveguide; one covering the frequency of the fundamental input frequency and the other covering the output harmonic frequency, and joined with a coupling hole between the common sides.
As illustrated in FIG. 1, fundamental waveguide section 16 is covered by harmonic waveguide section 12, and are joined with a coupling hole 14- between them. In the particular embodiment illustrated in the drawing rectangular waveguide is shown and the waveguides are oriented similar to conventional crossguide configuration. A support 16 having an adjustable positioning device 17 with a dielectric post 18, of Lucite or the like, is mounted on "ice fundamental waveguide 10, as shown. Dielectric post 18 supports a standard crystal microwave diode 20 with a harmonic probe extension 22 connected thereto. Harrnonic probe 22 extends through coupling hole 14 into the harmonic waveguide 12. Dielectric post 18 supplies no electrical connection to the diode 20.
In the case of a heterojunction diode, as illustrated in the embodiment of FIG. 1, a fundamental probe extension 24 is also connected to diode 20 and the diode is supported on post 18 by means of probe 24 which is connected thereto. Probes extend in each direction in this instance, diode 2t) and fundamental probe 24 being within fundamental waveguide 10, and harmonic probe 22 extending into harmonic waveguide 12.
Diode 20, with either one or two probes, is adjustably supported within waveguide 1%. In this device, diode 20 can be constructed external to the waveguide or mount and then can easily be positioned and adjusted within Waveguide 18 by means of support 16 and adjusting device 17. The diodes used in the present device, due to the construction configuration, are able to withstand higher input powers than heretofore.
In the configuration shown in FIG. 1, the fundamental energy is fed into waveguide 14} where it is coupled into diode 20 by probe 24 and then converted into a harmonic of the fundamental. This harmonic is then coupled into waveguide 12 by probe 22. The probe lengths are adjusted for maximum harmonic output. The harmonic probe, 22, depth (i.e., extension into harmonic waveguide 12) is adjusted by means of threaded adjusting device 17. Conventional adjustable shorts, not shown, can be used on each of the waveguides for matching purposes to maximize the output energy in a conventional manner.
The heterojunction diode shown in the illustrated embodiment of the invention is shown merely by way of example and is not necessary for the operation of the system. For the experimental data of FIG. 2, the metal probes on the ends of diode 21} were cut so that probe 24 was a quarter wavelength of the fundamental and probe 22 was a quarter wavelength of the third harmonic and the diode was in a pill configuration.
The graph, FIG. 2, of the output of the harmonic multiplier as a function of the input, shows that the efficiency of the device is increased with higher input power. In this instance a gallium arsenide germanium heterojunction diode was used. The fundamental frequency in this mode was 9.86 gI-lz. and the klystron output power was 300 milliwatts. However, in another mode, the fundamental frequency was 9.83 gHz. and the maximum power available was 2 watts. An attenuator was used to reduce the power to 300 milliwatts and tripler output of 6 mw. was measured. This represents a 2mW. gain over the operation at 9.86 gHz., but probably this was because the diode and holder were better matched for this frequency. The fundamental input power was then increased to 520 mw. and the output increased to 8.6 mw.
The above power measurements were made with a dry calorimeter using suitable transitions. The length of the harmonic waveguide was such that the fundamental propagation was not detectable.
Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.
What is claimed is:
1. A harmonic generator for waveguide frequencies comprising:
(a) a first section of waveguide for covering fundamental input frequencies,
(b) a second section of waveguide for covering output harmonic frequencies,
(c) said first and second sections of waveguide being joined together along adjacent sides thereof with a coupling aperture between common sides,
(d) a microwave diode assembly having a crystal diode and at least one harmonic probe extending therefrom,
(e) adjustable positioning means including a dielectric support being mounted On an outside wall of said first Waveguide section for adjustably supporting said diode assembly on said dielectric support within said first section of waveguide,
(f) said at least one harmonic probe extending through said coupling aperture into said second section of waveguide, wherein fundamental energy fed into said first section of waveguide is coupled into said diode and converted into a harmonic of the fundamental, and said harmonic then coupled into said second section of waveguide by said at least one probe.
2. A device as in claim 1 wherein the depth said at least one probe extends into said second section of waveguide is adjusted by said adjustable positioning means, and said dielectric support supplies no electrical connection to said diode.
3. A device as in claim 1 wherein said diode assembly can also be easily removed from said first section of waveguide for replacement and substitution by means of said adjustable positioning means.
4. A device as in claim 1 wherein the length of said at least one probe is adjusted for maximum harmonic output.
5. A device as in claim 1 wherein said microwave diode assembly includes a harmonic probe in addition to said at least one harmonic probe extending from said crystal diode in an opposite direction therefrom, the additional probe extending within said first waveguide section for coupling fundamental energy fed into said first waveguide section into said diode.
6. A device as in claim 5 wherein the lengths of said probes are adjusted for maximum harmonic output.
References Cited UNITED STATES PATENTS 2,970,275 1/1961 KurZrOk 32169 3,246,266 4/1966 Racy 33383 3,311,839 3/1967 Rutulis 330-49 3,320,516 5/1967 Lee 321-69 JOHN F. COUCH, Primary Examiner.
WARREN E. RAY, Examiner.
G. GOLDBERG, Assistant Examiner.