Negative resistance high-Q-microwave oscillator

• US 3,913,035 A
• Filed: 07/01/1974
• Issued: 10/14/1975
• Est. Priority Date: 07/01/1974
• Status: Expired due to Term

• Current Assignee: Richard Calvin Havens
• Original Assignee: Richard Calvin Havens
• Inventors: Havens, Richard Calvin
• Primary Examiner(s): Kominski, John
• Application Number:
  US05/484,502
• Time in Patent Office: 470 Days
• Field of Search: 331/107,101,96
• US Class Current: 331/107.0DP
• CPC Class Codes: H03B 2009/126 using impact ionization avalanche transit time [IMPATT] diodes
• CPC Class Codes: H03B 9/145 the frequency being determined by a cavity resonator, e.g. a hollow waveguide cavity or a coaxial cavity H03B9/141 - H03B9/143, H03B9/147, H03B9/148 take precedence

Abstract

A high-Q negative resistance microwave oscillator is disclosed which comprises a semiconductor diode, suitably a Gunn or Impatt diode, located within a low-Q resonant structure or cavity for generating a carrier frequency, f; and another waveguide cavity tuned to f having a very high-Q relative to the first cavity, and which is optimally coupled to the low-Q cavity. The microwave energy generated in the low-Q cavity is coupled to the high-Q cavity which reflects energy at frequency, f, back to the low-Q cavity to maintain oscillations at the aforementioned frequency. The microwave energy thus developed is supplied directly to a load by a microwave passage that is coupled to the low-Q cavity. An internal microwave load is employed to dissipate undesired frequencies thereby restricting these frequencies from being generated within the low-Q cavity and therefore enhancing the oscillator'"'"''"'"'s frequency stability.

Claims

1. A negative resistance microwave oscillator comprising in combination:

a low-Q resonating means including a negative resistance device which is disposed into and within a cylindrical cavity for generating microwave energy in a range of predetermined frequencies;

bias means electrically connected to said negative resistance device for providing a direct current bias to said negative resistance device for providing a direct current bias to said negative resistance device of sufficient energy to generate said microwave energy;

a high-Q resonating means resonant at a predetermined frequency and electromagnetically connected in series with said low-Q resonating means for receiving said microwave energy from said low-Q resonating means and reflecting back a substantial portion of said microwave energy at said predetermined frequency to said low-Q resonating means to maintain microwave frequency oscillation at said predetermined frequency;

first dissipative means electromagnetically connected in series with said high-Q resonating means and said low-Q resonating means for receiving said microwave energy at frequencies other than said predetermined frequency and dissipating said microwave energy at the undesirable frequencies to enhance frequency stability of the microwave oscillator;

first microwave transmission means electromagnetically coupled to said low-Q resonating means for transmitting said microwave energy supplied directly thereto from said low-Q resonating means at said predetermined frequency to an oscillator load; and

said bias means including transmission means electrically connected to said negative resistance device for applying direct current bias thereto, second dissipating means enclosing a first portion of said transmission means for dissipating microwave energy at undesired microwave frequencies, and coaxial transmission means enclosing a portion of said transmission means for directly reflecting back energy at said predetermined frequency to said negative resistance device.

2. The negative resistance microwave oscillator of claim 1 further includes:

second microwave transmission means for electromagnetically coupling said high-Q resonating means to said low-Q resonating means;

said high-Q resonating means being a cylindrical volume having a predetermined diameter of essentially one-half wavelength in electrical length at said predetermined frequency, and two end walls spaced at a predetermined lateral dimension;

a circular iris formed in one of said end walls and communicating with said second microwave transmission means; and

said negative resistance device including a Gunn diode.

3. A negative resistance microwave oscillator comprising:

a high-Q cylindrical cavity resonant at a predetermined frequency, said high-Q cavity having a predetermined diameter of essentially one-half wavelength in electrical length at said predetermined frequency and two end walls;

a first microwave transmission means;

a low-Q resonant structure having a floor and a side wall extending from said floor, terminus of said side wall defining an opening communicating with said first microwave transmission means;

oscillating generating means disposed into said low-Q structure for providing microwave oscillation energy in a range of frequencies including said predetermined frequency;

bias means electrically connected to said oscillating generating means for applying direct current bias voltage to said oscillating generating means;

coupling means formed in one of said walls of said high-Q cavity and communicating with said first microwave transmission means;

first dissipaTing means disposed in said first microwave transmission means providing a matched load to said range of frequencies, said first dissipating means being spaced beyond said high-Q cavity and terminating at one end of said first microwave transmission means;

second microwave transmission means electromagnetically coupled to said low-Q structure for receiving said microwave energy at said predetermined frequency and transmitting said microwave energy to a load; and

said high-Q cylindrical cavity reflecting a substantial portion of energy at said predetermined frequency to said low-Q resonant structure for enhancing the frequency stability of the oscillator.

4. The negative resistance microwave oscillator of claim 3 wherein said bias means includes in combination:

transmission means electrically connected to said oscillating generating means for applying direct current bias voltage to said oscillating generating means;

second dissipating means enclosing a first portion of said transmission means for dissipating microwave energy generated at undesired microwave frequencies; and

a coaxial transmission means enclosing a second portion of said transmission means for reflecting back energy at said predetermined frequency to said oscillating generating means.

5. The negative resistance microwave oscillator of claim 3 wherein said oscillating generating means includes a Gunn diode.

6. The negative resistance microwave oscillator of claim 3 further including:

said low-Q structure having a volume smaller than said high-Q cavity by a factor such that in combination with said oscillating generating means, said bias means and said low-Q structure, the resonant frequency of said low-Q structure is essentially the same as that of said high-Q cavity; and

said coupling means being a circular iris communicating with said first microwave means in such a manner as to cause said high-Q cavity to appear to be connected in series with said low-Q structure.

7. The negative resistance oscillator of claim 3 wherein said high-Q cavity further includes:

tuning means for changing the resonant frequency of said high-Q cavity to vary said predetermined frequency.

8. The negative resistance microwave oscillator of claim 3 further includes in combination:

bias means having said transmission means electrically connected to said oscillating generating means for applying direct current bias voltage to said oscillating generating means, a second dissipating means enclosing the first portion of said transmission means for dissipating microwave energy at undesired microwave frequencies, and a coaxial transmission means comprising a second portion of said transmission means for reflecting back energy at said predetermined frequency to said oscillating generating means;

said low-Q structure having a volume smaller than said high-Q cavity by a factor such that in combination with said oscillating generating means, said bias means and said low-Q structure the resonant frequency of said low-Q structure is essentially the same as that of high-Q cavity;

said coupling means being a circular iris communicating with said first microwave means in such a manner as to cause said high-Q cavity to appear to be series connected to said low-Q structure; and

tuning means for changing the resonant frequency of said high-Q cavity to vary said predetermined frequency of the microwave oscillator.