Microwave switched multiplexer and a mobile telecommunications device including such a multiplexer

• US 10,819,376 B2
• Filed: 09/08/2016
• Issued: 10/27/2020
• Est. Priority Date: 09/08/2015
• Status: Active Grant

• Current Assignee: Isotek Microwave Limited
• Original Assignee: Isotek Microwave Limited
• Inventors: Rhodes, David
• Primary Examiner(s): Jain, Raj
• Application Number:
  US16/326,610
• Publication Number:
  US 20190222234A1
• Time in Patent Office: 1,510 Days
• CPC Class Codes: H01P 1/2136 using comb or interdigital filters; using cascaded coaxial cavities H01P1/2131, H01P1/2135 take precedence
• CPC Class Codes: H03H 7/0161 Bandpass filters H03H7/12 takes precedence
• CPC Class Codes: H03H 7/465 having variable circuit topology, e.g. including switches
• CPC Class Codes: H03H 9/171 implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
• CPC Class Codes: H03H 9/706 Duplexers
• CPC Class Codes: H03H 9/725 Duplexers
• CPC Class Codes: H04B 1/0057 using diplexing or multiplexing filters for selecting the desired band
• CPC Class Codes: H04B 1/006 using switches for selecting the desired band H04B1/0057 takes precedence
• CPC Class Codes: H04B 1/69 Spread spectrum techniques
• CPC Class Codes: H05B 6/705 using microwave tuning

Abstract

A microwave switched multiplexer having a bandpass Δf between frequencies f1 and f2, Δf=f1−f2, the multiplexer comprising an input microwave resonant waveguide; an output microwave resonant waveguide; and, n transmission channels where n>1, each transmission channel coupled to the input microwave resonant waveguide and the output microwave resonant waveguide, each transmission channel having a transmission bandpass at a center frequency within Δf, the center frequencies of the transmission channels being equally spaced apart in frequency by Δf/n; each transmission channel comprising (a) an input resonator coupled to the input microwave resonant waveguide; (b) an output resonator coupled to the output microwave resonant waveguide: (c) a center resonator coupled to the input and output resonators, the three resonators being coupled together in cascade; (d) a tuning mechanism connected to the center resonator and adapted to be switched between on and off states, in the on state the resonant frequency of the center resonator being the same as that of the input and output resonators and in the off state the resonant frequency of the center resonator being outside the bandpass Δf.

Claims

1. A microwave switched multiplexer having a bandpass Δ

f between frequencies f1 and f2, Δ

f=f1−

f2, the multiplexer comprising;

an input microwave resonant waveguide;

an output microwave resonant waveguide; and

,

n transmission channels where n>

1, each transmission channel coupled to the input microwave resonant waveguide and the output microwave resonant waveguide, each transmission channel having a transmission bandpass at a center frequency within Δ

f, the center frequencies of the transmission channels being equally spaced apart in frequency by Δ

f/n;

each transmission channel comprising;

(a) an input resonator coupled to the input microwave resonant waveguide;

(b) an output resonator coupled to the output microwave resonant waveguide;

(c) a center resonator coupled to the input and output resonators, the three resonators being coupled together in cascade;

(d) a tuning mechanism connected to the center resonator and adapted to be switched between on and off states, in the on state the resonant frequency of the center resonator being the same as that of the input and output resonators and in the off state the resonant frequency of the center resonator being outside the bandpass Δ

f;

the admittances of the input microwave resonant waveguide, input resonator, center resonator and output resonator being in the ratio

y/n;

π

/2;

4x/π

;

π

/2

where x is ln the range 0.9 to 1.1 and where y is in the range 0.5 to 1.5; and

the admittances of the input, center and output resonators having absolute values such that for every transmission channel when the tuning mechanism of the transmission channel is in the on state and the tuning mechanisms of all other transmission channels are in the off state the width of the transmission bandpass of the transmission channel is substantially Δ

f/n.

2. A microwave switched multiplexer as claimed in claim 1, wherein y is in the range 0.8 to 1.2.

3. A microwave switched multiplexer as claimed in claim 1, wherein y is in the range 0.9 to 1.1.

4. A microwave switched multiplexer as claimed in claim 1, wherein y is in the range 0.95 to 1.05.

5. A microwave switched multiplexer as claimed in claim 1, wherein x is in the range 0.95 to 1.05.

6. A microwave switched multiplexer as claimed in claim 1, wherein x is in the range 0.97 to 1.03.

7. A microwave switched multiplexer as claimed in claim 1, wherein x is in the range 0.99 to 1.01.

8. A microwave switched resonator as claimed in claim 1, wherein n is odd.

9. A microwave switched resonator as claimed in claim 1, wherein n is even.

10. A microwave switched multiplexer as claimed in claim 1, wherein the admittance of the output microwave resonant waveguide is equal to the admittance of the input microwave resonant waveguide.

11. A microwave switched multiplexer as claimed in claim 1, wherein each resonator comprises an electrically conducting resonant cavity comprising first and second end faces and a side wall extending therebetween, the resonator further comprising a dielectric member arranged within the cavity and spaced apart from the end faces;

and

the distance between the first and second end faces defining the length of the cavity, the width of the cavity in a plane normal to the length being at least four times the length.

12. A microwave switched multiplexer as claimed in claim 11, wherein the dielectric member of the center resonator comprises an aperture extending therethrough, the tuning mechanism comprising a rod which can be inserted or removed from the aperture to switch the center resonator between on and off states.

13. A microwave switched multiplexer as claimed in claim 1, wherein each resonator comprises an electrically conducing cavity comprising first and second end faces and a side wall extending therebetween, the resonator further comprising a resonator post extending from an end face part, way to the opposite end face.

14. A microwave switched multiplexer as claimed in claim 13, wherein the tuning mechanism comprises an electrical switch extending between the resonator post of the center resonator to the spaced apart end face.

15. A microwave switched multiplexer as claimed in claim 1, wherein each resonator is an FBAR or SAW resonator.

16. A microwave switched multiplexer as claimed in claim 1, further comprising a microwave source connected to the input microwave resonant waveguide, the microwave source being adapted to provide a microwave signal having a frequency between f₁ and f₂.

17. A mobile telecommunications device comprising:

at least one microwave switched multiplexer having a bandpass Δ

f between frequencies f1 and f2, Δ

f=f1−

f2, the multiplexer comprising;

an input microwave resonant waveguide;

an output microwave resonant waveguide; and

,

n transmission channels where n>

1, each transmission channel coupled to the input microwave resonant waveguide and the output microwave resonant waveguide, each transmission channel having a transmission bandpass at a center frequency within Δ

f, the center frequencies of the transmission channels being equally spaced apart in frequency by Δ

f/n;

each transmission channel comprising;

(a) an input resonator coupled to the input microwave resonant waveguide;

(b) an output resonator coupled to the output microwave resonant waveguide;

(c) a center resonator coupled to the input and output resonators, the three resonators being coupled together in cascade;

(d) a tuning mechanism connected to the center resonator and adapted to be switched between on and off states, in the on state the resonant frequency of the center resonator being the same as that of the input and output resonators and in the off state the resonant frequency of the center resonator being outside the bandpass Δ

f;

the admittances of the input microwave resonant waveguide, input resonator, center resonator and output resonator being in the ratio

y/n;

π

/2;

4x/π

;

π

/2

where x is ln the range 0.9 to 1.1 and where y is in the range 0.5 to 1.5; and

the admittances of the input, center and output resonators having absolute values such that for every transmission channel when the tuning mechanism of the transmission channel is in the on state and the tuning mechanisms of all other transmission channels are in the off state the width of the transmission bandpass of the transmission channel is substantially Δ

f/n.