The document discusses the design of compact microstrip bandpass filters for microwave applications. It first provides background on microwaves and filter types/characteristics. Then it reviews recent works involving hairpin resonators, dual-mode resonators, and stepped impedance resonators. Hairpin resonators allow for dual band filters and transmission zeros. Dual-mode resonators reduce size but require strong coupling. Stepped impedance resonators improve matching and rejection band performance. The document proposes new compact bandpass filter designs utilizing these resonator techniques.

1. 02 January 2017
Design of Very Compact
Microstrip Bandpass Filter
with High-Selectivity for X-
& Ku-band Applications

2. Contents:
- Introduction to Microwave and
Filters
- Microstrip Structure
- Review of Recent Works
- Proposed Bandpass Filters
- Conclusion & Suggesion

3. Electromagnetic SpectrumElectromagnetic Spectrum
1
Microwave signals cover from 3 GHz to 300 GHz
Introduction to Microwave & Filters
Fig1. The Electromagnetic Spectrum [1]

4. Table2. U.S Military Microwave Bands
[2]
Introduction to Microwave & Filters
Table1. IEEEMicrowave Frequency Bands
[2].
2

5. Introduction to Microwave & Filters
Development of Telecommunication TechnologyDevelopment of Telecommunication Technology
Requirements::
•Compact SizeCompact Size
•Reducing the CostsReducing the Costs
•High PerformanceHigh Performance
•Low LossLow Loss
New Devices Multi-Band Performance
3
Fig1. Development of Technology of Communication

6. Introduction to Microwave & Filters
Applications of Filters:Applications of Filters:
 Transmitter & Receiver Stations
 Telecommunication Systems
 Medical Instruments
 VSATS
 …
4
Fig2. Application of Filters in Industry

7. Introduction to Microwave & Filters
Technologies of Implementing Microwave Filters:Technologies of Implementing Microwave Filters:
 Microelectromechanical Systems (MEMS)
 High-Temperature Superconductors
 Integrated Circuits (IC)
 Microstrip
 …
5
Fig3. FilterImplementation Technologies

8. Introduction to Microwave & Filters
Types of Filters:Types of Filters:
 Low-Pass Filter
 Band-Pass Filter
 Bandstop (Notch) Filter
 High-Pass Filter
Fig4. Types of Filter[3]
6

9. Introduction to Microwave & Filters
Filter Response Characteristics:Filter Response Characteristics:
 Butterworth
 Flat Passband
 Poor Rolloff
Fig5. Low-pass Butterworth Response
[4]
7

10. Introduction to Microwave & Filters
 Chebyshev
Filter Response Characteristics:Filter Response Characteristics:
Fig6. Low-pass Chebyshev Response
[4]
 Equilised ripple in Pass-band
 Steeper Rolloff than Butterworth
8

11. Introduction to Microwave & Filters
 Elliptic (Cauer)
Filter Response Characteristics:Filter Response Characteristics:
 Acceptable Rolloff
 Equiripple Behavior in Passband and Stopband
 Independently Adjustable Ripple in Each Band
Fig7. Low-pass Elliptic Response [4]
9

12. Introduction to Microwave & Filters
 Gaussian
Filter Response Characteristics:Filter Response Characteristics:
 Smooth Group Delay
 No overshoot to a step function input
 Minimizing the Rise and Fall time
Fig8. Gaussian response and group delay
[4]
10

13.  Microstrip Structure

14. Microstrip Structure
Fig9. Microstrip Structure [4]
W: microstrip line width
t: microstrip line thickness
εr: relative dielectric constant
h: relative dielectric thickness
12

15. Microstrip Structure
Guided Wavelength:Guided Wavelength:
For a Quasi-TEM mode microstrip defined as follow
Propagation Constant:Propagation Constant:
Group Delay:Group Delay:
φ21 is the response of S21 response in terms of radian.
13

16. Microstrip Structure
Fractional Bandwidth:Fractional Bandwidth:
 FBW varies between 0 and 2
 Quoted as percentage between 0% and 200%
 A measure of how wideband the filter is
14
20% ≤ FBW ≤ 50% Wideband Filter
50% ≥ FBW Ultra Wideband Filter

17.  Review of recent Works

18. 16
Review of Recent Works
Hairpin Resonators:Hairpin Resonators:
Fig10. Microstrip filterwith COBProcess [5].

19. 17
Review of Recent Works
Hairpin Resonators:Hairpin Resonators:
To design dualband filter:
1- Resonances occur in desired frequency by changing the
dimensions of resonator
2- properly arrange of resonators
Fig11. dualband bandpass filterwith hairpin resonators
[6]

20. Review of Recent Works
Hairpin Resonators:Hairpin Resonators:
Producing transmission zero in passband is advantage of
cross coupling :Out of band rejection improved
Control the transmission zeros by input branch
Fig12. bandpass filterwith hairpin resonators and cross coupling
[7].
18

21. Review of Recent Works
Dualmode Resonators:Dualmode Resonators:
Dual-bandpass filters are normally constructed in 3 types:
1- combining to independent bandpass filter with common
input/output port
2- cascading a broadband filter with a band-stop structure
3- using dual-mode resonator (leads to reducing size)
19

22. Review of Recent Works
Dualmode Resonators:Dualmode Resonators:
20
Disadvantages of coupled structure for wideband
bandpass filter designs:
1- multiple spurious responses
2- the need for structures with narrow gaps
3- narrow upper stopbands

23. 21
Review of Recent Works
Dualmode Resonators:Dualmode Resonators:
Providing strong coupling coefficient:
Dual-mode resonator in the form of feeding network
Semi-annular resonator
Folded Open-end stubs (PCML)
Fig13. simulation and measurement results of bandpass filterwith
PCMLstructure [8].

24. Review of Recent Works
Dualmode Resonators:Dualmode Resonators:
Design bandpass filter with Bragg Frequency:
At Bragg Frequency the characteristic impedance goes
to zero
Fig14. Design of bandpass filterwith 5 transmission zeros and
Bragg frequency [9].
22

25. Review of Recent Works
Stepped Impedance Resonators:Stepped Impedance Resonators:
23
 Plays important Role in circuit matching
 In order to reduce the circuit size, SIRs folded
 Circular SIR stubs improve the rejection band rather
than conventional SIRs
Fig15. Bandpass filters using stepped Impedanc Resonators [10-
11].