Filters

Substrate Integrated Waveguide Filter:

Substrate integrated waveguide filters at X and Ku band have been designed which involves determining the width of iris as a function of coupling factor. For this purpose, a design curve of iris width vs coupling was generated using HFSS. Two 5 pole Chebyshev bandpass filters have been fabricated on 4003 Rogers. Measured results at 10 GHz presents 380 MHz bandwidth, 6.6 dB insertion loss and return loss better than 12.5 dB. Measured results at 16 GHz presents 410 MHz bandwidth, 8.1 dB insertion loss and return loss better than 13 dB.

Publications:

  • Umar Hasan Khan, “A Narrow Band Subsrate Integrated Waveguide Filter using EM Simulation,” MS Thesis, College of E&ME, NUST, 2013.

Compact UWB Bandpass Filter with High Stopband Rejection:

Thesis research is based on the development of compact UWB bandpass filter for UWB communication in 3.1-10.6 GHz band. Two fourth order UWB filters are designed; one by direct coupling of three E-structures and other by capacitive coupling of two E-structures. Filter based on directly coupled E-shape structures has fractional bandwidth of 97%, maximum flat band insertion loss of 1.3dB, maximum returnloss of 9dB and rejection better than 20dB in GPS band. Chip loaded filterhas fractional bandwidth of 115%, maximum flat band insertion loss of 0.25dB, maximum return loss of 11 dB and rejection better than 25dB in GPS band.

Three cascaded E-shape Structure
Three cascaded E-shape Structure
Chip Loaded E-shape Structure
Chip Loaded E-shape Structure

Publications:

  • Bilal Aslam, “Packaged Ultra Wide Band Filter,” MS Thesis, College of E&ME, NUST, 2013.

Parallel Coupled Microstrip Bandpass Filter

A fourth order paralled coupled Microstrip band pass filter was designed using chebychev low pass prototype and was simulated on Harmonica and further on EM analysis tool Sonnet to take into account the physical layout and packaging effects. The filter was designed to operate at a centre frequency of 1 GHz and a bandwidth of 200 MHz with pass band ripple of 0.01 dB. The measured results show insertion loss of -1.2 dB and bandwidth of 220 MHz at centre frequency of 1 GHz.

Publications:

  • Tahir Abbas, Zubair Ahmed and Mojeeb Bin Ihsan “Parallel Coupled Microstrip Band Pass Filter Design using EM-Analysis”, Proceedings of IEEE INMIC 2004 8th International Multitopic Conference Islamabad Pakistan, 24-26 December 2004, pp 703-705.
  • Tahir Abbas, Zubair Ahmed and Mojeeb Bin Ihsan. “Design of Coupled-Line Coupled Hairpin-Line Filter Using EM Analysis for Parameter Extraction”, Third International Bhurban Conference on Applied Sciences and Technology, Bhurban, Pakistan, 7-12 June, 2004, pp 740-745.