MICROWAVE BANDPASS FILTER :MICROWAVE FILTER

MICROWAVE FILTER:

Filter which are designed at microwave frequency is called microwave filter. Microwave filter uses distributed elements . If lumped elements are used for filter design at microwave frequency ,microwave filter design becomes identical to low frequency filter design .

MICROWAVE BANDPASS FILTER

Microwaves are electromagnetic waves with wavelengths ranging from as long as one meter down to as short as one millimeter, or equivalently, with frequencies between 300MHz (0.3 GHz) and 300 GHz. This is an extremely broad definition including both UHF and EHF (millimeter waves), and various sources use different boundaries. In all cases, microwave includes the entire SHF band (3 to 30GHz, or 10 to 1cm) at minimum, with RF engineering often putting the lower boundary at 1GHz (30cm), and the upper around 100GHz (3mm).

There are different types of microwave filter .Among these we are focusing on microwave bandpass filter . It has

Different topologies :->

1. Hair pin

2. comb line

3. Ideal lumped

4. Ideal distributed

5. Inter digital

6. Edge coupled

7. stepped impedance

8. Tubular Waveguide

EDGE coupled filter: The topology consists of asymmetric coupled-slot pairs that symmetric about the center of CPW line. Experimental results are given for a 20GHz filter printed on high-resistivity silicon. As microstrip ,CPW filters may be comprised of coupled lines. Operating principle is based on propagation of two orthogonal modes on the coupled slot geometry and magnetic-wall symmetry is maintained along the center of the line.

Ø Equivalent circuit for an individual for individual coupling section in the bandpass filter (phi=∏/2)