Title :
Compact forward-coupled superconducting microstrip filters for cellular communication
Author :
Dawei Zhang ; Liang, G.-C. ; Shih, C.F. ; Withers, R.S. ; Johansson, M.E. ; Cruz, A.D.
Author_Institution :
Conductus Inc., Sunnyvale, CA, USA
fDate :
6/1/1995 12:00:00 AM
Abstract :
A compact forward-coupled microstrip filter structure is presented for narrow-band applications in cellular communications. The structure consists of a parallel array of fully aligned half-wavelength resonators. Coupling is controlled by the spacing of the adjacent resonators, and is based on the even- and odd-mode phase velocity difference of coupled lines in a microstrip configuration. Two filter designs, based on the forward-coupled structure, were fabricated using YBa/sub 2/Cu/sub 3/O/sub 7/ (YBCO) high-temperature superconducting (HTS) thin films on LaAlO/sub 3/ substrates. One filter, a 9-pole 2.8% fractional-bandwidth YBCO filter at 900 MHz, has less than 0.27 dB insertion loss and better than 16 dB return loss. The other filter, a 5-pole 1.2% fractional bandwidth YBCO filter with 10-/spl Omega/ internal impedance at 2 GHz, has less than 0.35 dB insertion loss and better than 12 dB return loss. All designs showed excellent measured frequency response.<>
Keywords :
UHF filters; barium compounds; cellular radio; high-temperature superconductors; microstrip filters; superconducting microwave devices; yttrium compounds; 0.27 dB; 0.35 dB; 12 dB; 16 dB; 2 GHz; 5-pole YBCO filter; 9-pole YBCO filter; 900 MHz; LaAlO/sub 3/; LaAlO/sub 3/ substrates; YBa/sub 2/Cu/sub 3/O/sub 7/; YBa/sub 2/Cu/sub 3/O/sub 7/ high-temperature superconducting thin films; cellular communication; compact forward-coupled microstrip filter structure; even-mode phase velocity difference; fractional-bandwidth; frequency response; fully aligned half-wavelength resonators; insertion loss; internal impedance; microstrip configuration; narrow-band filter; odd-mode phase velocity difference; parallel array; return loss; superconducting microstrip filters; Communication system control; High temperature superconductors; Insertion loss; Microstrip filters; Microstrip resonators; Narrowband; Resonator filters; Superconducting filters; Velocity control; Yttrium barium copper oxide;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
