Low density polyethylene (LDPE)/Alumina (Al<sub>2</sub>O<sub>3</sub>) composite systems have been studied as an alternate substrate for microstrip patch antennas (MPA). Morphological, thermal and microwave characterizations of the composites are carried out for different volume fractions of Al<sub>2</sub>O<sub>3</sub> in the LDPE matrix. The size and the distribution of alumina particles are quite uniform in the composite. Enhancement of thermal and microwave properties of the composite over the parent polymer is observed. Simple rectangular MPA in X-band is fabricated on the composite material to verify its applicability as substrates for MPA. A return loss of ~ -26dB is observed at the design frequency.
Expanded graphite/novolac phenolic resin (EG/NPR) composites are developed as dielectric absorbers with 4mm
thickness and its microwave absorption ability studied in the frequency range 8.4 to 12.4 GHz. A high reflection loss
~ -43 dB is observed at 12.4 GHz for 5 wt. % EG/NPR composites. With the increase in EG concentration in the
composite the reflection loss decreases and the absorption peak shifts towards lower frequency. 7 wt. %, 8 wt. % and 10 wt. % composites shows a 10dB absorption bandwidth of order of 1GHz. Light weight EG/NPR composite shows
potential to be used as cost-effective broadband microwave absorber over the X-band.
In the present investigation, microwave absorption properties of a conductor back single layer designed on graphite
flakes (GF)-novolac phenolic resin (NPR) composites is studied. The complex permittivity of the developed composite
enhance for higher GF percentages. The reflection loss(RL) measured using E8362C VNA shows a maximum RL values
-25 dB at 9.8 GHz for 7 wt. % composition with -10 dB bandwidth of 0.3 GHz. The developed composites are being
light weight and cost effective shows potential to be used as dielectric absorber.