The basic microstrip antenna (MSA) is a resonant patch of metal, etched on the surface of grounded
dielectric slab. The dielectric material is replaced with air to improve the bandwidth and to minimize
losses. The proposed space fed microstrip antenna (MSA) consists of fed patch and parasitic patch
separated by 0.5 ?0 to enhance the gain. The parasitic patch is printed on bottom side (inverted suspended configuration) of low cost FR4 substrate with dielectric constant 4.4 and loss tangent 0.02 respectively. The antenna is excited with coaxial probe feed using N type connector from the fed patch. The radiation from fed patch is intercepted electromagnetically by parasitic patch and it reconfigures the radiation and reradiates. The cavity formed between fed and parasitic patch maximizes field and enhances gain. This depends upon the spacing between fed and parasitic patch.
Key Words: Microstrip antenna; patch antenna; stacked antenna; ISM band
[...] Height mm 0.45 λ λ λ0 D G η SLL - 10.4 - 11.9 - 8.55 CP - 13.5 - 19.2 Table 2 Performance parameters for variation in Parasite patch heights Table 1 Performance parameters for variation in fed patch heights Fig Effect of Variation in Parasite Patch Length: The length of parasitic patch is decremented to 43 mm, the input impedance curve shits from its reference position slightly. The same thing happens when the parasitic patch length is incremented by 45 mm. [...]
[...] Figure 3.1 shows variation in impedance curve for these variations in heights of fed patch and table 1 gives antenna performance parameters for these variations. Height mm D G η SLL - 11.8 - 11.8 - 11.4 CP - 21.2 - 18.8 - Effect of Variation in Parasite Patch Height: The parasitic patch is placed at 0.5 λ0 over the fed patch. According to the cavity formed between fed patch and parasitic patch maximizes field with interaction and thereby enhances the gain. [...]
[...] The measured resonant frequency is 2.39 GHz while the theoretically obtained is 2.45 GHz with difference of Figure 4.7 shows the fabricated prototype antenna CONCLUSION A novel space fed microstrip antenna is designed. It provides theoretical gain of 11 dB with lobe side lobe level and high efficiency. Though it radiates linearly polarized radiation, it can be made to radiate circularly polarized wave by modifying geometry. The cost of manufacturability is low. The antenna can be used in point to [...]
[...] The VSWR plots for thickness variation are shown in figure Material Teflon HT-2 FR4 εr tanδ D dB G dB SLL dB - 15.2 - 18.1 - 18.2 Fig Table 3 Optimized dimension and antenna parameters for variation in dielectric material FP mm Thickness mm D dB G dB SLL dB - 18.2 -18 -18 CP dB -19 -20 - 20.9 Table 4 Optimized dimension and antenna parameters for variation in thickness of superstrate Fig Effect of Dielectric material and its thickness and loss tangent for Parasite Patch: The dielectric material of parasite patch is changed, keeping the same thickness of 1.59 mm. [...]
[...] Fig 2 Front View of inverted suspended space fed microstrip antenna structure 3. ANALYSIS AND RESULTS ON INFINTE GROUND PLANE Initially the fed patch is designed to resonate at 2.45 GHz frequency and to cover the bandwidth of 2.4 GHz to 2.5 GHz with VSWR = 2. The gain provided by this structure is very low. To enhance the gain, a parasite patch is placed at half wavelength above fed patch and the structure is optimized to resonate at same frequency. [...]
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