Planar L‐strip fed broadband microstrip antenna

Abstract

A broadband rectangular microstrip antenna utilizing an electromagnetically coupled L-strip feed is presented. Experimental study shows a 2:1 VSWR bandwidth of Ϸ 10% and excellent cross-polarization performance with a radiation coverage almost as same as that of the rectangular microstrip antenna fed by conventional methods. The variation of bandwidth for different feed param- ANTENNA GEOMETRYThe geometry of the proposed antenna is shown in Figure 1. Rectangular patch antenna of dimension L ϫ W is etched on a substrate of thickness h 2 and permittivity r2 . The patch is electromagnetically fed by the L-shaped 50⍀ microstrip feed fabricated on a substrate of thickness h 1 ϭ 1.6 mm and permittivity r1 ϭ 4.28. EXPERIMENTAL RESULTSA rectangular patch antenna with L ϭ 40 mm and W ϭ 20 mm is fabricated on a substrate with r2 ϭ 4.28, h 2 ϭ 1.6 mm. The parameters of the L-strip feed are optimized to obtain maximum percentage bandwidth. The variation of the return loss of the above antenna with the optimum feed parameters S 1 ϭ 8 mm, S 2 ϭ 6 mm and S 3 ϭ 25 mm is shown in Figure 2. The antenna operates in the 3.03-3.38-GHz band giving a 2:1 VSWR bandwidth of Ϸ 10% with a center frequency of 3.3 GHz. The experiment is repeated for antennas resonating at the same frequency, fabricated on different substrates. Variation in the percentage bandwidth with feed segment length (S 3 ) is shown in Figure 3. Radiation patterns of the antenna at the operating band edges and midband frequencies for the above feed parameters are shown in Figure 4. The HPBW of the antenna in the E and H planes are 92°and 66°, respectively, at the resonant frequency. The cross polarization of the antenna is better than Ϫ30 dB. CONCLUSIONSA microstrip antenna with an electromagnetically coupled L-strip feed giving large bandwidth is presented. The remarkable feature of the proposed antenna is its compact structure to achieve enhanced bandwidth. The feeding technique is very simple compared to the other methods. ANALYSIS AND DESIGN OF AN ADAPTIVE POLYNOMIAL PREDISTORTER WITH THE LOOP DELAY ESTIMATOR

Wideband cylindrical dielectric resonator antenna excited using an L‐strip feed

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