Left Hand Circularly Polarized Truncated Patch Antenna Array Research

The antenna array consisted of four LHCP truncated patches that were impedance matched using a quarter-wave transmission line and fed in-phase. The truncated patches also used an FR4 substrate with a relative permittivity of 4.4 and height of 1.6 mm. The characteristic impedance of the quarter-wave transmission line \(Z_0\) was determined by: \(Z_{in} = \frac{Z_0^2}{Z_L}\) where Zin is equal to the input impedance and ZL is equal to the load impedance. Re-writing this equation gives (17), where the characteristic impedance equals the square root of the load impedance times the desired input impedance. \(Z_0 = \sqrt{{Z_L}{Z_{in}}}\) The design of the LHCP truncated patch antenna array in HFSS can be seen below along with the fabricated design:

The simulated LHCP antenna array from HFSS produced an input reflection coefficient of -13.70 dB at 2 GHz, and the measured LHCP antenna array produced an input reflection coefficient of -11.56 dB at 2 GHz. It is worth noting that at a frequency of 1.95 GHz the input reflection coefficient would be -19.91 dB. This frequency shift is similar to the measured LHCP single truncated patch which had an input reflection coefficient of -13.70 dB at 1.95 GHz. These results can be seen below:

The simulated LHCP truncated patch antenna array produced a realized gain of 6.5 dBic and can be seen below:

Below it can be seen that the normalized radiation pattern of the measured results have a greater beam width than the simulated results. Comparing the realized gain of the LHCP single truncated patch to that of LHCP truncated patch antenna array, show that the gain was significantly increased by 5 dB.