# Antenna Design for Microwave and Millimeter Wave Applications: Latest Advances and Prospects
###### Abstract  
The data acquisition of the 2012 \(\mu\)m and 2013 \(\mu\)m channels is a challenging problem in the near-infrared region. The data acquisition of the 2012 \(\mu\)m channels is a challenging problem in the near-infrared region. 6.6 GHz (57.2-63.8 GHz) and a maximum gain of 11.6 dBi. The design was optimized by double T-shaped structures that were added in the rectangular slots, as well as two external stubs in order to achieve a highly directed radiation pattern. Moreover, ring and circular slots were made in the partial ground plane at an optimized distance as a defected ground structure (DGS) to improve the impedance bandwidth in the desired band. The two-element array was fed by a feed network, thus improving both the impedance bandwidth and gain. The single element and array were fabricated, and the measured and simulated results mimicked each other in both return loss and antenna gain. Method for Estimating Optimal Position of S-Band Relay Station through Path Loss Analysis in an Outdoor Environment  
[PERSON] et al. [3] investigated a novel estimation method to optimize the position of a relay station of the S-band telemetry system in outdoor environments. To determine an optimal relay station position, complex terrain surface and buildings near the Naro Space Center were included in the electromagnetic (EM) simulation. The optimal relay station position was then determined using the estimation method by comparing the path losses from the rocket to the main station and some candidate positions of the relay station. To better understand the path loss, the ray analysis was also conducted, and the result demonstrated that once the rocket altitude to be covered by the relay station is determined, it is possible to find the optimum position of the relay station. Numerical Study on the Feasibility of a 24 GHz ISM-Band Doppler Radar Antenna for Near-Field Sensing of Human Respiration in Electromagnetic Aspects  
In this paper [4], the feasibility study of a 24 GHz industrial, scientific, and medical (ISM) band Doppler radar antenna in electromagnetic aspects was numerically performed for near-field sensing of human respiration. The Doppler radar antenna consists of a transmitting (Tx) antenna and a receiving (Rx) antenna close to the human body for a wearable device. The designed slot-type Doppler radar antenna was embedded between an RO4350B superstrate and an FR-4 substrate. To obtain the higher radiation pattern of the antenna towards the human body, a ground plane reflector was placed underneath the substrate. The measured \(-\)10 dB reflection coefficient (S11) bandwidth was 23.74 to 25.56 GHz and the mutual coupling (S21) between Tx and Rx antennas was lower than \(-\)30 dB at target frequencies. The Doppler effect due to human respiration was investigated through the I/Q and arctangent demodulation of the returned signal. According to the results, the phase variation of the returned signal was proportional to the displacement of the body's surface, which was about 0.8 rad in accordance with 1 mm displacement. The numerical experiments indicated that the proposed Doppler radar antenna can be used for near-field sensing of human respiration in electromagnetic aspects. Design of an Electrically Small, Planar Quasi-Isotropic Antenna for Enhancement of Wireless Link Reliability under NLOS Channels  
The performance of wireless networks can be greatly influenced by the radiation pattern and polarization of the antennas at the nodes, especially when they are under non-line-of-sight (NLOS) channel environments. In this paper [5], a planar quasi-isotropic antenna based on the combination of a meandered electric dipole and an electrically small loop was designed at a frequency of 2.45 GHz. Its electrical size (_ka_) was 0.47 and showed a gain deviation of 3.01 dB with a radiation efficiency of 82.6% per the simulation.