# Antenna Design for Microwave and Millimeter Wave Applications: Latest Advances and Prospects
## 13 Wheeler Method for Evaluation of Antennas Submerged in Lossy Media  
[PERSON] et al. [12] presented a Wheeler method for the evaluation of the radiation efficiency of submerged antennas within lossy media for the first time in the literature. Extensive investigations have been devised by empirical and simulation methods. A normal-mode helical antenna (NMHA) was first designed and fabricated to exemplify a real-life application at the UHF band (0.3 to 3 GHz). The antenna under test (AUT) was evaluated within an artificial lossy material using a series of Wheeler caps featuring different radii to study the validity of this method. The error between the experimental and simulation radiation efficiency was below 3% near the theoretical radian length. The presented measurement method of radiation efficiency without any essential measurement facilities or accessoriescould be a promising candidate for fast and accurate evaluation for any wire-type antenna submerged within lossy media.  
A Low Profile Dual-Band High Gain Directional Antenna for Anti-Interference WLAN Station Applications  
[PERSON] et al. [13] presented a low-profile dual-band antenna with directional radiation characteristics for wireless local area network (WLAN) applications. The proposed directional antenna was composed of a coupling microstrip line, two F-shaped strips, two rectangular strips, and a defected ground plane. The measured impedance bandwidth of the proposed antenna was 180 MHz (2.33-2.51 GHz) and 830 MHz (5.09-5.92 GHz), which can cover Institute of Electrical and Electronic Engineers (IEEE) 802.11 a/b/g frequency bands. The dual-band antenna exhibited desirable directional radiation patterns in the vertical and horizontal planes, with a peak gain of 6.55 dBi in the lower frequency band and 8.1 dBi in the higher frequency band. The measured antenna efficiency was 70% at 2.4 GHz and 84.5% at 5.5 GHz. The proposed dual-band WLAN station antenna was designed on an FR-4 substrate with overall dimensions of 69 mm \(\times\) 50 mm \(\times\) 1.6 mm.  
Analysis of the Target Detection Performance of Air-to-Air Airborne Radar Using Long-Range Propagation Simulation in Abnormal Atmospheric Conditions  
[PERSON] et al. [14] proposed the analysis of the target detection performance of air-to-air airborne radars using long-range propagation simulations with a novel quad-linear refractivity model under abnormal atmospheric conditions. The radar propagation characteristics and the target detection performance were simulated using the Advanced Refractive Effects Prediction System (AREPS) software, where the refractivity along the altitude, array antenna pattern, and digital terrain elevation data were considered as inputs to obtain the path loss of the wave propagation. The quad-linear model was used to approximate the actual refractivity data, which were compared to the data derived using the conventional trilinear refractivity model. On the basis of the propagation simulations, a detection performance metric in terms of the atmosphere (DPMA) was proposed for intuitively examining the long-range propagation characteristics of airborne radars in air-to-air situations. To confirm the feasibility of using the DPMA map in various duct scenarios, two actual refractive indices were examined to observe the DPMA results in relation to the height of the airborne radar.  
This research received no external funding.  
I appreciate the opportunity to organize this Special Issue. Thanks to all authors and peer reviewers, this Special Issue was able to be completed successfully. I would also like to give special thanks to the editorial staff of _Applied Sciences_ for their best support on the publication of this issue.  
The author declares no conflict of interest.