VHF/UHF (30 - 512 MHz) Antenna for Man-Pack radio

Abstract

Like any other field, effective communication is critical in warfare. The earliest military communications were delivered by runners. Later, communications progressed to visual and audible signals, and then advanced into the electronic age. Present day military forces conduct intense and complicated communicating activities on a daily basis, using modern telecommunications and computing methods. One of the radio sets that is used by Pakistan Army for this purpose is the Software Designed Radio (SDR) set. Most of the communication in armed forces is carried out in VHF and UHF bands. SDR based radio sets used in Pakistan Army has limited performance due to lack of antenna that is optimized for all frequencies in range of 30 to 512 MHz. There are separate antennas optimized for different sub-bands in 30 – 512 MHz band which are needed for specific sub band. There is a need for an all range (30 to 512 MHz) Omni-directional whip antenna that can be integrated with man pack so that the user does not need different antennas every time frequency is changed to different sub bands. Therefore, a broadband monopole antenna with a very low-cost mechanical structure is proposed. This monopole with inductor/resistor (LR) loading circuits is designed to operate in the frequency range of 30-512 MHz. By choosing optimized locations of LR loads, the radiation pattern is controlled. Meanwhile, the VSWR is adjusted by an input matching circuit, tuning a number of LR loads, and using a transmission line transformer. The impedance matching is improved in whole frequency bandwidth and antenna gain is also increased than in the existing antennas. The antenna is considered to be used in portable applications.