MS Antenna Design for 3.5GHz WiMAX..

BS Antenna (vecima 3.5gHz) SS Antenna (Vecima 3.5Ghz)

As a new system, WiMAX has it special requirements and constraints.

• It operates at high frequency (2.5/3.5/5.5GHz)-> higher signal attenuation
• Deployment needs wide transmission bandwidth (5/10MHz)->high data rates per user
• It has the need to use high-level modulation (up to 64QAM)-> high capacity and high data rate per user
• it has the dimensioning with stringent indoor penetration requirements
• According to these requirements, I designed a patch antenna working at one of the possible WiMAX frequency, i.e. 3.5GHz. The design specification is as follows:

• 50Ω transmission line
• Substrate: FR4 (Flame Resistant 4)
  -Composite of a resin epoxy reinforced with a woven fiberglass mat
  -Єr = 4.4
  -tanδ = 0.01 @ 10GHz
  -Less lossy at high frequencies
  -Absorb less moisture
  -Greater strength and stiffness
  -Highly flame resistant compared to its less costly counterpart
  -Ultra high vacuum compatible


• Height of dielectric substrate (h): 1.5mm
  -for usage in cellular phones, it is essential that the antenna is not bulky.
• Patch
  -Conducting material such as copper or gold
  -Take rectangular shape as example
  -Large bandwidth and gain

The design procedure is as follows.

Other parameters are calculated as below.

Based on the above parameters, we get the following patch antenna.
This patch antenna has its advantages and disadvantages.

Advantages:

• Light weight and low volume
• Low profile planar configuration which can be easily made conformal to host surface
• Low fabrication cost, hence can be manufactured in large quantities
• Supports both, linear as well as circular polarization
• Can be easily integrated with microwave integrated circuits
• Capable of dual and triple frequency operations
• Mechanically robust when mounted on rigid surfaces

Disadvantages:

• Narrow bandwidth
• Low efficiency
• Low gain
• Extraneous radiation from feeds and junctions
• Poor end fire radiator except tapered slot antennas
• Low power handling capacity
• Surface wave excitation