A. Design of Long line-fed antenna
It is very well known that to improve the impedance bandwidth of a Long line-fed antenna is by increasing the thickness of the grounded substrate. However, this leads to several undesirable consequences. The larger contribution to surface waves which leads to decreased efficiency of the antenna. Another consequence of incorporating electrically thick substrate is the width of the microstrip line feeds increases. Figure 1 shows the geometry of an long line-fed patch microstrip antenna on a thick, low dielectric constant material at 5 GHz. A 30Ω microstrip feed line with a width of 4.5mm and a square patch of 15mm x 15mm are fabricated on a 3.175mm thick Alien higgs (εr = 2) substrate. A 100 x 100 mm ground plane is located on the reverse side of the substrate. Note that a 125Ω impedance transformation is used within the transmission line to enable the wide 30Ω feed lines to be connected directly to the edge of the radiating patch, and not be inset into the radiating patch. With this configuration a dual or circularly polarized printed antenna can be developed with the addition of an orthogonal feed line.