dshoter13
Member level 4
Hello all,
I am fairly new to EM and Antenna modelling and simulation, therefore, I beg a pardon on some of the following non-sense questions that I might inquire.
Recently I have been playing around with HFSS in order to simulate a patch antenna. The patch antenna is fed by a coax cable. To perform this simulation I followed the Help on the HFSS manual examples and set everything accordingly. Regarding the antenna simulation and modelling I understood its working principle. My main question is on the coax feed; according to the HFSS setup, the coax feed is simply set by using a inner conductor (PEC) with 0.7 mm radius and an vacuum outer cylinder with 1.6 mm radius, both considering 0.5 cm length. After this, we set up a circle with the same radius as the outer cylinder at the end and assign a wave port excitation. My question is concerning the behaviour of such structure, since in real life we will have both inner and outer conductors as well as a different dielectric. Since we do not set up the external shield, how can the simulator know the excitation mode/way we employ?
Other doubt I have concerns the usage of such feeding method when exciting either unbalanced or small antennas. Since this situation usually leads to higher currents on the outer shield of the coax cable, I am predicted that this kind of simulation won't be precise enough to predict the real world behaviour. Any thoughts on that? Also, why do antennas with small ground planes or electrically small usually force large currents on the outer shield of the coax?
I would sincerely appreciate any help in order to better understand this conditions.
Thank you for your time.
Kind regards.
I am fairly new to EM and Antenna modelling and simulation, therefore, I beg a pardon on some of the following non-sense questions that I might inquire.
Recently I have been playing around with HFSS in order to simulate a patch antenna. The patch antenna is fed by a coax cable. To perform this simulation I followed the Help on the HFSS manual examples and set everything accordingly. Regarding the antenna simulation and modelling I understood its working principle. My main question is on the coax feed; according to the HFSS setup, the coax feed is simply set by using a inner conductor (PEC) with 0.7 mm radius and an vacuum outer cylinder with 1.6 mm radius, both considering 0.5 cm length. After this, we set up a circle with the same radius as the outer cylinder at the end and assign a wave port excitation. My question is concerning the behaviour of such structure, since in real life we will have both inner and outer conductors as well as a different dielectric. Since we do not set up the external shield, how can the simulator know the excitation mode/way we employ?
Other doubt I have concerns the usage of such feeding method when exciting either unbalanced or small antennas. Since this situation usually leads to higher currents on the outer shield of the coax cable, I am predicted that this kind of simulation won't be precise enough to predict the real world behaviour. Any thoughts on that? Also, why do antennas with small ground planes or electrically small usually force large currents on the outer shield of the coax?
I would sincerely appreciate any help in order to better understand this conditions.
Thank you for your time.
Kind regards.