Unterschiede

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--- project:hgg:antenna_design:omidirectional [2012-01-01 04:05] – 85.179.243.149
+++ project:hgg:antenna_design:omidirectional [2012-03-26 09:16] (aktuell) – alte Version wieder hergestellt 85.214.34.41
@@ Zeile 21: / Zeile 21: @@
-======= More Gain =======
+====== More Gain ======
-I found out that comercial antennas with high gain often are very long like in 1.2 to 3.5 Meters. In the antenna Manuals (eg see [[http://www.scribd.com/doc/20515944/Kathrein-Antennas|Different Types of Kathrein Antennas]], in the section VPol Omnidirectional Antenna 1087 to 1093 Mhz) they talk about decouploed Dipoles. As far as i get it, that means that you put more than one Dipole into an Antenna. To make the antenna not have different gains for different directions, the dipoles are stacked. Since the signal is vertically polarized, the antenna won't become direction-dependent if the dipoles are above each other.
+I found out that comercial antennas with high gain often are very long like in 1.2 to 3.5 Meters.
+Omni antennas by definition offer 0 dB gain (1).
+To generate higher gain, one must increase the directionality of the antenna, and therefore make it directional (ie not omni directional).
+The gain of the antenna is given by:
+G = η(πD/λ)^2
+Where:
+η = efficiency (0.65 good initial value)
+D = Diameter
+λ = wavelength of signal being received/transmitted.
+ In the antenna Manuals (eg see [[http://www.scribd.com/doc/20515944/Kathrein-Antennas|Different Types of Kathrein Antennas]], in the section VPol Omnidirectional Antenna 1087 to 1093 Mhz) they talk about decouploed Dipoles. As far as i get it, that means that you put more than one Dipole into an Antenna. To make the antenna not have different gains for different directions, the dipoles are stacked. Since the signal is vertically polarized, the antenna won't become direction-dependent if the dipoles are above each other.
 It's not clear if that also works for groundplane antennas.
@@ Zeile 30: / Zeile 45: @@
-===== Link-Dump =====
+====== Link-Dump ======
 [[http://www.hindawi.com/journals/ijap/2010/843624/]]