From ad6ef3ed59738fa5bb351f7410489a520350e769 Mon Sep 17 00:00:00 2001 From: Tyler Perkins Date: Fri, 12 Nov 2021 13:15:01 -0500 Subject: [PATCH] Update for 12-11-21 13:15 --- tech/Antenna.wiki | 16 +++++++++++++--- tech/Ham.wiki | 3 +++ tech/Modulation.wiki | 10 ++++++++++ tech/SWR.wiki | 9 +++++++++ 4 files changed, 35 insertions(+), 3 deletions(-) create mode 100644 tech/Modulation.wiki diff --git a/tech/Antenna.wiki b/tech/Antenna.wiki index 5de65b9..80db783 100644 --- a/tech/Antenna.wiki +++ b/tech/Antenna.wiki @@ -32,7 +32,8 @@ height above ground. A common feed line in Coax, due to its ease of use. Most for radio coax has an characteristic impedance of *50 ohms*. TV coax has an impedance of -75 ohms. +75 ohms. In general, larger diamater coax has less loss compared to thinner +cable. Performance of Coax is dependent on the integrity of the outer jacket. Another common feed line is made of two leads, seperated by plastic. It is called open wire, ladder line, window line, or twin lead. Becuase there is @@ -96,6 +97,15 @@ physically. *Ground plane antennas are omnidirectional when mounted parallel to the ground* -== Yagis == +=== Yagis === -Yagi antennas are the common house mounted antenna you see for TV. +Yagi antennas are the common house mounted antenna you see for TV. They are +very directional, focusing half of their power 60 degrees, along the axis of +the Yagi. They also can ignore the interference caused by other signals coming +from the sides of the antenna. + +=== Dish === + +A Dish in a very focused type of antenna, often used for the 1Ghz+ range of +frequencies. They are directional in the dirction of the dish, and can send and +recieve very focused signals. diff --git a/tech/Ham.wiki b/tech/Ham.wiki index d16230c..c67bbd0 100644 --- a/tech/Ham.wiki +++ b/tech/Ham.wiki @@ -36,3 +36,6 @@ see [[electronics]] [[Propagation]] [[Antenna]] [[SWR]] + +== [[Modulation]] == + diff --git a/tech/Modulation.wiki b/tech/Modulation.wiki new file mode 100644 index 0000000..697d2d4 --- /dev/null +++ b/tech/Modulation.wiki @@ -0,0 +1,10 @@ += Modulation = + +Modulation is the altering of a carrier signal to add infomration. This is done +in everything from raido, to Ethernet. + +== Bandwidth == + +Bandwidth is the amount of frequencies that a signal occupies. For example, the +Human voice can make frequencies from 300Hz to 3000Hz, therefore having a +bandwidth of 3000 - 300 = 2700Hz. diff --git a/tech/SWR.wiki b/tech/SWR.wiki index 872b4da..f9be7aa 100644 --- a/tech/SWR.wiki +++ b/tech/SWR.wiki @@ -24,3 +24,12 @@ If you expereince SWR, check * Antenna length vs frequency * Faulty feed lines/feed line connectors * Erratic SWR means loose connections in feed line + +== Meters == + +An SWR meter allows you to measure the power flowing to and from the antenna, +therefore calculating the amount of SWR. Another type of SWR meter is a +directional Wattmeter, determining the amount of power in each direction. + +Antenna tuners exist, which alter the Impedance of the feed line to match that +of the antenna, so make the SWR 1:1. This is either manual or automatic.