Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
Search
RF Antenna question
|
Mounir Shita
开云体育Anyone
know about the MICRF102 Micrel part? It's a 300-470MHz transmitter chip. I don't
know anything about RF transmission and I'm just reading the ad on the current
issue of EDN magazine. It says here:
?
"The
MICRF102 QwikRadio transmitter is an easy to use, easy to manufacture
transmitter designed for use with a low cost PCB trace
antenna"
?
This
doesn't mean a I can only use a loop back trace on the circuit board to make the
antenna for the chip?
?
Mounir
? |
|
Shawn W. McClintock
开云体育Not at
all. Although the application this device was designed for?utilize a PCB
trace type antenna, it by no means limits you to such an item. There are of
course, several things you must remember with any antenna, PCB, wire or
otherwise.
1)
Ensure proper impedance from antenna to transmitter circuit. If need be, it may
be necessary to include some type?of? impedance matching
circuit.
2)
Maintain proper impedance through out your transmission
line.
3) The
actual antenna be a function of wavelength for the frequency you are operating
at.
?
You
can find out more about antenna design and building by exploring amateur radio
sites on the web. a search on most search engines for antenna design should get
you started.
?
Shawn
?
|
|
Mounir Shita
开云体育Actually, a PCB trace antenna sounds like a perfect fit
for my project. However, the circuit will be going on my cat. On the datasheet
it says that this type on an antenna is very directional. How true is that? And
is there a way around that problem.
?
Hope
the questions aren't to stupid. I'm very illiterate when it comes to
RF.
?
Mounir
|
|
Shawn W. McClintock
开云体育Only
too glad to help. Yes, the PCB trace antenna is directional.. however, for short
distances of say under 300 ft. this is not very apparent. so if the cat is in
the house, you shouldnt have too many problems. if the transmiter output is 50
ohm, you can use a simple loop antenna that would fit inside the cat's collar.
all this would require is a 4:1 matching transformer because a loop antenna is
300 ohm, the matching transformer?is very easy to build or, if you want,
buy at many electronics stores. These are commonly known as CATV adaptors, for
older sets that have screw terminals for the flat twin lead type antenna cable
to be able to use the new coax based devices. Many TV shops have them and may
give you one for the asking, they can also be found at?Wal-Mart,
ect..?
?
Shawn
?
|
to navigate to use esc to dismiss