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# Need advise on designing microstrip antenna 315MHz

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#### zeese

##### Member level 1
tx/rx antenna 315 mhz

Hi...
I need advices from everybody on how to design a microstrip antenna (on pcb)
for 315mhz. For Tx, it's a loop antenna, and rx, it's a monopople PCB trace antenna.
Also, one more thing, I just need to do transmission for a short distance
only about 3 or 4 meters. Once, I just bluntly design the antenna as has suggested
by the datasheet of the tx/rx IC but it only works for not even 1 meter.

Also, is the antenna dimensions important? Isn't it the longer the antenna, the better it
is.. so, why do I need to calculate dimensions?

The pcb has limited space for antenna, i need to increase the range without increasing
the space that antenna used.

This is my new assignment in my workplace, even though I really have no idea, no
experience in this thing. Never taken antenna design course. So, I need quidance
and maybe some reference on me to do research and study.

You help is appreciated.

315mhz pcb antenna

Well 315MHz is a very long wave length (for a PCB).
WavLen=C/F
C=speed of light
F=Frequency

--> WavLen~0.95Meters ~ 2.8 ft
anntenas are usually (1/4) WavLen --->8.5 inches long
in a dipole configuration you'll need 17inches + sum buffer room

|
| 8.5inches (+)
|
[ TX ]========
|
| 8.5inches (-)
|

Plus you need to calulate Zo, is it 50ohm's or 75ohm's
I think "HP APLAC" dose this, or search for other free microstrip tools.
They will explain some of the other parameters to consider.

Hope this helps
Cheers

pkg

### pkg

Points: 2
315 mhz patch antenna

Usually at this frequency there's no patch antenna. Now designing something for the 12 GHz band...different matter 8O

loop antenne 315mhz

APLAC is Nokia's Desing simulator.

a23723m

### a23723m

Points: 2
315mhz antenna design

h**p://www.kilomega.com/software/awas.zip

Hope a little help

Re: tx/rx antenna 315 mhz

Hi...
I need advices from everybody on how to design a microstrip antenna (on pcb)
for 315mhz. For Tx, it's a loop antenna, and rx, it's a monopople PCB trace antenna.
Also, one more thing, I just need to do transmission for a short distance
only about 3 or 4 meters. Once, I just bluntly design the antenna as has suggested
by the datasheet of the tx/rx IC but it only works for not even 1 meter.

Also, is the antenna dimensions important? Isn't it the longer the antenna, the better it
is.. so, why do I need to calculate dimensions?

The pcb has limited space for antenna, i need to increase the range without increasing
the space that antenna used.

This is my new assignment in my workplace, even though I really have no idea, no
experience in this thing. Never taken antenna design course. So, I need quidance
and maybe some reference on me to do research and study.

You help is appreciated.
can u explain me about how to design that patch antenna.
thank you.

there are plenty of applications that print 315 MHz antennas on a small PCB. A handheld keyfob is a typical example.

The loop length of the antenna is much shorter than the length required for resonance. One way to overcome that is to add a series reactance in the loop to "tune it" to 315 MHz.

Also, since he loop is too small physically, it will not radiate energy into free space with great efficiency.

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