Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

inductive coupling of UHF

Status
Not open for further replies.

dz99

Member level 5
Member level 5
Joined
Feb 13, 2006
Messages
89
Helped
5
Reputation
12
Reaction score
1
Trophy points
1,288
Location
Between East and West Europe
Activity points
1,929
Hello!

I want to couple out the RF power form my small radio (f=446 MHz lamd=67.2 cm=26.48 inch PWR_OUT=26dBm) without opening it, and solder a coax line to the HPA's output. Inductive couping seems to be a good solution (or the conductive coupling better? I haven't got reference.)

The transceivers antenna is a lambda/4 rod ( 80 mm )

1. How can I calculate which coil dimensions would resonate out the maximal power?

2. The coil end will be a differenital (push-pull) output. Thus I can't use coaxial cabel as a transport line. --> a. feed a symetrical dipol directly by the coil or
b. use of a balun transformer?

In case of "instant dipole sticking" I can't transport the signal to (for instance) higher positined antennas.

EDA tools also welcome!
Bye!
Thanks a lot!
Z.
 

bingjiang99

Advanced Member level 4
Full Member level 1
Joined
Apr 27, 2005
Messages
115
Helped
5
Reputation
10
Reaction score
0
Trophy points
1,296
Activity points
2,303
1) You have to use EDA software to simulate your antenna. You can use HFSS, which is very accurate.
2) I believe that you have to use a balun to drive your signal. However, if you didn't expect too much, a direct feeding can work OK.
3) If you want to use inductive coupling, you should put a loop antenna pair to do that.

dz99 said:
Hello!

I want to couple out the RF power form my small radio (f=446 MHz lamd=67.2 cm=26.48 inch PWR_OUT=26dBm) without opening it, and solder a coax line to the HPA's output. Inductive couping seems to be a good solution (or the conductive coupling better? I haven't got reference.)

The transceivers antenna is a lambda/4 rod ( 80 mm )

1. How can I calculate which coil dimensions would resonate out the maximal power?

2. The coil end will be a differenital (push-pull) output. Thus I can't use coaxial cabel as a transport line. --> a. feed a symetrical dipol directly by the coil or
b. use of a balun transformer?

In case of "instant dipole sticking" I can't transport the signal to (for instance) higher positined antennas.

EDA tools also welcome!
Bye!
Thanks a lot!
Z.
 

    dz99

    Points: 2
    Helpful Answer Positive Rating

dz99

Member level 5
Member level 5
Joined
Feb 13, 2006
Messages
89
Helped
5
Reputation
12
Reaction score
1
Trophy points
1,288
Location
Between East and West Europe
Activity points
1,929
OK, but I don't know HFSS yet. Maybe I will.

Any other ideas?

Some guys told me, that forget it! You can't manage that! Losses will be eat up the tiny 0.5W @ 446 MHz. It's true, or can be achived good efficiency with (narrow band) inductive coupling at this freq?

Bye!
Z.
 

vfone

Advanced Member level 6
Advanced Member level 6
Joined
Oct 10, 2001
Messages
5,538
Helped
1,598
Reputation
3,201
Reaction score
1,203
Trophy points
1,393
Activity points
35,183
In a conducted connection the loss is insignificant, when inductive coupling introduce some loss, and also is bandwidth limited.
 

dz99

Member level 5
Member level 5
Joined
Feb 13, 2006
Messages
89
Helped
5
Reputation
12
Reaction score
1
Trophy points
1,288
Location
Between East and West Europe
Activity points
1,929
Than first I have to plan a coil (around the ant) which is resonant @446 MHz.
Planing with, I don't know what. Maybe simple jwL calculations, and then inductance calc. I will see after the formulas!

Then measureing it with a VNA is getting complicated...
Considering that tha VNA's input is assymetrical (let mesure S11), and designed for 50 ohm. So I'm stucked with my differential coil, which has unknow impedance.

:|
 

bingjiang99

Advanced Member level 4
Full Member level 1
Joined
Apr 27, 2005
Messages
115
Helped
5
Reputation
10
Reaction score
0
Trophy points
1,296
Activity points
2,303
Inductance calculation will not give you the correct answer for sure, although it will give you some ideas. (This works in low frequency, such as 10 MHz) The truth is simple. The trace also introduces the parasatic capacitance, which may contribute a lot to the impedance.

It is better to simulate it with EM software. VNA will predict how to tune your loop.

Good luck.


dz99 said:
Than first I have to plan a coil (around the ant) which is resonant @446 MHz.
Planing with, I don't know what. Maybe simple jwL calculations, and then inductance calc. I will see after the formulas!

Then measureing it with a VNA is getting complicated...
Considering that tha VNA's input is assymetrical (let mesure S11), and designed for 50 ohm. So I'm stucked with my differential coil, which has unknow impedance.

:|
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top