Simple AM/FM antenna design for RF signal generator

[davorin]

Good evenin' (o;

As now my Fluke 6060a/AN seems to have repaired himself I would like to use it also for testing older AM/FM radios as my lab is in the basement and no AM/FM reception is possible at all...

What would be the simplest design for an AM and FM antenna which can be directly plugged into the 6060a/AN signal generator?

[SeanB]

Simplest is a random wire antenna, preferably something about a quarter wave long at the frequencies of interest, but with low power and short range not necessarily so. If you are worried about SWR use a series 47R resistor to reduce reflections, and simply place one end in the BNC output connector.

If you want to get fancier use a quarter wave vertical dipole and a ground plane. Simplest for FM use is to go and buy a car antenna and simply plug it into the signal generator after replacing the antenna plug with a BNC connector. for better results use an external FM antenna without the reflector and director. I cut one down for use on 2m and it works well even with a 0.5W transmit power.

[davorin]

Can you recommend a good book/ebook for absolute beginners wanting to do antenna designs and RF transmitters? (o;

[poorchava]

Ditto that, I became interested in RF lately and it's surprisingly hard to find any sources for total beginners.

[Fank1]

Experimental Methods in RF Design
By:
     Les Hayward W7ZOI
     Rick Campbell KK7B
     Bob Larkin W7PUA

Available from ARRL
Best book I've seen in years.

[calexanian]

Grab an ARRL antenna book/handbook and grab a ARRL general handbook while you are at it. All of the basics presented in a manner where anybody with basic electronics knowledge (that's in there too) can conceptualize how antennas work. A must have for RF basics.

[davorin]

Found a program to calculate, which gives me around a 8cm sized antenna for 93.8MHz:

http://www.hamuniverse.com/dipivcal.html

Now for AM bands...this gets quite big....is there a calculator to make a transformer with 50Ohm input for the Fluke 6060a/AN and outputs directly to my AM band radios for testing?

[JOERGG]

Can you recommend a good book/ebook for absolute beginners wanting to do antenna designs and RF transmitters? (o;

Living in Switzerland you probably can read german. Then i would recommend this book about antennas:

http://darcverlag.de/Rothammels-Antennenbuch

[davorin]

Thanks..looks more like a bible than a book (o;

An Australian tour guide and book writer described our language like:

"We write a language we don't speak, and we speak a language we don't write" (o;

[PA0PBZ]

Found a program to calculate, which gives me around a 8cm sized antenna for 93.8MHz:

 
That can't be correct. Since the wavelength is about 3 meters in the FM band a quarter wave dipole or groundplane should have elements with a length of about 75 cm.

So for a dipole:

 <-75->   <-75->
_______  _______
       ||
 
 That's probably the easiest to do, just hang it vertical and you will not have a directional effect and you will not need a ground plane.

[miguelvp]

Found a program to calculate, which gives me around a 8cm sized antenna for 93.8MHz:

 
That can't be correct. Since the wavelength is about 3 meters in the FM band a quarter wave dipole or groundplane should have elements with a length of about 75 cm.

So for a dipole:

 <-75->   <-75->
_______  _______
       ||
 
 That's probably the easiest to do, just hang it vertical and you will not have a directional effect and you will not need a ground plane.

Math is simple.

Speed of light: 299,792,458 meters per second
Frequency: 93,800,000 cycles per second.

so 299,792,458  m/s divided by 93,800,000 cycles/s = X meters per cycle (seconds cancel each other), so 3.1960816417910447761194029850746 m per wavelengh cycle.

quarterwave 0.79902041044776119402985074626866 m or 80 cm (not 8cm)

Edit: 8cm would be for 10 times the frequency so 938MHz, maybe you put one 0 too many

[Zad]

For FM, use a telescopic antenna from an FM broadcast receiver. For AM, salvage a ferrite antenna out of the same broadcast receiver!

[davorin]

Ah...know now what confused the software....it ignored the decimal point...so 93.8MHz was for it 938MHz (o;

[eneuro]

What do you think about this amazon: Practical antenna handbook by Joseph Carr book?

Looks not so bad.

I need to send encrypted Morse coded bits from meteo station and receive hundreds of meters or a few kilometers/miles away using radio.