Simple AM/FM antenna design for RF signal generator - Page 1
Forum section: electronics / projects

author: davorin
author_rank: Unknown
timestamp: July 02, 2014, 05:34:44 pm
content: 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?

author: SeanB
author_rank: Super Contributor
timestamp: July 02, 2014, 06:00:30 pm
content: 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.

author: davorin
author_rank: Unknown
timestamp: July 02, 2014, 06:05:18 pm
content: Can you recommend a good book/ebook for absolute beginners wanting to do antenna designs and RF transmitters? (o;

author: poorchava
author_rank: Super Contributor
timestamp: July 02, 2014, 07:03:24 pm
content: Ditto that, I became interested in RF lately and it's surprisingly hard to find any sources for total beginners.

author: Fank1
author_rank: Regular Contributor
timestamp: July 02, 2014, 11:20:46 pm
content: Experimental Methods in RF DesignBy:Les Hayward W7ZOIRick Campbell KK7BBob Larkin W7PUAAvailable from ARRLBest book I've seen in years.

author: calexanian
author_rank: Super Contributor
timestamp: July 03, 2014, 01:27:55 am
content: 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.

author: davorin
author_rank: Unknown
timestamp: July 08, 2014, 12:08:08 pm
content: Found a program to calculate, which gives me around a 8cm sized antenna for 93.8MHz:http://www.hamuniverse.com/dipivcal.htmlNow 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?

author: JOERGG
author_rank: Contributor
timestamp: July 09, 2014, 01:36:17 am
content: Quote from: davorin on July 02, 2014, 06:05:18 pmLiving in Switzerland you probably can read german. Then i would recommend this book about antennas:http://darcverlag.de/Rothammels-Antennenbuch

author: davorin
author_rank: Unknown
timestamp: July 09, 2014, 08:43:14 am
content: 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;

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 09, 2014, 09:06:05 am
content: QuoteThat 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.

author: miguelvp
author_rank: Super Contributor
timestamp: July 10, 2014, 03:08:17 am
content: Quote from: PA0PBZ on July 09, 2014, 09:06:05 amMath is simple.Speed of light: 299,792,458 meters per secondFrequency: 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

author: Zad
author_rank: Super Contributor
timestamp: July 10, 2014, 03:49:48 am
content: For FM, use a telescopic antenna from an FM broadcast receiver. For AM, salvage a ferrite antenna out of the same broadcast receiver!

author: davorin
author_rank: Unknown
timestamp: July 10, 2014, 04:34:11 pm
content: Ah...know now what confused the software....it ignored the decimal point...so 93.8MHz was for it 938MHz (o;

author: eneuro
author_rank: Super Contributor
timestamp: July 11, 2014, 08:34:26 am
content: What do you think about thisamazon: Practical antenna handbook by Joseph Carrbook?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.