Another antenna option....

Status
Not open for further replies.

mcarrico2

Member
Premium Subscriber
Joined
Apr 13, 2008
Messages
10
Location
Warner Robins Ga
I built a dipole antenna with a balun and copper wire. My reception on air band is 100 percent better. I just have the antenna hanging in the corner of my room. I want to put an antenna in the attic. Is there a better option for an antenna if I go through the trouble of running coax through the wall. I listen to air band and 800 mhz however I am so close to the repeaters I am focusing more on air band ....would anything work better than my home brew?
 

rbrtklamp2

Member
Premium Subscriber
Joined
Dec 8, 2005
Messages
845
Location
Dupage County, Illinois
Got pictures? That sounds like a fun project when I have some time off in August although I may build a few VHF, UHF and 700 MHz. But I would love to see the design and materials your using. I just have black and white schematics for building them.

Sent from my SM-N910V using Tapatalk
 

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
13,845
Location
SNCZCA01DS0
Off-center fed dipole, AKA OCF.

If you want to make a more permanent version, you can use copper pipe. It's cheap, easy to solder, easy to cut.
Other option is to make a wire one and mount it in some PVC pipe.

A 1/4 wave vertical is easy to build and will work well. It's natively 50Ω, so no need for a balun.

Either one is cheap and easy to build. As an option, you could build one for each band (VHF, UHF, 800MHz) and switch between them as needed.
 

Ubbe

Member
Joined
Sep 8, 2006
Messages
5,123
Location
Stockholm, Sweden
If you want to focus on airband 118-136MHz then make each pole 24 inches long and use the balun, otherwise it will
be a 1/4 wave antenna with less gain than a 1/2 wave dipole and you will also lose the extra bandwidth you get with a balun.

/Ubbe
 

popnokick

Member
Premium Subscriber
Joined
Mar 21, 2004
Messages
2,085
Location
Northeast PA
What you've made is an Off-Center Fed Dipole, hopefully using the same method shown here in the RR Antenna Wiki - Homebrewed Off-Center Fed Dipole - The RadioReference Wiki
Are there better antennas for 800 mHz? Yes, but you said airband was your primary interest, and the OCFD was working with the 800 signals which are strong for your location. Will the OCFD perform better in the attic? Most likely unless there is a metal roof, foil insulation, or other large metal surfaces in the attic. I have the copper pipe version standing vertically in my attic near a window and it is a very good performer for aircraft reception - both civil and military air bands. Could you buy something equivalent or perhaps better for the airband and other frequencies you listen to? Perhaps. You might want to try the DPD Productions Omni-X DPD Productions - Base & Mobile Antennas for Radio Scanners: VHF, UHF, NOAA, Low-Band, 700 MHz, Police, Fire, Public Safety
 

ladn

Explorer of the Frequency Spectrum
Premium Subscriber
Joined
Oct 25, 2008
Messages
581
Location
Southern California and sometimes Owens Valley
I've built several OCF dipoles from the RR Wiki plans (one using aluminum tubing, others with wire) and have found them to be quite satisfactory from lowband to 800 MHz. Yes, there are more efficient designs, but this is an easy to build, inexpensive antenna that simply works.
 

mcarrico2

Member
Premium Subscriber
Joined
Apr 13, 2008
Messages
10
Location
Warner Robins Ga
So instead of 48 and 18 inches just make 24 inches on both ends?
If you want to focus on airband 118-136MHz then make each pole 24 inches long and use the balun, otherwise it will
be a 1/4 wave antenna with less gain than a 1/2 wave dipole and you will also lose the extra bandwidth you get with a balun.

/Ubbe
 

mcarrico2

Member
Premium Subscriber
Joined
Apr 13, 2008
Messages
10
Location
Warner Robins Ga
That is exactly how I made it.
I did see that one antenna in your link. Was just curious if it would be real big improvement over my home made deal. I have vinyl siding....very high roof and no metal or anything in the attic. Guess it's prob one of those trial and error deals.
What you've made is an Off-Center Fed Dipole, hopefully using the same method shown here in the RR Antenna Wiki - Homebrewed Off-Center Fed Dipole - The RadioReference Wiki
Are there better antennas for 800 mHz? Yes, but you said airband was your primary interest, and the OCFD was working with the 800 signals which are strong for your location. Will the OCFD perform better in the attic? Most likely unless there is a metal roof, foil insulation, or other large metal surfaces in the attic. I have the copper pipe version standing vertically in my attic near a window and it is a very good performer for aircraft reception - both civil and military air bands. Could you buy something equivalent or perhaps better for the airband and other frequencies you listen to? Perhaps. You might want to try the DPD Productions Omni-X DPD Productions - Base & Mobile Antennas for Radio Scanners: VHF, UHF, NOAA, Low-Band, 700 MHz, Police, Fire, Public Safety
 

popnokick

Member
Premium Subscriber
Joined
Mar 21, 2004
Messages
2,085
Location
Northeast PA
The OCFD antenna shown in the RR Wiki is a multi band antenna with very broad coverage overall and resonant points in the popular scanning bands from 30 mHz to UHF and even some 800 mHz IF AND WHEN it is built to the specs in the RR Antenna Wiki, i.e. with "legs" of 18 and 48 inches. If you make both legs equal you will have created a dipole for the band you have cut it to (e.g. civil aircraft 108-136 mHz) and severely attenuate or even eliminate other bands (e.g. 800 mHz). One of the RR WikI OCFD's "natural" coverage bands is in fact the 108-136 mHz cutting it into a dipole will actually reduce the aircraft performance. The OCFD antenna exhibits gain over a dipole and you will remove that gain if you make the legs equal.
Regarding the other question posted in this thread ("What measurements required for a 30 to 50 loband OCF?").... the same as shown in the RR Antenna Wiki for making the antenna (18 and 48 inches).
 
Status
Not open for further replies.
Top