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Hey Antenna Gurus !
I want to screw around and build some homemade antennas.
Will this single quad loop work throughout the band? Says it's 1.8 DB gain over dipole. I was going to build a dipole, but looked rather boring. http://signalengineering.com/ultimate/cubical_quad.html Expert opinions are welcomed. Thanks. Vinnie S. |
Hey Antenna Gurus !
On May 1, 8:43 pm, Vinnie S. wrote:
I want to screw around and build some homemade antennas. Will this single quad loop work throughout the band? Says it's 1.8 DB gain over dipole. I was going to build a dipole, but looked rather boring. http://signalengineering.com/ultimate/cubical_quad.html Expert opinions are welcomed. Thanks. First off... don't claim to be an expert... If you're talking about covering the CB band... don't think you'd have any problem with coverage. www.telstar-electronics.com |
Hey Antenna Gurus !
On Tue, 01 May 2007 21:43:01 -0400, Vinnie S.
wrote: +++I want to screw around and build some homemade antennas. +++ +++Will this single quad loop work throughout the band? Says it's 1.8 DB gain over +++dipole. I was going to build a dipole, but looked rather boring. +++ +++ +++http://signalengineering.com/ultimate/cubical_quad.html +++ +++Expert opinions are welcomed. Thanks. +++ +++Vinnie S. *************** Vinnie By band how much outside teh normal 40 channel band are you expecting to operate? I used a single loop on 6 meters and got about 600KHz bandwidth with good results. A single loop is rather easy to build and rather cheap. There are more pronounced nulls off the quad loop compared to a dipole. Also th efeed impedance is about 100 Ohms so a simple quarter wave section of 75 Ohm cable will be all that is needed to match the antenna. james |
Hey Antenna Gurus !
On Tue, 01 May 2007 21:43:01 -0400, Vinnie S.
wrote: I want to screw around and build some homemade antennas. Will this single quad loop work throughout the band? Says it's 1.8 DB gain over dipole. I was going to build a dipole, but looked rather boring. http://signalengineering.com/ultimate/cubical_quad.html Expert opinions are welcomed. Thanks. Vinnie S. Add a reflector and become single directional with more gain. |
Hey Antenna Gurus !
By band how much outside teh normal 40 channel band are you expecting to operate? I used a single loop on 6 meters and got about 600KHz bandwidth with good results. A single loop is rather easy to build and rather cheap. There are more pronounced nulls off the quad loop compared to a dipole. Also th efeed impedance is about 100 Ohms so a simple quarter wave section of 75 Ohm cable will be all that is needed to match the antenna. james Just 11 meters. I have a Hustler 5BTV for my ham rig. I just wanted to try it because it looked cool. I am confused about the 75 ohm cable you mention. Vinnie S. |
Hey Antenna Gurus !
On Wed, 02 May 2007 17:30:22 -0400, wrote:
On Tue, 01 May 2007 21:43:01 -0400, Vinnie S. wrote: I want to screw around and build some homemade antennas. Will this single quad loop work throughout the band? Says it's 1.8 DB gain over dipole. I was going to build a dipole, but looked rather boring. http://signalengineering.com/ultimate/cubical_quad.html Expert opinions are welcomed. Thanks. Vinnie S. Add a reflector and become single directional with more gain. That will be part II. Vinnie S. |
Hey Antenna Gurus !
On 2 May 2007 04:17:25 -0700, Telspam Electronics
wrote in .com: On May 1, 8:43 pm, Vinnie S. wrote: I want to screw around and build some homemade antennas. Will this single quad loop work throughout the band? Says it's 1.8 DB gain over dipole. I was going to build a dipole, but looked rather boring. http://signalengineering.com/ultimate/cubical_quad.html Expert opinions are welcomed. Thanks. First off... don't claim to be an expert... At one time you did. What changed your mind, Brian? If you're talking about covering the CB band... don't think you'd have any problem with coverage. As long as the ground plane is at least nine square feet? |
Hey Antenna Gurus !
On May 4, 2:53 am, Frank Gilliland
wrote: As long as the ground plane is at least nine square feet? Polly wanna a cracker? www.telstar-electronics.com |
Hey Antenna Gurus !
On Thu, 03 May 2007 20:02:52 -0400, Vinnie S.
wrote: +++ +++ +++By band how much outside teh normal 40 channel band are you expecting +++to operate? +++ +++I used a single loop on 6 meters and got about 600KHz bandwidth with +++good results. A single loop is rather easy to build and rather cheap. +++There are more pronounced nulls off the quad loop compared to a +++dipole. Also th efeed impedance is about 100 Ohms so a simple quarter +++wave section of 75 Ohm cable will be all that is needed to match the +++antenna. +++ +++james +++ +++ +++Just 11 meters. I have a Hustler 5BTV for my ham rig. I just wanted to try it +++because it looked cool. I am confused about the 75 ohm cable you mention. +++ +++Vinnie S. *********** Tomatch an antenna that is around 100 Ohms impedance needs only what is called a quarter wave matching stub. It is simply an electrical quarterwave length of 75 Ohm coax from the feedpoint to the 50Ohm transmission line. Simple and works well. james |
Hey Antenna Gurus !
On May 4, 6:51 am, james wrote:
Tomatch an antenna that is around 100 Ohms impedance needs only what is called a quarter wave matching stub. It is simply an electrical quarterwave length of 75 Ohm coax from the feedpoint to the 50Ohm transmission line. Simple and works well. Problem is... the stub would be quite long... about nine feet. I wouldn't want that much coax kicking around as a matching network. www.telstar-electronics.com |
Hey Antenna Gurus !
On 4 May 2007 05:46:49 -0700, Telstar Electronics
wrote: +++On May 4, 6:51 am, james wrote: +++ Tomatch an antenna that is around 100 Ohms impedance needs only what +++ is called a quarter wave matching stub. It is simply an electrical +++ quarterwave length of 75 Ohm coax from the feedpoint to the 50Ohm +++ transmission line. +++ Simple and works well. +++ +++Problem is... the stub would be quite long... about nine feet. +++I wouldn't want that much coax kicking around as a matching network. +++ +++www.telstar-electronics.com ************** IF coax length is a hangup then you can use a two to one balun. Actually the length will be between 66% and 80% of ~9 feet depending on the dielectric constant of the material that comprises the coaxial cable's center. Using RG11 polyethelene dielectric will yield about 6 feet. Also considering that if you want vertical polarization the feedline must come away from the feedpoint orthogonally the run of any length of matching stub would be immaterial. james |
Hey Antenna Gurus !
On May 4, 10:08 am, james wrote:
IF coax length is a hangup then you can use a two to one balun. Much better idea... www.telstar-electronics.com |
Hey Antenna Gurus !
On 4 May 2007 10:34:25 -0700, Telstar Electronics
wrote: +++On May 4, 10:08 am, james wrote: +++ IF coax length is a hangup then you can use a two to one balun. +++ +++Much better idea... +++ +++www.telstar-electronics.com ********* Actually a quarter wave matching section is better in some ways. All you really do is shorten the main transmission line by the length of the matching section. No real big deal if you can use a ruler. Then using a matching section does predicate the knowledge of using certain tools like a calculator, ruler, a coax cutting and stripping tool and finally a soldering iron. james |
Hey Antenna Gurus !
On 4 May 2007 10:34:25 -0700, Telspam Electronics
wrote in .com: On May 4, 10:08 am, james wrote: IF coax length is a hangup then you can use a two to one balun. Much better idea... Not really. Insertion loss of a [ferrite] balun could negate any gain you may get by impedance matching. It is also fixed, while a coax stub can be easily 'retuned' by simply pinning the coax. Not only that, since the antenna is (hopefully) way up in the air, the coax used for matching is either incorporated in the line or hung from the side, making any worries about extra coax "kicking around" a non-issue. You should be more worried about where you're going to put that nine square feet of ground plane. |
Hey Antenna Gurus !
On May 4, 5:44 pm, Frank Gilliland wrote:
Not really. Insertion loss of a [ferrite] balun could negate any gain you may get by impedance matching. It is also fixed, while a coax stub can be easily 'retuned' by simply pinning the coax. Not only that, since the antenna is (hopefully) way up in the air, the coax used for matching is either incorporated in the line or hung from the side, making any worries about extra coax "kicking around" a non-issue. You should be more worried about where you're going to put that nine square feet of ground plane. Pure rubbish... a balun would have perhaps 0.1dB insertion loss. The antenna gain is perhaps twenty times that! www.telstar-electronics.com |
Hey Antenna Gurus !
IF coax length is a hangup then you can use a two to one balun. This would be better. Vinnie S. |
Hey Antenna Gurus !
On 4 May 2007 16:17:09 -0700, Telspam Electronics
wrote in . com: On May 4, 5:44 pm, Frank Gilliland wrote: Not really. Insertion loss of a [ferrite] balun could negate any gain you may get by impedance matching. It is also fixed, while a coax stub can be easily 'retuned' by simply pinning the coax. Not only that, since the antenna is (hopefully) way up in the air, the coax used for matching is either incorporated in the line or hung from the side, making any worries about extra coax "kicking around" a non-issue. You should be more worried about where you're going to put that nine square feet of ground plane. Pure rubbish... a balun would have perhaps 0.1dB insertion loss. The antenna gain is perhaps twenty times that! "LOL!" |
Hey Antenna Gurus !
On 4 May 2007 16:17:09 -0700, Telstar Electronics
wrote: +++On May 4, 5:44 pm, Frank Gilliland wrote: +++ Not really. Insertion loss of a [ferrite] balun could negate any gain +++ you may get by impedance matching. It is also fixed, while a coax stub +++ can be easily 'retuned' by simply pinning the coax. Not only that, +++ since the antenna is (hopefully) way up in the air, the coax used for +++ matching is either incorporated in the line or hung from the side, +++ making any worries about extra coax "kicking around" a non-issue. You +++ should be more worried about where you're going to put that nine +++ square feet of ground plane. +++ +++Pure rubbish... a balun would have perhaps 0.1dB insertion loss. The +++antenna gain is perhaps twenty times that! +++www.telstar-electronics.com +++ ************* Baluns and RF transformers can be loss. Many factors come into effect. These include wire guage, operating frequency, power levels, load and source vriations and core material. Also not to forget connetor losses. A well designed Balun or RF transformer will comparable low loss performance of a coaxial matching section. There are some benefits for RF transformers and baluns in that they are considerably more broadbanded. Over narrow bandwidths the coaxial matching section can be more tolerable to impedance variation from both the load and the source. james |
Hey Antenna Gurus !
On Fri, 04 May 2007 20:00:45 -0400, Vinnie S.
wrote: +++ +++IF coax length is a hangup then you can use a two to one balun. +++ +++This would be better. +++ +++Vinnie S. ********** 2:1 RF transformers can be a tricky item to build. IF you use air core you need sufficient inductance in both the primary and and secondary. Our amatuer radio club did a 40 M and 80 M full wave loop for Field Day about 20 yrs ago and used air core RF transformers. They were rather large and the windings required support. They worked very well. We were making contacts when otheres were complaining how poor the bands were. Good luck on which direction you choose. ps. If you plan to add a reflector to the system then I would suggest other methods of matching than a balun or RF transformer. With a reflector, a gamma match would be suitable. So temper that with your decision for future expansion. james |
Hey Antenna Gurus !
2:1 RF transformers can be a tricky item to build. IF you use air core you need sufficient inductance in both the primary and and secondary. Our amatuer radio club did a 40 M and 80 M full wave loop for Field Day about 20 yrs ago and used air core RF transformers. They were rather large and the windings required support. They worked very well. We were making contacts when otheres were complaining how poor the bands were. Good luck on which direction you choose. ps. If you plan to add a reflector to the system then I would suggest other methods of matching than a balun or RF transformer. With a reflector, a gamma match would be suitable. So temper that with your decision for future expansion. james If I hook it up without a balun, I would get a 2:1 SWR. I guess I can lower it slightly to 1.5 to 1.7 with someof that 75 ohm coax. I only use the center conductor when using that method? Vinnie S. |
Hey Antenna Gurus !
"Vinnie S." wrote....
Expert opinions are welcomed. Wrong group. :~) Peter. http://www.citizensband.radiouk.com/ |
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