Material for quad?

[Singularity35]

Hello forumites, I'd like to pick your brains again if I may. I saw a design for a quad antenna for uhf and the list of materials says #18 solid electrical wire. Can I use an uninsulated bronze rod in it's place? I was thinking that it would be more rigid. Thanks in advance.

 

[Captain Kilowatt]

Yes but why do you want it rigid? No flexing yields to breaking over time due to stress especially where it is soldered unless you braze it.

 

[Singularity35]

Yes but why do you want it rigid? No flexing yields to breaking over time due to stress especially where it is soldered unless you braze it.

Thanks for the quick reply. I was thinking that since I wouldn't have to use spreader arms, that it would be lighter. Also I had a cubic quad for VHF some time back and I had to keep straightening it after birds lit on it.

I was thinking of a 2mm bronze rod that starts at around 30" in length. The quad calculator gave me around 7" per side which means that I'll only have to solder the feed line and I won't have to join the corners.

Do you think that would work? Or should I just forget this notion and go with the traditional material?

 

[Captain Kilowatt]

OK Iwas thinking this was fof 2meters. Sounds like something for just inder 400 MHz from the dimensions. Bronze rod should work good up tbere then. What is it for?

 

[GnG8d]

You might want to do a test bend, some bronze alloys can be brittle.

 

[Singularity35]

OK Iwas thinking this was fof 2meters. Sounds like something for just inder 400 MHz from the dimensions. Bronze rod should work good up tbere then. What is it for?

Thanks for the reply. I was thinking around 440 mhz. This is what the calculator came up with for dimensions. Does this look right? I was thinking just a single quad with no reflectors.

You might want to do a test bend, some bronze alloys can be brittle.

Thanks, good idea.

 

[Beetle]

Thanks for the reply. I was thinking around 440 mhz. This is what the calculator came up with for dimensions. Does this look right? I was thinking just a single quad with no reflectors.

Thanks, good idea.

By "single quad with no reflectors", do you mean just one square of brass, copper, bronze or whatever, all by itself?. The idea of a basic quad antenna requires a driven element AND a reflector. Notice that all of the "directors" in the chart are listed as "optional", but the reflector isn't. It's needed.

 

[Captain Kilowatt]

Thanks for the reply. I was thinking around 440 mhz. This is what the calculator came up with for dimensions. Does this look right? I was thinking just a single quad with no reflectors.

Thanks, good idea.

Yeah I was off in my thinking. That's what I get for doing some mental math without my morning coffee.

 

[Singularity35]

By "single quad with no reflectors", do you mean just one square of brass, copper, bronze or whatever, all by itself?. The idea of a basic quad antenna requires a driven element AND a reflector. Notice that all of the "directors" in the chart are listed as "optional", but the reflector isn't. It's needed.

Yes, just one square. Won't it work?

Yeah I was off in my thinking. That's what I get for doing some mental math without my morning coffee.

At least you got close.

I don't get anywhere near even with a calculator.

 

[Beetle]

There's nothing that prevents experimentation by a duly licensed ham, but you won't get much (if any) gain or directivity out of a single loop on UHF. At that high a frequency (in other words: at that short a wavelength), you can have many elements in quite a small package and you WILL get both gain and directivity.

 

[Singularity35]

There's nothing that prevents experimentation by a duly licensed ham, but you won't get much (if any) gain or directivity out of a single loop on UHF. At that high a frequency (in other words: at that short a wavelength), you can have many elements in quite a small package and you WILL get both gain and directivity.

I understand but directivity is exactly what I was hoping to avoid. At the moment, I am using a quarter wave ground plane tuned to around 440mhz. I was thinking that I might have a bit more gain with a full wavelength(or two half waves, as I read somewhere) element on the quad over the ground plane. That was just the my thought process but I'm a noob and I'm here to learn. Am I way off base with my thoughts? Thanks BTW, I appreciate all and any feedback. Let me say that I am not trying to be argumentative but that I just wanted to explain why I was thinking of doing the single quad.

 

[guitarpicva]

Look up J-pole and SlimJim antennas. Omnidirectional and gain. Still pretty small on 70 cm.

Sent from my XT1030 using Tapatalk

 

[Singularity35]

Look up J-pole and SlimJim antennas. Omnidirectional and gain. Still pretty small on 70 cm.

Sent from my XT1030 using Tapatalk

Thank you, I've seen those. Maybe later on in my "career".

 

[Beetle]

A "full-wave loop" in the form of a square will have a feedpoint impedance around 100 - 110 ohms. If you're using 50-ohm coax, you'd probably want some transformation, which could be a quarter-wavelength (electrical, not physical) of 75-ohm coax (RG-6 or RG-11, for example).

Problem is, you want to keep the feedline as short as possible, particularly at UHF. Of course, 1/4 wavelength at 450 MHz is only around six inches.

 

[Singularity35]

Thank.you. That's really helpful.