With steel siding, is an attic antenna a waste of time?

[SD2007]

Hi all,

I'd like to install an antenna for scanning at home with my BR330T. I was thinking of two antennas actually, one for short-wave and one for 800MHz. I'm pretty sure city regulations (and my wife) will prohibit me from mounting anything on the roof of the house. I have a roomy attic that will accommodate a sizable antenna, but I'm afraid the steel siding on the exterior of the house will render the antenna basically useless. Does anyone have any experience or insight as to what I should expect with an attic mounted antenna in a house with steel siding?

Thanks...

 

[CapnRefsmmat]

As long as you don't have a tin roof too, I don't think there'd be too much of a problem. It's only a Faraday cage if it's totally enclosed.

 

[k9rzz]

It wouldn't hurt to try it.

jw

 

[gmclam]

It all depends on your options and what you are trying to receive.
If you have no other choice but for an attic antenna, then it is your best choice. The metal siding will certainly attenuate the signal, but it depends on what you are trying to receive, the frequency, their power & distance from you, the gain of your antenna and the loss of your downlead. In theory you could calculate the signal gain/loss for a given frequency with all the parameters.

Are you using something like a rubber duckie antenna now? Inside the house? Doesn't the signals have to penetrate the same metal siding? If true, then an antenna which collects more signal that you want and has a better gain should give you better performance.

Good luck.

 

[SD2007]

Thanks for the replies... Given my options, I think I'll see what an antenna in the attic can do for me. In my search for an 800 MHz antenna, if I find that brand A is better than brand B when tested outdoors, is it reasonable to think brand A will perform better than brand B in my attic? There's probably not a simple answer to this question but I thought I'd ask anyway.

Thanks again...

 

[JohnSPWD]

I was just thinking.....if you install an antenna in your attic,isn't your attic above the sides of your house?would the aluminum siding still be a problem.

 

[ampulman]

I was just thinking.....if you install an antenna in your attic,isn't your attic above the sides of your house?would the aluminum siding still be a problem.

You beat me to it. I just read this thread (3:03 P.M. EST), and yes, it will not affect reception unless, as you indicated, or if there is foil coated insulation on the inside of the roof above any antennas.

I have installed 2 short wave ants. in my attic and am planning one or more for scanning. No problems.

AM

 

[SD2007]

I was just thinking.....if you install an antenna in your attic,isn't your attic above the sides of your house?would the aluminum siding still be a problem.

To the East and West it’s roof shingles, but to the North and South I've got vertical walls with siding that goes all the way to the peak of the roof. I guess that’s unfortunate.

 

[ka3jjz]

Yeah, an attic antenna is better than none at all, especially in this instance. I live in a condo with siding, but a standard construction roof - not tin, real wood (thank heavens), so it's not a total loss. I've got a few antennas up there (don't tell the association, hihi) and they work OK, but would work a whole lot better if they were outside on a tower....condos are hell for hams...

I don't think you're going to be able to put up any sizable shortwave antenna for the BR330. Anything of any significant size is very likely to overload it on HF. It simply is not designed to handle the signal level that a good sized antenna might provide, particularly under heavy signal conditions (say 6 mhz at 0000 UT) . You'd be much better off with a used desktop if you want to put a shortwave antenna up on any decent size. I doubt the 330 could handle much beyond a few feet - say 10 or 20 feet or so, and even that might be too much under some conditions - of wire.

73s Mike

 

[SD2007]

Yeah, an attic antenna is better than none at all, especially in this instance. I live in a condo with siding, but a standard construction roof - not tin, real wood (thank heavens), so it's not a total loss. I've got a few antennas up there (don't tell the association, hihi) and they work OK, but would work a whole lot better if they were outside on a tower....condos are hell for hams...

I don't think you're going to be able to put up any sizable shortwave antenna for the BR330. Anything of any significant size is very likely to overload it on HF. It simply is not designed to handle the signal level that a good sized antenna might provide, particularly under heavy signal conditions (say 6 mhz at 0000 UT) . You'd be much better off with a used desktop if you want to put a shortwave antenna up on any decent size. I doubt the 330 could handle much beyond a few feet - say 10 or 20 feet or so, and even that might be too much under some conditions - of wire.

73s Mike

I don't fully understand the overloading concept. Would too strong a signal damage my scanner or would it just result in distorted sound? Could I use an attenuator for shortwave to prevent overload? Maybe I'll use that old roll of high-loss 75 ohm cable as the feedline. I'm an electrical engineer, but I'm pretty clueless when it comes to radios and RF in general.

 

[N_Jay]

. . . I'm an electrical engineer, but I'm pretty clueless when it comes to radios and RF in general.

What school gives an EE without teaching the basics?

 

[gmclam]

Agc

I don't fully understand the overloading concept. Would too strong a signal damage my scanner or would it just result in distorted sound? Could I use an attenuator for shortwave to prevent overload? Maybe I'll use that old roll of high-loss 75 ohm cable as the feedline. I'm an electrical engineer, but I'm pretty clueless when it comes to radios and RF in general.

When the RF signal at the antenna input is within a designed range, an AGC (automatic gain control) circuit adjusts the scanner's RF gain to provide a preset level to the next stage of the receiver. If there is more signal at the input than the AGC can reduce, the input is overloaded. Some scanners now have internal ATTenuators to insert a fixed signal drop, but why (effectively) (over)amplify a signal just to reduce it again? If you've got some weak signals you want to hear, and there are only a couple of strong signals, and those strong signals are within the range of the scanner's receiver with the attenuator on; then you can turn on the attenuator for just those channels (assuming your scanner has that option).

 

[SD2007]

What school gives an EE without teaching the basics?

Obviously you're not an Electrical Engineer...

 

[SD2007]

When the RF signal at the antenna input is within a designed range, an AGC (automatic gain control) circuit adjusts the scanner's RF gain to provide a preset level to the next stage of the receiver. If there is more signal at the input than the AGC can reduce, the input is overloaded. Some scanners now have internal ATTenuators to insert a fixed signal drop, but why (effectively) (over)amplify a signal just to reduce it again? If you've got some weak signals you want to hear, and there are only a couple of strong signals, and those strong signals are within the range of the scanner's receiver with the attenuator on; then you can turn on the attenuator for just those channels (assuming your scanner has that option).

What ka3jjz seems to suggest is that the over amplification of the signal is inherent to the type of antenna I might install in my attic, not something I'd bring about intentionally.

 

[N_Jay]

Obviously you're not an Electrical Engineer...

BSEE:wink:

 

[SD2007]

BSEE:wink:

If that's true then you should know better than to make statements like the one above.

 

[N_Jay]

If that's true then you should know better than to make statements like the one above.

I should, but it still amazes me with how much is skipped at some schools.

 

[mancow]

Just be thankful you two had the ability to obtain those degrees. That's what I have always wanted to do but there's just no way with the math involved. I just can't seem to get my head around it, especially when the formulas look like the name of some fraternity house.

 

[DickH]

I should, but it still amazes me with how much is skipped at some schools.

Right. Most curricula don't include courses in common sense.

 

[SD2007]

I should, but it still amazes me with how much is skipped at some schools.

Yeah it seems like an EE degree can be earned through an amazingly broad range of curriculums these days. My program was a traditional ABET accredited BSEE. I took the required EM theory class, which at the time seemed like mostly an applied math class with Maxwell at the helm. That was 15 years ago. My academic emphasis and subsequent work experience took me into the power systems, power electronics, control systems and microcontroller arenas. I’m a capable engineer, just not an RF guy, and I'm not ashamed to admit it.