eHam

eHam Forums => Antenna Restrictions => Topic started by: KC0QLZ on September 02, 2022, 08:43:09 PM

Title: Indoor Antenna
Post by: KC0QLZ on September 02, 2022, 08:43:09 PM
Can someone recommend a good vertical antenna that will work indoors on the second floor of a condo in a HOA? Thanks
Title: Re: Indoor Antenna
Post by: AI5BC on September 02, 2022, 09:23:59 PM
Good luck.
Title: Re: Indoor Antenna
Post by: W7XTV on September 02, 2022, 09:34:49 PM
Depends.  Is your building frame, frame w/stucco, or steel/concrete?  The latter two are show-stoppers for HF.  Not only are the latter two high attenuators between inside and outside, but the RF hash from any devices that you have inside will override any outside signals. 

My house is frame/stucco and the outside walls attenuate 20-40 dB depending on the frequency.  HF does not work with an antenna inside the house.  AM reception is nonexistent.  TV only works if I put an antenna in a window that faces toward the TV towers.  The VHF/UHF ham bands would be similar.
Title: Re: Indoor Antenna
Post by: KE0VT on September 02, 2022, 10:48:32 PM
Pay no attention to W7XTV when he says HF does not work with an antenna in the house. I have 6 antennas in my attic and they all work. Here they are. Broadband Terminated Dipole (BBTD), Isotrons on 6, 10, 15 and 20 plus a dual band 2m/70cm. Incoming signal reports are not all 5/9, mostly
5/4 or 5/5. To get a good vertical is another matter and basically depends on if you have enough height. The BBTD with 100W in puts out about 25W
and is flat from 10-160M across all the phone bands plus 6M with 2.35/1 swr that is easily handled by my TS 590SG internal tuner. I have worked
Japan (5700 miles), Slovenia, Italy and Spain about (5300 miles) and Near Sao Paulo, Brazil. Do I work them all? NO. Good operating practices help
and determination. YOU can have fun with antennas in the attic.
Title: Re: Indoor Antenna
Post by: W4FID on September 03, 2022, 05:04:39 AM
Whatever you do remember there is likely to be high voltage at the ends of the antenna and counterpoise wires. Even at low power. A shock is a serious concern if some one/thing touches it. A fire is also possible if there is arcing or current exchange between the wire and something flammable. At one point in my life I did run a wire around the ceiling and a counterpoise around the base board -- but only at low power and with the mentioned cautions. The construction of the building will have some effect. But you do what you can with what you've got. Maybe a loop by a window?
Title: Re: Indoor Antenna
Post by: N8TGQ on September 03, 2022, 05:53:42 AM
What bands do you want to work?
Title: Re: Indoor Antenna
Post by: AI5BC on September 03, 2022, 08:36:26 AM
Whatever you do remember there is likely to be high voltage at the ends of the antenna and counterpoise wires.

Now that is funny. You assumed he knows something. If he did would not be asking such a stupid question. Like most hams, have no clue what they are doing and present a clear a present danger to themselves and neighbors.  So let's be a good Elmer and help this guy fry himself.
Title: Re: Indoor Antenna
Post by: W7XTV on September 03, 2022, 09:59:14 AM
Pay no attention to W7XTV when he says HF does not work with an antenna in the house. I have 6 antennas in my attic and they all work. Here they are. Broadband Terminated Dipole (BBTD), Isotrons on 6, 10, 15 and 20 plus a dual band 2m/70cm. Incoming signal reports are not all 5/9, mostly 5/4 or 5/5. To get a good vertical is another matter and basically depends on if you have enough height. The BBTD with 100W in puts out about 25W and is flat from 10-160M across all the phone bands plus 6M with 2.35/1 swr that is easily handled by my TS 590SG internal tuner. I have worked Japan (5700 miles), Slovenia, Italy and Spain about (5300 miles) and Near Sao Paulo, Brazil. Do I work them all? NO. Good operating practices help and determination. YOU can have fun with antennas in the attic.

I didn't say "attic," and neither did the OP.  He said "on the second floor of a condo," which may or may not allow attic access.  I have never lived in a place where an attic antenna would work (either I had no access, or the construction of the house/apt wouldn't allow for it), therefore I have never been able to try it. 

I'm not doubting what you're saying about an attic antenna, but I was talking about an indoor antenna inside a room.  In a wood-frame house with no stucco, it might work a bit, but will still be susceptible to noise from other devices.  In a house with stucco siding or a steel/concrete building, it probably won't work at all due to the shielding that those constructions provide.

If he can get to the attic, that's probably the best solution.
Title: Re: Indoor Antenna
Post by: K0UA on September 03, 2022, 01:47:41 PM
Can someone recommend a good vertical antenna that will work indoors on the second floor of a condo in a HOA? Thanks

We would all be happy to assist you if we just knew a few more things. The most important of these things we would like to know is what band or bands do you intend to operate on. And why a vertical antenna? Are you talking about a VHF/UHF antenna for FM here?  But we are all just guessing at this point.
Title: Re: Indoor Antenna
Post by: WA3SKN on September 18, 2022, 09:16:24 AM
What bands?

-Mike.
Title: Re: Indoor Antenna
Post by: AI5BC on September 18, 2022, 09:51:58 AM
For VHF and UHF use a mag mount mobile antenna on a cookie sheet. For HF you are SOL and wasting your time. 
Title: Re: Indoor Antenna
Post by: N8TGQ on September 19, 2022, 04:16:51 AM
 For HF, try a 29' random wire around the ceiling, with a 29' wire counterpoise around the floor in the opposite direction. You will need a tuner.

 I've been using this setup for more than 15 years in different apartments and places where I need a quick semi-permanent antenna.

With 5 watts out (another consideration in close-living situations), I get out to 500 miles on 40m and to the west coast on 20m from here in Ohio. I have made it into eastern Europe on occasion.

It's not perfect,but no antenna is.
Title: Re: Indoor Antenna
Post by: KH6AQ on November 09, 2022, 05:02:41 PM
An HF vertical antenna inside a condo is a recipe for RFI into the neighbor's electronic devices. That is because unless the feedline is well decoupled by sufficient common-mode impedance, and the vertical has its own counterpoise, the entire condo building AC wiring will be hot with RF. The wiring can become the dominant radiating antenna. The best HF indoor apartment/condo antenna I have tried is a loop tuned using a MFJ-93X series loop tuner.

MFJ-935C   https://www.gigaparts.com/nsearch/?q=MFJ-935C

Title: Re: Indoor Antenna
Post by: K3ZD on November 10, 2022, 10:22:26 AM
Indoor antennas can work but not very well.  I've found them to be not much fun.  Might consider going to a local park and setting up on a picnic bench with some variety of antenna you can set up and take down. 
Title: Re: Indoor Antenna
Post by: KK4GGL on November 12, 2022, 05:57:00 PM
Can someone recommend a good vertical antenna that will work indoors on the second floor of a condo in a HOA? Thanks

Depending on the bands you want, you can try a magnetic loop, or a mobile vertical over a ground pane/counterpoise of some kind.
Title: Re: Indoor Antenna
Post by: ONAIR on November 14, 2022, 09:37:16 PM
I travel often on business, and I run an ELK portable beam inside hotel rooms for vhf/uhf FM.  I also run a 23 foot end fed diagonally across the room, and have had good results on 20, 17, and 10 meters using 100 watts SSB.  I have even had success on 80 meters NVIS late evenings!