I think I found the ultimate indoor antenna

[dinger]

Made another one. Orientated it for 98.9 and it didn't disappoint.

 

[k6sti]

Not exactly wife friendly!

I misread your post. I see now that you oriented the antenna for the 98.9 MHz station. It should yield a much greater signal than the vertical FD. But I guess that's not possible since the meter maxes out at 5! Is 102.9 in the same direction? The loop raised that signal a fair amount.

Decoupling the feedline is more important for the loop than for other antennas because of the short wire at one side of the feedpoint. It's pretty easy for signals picked up on the outside of the coax to compete with it if the 300:75 ohm balun lets them through..

Brian

 

[dinger]

I kept it 300ohm all the way to the receiver. I'll try a balun and coax tomorrow and see how it goes. Have some chokes too I can throw on. Not sure about 102.9's direction. Will look into that too.

 

[dinger]

Made the transition to 75 ohms on the Circular. Moving the antenna to the garage bay wall for longer term next. Didn't get to adding chokes. 102.9 Was about 55 degrees off 98.9 but 98.9 has an edge so maybe that's in play.

 

[k6sti]

If your wall isn't oriented favorably, this directional antenna may do more harm than good. The stations you want to receive should be in the same general direction.

Brian

 

[dinger]

So far so good. The garage receiver has locked on to 98.9 with no dropouts. It's only 10 or 15 degrees from where the signal peaked upstairs. Will be offline for awhile. When I return I'll do a partial disassembly so I can get it into a storage dormer where I can tune the direction in. This has been fun!!!

 

[peterp1]

Not exactly wife friendly!

It's the exact same shape that your wife makes with her arms as soon as you show her the antenna

If the antenna works it works -- that's no small feat -- I've had a bunch that disappoint

 

[dinger]

She loved it! That's where we watch TV at night. When she came in she said "I'm not even going to ask." Hence, it has a new location!

 

[peterp1]

She loved it! That's where we watch TV at night. When she came in she said "I'm not even going to ask." Hence, it has a new location!

She's a keeper!!!!

 

[dinger]

Threw the nano VNA on it (homemade circular) tonight just to see what's up. Looks like it came out on target in the center of the FM band.
Measurement is based on a 50ohm calibration with a simple 50 to 75 ohm adaptor (not xfrmer) to the 25' coax going to the antenna.

 

[dinger]

Just to stay on topic, here's the Stellar on the same setup.

 

[k6sti]

SWR target values are given in the loop writeup. But unless you calibrate the VNA through the coax, don't expect those values.

Use the VNA impedance renormalization function instead of a lossy 75:50 ohm adapter.

Brian

 

[dinger]

I have to use the adaptor anyway or there is no way to attach the coax to the VNA. What I tried today is calibrate at the antenna end of the coax with a 75 ohm load.
Homemade Circular:


Stellar:


I did re-route the feedline from the homemade circular directly away from the corner feedpoint instead of over and up adjacent to the right vertical leg. This improved the overall SWR. A ferrite near the feedpoint helped too, but only .02. I didn't have enough slack to make a multi-coil.

 

[k6sti]

The SWR curve is nothing like that of the model. You may have the dimensions wrong, the impedance adaptor may be goofed up, the 300:75 ohm transformer may be bad, nearby objects may be affecting the antenna, or you may have common-mode current. Something is not right. But if the antenna receives the stations you want, it may be best to just move on.

Brian

 

[dinger]

Yeah, it does work great. I can see that just being near the antenna changes everything wildly. I did try without the cable right at the antenna and that flattens out the side SWR humps quite a bit. Anyway, this has been fun and I appreciate your inputs. I might revive this thread in the future if I try a better non rushed build.

 

[Bob@FM]

You can get SMA to F connectors Amazon SMA to F
I also use these for connecting my roof antenna to an SDRPlay RSP1A spectrum analyzer...among other things