Mini Nagoya antenna, how lossy is rg174.

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Mini Nagoya antenna, how lossy is rg174.

Postby Southwales » Mon May 07, 2018 12:05 pm

Using one of these mini naygoya https://www.gearbest.com/walkie-talkie/ ... id=1433363 mounted to a biscuit tin and placed on top of my caravan roof, good results for both military band and 446 pmr etc, why scanning with uniden 125, did have my diamond antenna and larger mag mount but the mini naygoya with its much thinner coax allowed me to close the caravan door of a night or if it started raining, my only thought is that I imagine the thin rg174 coax to have a high signal loss even though it is only 9ft of coax, I only need half this length of coax as the Nagoya is placed on the roof just above the caravan door and the scanner sits on a shelf just as you enter the caravan door, would it be worth removing the excess coax as at the moment it is just slack anyway, I would resolder the coax straight back into the base is the Nagoya, so my question is would it be worth going to the trouble of shortening the coax to help with any signal loss, even though I would only be removing about 4ft of coax? Would also have the advantage of not having slack coax dangling inside of caravan.
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Re: Mini Nagoya antenna, how lossy is rg174.

Postby m0lsx » Mon May 07, 2018 2:49 pm

I could look it up for you. But it's only a few feet of coax & probably not worth the effort.
But what I can tell you is.
I have been using these since my daughter got her foundation licence aged 12 in 2007. I initially brought it to give her a more usable handheld in the back of the car. But I have found them to be very proficient for what they are & great value for a sub £20 plug & play antenna system.
I mainly use my mini mags on the scanners. But I do also sometimes use them in transmit situations too. And yes they are a compromise antenna. But any antenna, other than a real discone or a Log Perodic is a compromise scanning antenna & every modern antenna sold as a discone,that I have seen, is not really real broadband discone.
A real discone should show low SWR across several octaves. And a single Octave is a doubling of the frequency. So say from 30 to 60Mhz. 60 to 120 Mhz. 120 to 240Mhz etc etc. Yet few discones are capable of being transmitted into & those that are can only cover a couple of amateur bands & even then only due to a mobile whip above the disc of horizontal elements & the cone of inverted elements.
So. Personally speaking I would say the small micro mag is as good as it gets if you want a small magnetic antenna & it's not far behind any larger & more expensive amateur radio dual band antenna, no matter what make they are.

Edited to add. What I would do is simply loop the coax into some small loops shortly before it connects to the radio. This would give you the advantage of shortening the coax whilst at the same time reducing the risks of picking up electrical noise on the coax. It's what I nearly always do with my mobile set up. It's commonly called an ugly, or air wound Balun or more properly a 1:1 choke.
People normally use formers for nice looking ugly baluns. But simply making a few loops & securing them with a couple of cable ties is fine.
Normally baluns are at the antenna end of the coax. But it's a great way of shortening your coax by a small amount & helping yourself to reduce interference, if added at the radio end.
And if anyone says anything. It's not called an ugly balun for nothing.
Image
Last edited by m0lsx on Mon May 07, 2018 3:03 pm, edited 1 time in total.
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Re: Mini Nagoya antenna, how lossy is rg174.

Postby m0lsx » Mon May 07, 2018 2:52 pm

Just to add if you want a cheap & simple antenna to make, a bow tie antenna, or a small nest of dipoles would give you something better than a micro mag. But for similar money, including coax, plugs etc.
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Re: Mini Nagoya antenna, how lossy is rg174.

Postby Southwales » Mon May 07, 2018 9:09 pm

Hi, Thank you for the reply, is the bowtie fairly directional? Also would the copper wire last long outdoors, I guess I could leave on the shielding for some weather protection, could I make a mini version of the bicone antenna using my copper wire or would I just be better making the longer bowtie? Will just need some fairly thin coax wire for the caravan door seals, thinking maybe sky twin shotgun coax split as that is normally quite thin and hopefully being 75ohm not to lossy, especially as I will only need 5ft max, good idea or not?
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Re: Mini Nagoya antenna, how lossy is rg174.

Postby Southwales » Tue May 08, 2018 12:22 am

The homemade antenna above looks interesting, what is it used for? Also the way it looks to be soldered to the pipe makes it look as though the outer braid of the coax will be allowed to short with the centre, does that not cause problems?
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Re: Mini Nagoya antenna, how lossy is rg174.

Postby m0lsx » Tue May 08, 2018 11:56 am

The above antenna is either a J pole, slim or a folded Dipole. Both are very similar. And they make great self build antennas. I use folded dipoles made from ladder line as my portable VHF pocket antenna of choice.
https://www.essexham.co.uk/slim-jim

http://www.warc.byethost5.com/Projects/Antenna_Projects.html?i=1

http://ac8gy.com/dual_band_slim_jim_antenna.html

https://m0ukd.com/calculators/slim-jim-and-j-pole-calculator/

My daughters antenna when she first got licenced was a roll up slim jim, taped to a leg on her cabin bed. I have used mine taped to a 10 meter fibreglass roach rod outside. to a shorter roach rod poking out of a rucksack for improved pedestrian operation. With it hanging in a window for improved alternative address operations & hanging in trees & even off a wooden goal post for field operations.
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Re: Mini Nagoya antenna, how lossy is rg174.

Postby Southwales » Tue May 08, 2018 11:24 pm

m0lsx wrote:Just to add if you want a cheap & simple antenna to make, a bow tie antenna, or a small nest of dipoles would give you something better than a micro mag. But for similar money, including coax, plugs etc.


How would I make a small nest of dipoles and have got any images?
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