Antenna Conundrum

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Goffy
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Antenna Conundrum

Post by Goffy »

If you lived in a dip, where your rooftop was lower than surrounding ground level, and you had tall buildings and trees surrounding you, would you still attempt to improve things with a rooftop antenna?

Thats my situation. At my last place I was lucky to have a 360 deg line of sight to the horizon. However I do get some strong signals here indoors on a magmount on a big old tin box. I can get some hissy fm from the strongest local transmitters and some dmr on my chinese handy. So i reckon I can improve this by sticking a white stick 2m/70cm or discone up on the roof even though it won't clear the surrounding buildings and trees. Its gotta be better than nowt? Right? I'll buy a 30 ft pole and thge lowest loss coax (RG213 or LMR400?).

Will a Watson W30 white stick tuned for 2m/70cm perform ok in the ranges 156mhz-174mhz and 380-470 mhz? UHF mil band would be a bonus too. I read somewhere it might be a better bet than a discone now that thers nothing going on below 118mhz or above 470mhz. Back in the day i had a discone but that was when vhf low was busy and there was stuff at 800megs too. These days its only 150-470 that I would bother with.
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Andy
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Re: Antenna Conundrum

Post by Andy »

Yes, always aim for height no matter what. Radio waves tend to refract a bit over hills, so just a few extra feet of height will get it into an area of better signal (unless cancellation effects make it worse, ahem).
Re amateur band antennas for scanning. Some work well, some don't. It probably depends on how they are matched. Maybe the high-gain ones don't work out of band too well as they will use many sections and will be more tightly tuned and more likely to reject frequencies away from their favoured bands.
Coax-wise, I've been using CT100 satellite cable for about 30 years and it's a treat. It's cheap, flexible, well-screened and low loss all the way into the upper reaches of UHF. Stay away from DIY shop stuff unless it says CT100 or WF125 or similar. Just one thing - satellite coax is 7mm diameter so you may have to be creative with connectors. I tend to fit 7mm F-types to the cable and then use adaptors to suit my radios, switches etc.
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Goffy
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Re: Antenna Conundrum

Post by Goffy »

Thanks for the reply Andy. The Watson W30 white stick was mentioned on a forum as performing well out of band, as good as the discone for uhf mil air and even better than the discone on the business radio bands so I'm going for that one unless someone posts to say the discone is better then I will reconsider if I get any replies. Tried to join that UK Scanning forum twice but no joy....and the NUKS facebook page ignore my requests too....its not that aspergers guy who used to run proma is it? I'll probably have to send a copy of my passport before they let me join.

Re getting that extra height at a reasonable price. Ebay has these sections of aluminium tube that slot into the end of each other, four of which will give me 10m. Just hope they stay together when the wind is making the pole sway about, looks like only gravity and friction hold them together.
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Andy
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Re: Antenna Conundrum

Post by Andy »

OK Goffy. Yes, those swaged mast sections can be handy but I wouldn't go too high with a big aerial on top as I think the aluminium is fairly thin. I'd also be tempted to slap a nut & bolt through each joint. Watch how you clamp the base as well, as it can buckle at this point if the wind blows hard. It's all good fun innit?
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Goffy
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Re: Antenna Conundrum

Post by Goffy »

Thanks for the advice.
jhampton2000
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Re: Antenna Conundrum

Post by jhampton2000 »

Goofy - IMHO that's all good advice from Andy. I have a similar challenge (hills on 3 sides) yet with a roof mounted antenna I can still pull things in. Makes a world of difference. There's some line of sight UHF stuff and even VHF simplex that I get that the theory and propagation tools will tell you is impossible.

Before it went up on the roof, I invested in a discone and a white stick - tried both out in the loft to compare. I went with the white stick (Moonraker SSS-MKII) as it was at least as good and nowhere near as ugly as a discone. If you have a really long cable run consider very very low loss cable (as good as your budget can afford, and a hole into your loft can withstand) and a loft mounted pre-amp: the latter isn't for everyone, and comes with some cons too.

Also, you might want to check out the regs for planning permission - think it used to be that you needed permission for non-TV aerials, but now its done on aerial dimensions/property size/location.
Goffy
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Re: Antenna Conundrum

Post by Goffy »

Thanks for the reply jhampton. I have decided on the Watson white stick and the best lowest loss cable I can afford. I'm slightly concerned about the swaged aluminium poles after reading andy's comments about their strength (or lack of). I might phone a few local areal installers and see what they can provide by way of masts/poles. Six meters was what I was thinking of but even 3 or 4 would be a decent compromise.
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Re: Antenna Conundrum

Post by paulears »

I have a discone and a white stick dual band similar to the Watson, but the brand fell off years ago. It absolutely works better on ham bands than the discone, but the discone is heaps better on civil and military airband. The marine band is about the same as the discone - which after all is a 0dB gain antenna, suggesting the white stick is the proverbial bit of metal in the sky for frequencies other than ham bands.
Goffy
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Re: Antenna Conundrum

Post by Goffy »

Hmmm I'm veering back in favour of the discone now as I did have one 20 odd years ago and felt it was pretty good...although I never owned a white stick to compare it too.
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Re: Antenna Conundrum

Post by baz1 »

they say a diamond D777 is good for military on uhf/vhf I myself use a Bowtie 25ft up a pole with guy ropes attached with good results cheap and easy to make.
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