Wednesday, 6 December 2017

Review: RTL-SDR Blog Multipurpose Dipole Antenna Kit

What is this? Four antennas, two mounts, one antenna holder with cable and one more extension cable. Costs $10 on its own, or $25 with rtl-sdr.com v.3 dongle. Was at my doorstep in two weeks from China to Ireland, observations below are based on two months' of constant use.
Please read the official how-to guide for more information, this post is a practical look at what you get and what you can do with it.

In the envelope


Bubble wrap surrounding a cardboard box. And the box is full:



Sang the song for the dongle already, so I'll concentrate on the antenna pack:
- bendable antenna mount / tripod with camera connector screw,
- suction cup with camera connector screw,
 - mount for antennas with camera connector screw,
- two large antennas,
- two small antennas,
- 3m / 10 ft extension coax.

Bendable tripod


About hand-sized including top screw, legs are 5" / 13 cm, similar products are also called gorilla pods / bendy tripods, 'cause legs are flexible to wrap around anything a primate can grip.



Built-in ballhead with lock-down screw:



Top screw is industry-standard mount for cameras, held pocket digital camera (245g / 8 5/8 oz) without effort, hopeless with heavy Nikon body, rock solid with antenna base. Even a thrift store tripod features the same screw:



Antenna base screws onto mount or suction cup (later, read on), so if you've got a more substantial tripod for photography e.g. a Manfrotto with a ball head, an earthquake-proof setup can be done in no time.
Similar tripods can be bought on eBay for $2-4 dollars if you like the concept:



Suction cup mount


Comes in several pieces, quite confident that if you've completed any LEGO aimed for 6-9 year old kids without shrieks you'll manage, end up with this:



Hands up if you carry isopropyl alcohol or window cleaner around, which is the official procedure, preparations are the same as with any other suction cup mount used for smartphones / GPS / tablets etc: clean surface with any cloth at hand or on you, spit on / lick finger, then distribute saliva evenly on circle, push on flat surface, lock down by pressing lever down, check for firm hold.
Was holding casserole pot attached to mirror, weight unknown (digital scale said "err") but bloody heavy, the two-person dinner / straining to lift out from oven variety.
Functioned on the car, either on windowpanes or on the roof, on the trunk / boot lid, and on RV, two larger antennas fully extended at 70 mhp / 120 kmph for 800 km / 500 miles did not come off.

Antenna mount


Holds four supplied antennas, obviously two at a time, screws onto two supplied mounts detailed above. Antennas and angles can be adjusted with screw, no screwdriver supplied:


With two smaller antennas:



Not for outdoor use as per official recommendation, Hurricane Ophelia hit where I live with sustained 60-80 mph winds and copious rain to make matters worse, mount was outdoors during that period on comparative ADS-B duty without any illness.
Sidenote: manufacturers must warn against outdoor use, 'cause if your house burns down, user collects an STD whilst looking at an outside setup or what have you, insurance companies can blame any outdoor antenna as the culprit. Rtl-sdr.com previous mag mounts, Nooelec mounts with innumerable antennas, FlightAware ADS-B antenna and quite a few homemade aerials never gave me any trouble.
Not for outdoor use, again: here's what mount looked like after living outside in wet, rainy, utterly miserable conditions a.k.a. Irish winter for two months:



De-assembled mount:



For outdoor use, a barrier sealant (wax / fat / WD40 / anything acting as a barrier against water) is a must.


Four supplied antennas


Two small and two large, covering shortwave to Gigahertz range.
Fantastic feature of extendable antennas that users must understand frequency / antenna length relationship, rtl-sdr.com posted specific frequencies of common interest:



A dipole antenna, by its very nature, will be useful around the desired frequency - two shorter antennas fully collapsed (1030 MHz as above) performed well when pitted against a dedicated $45 ADS-B FlightAware antenna: 20,705 vs 11,386 positions reported over 21 hour period:



Because antennas are adjustable, fine-tuning for the desired frequency is easy-peasy and recommended for best performance.

Coax cables


Short and thin attached to base, there's an extra 10 foot / 3m extension just in case in the box. Best you get with any RTL-SDR dongle, generics' arm-length is a joke in comparison.




Antenna location is everything, take home one lesson from this post: antenna location is everything. Having cable at hand will let you place antenna in an ideal location: outdoors, away from electronics, as high as possible.


What will the neighbor say?


Nothing. People who don't know, nor care about antennas have seen or painstakingly adjusted bunny ears antennas for televisions, therefore those lovely peeking senior citizens won't move the curtain unnecessarily. Looks like a TV antenna, here's what people are accustomed to:



... but it's not a bunny ears, as I found out. For best performance, orient legs vertical / up and down, once problem sources got used to the sight of the antenna.
You'll be able to hold a painful conversation with Mary when she deliberately cuts her roses waiting for a chat without daydreaming about a cleaver, a feat you can't repeat with a discone. On the other hand, a TV License inspector will have yee (SW Ireland pronunciation of "you") over the barrel in no time if you live with stupid rules, say here or in the UK.

Competitors


None. No other manufacturer offers an equivalent antenna kit; especially not at $10. A single SMA connector telescopic costs 5-8 USD on eBay, and lest you go on any ham radio website, be prepared to pay over $20 for one antenna. A pro ADS-B antenna or discone costs around $50 at the bottom end, near $70-100 for midrange, so $10 is peanuts without monkeys.
Nooelec's SMArt family antenna kit (comes standard with regular SMArt, XTR and XTRTee) is better quality overall but without the flexibility and adjustability, generic's one puny antenna simply can not compete with what you get.

Worth the money?


Count together: bendy pod $3, suction cup $3, four telescopic antennas $1 each, 3m / 10 ft coax coax is around, say $3, toroid $1, and prices are low estimates.
Without hesitation. Antenna kit is sold out now, so I ordered the full bundle after handling the review sample, as $25 is a no-brainer for the antenna kit and dongle.

No comments:

Post a Comment