Thursday, 6 July 2017

Nagoya NA-771 antenna review

Practically all handheld radios are sold with a small whip or "rubber duck" type antenna. Sometimes this antenna is so small than it is not even 1/4 wave length at UHF (440Mhz). As you probably know, these small antennas are not very performant, specially on the VHF band (136-174Mhz), where the whip is so short that performance is severely affected.

For better performance a bigger antenna is needed. The Nagoya NA-771 is a dual band VHF/UHF (144/430Mhz) antenna that delivers improved performance compared to the typical "stock" whip or "rubber duck" antennas. The Nagoya NA-771 is about 39cm in length, much bigger than the typical handheld radio "stock" antenna, but still a good match for small handheld radios. For a review of the Baofeng antennas that come with Baofeng handheld radios, please check my previous post.

Nagoya NA-771 antenna
Nagoya NA-771.

Disassembled Nagoya NA-771 matching circuit
Disassembled Nagoya NA-771 with matching circuit.

As always, the laws of physics rule and, as expected, compared to the antennas that come with most portable radios (Baofeng and others), performance is noticeably better, specially in the VHF 2 meter band and the commercial FM band. But UHF performance is also improved. Nagoya claims a gain of 2.15 dBi and a VSWR of less than 1.5:1. I don't trust this specs since this is a 5/8 wave antenna and a higher maximum gain is to be expected. A 5/8 wavelength pole has more gain at lower elevation angles (i.e. near the horizon) than a 1/4 wave pole, which it is what is normally desired. Also, Nagoya's claims the same gain for the NA-701, a much smaller antenna! Don't confuse the NA-771 with the NA701, which is only 22 cm in length. The NA-771 has more gain than the NA-701!

Nagoya NA-771 VSWR and return loss chart
Nagoya NA-771 VSWR and Return Loss chart.

Some people say that the NA-771 is no better than the "stock" antenna that comes with your radio. That is not my experience. Probably they have a negative opinion of the NA-771 because their antenna is defective. Unfortunately it seems that many NA-771's sold are not the original product, but imitations!

A "fake" NA-771 antenna could be as good as a genuine Nagoya NA-771, but you are more likely to get a defective product. In case of the NA-771, if your new NA-771 offers no improvement over the smaller stock "rubber duck" antenna, probably you where sold a defective antenna. If you were to disassemble the antenna you would probably find a bad solder joint in the matching circuit.

You can buy a NA-771 for about 4 USD delivered from Banggood here.

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