Sanyo retracable antenna - FAKE JUNK

[N6JSX*]

I live in a margin zone with a single Sprint cell tower. I get maybe three bars at home ground level and in my basement office 1-1.5 bars (maybe) with calls constantly fading into disconnection even though the phone is plugged into the power supply sitting in my (home-made) vertical cradle.

BIG issue Sanyo 8400 does not have an external antenna jack (my stupid mistake).

In the interim of buying a +$200 PCS repeater I thought I'd swap out the Sanyo original wire whip antenna with a bullet telescoping antenna. I got the bullet today and have seen a one bar increase even though the telescoping antenna is only half the length of Sanyo's original wire whip antenna. :frustrate

Upon further analysis of the antennas I found:
Sanyo original to be virtually a FAKE. The retractable wire has NO metal interface with the screw-in antenna mount. It's all plastic - there maybe a wire inside but it makes NO metal to metal contact. So what little RF energy is coming form the cell tower is additionally wasted crossing this insulated capacitive coupling to the screw-in housing.
Also the wire whip measures 3.4" which is NOT a tuned 1900MHz 1/2 wavelength (2.96") further reducing its signal capturing capability! The whip base appears to be about 1/4 wavelength (1.48") overall length (remember the internal antenna mount to the receive will also act as an antenna.) :td:

Conversely, the telescopic bullet metal portions of the antenna make direct solid contact with the screw-in metal base coupling the most RF energy into the phone receiver. The fully extended antenna dimension appear to make it a tuned 1/2 wavelength. :tu:

I just looked at my older Samsung and found that their original retractable wire whip antenna has a crimped metal bead on the bottom of the wire whip. This metal whip makes sound direct metal-to-metal contact to the housing base when fully extended. No wonder my Samsung operated far better in my basement office (plus Samsung has an external antenna connector built into the cell phone). :thought:

I know who will get my next phone purchase. :laughing:

Sanyo's retractable wire whip antenna IS AN engineering BLUNDER (or skillfully created business maker for the after-market antenna sales). Get rid of your original wire whip and get an antenna that expends but makes good metal-to-metal connection to the phone receiver!!!! :dazed:

[TheEsupremacy]

Nice.

[bikerich69]

I live in a margin zone with a single Sprint cell tower. I get maybe three bars at home ground level and in my basement office 1-1.5 bars (maybe) with calls constantly fading into disconnection even though the phone is plugged into the power supply sitting in my (home-made) vertical cradle.

BIG issue Sanyo 8400 does not have an external antenna jack (my stupid mistake).

In the interim of buying a +$200 PCS repeater I thought I'd swap out the Sanyo original wire whip antenna with a bullet telescoping antenna. I got the bullet today and have seen a one bar increase even though the telescoping antenna is only half the length of Sanyo's original wire whip antenna. :frustrate

Upon further analysis of the antennas I found:
Sanyo original to be virtually a FAKE. The retractable wire has NO metal interface with the screw-in antenna mount. It's all plastic - there maybe a wire inside but it makes NO metal to metal contact. So what little RF energy is coming form the cell tower is additionally wasted crossing this insulated capacitive coupling to the screw-in housing.
Also the wire whip measures 3.4" which is NOT a tuned 1900MHz 1/2 wavelength (2.96") further reducing its signal capturing capability! The whip base appears to be about 1/4 wavelength (1.48") overall length (remember the internal antenna mount to the receive will also act as an antenna.) :td:

Conversely, the telescopic bullet metal portions of the antenna make direct solid contact with the screw-in metal base coupling the most RF energy into the phone receiver. The fully extended antenna dimension appear to make it a tuned 1/2 wavelength. :tu:

I just looked at my older Samsung and found that their original retractable wire whip antenna has a crimped metal bead on the bottom of the wire whip. This metal whip makes sound direct metal-to-metal contact to the housing base when fully extended. No wonder my Samsung operated far better in my basement office (plus Samsung has an external antenna connector built into the cell phone). :thought:

I know who will get my next phone purchase. :laughing:

Sanyo's retractable wire whip antenna IS AN engineering BLUNDER (or skillfully created business maker for the after-market antenna sales). Get rid of your original wire whip and get an antenna that expends but makes good metal-to-metal connection to the phone receiver!!!! :dazed:
i am in the same basement situation. i just checked my debug
screen With and Without the antenna on my 8400. the results are: with the antenna my db level fluctuates between -101 and -105 but mostly around -102. without the antenna my db level is -105 or no signal. this is unscientific but my antenna seems to make a difference.

[chamb]

i am in the same basement situation. i just checked my debug
screen With and Without the antenna on my 8400. the results are: with the antenna my db level fluctuates between -101 and -105 but mostly around -102. without the antenna my db level is -105 or no signal. this is unscientific but my antenna seems to make a difference.

YES YES YES, the antenna on the 8400 is functional. I also get about a 2-3 DB improvement with the antenna extended. I am not guessing either. It helps slightly and you can prove it.

[BrettW]

my girlfriend gets better reception (db to db) with her aftermarket led antenna then with the stock sanyo antenna (this is also including the stock antenna up or down) its about 5-10db difference on average

[bikerich69]

my girlfriend gets better reception (db to db) with her aftermarket led antenna then with the stock sanyo antenna (this is also including the stock antenna up or down) its about 5-10db difference on average
My 8400 antenna does work but i can use better signal. 5-10db signal boost would help alot. can you please give me info on the aftermarket antenna your girlfriend uses. thanks.

[BrettW]

its just one of thoes generic run of the mill LED antennas you see in shopping malls and such

[bikerich69]

its just one of thoes generic run of the mill LED antennas you see in shopping malls and such
ill pick one up and see what happens. its worth a shot.thanks.

[N6JSX*]

If you read my posting you will see I stated "virtual Fake". Having any extra metal will capture some amount of RX signal that it the premise for that "signal booster" piece of junk you put in your battery compartment. You may see a very slight increase in signal strength BUT the cell meters are calibrated to NIST nor equal in each phone. So quantifying your readings is only relative to that phone. And I'm confident that every 3 dB is NOT a doubling of the energy measured!!!!!!

This whip antenna is just a shorter version of the passive vehicle antenna that hangs off the vehicle window making no "direct phone connections". It may capture a lil signal but retransmit the cell signal around your car without amplification is a joke. In the world of RF energy you don't get something for nothing. :frustrate

Think about this - why are antennas connected to radios/TV using a feed line coax/ladder/wire? Could it be due to being the most efficient method of coupling RF energy? :rolleyes:

I design/test antennas for a hobby and business (Magellan GPS - quadrafiler helix/patch). The most optimal antennas are designed for 1/4 wavelength multiples at the impedance of the RX/TX circuitry. (5/8 wave uses a base loading coil to create a 1/4 wave multiple.)

The Sanyo antenna could be so much better IF it only made metal-to-metal direct coupling and it was a tuned 1/2 wavelength. :laughing:

I hope you realize that the Sanyo whip does not radiate TX energy - without metal-to-metal connection the energy isn't coupled to this wire whip for transmission. So all the TX energy is ONLY put into the phone body and the base of the wire whip holder (1/4 wave stub). :headbang2

MS-EET & Extra HAM +35yrs.

[chamb]

Proving the antenna helps on the transmit side is very difficult. But looking at received signal strength in debug mode tells me I have 2-3 DB better signal. Also, in my basement, it is impossible to use the phone without the antenna being extended. With the antenna extended, the phone does work sometimes but not everytime. The extended antenna helps slightly but it is a very marginal boost.

[whiskey7]

N6JSX -

thanks for the informative posts. Could you share any info on where to get good replacement antennas for the 8400?

[whiskey7]

N6JSX -
Also, you said your replacement antenna, when fully extended, "appears to make it a tuned 1/2 wavelength."

What is the optimal length for a Sprint PCS antenna?

Edit: nevermind...you gave this info in your first post (2.96")

[BlaQueAzz]

Man I am in need of a Sanyo mm-5600 OEM Retracable Antenna do anybody have one that they are lookinG to sell ?