DC Entries: LVP/Logic Probe And A Wireless Antenna

I’m sick today, but finally getting some entries up. [Albert] designed this board which can be either a low voltage PIC programmer or, if you lack a programmer to get the initial flash data on the PIC, the through hole components make a logic probe. He rounded out the board with a silk screened logo and a prototyping area. He was also kind enough to provide an eagle library with the Hack-A-Day logo.

Our second featured entry of the day: [Pablo] put together a simple Hack-A-Day 2.4ghz antenna. He built and tested it – It functions nicely as a directional 2db antenna. His proposed use: limit your neighbors access to your AP by aiming the unetched backside at them.

16 thoughts on “DC Entries: LVP/Logic Probe And A Wireless Antenna

  1. i don’t really get what the first person’s first project is meant to do.

    I understand it’s a pic programmer, and it seems to use ICSP, but where does it get the source hex to upload? can it be stored in the onboard pic (which i gather is used to facilitate the uploading)?
    If so, 10 points, that could be useful for some hardcore hacking.. say a common device that begs for a new, more flexible firmware, and you can upload it with a simple harness connection and the press of a button.

    But if it requires a computer to host the .HEX, then i can’t see this device being useful at all, since there are simpler programmers that do not require a PIC in the first place (and the whole catch 22 there for new users).

    The first person’s second submission is fine and dandy, except that who wants to use a logic probe in the dimensions of a business card? it is much better suited to a longer shape so it can be put in a case and held like a pen. Much easier to use when you don’t have a table to put things down on.

    The second person’s submission is very neat, just rather simple.. unless of course he’s actually done the wizard math required to figure out the optimal shape and really made it work. but as to the matter of directionality, does printed circuit board block signals? i’d like to see it tested. sorry, call me skeptical. :)

    i wonder if i should even post this, i don’t want to discourage anyone in the contest. i hope there are even more clever things on the way. and i have to admit that i haven’t submitted anything, so every entry is better than what i’ve done.

  2. @ Mr. Grim
    As to the first project, you get the data on with the USB connector (you did click the link, right?). I would like to see your usb pic programmer that does not require a some onboard intelligence (be it a pic or some other microcontroller)…

    The logic anailier is a little big… But it does show high/low and even keeps the undefined light on for a while whenever it finds an undefined signal ;)

    As to the antenna, the pcb antenna isn’t what makes the antenna directional. It is the design of the antenna. And yes he did the calculation to find the optimal area for the logo (if you look at his site you would see the data he used, but not the formulas). I should also point out that for the antenna to do much you need the back of the board to be covered with copper (make sure to use double sided 1/16″ thick pcb, and tape over the back when you etch)

  3. I probably should have put that the PIC is just used for a USB to serial converter but it would be cool if it did what Factor Grimm said. I don’t expect to win but it was fun making the boards. If anyone has bootloader experience with the USB PIC, then by all means use the design and make something cool.

  4. The copper is an integral part of the antenna; you need to have a ground plane for the antenna to do anything…

    Try making the antenna without the copper and see how well it performs (and hope it doesn’t blow out your wifi card)

  5. Hmm… I don’t know about “optimum”… 2dBi isn’t an amazing amount.

    Here’s a PCB antenna that supposedly has a 9dBi gain:
    No word on the dimensions, but I’m guessing half that of the business card.

    Not a lot of details on it, but fairly consistent with what I’d expect from a PCB patch antenna.

    I don’t think the card was designed to be optimal however, just fun :)

    I’d be interested in the software he used to simulate it.

  6. somme comments about some comments:

    it was mainly designed to fullfill the contest specifications so them were the primary design restrictions, along with making it work for the 2.4GHz band.

    the radiating element of the antenna is the copper with the shape of the skull logo and the port(part to b connected to the wifi card) it is exited with an electric field through the port and then that field is inmediatelly radiated to the air with minimum losses(copper related losses), the field then travels through the fr4 to the back plate wich is the ground plate and inmediatelly reflected almost as metals reflect light(another EM wave, just different frecuency), the back plate is what limits the amount of field radiated in the backwards direction then the amount of signal received in that direction.

    the wizards math to make that exact skull design operate at 2.4GHz would drive anyone nuts, suposing it can be done. So you start by aproximating using formulaes for patch antenna and then plan the shape and simulate a lot, i personally knew what i wanted and the design restrictions made the number of simulations a finite and small number, Some details of the logo had to go so it could be simulated on a reasonable amount of time (3 to 4 hours per simulation)

    a patch antenna made of a regular shape can perform much better because their behaviour is well known, but -11Db of reflected power is an acceptable measurement considering the weirdness of the antenna.

    the simulation was done in using MOM(method of momentum) software so any nec can work will make a nigthmare the design process so i used Ansofts HFSS unfortunatedly the simulations were lost but once printed i was able to make some measurements in my university network analizer and loaded them in hfss so you can see the power reflected(S11) graph in the post.

    sorry im not a english native speaker

  7. The Patch antenna is very ingenious. I’m still trying to find a plan for a ‘conventional’ PCB Patch @2.4GHz, apparently very hard? maths is not my strong point, but PCB design is, so hopefully, someone may popup with some info or a link.

    thanks in advance..


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