EXHIBIT 10.5
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                          PLEDGE AND SECURITY AGREEMENT
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         THIS PLEDGE AND SECURITY  AGREEMENT (this  "Agreement") is entered into
as of March ___, 1997,  between STEVEN E. BERNSTEIN,  an individual  ("Pledgor")
and SBA COMMUNICATIONS CORPORATION, a Florida corporation ("Pledgee").

                              PRELIMINARY STATEMENT
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         A. Pledgor has  executed  that certain  Promissory  Note,  of even date
herewith (the "Note"),  evidencing  the  obligation of Pledgor to pay to Pledgee
$3,500,000.00 plus accrued interest thereon.

         B. To secure  repayment  of the Note,  Pledgor has granted to Pledgee a
security interest in the Collateral (as defined below), subject to the terms and
conditions of this Agreement.

         C. In  consideration  of Ten  Dollars  ($10.00),  and  other  good  and
valuable   consideration,   the  receipt   and   adequacy  of  which  is  hereby
acknowledged, the parties hereby agree as follows.

                  1.  Pledge of  Collateral.  Pledgor  hereby  grants  Pledgee a
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security  interest  in the  following  property  of Pledgor  (collectively,  the
"Collateral"):  (a) Eight Hundred  Twenty Three Thousand Five Hundred and Thirty
(823,530)  shares of Class B common stock ($.01 par value per share) of Pledgee,
which Pledgor has delivered to Pledgee in the form of stock  certificate  No. 2.
Pledgee  shall  hold the  Collateral  under  the terms  and  conditions  of this
Agreement.

                  2.  Obligations   Secured.   The  security   interest  in  the
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Collateral  granted hereby secures payment and performance of all liabilities of
Pledgor to Pledgee under the Note (all of Pledgor's  liabilities and obligations
under the Note being hereinafter referred to as the "Obligations").

                  3. Rights of Pledgee with Respect to the  Collateral.  Pledgee
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shall have the right but not the  obligation to (a) protect,  preserve or assert
any other  rights  of  Pledgor  or take any other  action  with  respect  to the
Collateral,  and (b) pay any taxes,  liens,  assessments,  insurance premiums or
other charges  pertaining to the  Collateral.  Any expenses  incurred by Pledgee
under the preceding  sentence shall be paid by Pledgor upon demand,  become part
of the  Obligations  secured by the  Collateral  and bear  interest  at the rate
provided  in the Note  until  paid.  Pledgee  shall use  reasonable  care in the
custody and preservation of the Collateral, but Pledgee shall be relieved of all
responsibility for the Collateral upon surrendering it to Pledgor.

                  4.   Pledgor's   Representations   and   Warranties.   Pledgor
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represents  and warrants that (a) Pledgor is and will be the lawful owner of the
Collateral, (b) the Collateral is and will be fully paid and non-assessable, (c)
the Collateral is and will remain free and clear of all liens,  encumbrances and
security   interests  other  than  the  security  interest  granted  by  Pledgor
hereunder, and (d) Pledgor has the sole right and lawful authority to pledge the
Collateral and otherwise to comply with the provisions hereof.

 
                  5.  Voting of  Collateral.  While  Pledgor  is not in  default
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hereunder or under the Note,  Pledgor may vote the stock  herein  pledged as the
Collateral.

                  6. Dividends and Other Distributions.  While Pledgor is not in
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default  hereunder,  Pledgor  shall retain rights to (a) all dividends and other
cash distributions  payable to Pledgor as a result of Pledgor's record ownership
of any of the  Collateral,  and (b) any stock  dividends,  stock splits or other
distributions  of securities in respect of the  Collateral.  Any such dividends,
splits  or  distributions  under  clause  (b)  above  shall  become  part of the
Collateral.

                  7. Pledgor's  Default.  Pledgor shall be in default  hereunder
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upon the occurrence of any of the following events:

     (a) If any lien,  encumbrance  or adverse  claim of any  nature  whatsoever
(other than those created by Pledgee) is asserted with respect to any Collateral
and is not dismissed, released or discharged within ninety (90) days; or

     (b) If Pledgor fails to pay or perform any of the  Obligations  by the date
when such payment or performance is due.

                  8. Pledgee's  Rights upon Default.  Upon the occurrence of any
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default as defined in the preceding  section,  Pledgee may, if Pledgee so elects
in its sole  discretion,  exercise all rights available to a secured party under
the Uniform  Commercial Code as then in effect in the State of Florida and under
any other applicable law.

                  9. Application of Sale Proceeds. In the event of a sale of the
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Collateral upon a default, the proceeds shall first be applied to the payment of
the reasonable expenses of the sale, including broker's commissions,  reasonable
attorneys'  fees, any taxes or other charges  imposed by law upon the Collateral
or the  transfer  thereof  and all other  charges  paid or  incurred  by Pledgee
pertaining to the sale; second, to satisfy outstanding  Obligations;  and third,
the surplus (if any) shall be paid to Pledgor.

                  10. Termination.  Upon payment in full of the Obligations, any
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remaining Collateral shall be promptly returned to Pledgor.

                  11. Miscellaneous.
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     (a) This  Agreement  shall be governed by and construed in accordance  with
the internal laws of the State of Florida,  without  regard to the principles of
conflicts of laws.

     (b) All of the terms and  provisions  of this  Agreement  shall be  binding
upon,  inure to the  benefit  of, and be  enforceable  by the  parties and their
respective  administrators,  executors,  other legal representatives,  heirs and
permitted  assigns,  whether so  expressed  or not.  Any rights  given or duties
imposed upon the estate of a deceased  shareholder shall inure to the benefit of
and be binding upon the  fiduciary of such  decedent's  estate in his  fiduciary
capacity.


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     (c) This Agreement may not be changed or terminated  orally,  but only by a
writing  signed  by the  party  against  whom  enforcement  of  such  change  or
termination is sought.

     (d) If any provision of this Agreement or any other agreement  entered into
pursuant hereto is contrary to, prohibited by or deemed invalid under applicable
law or regulation,  such provision shall be  inapplicable  and deemed omitted to
the extent so contrary,  prohibited or invalid,  but the remainder  hereof shall
not be  invalidated  thereby  and shall be given full force and effect so far as
possible.  If any  provision of this  Agreement  may be construed in two or more
ways, one of which would render the provision  invalid or otherwise  voidable or
unenforceable  and  another  of which  would  render  the  provision  valid  and
enforceable,  such  provision  shall have the meaning which renders it valid and
enforceable.

     (e) THIS AGREEMENT IS WITHOUT ANY RECOURSE  WHATSOEVER AGAINST PLEDGOR.  IN
ANY ACTION BROUGHT TO ENFORCE THE OBLIGATIONS OF PLEDGOR UNDER THIS AGREEMENT OR
UNDER THE NOTE, THE JUDGMENT OR DECREE SHALL BE ENFORCEABLE AGAINST PLEDGOR ONLY
TO THE EXTENT OF PLEDGOR'S INTEREST IN THE COLLATERAL,  AND ANY SUCH JUDGMENT OR
DECREE SHALL NOT BE SUBJECT TO EXECUTION ON, OR BE A LIEN ON ASSETS OF,  PLEDGOR
(OTHER THAN PLEDGOR'S  INTERESTS IN THE  COLLATERAL).  IN NO EVENT SHALL PLEDGEE
SEEK OR OBTAIN A DEFICIENCY OR OTHER MONEY JUDGMENT AGAINST PLEDGOR.

         This  Agreement has been executed by Pledgor and Pledgee as of the date
first set forth above.


                                    PLEDGOR:

                                     /s/ Steven E. Bernstein
                                    ----------------------------------
                                    STEVEN E. BERNSTEIN


                                    PLEDGEE:

                                    SBA COMMUNICATIONS CORPORATION,
                                        a Florida corporation

                                          /s/ Steven E. Bernstein
                                    By:______________________________
                                        Steven E. Bernstein, President


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