<PAGE>   1
                                                                    EXHIBIT 3.18


                          CERTIFICATE OF INCORPORATION
                                       of
                      HOUNDSTOOTH BROADCASTING CORPORATION


         The undersigned incorporator, in order to form a corporation under the
General Corporation Law of the State of Delaware (the "General Corporation
Law"), certifies as follows:

         1.      Name.  The name of the corporation is Houndstooth Broadcasting
Corporation (the "Corporation").

         2.      Address; Registered Office and Agent.  The address of the
corporation's registered office is 1013 Centre Road, City of Wilmington, County
of New Castle, State of Delaware 19805; and its registered agent at such
address is The Prentice-Hall Corporation System, Inc.

         3.      Purposes.  The purpose of the Corporation is to engage in any
lawful act or activity for which corporations may be organized under the
General Corporation Law.

         4.      Number of Shares.  The total number of shares of stock that
the Corporation shall have authority to issue is:  one thousand (1,000), all of
which shall be shares of Common Stock of the par value of one cent ($0.01)
each.

         5.      Name and Mailing Address of Incorporator.  The name and
mailing address of the incorporator are:  Scott Grader, 1285 Avenue of the
Americas, New York, Now York 10019-6064.
<PAGE>   2
         6.      Election of Directors.  Members of the Board of Directors of
the Corporation (the "Board") may be elected either by written ballot or by
voice vote.

         7.      Limitation of Liability.  No director of the Corporation shall
be personally liable to the Corporation or its stockholders for monetary
damages for breach of fiduciary duty as a director, provided that this
provision shall not eliminate or limit the liability of a director (a) for any
breach of the director's duty of loyalty to the Corporation or its
stockholders, (b) for acts or omissions not in good faith or which involve
intentional misconduct or a knowing violation of law, (c) under section 174 of
the General Corporation Law or (d) for any transaction from which the director
derived any improper personal benefits.

         Any repeal or modification of the foregoing provision shall not
adversely affect any right or protection of a director of the Corporation
existing at the time of such repeal or modification.

         8.      Indemnification.

                 8.1      To the extent not prohibited by law, the Corporation
shall indemnify any person who is or was made, or threatened to be made, a
party to any threatened, pending or completed action, suit or proceeding (a
"Proceeding"), whether civil, criminal, administrative or investigative,
including, without limitation, an action by or in the right of the Corporation
to procure a judgment in its favor, by reason of the fact that such person, or
a person of whom such person is the legal representative, is or was a director
or officer of the Corporation, or, at the request of the Corporation, is or was
serving as a director or officer of any other corporation or in a capacity with
comparable authority or responsibilities for any partnership, joint venture,
trust, employee benefit plan or other enterprise (an "Other Entity"), against
judgments, fines, penalties, excise taxes,





                                      -2-
<PAGE>   3
amounts paid in settlement and costs, charges and expenses (including
attorneys' fees, disbursements and other charges).  Persons who are not
directors or officers of the Corporation (or otherwise entitled to
indemnification pursuant to the preceding sentence) may be similarly
indemnified in respect of service to the Corporation or to an Other Entity at
the request of the Corporation to the extent the Board at any time specifies
that such persons are entitled to the benefits of this Section 8.

         8.2     The Corporation shall, from time to time, reimburse or advance
to any director or officer or other person entitled to indemnification
hereunder the funds necessary for payment of expenses, including attorneys fees
and disbursements, incurred in connection with any Proceeding, in advance of
the final disposition of such Proceeding; provided, however, that, if required
by the General Corporation Law, such expenses incurred by or on behalf of any
director or officer or other person may be paid in advance of the final
disposition of a Proceeding only upon receipt by the Corporation of an
undertaking, by or on behalf of such director or officer (or other person
indemnified hereunder), to repay any such amount so advanced if it shall
ultimately be determined by final judicial decision from which there is no
further right of appeal that such director, officer or other person is not
entitled to be indemnified for such expenses.

         8.3     The rights to indemnification and reimbursement or advancement
of expenses provided by, or granted pursuant to, this Section 8 shall not be
deemed exclusive of any other rights to which a person seeking indemnification
or reimbursement or advancement of expenses may have or hereafter be entitled
under any statute, this Certificate of Incorporation, the By-laws of the
Corporation (the "By-laws"), any agreement, any vote of stockholders or
disinterested directors or otherwise, both as to action in his or her official
capacity and as to action in another capacity while holding such office.





                                      -3-
<PAGE>   4
         8.4     The rights to indemnification and reimbursement or advancement
of expenses provided by, or granted pursuant to, this Section 8 shall continue
as to a person who has ceased to be a director or officer (or other person
indemnified hereunder) and shall inure to the benefit of the executors,
administrators, legatees and distributors of such person.

         8.5     The Corporation shall have power to purchase and maintain
insurance on behalf of any person who is or was a director, officer, employee
or agent of the Corporation, or is or was serving at the request of the
Corporation as a director, officer, employee or agent of an Other Entity,
against any liability asserted against such person and incurred by such person
in any such capacity, or arising out of such person's status as such, whether
or not the Corporation would have the power to indemnify such person against
such liability under the provisions of this Section 8, the By-laws or under
section 145 of the General Corporation Law or any other provision of law.

         8.6     The provisions of this Section 8 shall be a contract between
the Corporation, on the one hand, and each director and officer who serves in
such capacity at any time while this Section 8 is in effect and any other
person entitled to indemnification hereunder, on the other hand, pursuant to
which the Corporation and each such director, officer, or other person intend
to be, and shall be, legally bound.  No repeal or modification of this Section
8 shall affect any rights or obligations with respect to any state of facts
then or theretofore existing or thereafter arising or any proceeding
theretofore or thereafter brought or threatened based in whole or in part upon
any such state of facts.

         8.7     The rights to indemnification and reimbursement or advancement
of expenses provided by, or granted pursuant to, this Section 8 shall be
enforceable by any person entitled to such indemnification or reimbursement or
advancement of expenses in any court of competent jurisdiction.  The burden of
proving that such indemnification or reimbursement or advancement of expenses
is not appropriate shall be on the Corporation.  Neither the failure of the
Corporation (including its Board, its independent legal counsel and its
stockholders) to have made a determination prior to the commencement of such
action that such indemnification or reimbursement or advancement of expenses is
proper in the circumstances nor an actual determination by the Corporation





                                      -4-
<PAGE>   5
(including its Board, its independent legal counsel and its stockholders) that
such person is not entitled to such indemnification or reimbursement or
advancement of expenses shall constitute a defense to the action or create a
presumption that such person is not so entitled.  Such a person shall also be
indemnified for any expenses incurred in connection with successfully
establishing his or her right to such indemnification or reimbursement or
advancement of expenses, in whole or in part, in any such proceeding.

         8.8     Any director or officer of the Corporation serving in any
capacity (a) another corporation of which a majority of the shares entitled to
vote in the election of its directors is held, directly or indirectly, by the
Corporation or (b) any employee benefit plan of the Corporation or any
corporation referred to in clause (a) shall be deemed to be doing so at the
request of the Corporation.

         8.9     Any person entitled to be indemnified or to reimbursement or
advancement of expenses as a matter of right pursuant to this Section 8 may
elect to have the right to indemnification or reimbursement or advancement of
expenses interpreted an the basis of the applicable law in effect at the time
of the occurrence of the event or events giving rise to the applicable
Proceeding, to the extent permitted by law, or on the basis of the applicable
law in effect at the time such indemnification or reimbursement or advancement
of expenses is sought.  Such election shall be made, by a notice in writing to
the Corporation, at the time indemnification or reimbursement or advancement of
expenses is sought; provided, however, that if no such notice is given, the
right to indemnification or reimbursement or advancement of expenses shall be
determined by the law  in effect at the time indemnification or reimbursement
or advancement of expenses is sought.





                                      -5-
<PAGE>   6
         9.      Adoption, Amendment and/or Repeal of By-Laws.  The Board may
from time to time adopt, amend or repeal the By-laws of the Corporation;
provided, however, that any By-laws adopted or amended by the Board may be
amended or repealed, and any By-laws may be adopted, by the stockholders of the
Corporation by vote of a majority of the holders of shares of stock of the
Corporation entitled to vote in the election of directors of the Corporation.

         10.     Action by Stockholders.  Notwithstanding the provisions of
section 228 of the General Corporation Law (or any successor statute), any
action required or permitted by the General Corporation Law to be taken at any
annual or special meeting of stockholders of the Corporation may be taken only
at such an annual or special meeting of stockholders and cannot be taken by
written consent without a meeting.

         WITNESS the signature of this Certificate this of November 5, 1996.



                                        /s/ Scott Grader
                                        ---------------------------------------
                                        Scott Grader, Incorporator





                                      -6-